Michael Cosca is a research geologist with the U.S. Geological Survey, who combines 40Ar/39Ar geochronology with mineralogy, petrology, and field geology to understand igneous, metamorphic, and tectonic processes at the regional, local, and sub-grain scale.
Mike received his undergraduate degree in geology from the University of California, Berkeley (1981) and M.Sc. (1985) and Ph.D. (1989) in geology from the University of Michigan, Ann Arbor. After completing his Ph.D., he moved to Switzerland and for nearly 19 years conducted scientific research at the University of Lausanne. During this time he constructed a 40Ar/39Ar research laboratory and obtained research funding that supported 4 Ph.D. students, 2 M.Sc. students and 2 post-doctoral scholars and worked closely with colleagues from Lausanne. This research was funded primarily with grants he obtained from the Swiss National Science Foundation with additional support from the University of Lausanne.
Mike joined the U.S Geological Survey in 2008 and supervises the 40Ar/39Ar geochronology laboratory in Denver. His research is broadly focused on understanding the geochronology of ore deposits, mountain building, volcanic stratigraphy, landscape formation, near-surface faulting, physical and chemical controls of argon distribution in minerals and rocks, and developing novel methods for 40Ar/39Ar analysis. Much of his research involves collaborations with USGS scientists from the Geology, Geophysics, and Geochemistry Science Center and the Geosciences and Environmental Change Science Center. Current research projects include the Cenozoic landscape evolution of the Southern Rocky Mountains, igneous activity related to mineralization in the Basin and Range province, and the timing of fluid flow and mineralization in the Proterozoic mid continent rift of North America.
Science and Products
Argon Geochronology
This project supports the USGS argon geochronology laboratory in Denver. The USGS 40Ar/39Ar geochronology laboratory is a state-of-the-art research facility for determining absolute ages of minerals and rocks. The 40Ar/39Ar laboratory contributes critical geochronology to individual USGS research projects and to partners in academia and other Federal agencies. This laboratory develops methodology...
Serving the U.S. Geological Survey’s geochronological data
Geochronological data provide essential information necessary for understanding the timing of geologic processes and events, as well as quantifying rates and timescales key to geologic mapping, mineral and energy resource and hazard assessments. The USGS’s National Geochronological Database (NGDB) contains over 30,000 radiometric ages, but no formal update has occurred in over 20 years. This proj
Geochronologic Investigations
The present landscape of the Southern Rocky Mountains and surrounding physiographic areas results from time-integrated interaction between the asthenosphere, lithosphere, and hydrosphere. Large-scale phenomena, such as asthenospheric upwelling directly or indirectly affect lithospheric thinning, faulting, basin development, and igneous activity sometimes associated with ore deposits. During the...
Argon and SHRIMP-RG Data for Magmatic Steam Alunite, Sericite, and Zircon from Alunite Ridge and Deer Trail Mountain, Marysvale, Utah
Samples of vein-type magmatic-steam alunite were collected over several field seasons from five mines and prospects (L&N, Mt. Edna, Christmas, upper Mineral Products, and Close In) in the Alunite Ridge and Deer Trail Mountain area, Marysvale, Utah, as well as a sample from the Deer Trail mine workings from which sericite was separated. The magmatic-steam alunite and sericite were analyzed by the 4
USGS Geochron: A Database of Geochronological and Thermochronological Dates and Data
USGS Geochron is a database of geochronological and thermochronological dates and data. The data set contains published ages, dates, analytical information, sample metadata including location, and source citations. The following analytical techniques are represented in the data set: 40Ar/39Ar, K-Ar, U-Th-Pb, Sm-Nd, Rb-Sr, Lu-Hf, fission track, and luminescence. This data set incorporates data prev
Data release for geochronology and geochemistry of volcanic rocks in the Southern Rocky Mountains and Taos Plateau volcanic fields and other Oligocene to Pleistocene volcanic rocks within the southern San Luis Basin and San Juan Mountains, southern Colora
The dataset includes whole-rock geochemistry and 40Ar-39Ar geochronology for Pleistocene to Oligocene volcanic and intrusive rocks. These data support figures and tables in days 2 and 3 of the Field-trip guide to continental arc to rift volcanism of the southern Rocky Mountains-Southern Rocky Mountain, Taos Plateau, and Jemez Mountains volcanic fields of southern Colorado and northern New Mexico (
Data to accompany U.S. Geological Survey Data Series 1099: Petrographic, geochemical and geochronologic data for Cenozoic volcanic rocks of the Tonopah, Divide, and Goldfield Mining Districts, Nevada
This dataset is the assembled analytical results of geochemical, petrographic, and geochronologic data for samples, principally those of unmineralized Tertiary volcanic rocks, from the Tonopah, Divide, and Goldfield mining districts of west-central Nevada. Much of the data presented here for the Tonopah and Divide districts are for samples collected by Bonham and Garside (1979) during geologic map
Data release of geospatial map database, argon geochronology and geochemistry data for: Geologic map of the San Antonio Mountain area, northern New Mexico and southern Colorado
This dataset accompanies publication "Geologic map of the San Antonio Mountain area, northern New Mexico and southern Colorado". Data presented here include the digital geologic database, 40Ar/39Ar geochronology and major and trace element chemistry from lava flows and an ignimbrite. The geologic database includes spatial feature classes and non-spatial tables that collectively contain the geologi
U-Pb SHRIMP and 40Ar/39Ar geochronologic data and backscatter electron (BSE) and panchromatic cathodoluminescent (CL) imagery of sample materials for study of dikes, country rock, and alteration systems, Butte, U.S.A.
These data are for a multidisciplinary study of dikes, country rock, and alteration systems, Butte, U.S.A. Results of the study are described and interpreted in Lund and others (2018). Data included are U-Pb SHRIMP geochronology for quartz porphyry dikes, 40Ar/39Ar thermochronologic data for biotite, hornblende, and K-feldspar from Butte granite country rock, and 40Ar/39Ar thermochronologic data f
40Ar/39Ar geochronology of the Tonopah, Divide, and Goldfield districts, Nevada
Ar/Ar data are reported from minerals and rocks that were collected as part of a mineral resource investigation of the Tonopah, Divide, and Goldfield districts in Nevada. Data are reported from 92 samples and associated standards from eight separate neutron irradiations in the Denver USGS TRIGA reactor, including separated mineral grains and whole rocks. Data were collected by infrared laser heati
Argon geochronology data from the Austroalpine-Pennine boundary, Central Alps, Switzerland
Ar/Ar data are reported from eight samples of white mica separated from rock samples collected along the Austroalpine-Pennine boundary in the Central Alps of Switzerland. These samples were collected as part of a Caltech PhD study to examine the tectonic history of this boundary and these argon geochronology data represent one small part of the study. Data are reported from these eight samples tog
Data release of Geologic Map of the Upper Arkansas River Valley Region, North-Central, Colorado
This 1:50,000-scale geologic map represents a compilation of the most recent geologic studies of the upper Arkansas River valley, between Leadville and Salida, Colorado. The valley is structurally controlled by an extensional fault system that forms part of the prominent northern Rio Grande rift, an intra-continental region of crustal extension. This work also incorporates new detailed geologic ma
Argon data for Poncha Pass Geologic Map
This dataset was collected by Leah E. Morgan and Michael A. Cosca in the Argon Geochronology Laboratory of the USGS in Denver, Colorado in 2015. The dataset contains full raw argon isotopic data for samples presented in: Geologic Map of the Poncha Map Area, Chaffee, Fremont, and Saguache Counties, Colorado.
Geologic map of the Poncha Pass area, Chaffee, Fremont, and Saguache Counties, Colorado
This report presents a 1:24,000-scale geologic map, cross sections, and descriptive and interpretative text for the Poncha Pass area in central Colorado. The map area is irregular in shape, covering all of one 7 ½' quadrangle (Poncha Pass) and parts of five others (Mount Ouray, Maysville, Salida West, Salida East, and Wellsville). The map boundaries were drawn to cover all of the “Poncha mountain
Geologic map of the San Antonio Mountain area, northern New Mexico and southern Colorado
The geologic map of the San Antonio Mountain area in northern New Mexico and southern Colorado is located along the west-central part of the San Luis Valley. The San Luis Valley is the geomorphic expression of the San Luis Basin, an extensional basin associated with the northern Rio Grande rift. Deposits within the map area record volcanic, sedimentary, and tectonic processes over the last ~33 mil
Geologic map of the upper Arkansas River valley region, north-central Colorado
This 1:50,000-scale U.S. Geological Survey geologic map represents a compilation of the most recent geologic studies of the upper Arkansas River valley between Leadville and Salida, Colorado. The valley is structurally controlled by an extensional fault system that forms part of the prominent northern Rio Grande rift, an intra-continental region of crustal extension. This report also incorporates
Geologic map of the Rio Rico and Nogales 7.5’ quadrangles, Santa Cruz County, Arizona
The Rio Rico and Nogales (Arizona) 1:24,000-scale quadrangles are located in the Basin and Range Province of southern Arizona, and the southern edge of the map is the international border with Sonora, Mexico. The major urban area is Nogales, a bi-national city known as “the gateway to Mexico.” Rocks exposed in the map area range in age from Jurassic through Quaternary. Major physiographic, geol
Geologic map of the Alamosa 30’ × 60’ quadrangle, south-central Colorado
The Alamosa 30'× 60' quadrangle is located in the central San Luis Basin of southern Colorado and is bisected by the Rio Grande. The Rio Grande has headwaters in the San Juan Mountains of Colorado and ultimately discharges into the Gulf of Mexico 3,000 kilometers (km) downstream. Alluvial floodplains and associated deposits of the Rio Grande and east-draining tributaries, La Jara Creek and Conejos
Geologic map of the Sunshine 7.5' quadrangle, Taos County, New Mexico
The Sunshine 7.5' quadrangle is located in the south-central part of the San Luis Basin of northern New Mexico, in the Rio Grande del Norte National Monument, and contains deposits that record volcanic, tectonic, and associated alluvial and colluvial processes over the past four million years. Sunshine Valley, named for the small locale of Sunshine, is incised by a series of northeast-trending dra
Geologic map of the Ute Mountain 7.5' quadrangle, Taos County, New Mexico, and Conejos and Costilla Counties, Colorado
The Ute Mountain 7.5' quadrangle is located in the south-central part of the San Luis Basin of northern New Mexico, in the Rio Grande del Norte National Monument, and contains deposits that record volcanic, tectonic, and associated alluvial and colluvial processes over the past four million years. Ute Mountain has the distinction of being one of the largest intermediate composition eruptive center
Geologic map of the Ute Mountain 7.5' quadrangle, Taos County, New Mexico, and Conejos and Costilla Counties, Colorado
The Ute Mountain 7.5' quadrangle is located in the south-central part of the San Luis Basin of northern New Mexico, in the Rio Grande del Norte National Monument, and contains deposits that record volcanic, tectonic, and associated alluvial and colluvial processes over the past four million years. Ute Mountain has the distinction of being one of the largest intermediate composition eruptive center
Geologic map of the Sunshine 7.5' quadrangle, Taos County, New Mexico
The Sunshine 7.5' quadrangle is located in the south-central part of the San Luis Basin of northern New Mexico, in the Rio Grande del Norte National Monument, and contains deposits that record volcanic, tectonic, and associated alluvial and colluvial processes over the past four million years. Sunshine Valley, named for the small locale of Sunshine, is incised by a series of northeast-trending dra
Geologic map of the Harvard Lakes 7.5' quadrangle, Park and Chaffee Counties, Colorado
The Harvard Lakes 1:24,000-scale quadrangle spans the Arkansas River Valley in central Colorado, and includes the foothills of the Sawatch Range on the west and Mosquito Range on the east. The Arkansas River valley lies in the northern end of the Rio Grande rift and is structurally controlled by Oligocene and younger normal faults mostly along the west side of the valley. Five separate pediment su
Mineral resource potential map of the Laurel-McGee Roadless Area, Mono County, California
No abstract available.
Filter Total Items: 50
Constraints on near-ridge magmatism using 40Ar/39Ar geochronology of enriched MORB from the 8°20' N seamount chain
Our understanding of the spatial-temporal-compositional relationships between off-axis magmatism and mid-ocean ridge spreading centers is limited. Determining the 40Ar/39Ar ages of mid-ocean ridge basalt (MORB) lavas erupting near mid-ocean ridges (MOR) has been a challenge due to the characteristically low K2O contents in incompatible element-depleted normal MORB (NMORB). High-precision 40Ar/39Ar
Authors
Molly Anderson, Michael Perfit, Leah E. Morgan, Daniel Fornari, Michael A. Cosca, V. Dorsey Wanless
40Ar/39Ar geochronology of magmatic-steam alunite from Alunite Ridge and Deer Trail Mountain, Marysvale Volcanic Field, Utah: Timing and duration of miocene hydrothermal activity associated with concealed intrusions
Porphyry and epithermal deposits are important sources of base and precious metals. Most actively mined deposits have been exhumed such that ore bodies are relatively close to the surface and are therefore locatable and economic to extract. Identifying and characterizing concealed deposits, particularly more deeply buried porphyry deposits, represents a far greater challenge for mineral exploratio
Authors
Cameron Mark Mercer, M. Cosca, Albert H. Hofstra, Wayne R. Premo, Robert O. Rye, Gary P. Landis
Two-event genesis of Butte lode veins: Geologic and geochronologic evidence from ore veins, dikes, and host plutons
The long-standing ore-genesis model for world-class deposits of the Butte mining district, Montana, is of deep pre-Main Stage porphyry Cu-Mo and overlying Main Stage Ag-Zn-Cu-zoned lode veinsformed from discrete hydrothermal systems related to rhyolite dikes. The lode-specific model describes metals zones that formed in the lode veins as hydrothermal processes diminished in intensity (changing tem
Authors
Karen Lund, Ryan J. McAleer, John N. Aleinikoff, Michael Cosca
Age and mantle sources of Quaternary basalts associated with “leaky” transform faults of the migrating Anatolia-Arabia-Africa triple junction
The Anatolia (Eurasia), Arabia, and Africa tectonic plates intersect in southeast Turkey, near the Gulf of İskenderun, forming a tectonically active and unstable triple junction (the A3 triple junction). The plate boundaries are marked by broad zones of major, dominantly left-lateral transform faults including the East Anatolian fault zone (the Anatolia-Arabia boundary) and the Dead Sea fault zo
Authors
Michael Cosca, Mary Reid, Jonathan Delph, Gonca Gençalioğlu Kuşcu, Janne Blichert-Toft, Wayne R. Premo, Donna Whitney, Christian Teyssier, Bora Rojay
Cenozoic tectonic evolution of the Ecemiş fault zone and adjacent basins, central Anatolia, Turkey during the transition from Arabia - Eurasia collision to escape tectonics
The effects of Arabia-Eurasia collision are recorded in faults, basins, and exhumed metamorphic massifs across eastern and central Anatolia. These faults and basins also preserve evidence of major changes in deformation and associated sedimentary processes along major suture zones including the Inner Tauride suture where it lies along the southern (Ecemiş) segment of the Central Anatolian fault zo
Authors
Paul J. Umhoefer, Stuart Thompson, Come Lefebre, Michael Cosca, Christian Teyssier, Donna L. Whitney
Petrology of volcanic rocks associated with silver-gold (Ag-Au) epithermal deposits in the Tonopah, Divide, and Goldfield Mining Districts, Nevada
Miocene calc-alkaline volcanic rocks, part of the southern segment of the ancestral Cascades magmatic arc, are spatially, temporally, and likely genetically associated with precious metal epithermal deposits in the Tonopah, Divide, and Goldfield Districts of west-central Nevada. In the Tonopah mining district, volcanic rocks include the Mizpah Trachyte, Fraction Tuff, and Oddie Rhyolite; in the Di
Authors
Edward A. du Bray, David A. John, Joseph Colgan, Peter G. Vikre, Michael A. Cosca, Leah E. Morgan
Petrographic, geochemical, and geochronologic data for cenozoic volcanic rocks of the Tonopah, Divide, and Goldfield Mining Districts, Nevada
The purpose of this report is to summarize geochemical, petrographic, and geochronologic data for samples, principally those of unmineralized Tertiary volcanic rocks, from the Tonopah, Divide, and Goldfield mining districts of west-central Nevada (fig. 1). Much of the data presented here for the Tonopah and Divide districts are for samples collected by Bonham and Garside (1979) during geologic map
Authors
Edward A. du Bray, David A. John, Peter G. Vikre, Joseph Colgan, Michael A. Cosca, Leah E. Morgan, Robert J. Fleck, Wayne R. Premo, Christopher S. Holm-Denoma
A supervolcano and its sidekicks: A 100 ka eruptive chronology of the Fish Canyon Tuff and associated units of the La Garita magmatic system
Establishing temporal constrains on major volcanic eruptions is limited by the precision of existing geochronometers. Prior work on the La Garita caldera, created by the eruption of the Fish Canyon Tuff, failed to resolve temporal differences between pre-, syn-, and post-collapse eruptive units. Here, we report 40Ar/39Ar geochronologic data supporting a ca. 100 ka eruptive history of the La Garita
Authors
Leah E. Morgan, Samuel Johnstone, Amy K. Gilmer, Michael A. Cosca, Ren A. Thompson
C–O stable isotope geochemistry and 40Ar/39Ar geochronology of the Bear Lodge carbonatite stockwork, Wyoming, USA
The carbonatite dike swarm and vein stockwork at the center of the Paleogene Bear Lodge alkaline complex (BLAC), Wyoming, USA, is host to diverse REE mineral assemblages that are largely a result of subsolidus modification and REE redistribution. Pseudomorphic replacement of primary burbankite by an assemblage of ancylite, strontianite, and barite is the result of interaction with late-stage hydro
Authors
Allen K. Andersen, Peter B. Larson, Michael A. Cosca
Two-event lode-ore deposition at Butte, USA: 40Ar/39Ar and U-Pb documentation of Ag-Au-polymetallic lodes overprinted by younger stockwork Cu-Mo ores and penecontemporaneous Cu lodes
The ore-genesis model for world-class deposits of the Butte mining district, Montana, USA, is deep pre-Main Stage porphyry Cu-Mo and overlying Main Stage Ag-Zn-Cu zoned-lode deposits, both of which formed from hydrothermal fluids driven by minor volumes of rhyolitic magma. The lode-specific model is that hydrothermal processes diminished in intensity outward from district center along lode veins,
Authors
Karen Lund, Ryan J. McAleer, John N. Aleinikoff, Michael A. Cosca, Michael J. Kunk
Rapid late Miocene surface uplift of the Central Anatolian Plateau margin
The Central Anatolian Plateau (CAP), Turkey, is bordered to its south by a steep mountain belt that emerged ∼8–7 Ma ago from the Mediterranean Sea. Knowledge of the onset, duration and rate of surface uplift and orographic barrier formation along the plateau margin is crucial for understanding the geodynamic drivers of plateau uplift. We present a new comprehensive data set that includes 12 40Ar/3
Authors
Maud J.M. Meijers, Gilles Y. Brocard, Michael A. Cosca, Tina Lüdecke, Christian Teyssier, Donna L. Whitney, Andreas Mulch
Climate stability in Central Anatolia during the Messinian Salinity Crisis
Deposition of large amounts of evaporites and erosion of deep canyons within the Mediterranean Basin as a result of reduced basin connectivity with the Atlantic Ocean and the epicontinental Paratethys Sea characterized the Messinian Salinity Crisis (MSC, 5.97–5.33 Ma). The influence of the MSC on Mediterranean environmental conditions within the basin itself has been intensely studied from marine
Authors
Maud J.M. Meijers, Ahmet A Peynircioğlu, Michael A. Cosca, Gilles Y. Brocard, Donna L. Whitney, Cor G. Langereis, Andreas Mulch
Non-USGS Publications**
Mulch, A., Teyssier, C., Cosca, M A., and Chamberlain, C.P., 2007, Stable isotope paleoaltimetry of Eocene core complexes in the North American Cordillera, Tectonics, 26 (4), TC4001, doi:10.1029/2006TC00199.
Zechmeister, M.S., Ferre, E., Cosca, M.A., Geissman, J.W., 2007, Slow and fast deformation in the Dora Maira Massif, Italian Alps: Pseudotachylytes and inferences on exhumation history. Journal of Stuctural Geology, 29 (7), p. 1114-1130, doi:10.1016/j.jsg.2007.03.009.
Cosca, M. A., Giorgis, D., Rumble, D., and Liou, J. G. 2006, Limiting effects of UHP metamorphism on length scales of oxygen, hydrogen, and argon isotope exchange: an example from the Qinglongshan UHP ecologites, Sulu Terrain, China: In: Phase relations, high-pressure terranes, P-T-ometry, and plate pushing: a tribute to W. G. Ernst. International Book Series, v. 9, p. 290-323.
Keane, S.D., DeWolf, C.P., Essene, E.J., Halliday, A.N., Hall, C.M., Cosca, M.A., 2006, Isotopic Constraints on the Thermal History of the Wind River Range, Wyoming: Implications for Archean Metamorphism. Canadian Journal of Earth Science, 43 (10), 1511-1532, doi:10.1139/e06-090.
Manatschal, G., Engström, A., Desmurs, L., Schaltegger, U., Cosca, M., Müntener, O., Bernoulli, D., 2006, What is the tectono-metamorphic evolution of continental break-up: the example of the Tasna ocean-continent transistion. Journal of Structural Geology,28 (10), 1849-1869, doi:10.1016/j.jsg.2006.07.014.
Mulch, A., Teyssier, C, Cosca, M.A, and Vennemann, T.W., 2006, Thermomechanical analysis of strain localization in a ductile detachment zone. Journal of Geophysical Research Solid Earth, 111 (B12), doi:10.1029/2005JB004032.
Cosca, M.A., Caby, R., and Bussy, F., 2005, Geochemistry and 40Ar/39Ar geochronology of pseudotachylyte associated with UHP whiteschists from the Dora Maira massif, Italy. Tectonophysics, 402 (1-4), 93-110, doi:10.1016/j.tecto.2004.12.033.
Cosca, M.A., Giorgis, D., Rumble, D., Liou, J.G., 2005, Limiting effects of UHP metamorphism on length-scales of oxygen, hydrogen, and argon isotope exchange: an example from the Qinglongshan UHP eclogites. International Geology Review, 47 (7), 716-749, doi:10.2747/0020-6814.47.7.716.
Mulch, A., Cosca, M.A., Fiebig, J., and Andresen, A., 2005, Time scales of deformation and exhumation in extensional detachment systems determined by high-spatial resolution in situ UV-laser 40Ar/39Ar dating. Earth and Planetary Science Letters, 233 (3-4), 375-390, doi:10.1016/j.epsl.2005.01.042.
Putlitz, B., Cosca, M.A., and Schumacher, J., 2005, Prograde mica 40Ar/39Ar growth ages recorded in high pressure rocks (Syros, Cyclades, Greece). Chemical Geology, 214 (1-2), 79-98, doi:10.1016/j.chemgeo.2004.08.056.
Haeberlin, Y., Moritz, R., Fontboté, L., and Cosca, M., 2004, Carboniferous orogenic gold deposits at Pataz, Eastern Andean Cordillera, Peru: Geological and structural framework, paragenesis, alteration, and 40Ar/39Ar geochronology. Economic Geology, 99 (1), 73-112, doi:10.2113/gsecongeo.99.1.73.
Mulch, A. and Cosca, M.A., 2004, Recrystallization or cooling ages? In situ UV-laser 40Ar/39Ar geochronology of muscovite in mylonitic rocks. Journal of the Geological Society of London, 161 (4), 573-582, doi:10.1144/0016-764903-110.
Mulch, A., Teyssier, C., Cosca, M.A., Vanderhaeghe, O., and Vennemann, T., 2004, Reconstructing paleoelevation in eroded orogens. Geology, 32 (6), 525-528, doi:10.1130/G20394.1.
Vannay, J-C., Grasemann, B., Rahn, M., Frank, W., Carter, A., Baudraz, V., Cosca, M., 2004, Miocene to Holocene exhumation of metamorphic crustal wedges in the NW Himalaya: evidence for tectonic extrusion coupled to fluvial erosion. Tectonics, 23 (1), doi:10.1029/2002TC001429.
Winer, G.S., Feeley, T.C., and Cosca, M.A., 2004, Basaltic volcanism in the Bering Sea: geochronology and volcanic evolution of St. Paul Island, Pribilof Islands, Alaska. Journal of Volcanology and Geothermal Research, 134 (4), 277-301, doi:10.1016/j.jvolgeores.2004.02.003.
Bendezú, R., Fontbonté, L., Cosca, M., 2003, Relative age of Cordilleran base metal lode and replacement deposits, and high sulfidation Au-(Ag) epithermal mineralization in the Colquijirca district, central Peru. Mineralium Deposita, 38, 683-694, doi:10.1007/s00126-003-0358-z.
Camprubí, A., Ferrari, L., Cosca, M.A., Cardellach, E., Canals, A., 2003, Ages of epithermal deposits in Mexico: regional significance and links with the evolution of Tertiary volcanism. Economic Geology, 98 (5), 1029-1037, doi:10.2113/gsecongeo.98.5.1029.
Feeley, T.C., and Cosca, M.A., 2003, Time vs. composition trends of magmatism at Sunlight volcano, Absaroka Volcanic Province, Wyoming. Geological Society of America Bulletin, 115 (6), 714-728, doi:10.1130/0016-7606(2003)115<C0714:TVCTOM>2.0.CO;2.
Giorgis, D., Cosca, M.A., Rumble, D., 2003, Pre-metamorphic d18O signatures in morphologically complex zircons from the Qinglongshan UHP meta-granite (Sulu terrain, China). Swiss Bulletin of Mineralogy and Petrology, 83 (2), 133-144, https://www.ingentaconnect.com/content/ssmp/sbmp/2003/00000083/00000002/art00002.
Jourdan, F., Marzoli, A., Bertrand, H., Cosca, M., Fontignie, D., 2003, The Northernmost CAMP: 40Ar/39Ar age, petrology and Sr-Nd-Pb isotope geochemistry of the Kerforne dike, Brittany, France. In: Hames, W.C et al. (eds.) The Central Atlantic Magmatic Province: Fragments of Pangea, AGU Geophysical Monograph, 136, 209-226, doi:10.1029/136GM11.
Kirschner, D.L., Cosca, M.A., and Masson, H., 2003, An 40Ar/39Ar, Rb/Sr, and stable isotope study of micas in low-grade fold-and-thrust belt: An example from the Swiss Helvetic Alps. Contributions to Mineralogy and Petrology, 145 (4), 460-480, doi:10.1007/s00410-003-0461-2.
Kramar, N., Cosca, M.A., Buffat, P.A., and Baumgartner, L.P., 2003, Stacking fault-enhanced argon diffusion in naturally deformed muscovite. In Vance, D., Muller, W., and Villa, I., eds., Geochronology: Linking the Isotopic Record with Petrology and Textures, Geological Society of London. Special Publication, 220, 249-260, doi:10.1144/GSL.SP.2003.220.01.15.
Rodríguez Aller, J., Cosca, M. A., Gil Ibarguchi, J. I., and Dallmeyer, R. D., 2003, Strain partitioning and preservation of 40Ar/39Ar ages for the eclogite-facies stage during Variscan exhumation of a subducted crust (Malpica-Tui allochthon, NW Spain) Lithos, 70 (3-4), 111-139, doi:10.1016/S0024-4937(03)00095-1.
Schlup, M., Carter, A., Cosca, M., and Steck, A., 2003, Exhumation history of eastern Ladakh revealed by 40Ar/39Ar and fission-track ages: the Indus River-Tso Morari transect, NW Himalaya. Journal of the Geological Society of London, 160, 385-369, doi:10.1144/0016-764902-084.
Feeley, T.C., Cosca, M.A., and Lindsay, C.R., 2002, Petrogenesis and implications of calc-alkaline cryptic hybrid magmas from Washburn volcano, Absaroka Volcanic Province, USA. Journal of Petrology, 43 (4), 663-703, doi:10.1093/petrology/43.4.663.
Markley, M., Teyssier, C., and Cosca, M., 2002, The relation between grain size and 40Ar/39Ar date for Alpine white mica from the Siviez-Mischabel Nappe, Switzerland. Journal of Stuctural Geology, 24 (12), 1937-1955, doi:10.1016/S0191-8141(02)00006-8.
Mulch, A., Cosca, M.A., and Handy, M.R., 2002, In situ UV-laser 40Ar/39Ar geochronology of a micaceous mylonite: an example of defect-enhanced argon loss. Contributions to Mineralogy and Petrology, 142, 738-752, doi:10.1007/s00410-001-0325-6.
Solé, J., Cosca, M., Sharp, Z., and Enrique, P, 2002, 40Ar/39Ar geochronolgy and stable isotope geochemistry of late-Hercynian intrusions from north-eastern Iberia with implications for argon loss in K-feldspar. International Journal of Earth Science, 91, 865-881, doi:10.1007/s00531-001-0251-x.
Crowe, W.A., Cosca, M.A., Harris, L.B., 2001, 40Ar/39Ar geochronology and Neoproterozoic tectonics along the northern margin of the Eastern Ghats Belt in north Orissa, India. Precambrian Research, 108 (3-4), 237-266, doi:10.1016/S0301-9268(01)00132-2.
D’Atri, A., Dela Pierre, Ruffini, R., Novaretti, A., Cosca, M., Hunziker, J.C., 2001, Calcareous plankton biostratigraphy and 40Ar/39Ar dating of Miocene volcanoclastic layers from Monferrato (NW Italy). Eclogae Geologicae Helvetiae, 94 (2), 137-144.
de Sigoyer, J., Chavagnac, V., Blichert-Toft, J., Villa, I., Luais, B., Guillot, S., Cosca, M., and Mascle, G., 2001, Dating the Indian continental subduction and collisional thickening in the northwest Himalaya: Multichronology of the Tso Morari eclogites. Comment and Reply, Geology, 29 (2), 192-193, doi:10.1130/0091-7613(2001)029<0192:R>2.0.CO;2.
Edel, J-B., Dubois, D., Marchant, R., Hernandez, J., and Cosca, M., 2001, La rotation miocène inférieur du bloc corso-sarde. Nouvelles contraintes paléomagnetiques sur la fin du mouvement. Bulletin Societé Géologique de France, 172 (3), 275-283, doi:10.2113/172.3.275.
Janák, M., Plašienka, D., Frey, M., Cosca, M., Schmidt, S., Lupták, B., and Meres, S., 2001, Cretaceous evolution of a metamorphic core complex, the Verporic unit, Western Carpathians (Slovakia): P-T conditions and in situ 40Ar/39Ar UV laser probe dating of metapelites. Journal of Metamorphic Geology, 19 (2), 197-216, doi:10.1046/j.0263-4929.2000.00304.x.
Kramar, N., Cosca, M.A., Hunziker, J.C., 2001, Heterogenous 40Ar* distributions in naturally deformed muscovite: in situ UV-laser ablation evidence for microstructurally controlled intragrain diffusion. Earth and Planetary Science Letters, 192 (3), 377-388, doi:10.1016/S0012-821X(01)00456-3.
Odin, G.S., Takahashi, M., and Cosca M.A., 2001, 40Ar/39Ar geochronology of Middle Miocene calcareous nannofossil biohorizhons in central Japan. Chemical Geology, 171 (3-4), 239-252, doi:10.1016/S0009-2541(00)00250-3.
de Sigoyer, J., Chavagnac, V., Blichert-Toft, J., Villa, I., Luais, B., Guillot, S., Cosca, M., and Mascle, G., 2000, Dating the Indian continental subduction and collisional thickening in the northwest Himalaya: Multichronology of the Tso Morari eclogites. Geology, 28 (6), 487-490, doi:10.1130/0091-7613(2000)28<487:DTICSA>2.0.CO;2.
Giorgis, D., Cosca, M.A., Li, S., 2000, Distribution and significance of extraneous argon in UHP eclogite (Sulu terrane, China): insights from in-situ 40Ar/39Ar UV-laser ablation analysis. Earth and Planetary Science Letters, 181 (4), 605-615, doi:10.1016/S0012-821X(00)00221-1.
Zeh, A., Cosca, M., Brätz, H., Okrusch, M., and Tichomirova, M., 2000, Simultaneous horst-basin formation and magmatism during Late Variscan transtension: evidence from40Ar/39Ar and 207Pb/206Pb geochronology of the Ruhla Crystalline Complex, International Journal of Earth Science, 89 (1), 52-71, doi:10.1007/s005310050317.
Cosca, M.A., Shimron, A., and Caby, R., 1999, Late Precambrian metamorphism and cooling in the Arabian-Nubian Shield: petrology and 40Ar/39Ar geochronology of metamorphic rocks of the Elat area (southern Israel). Precambrian Research, 98 (1-2), 107-127, doi:10.1016/S0301-9268(99)00044-3.
Dèzes, P.J., Vannay, J.-C., Steck, A., Bussy, F., and Cosca, M., 1999, Synorogenic extension: quantitative constraints on the age and throw of the Zanskar Shear Zone (NW Himalaya). Geological Society of America Bulletin, 111 (3), 364-374, doi:10.1130/0016-7606(1999)111<0364:SEQCOT>2.3.CO;2.
Guillot, S., Cosca, M.A., Allemand, P., and Le Fort, P., 1999, Contrasting metamorphic and geochronologic evolution along the Himalayan Belt. In: Macfarlane, A., Sorkhabi, R.B., Quade, J. (eds) Himalaya and Tibet: Mountain Roots to Mountain Tops. Geological Society of America Special Paper, 328, 117-128, doi:10.1130/0-8137-2328-0.117.
Haeberlin, Y., Moritz, R., Fontboté, L., and Cosca, M., 1999, The Pataz gold province (Peru) within the frame of a mesothermal gold and antimony belt of the Eastern Andean Cordillera. In: Stanley, C.J., et al. (eds.) Mineral deposits: processes to processing. Balkema, 2, 1323-326.
Jaboyedoff, M., and Cosca, M.A., 1999, Dating incipient metamorphism using 40Ar/39Ar geochronolgy and XRD modeling: a case study from the Swiss Alps. Contributions to Mineralogy and Petrology, 135, 93-113, doi:10.1007/s004100050500.
Mezger, K., and Cosca, M.A., 1999, The thermal history of the Eastern Ghats (India) as revealed by U-Pb and 40Ar/39Ar dating of metamorphic and magmatic minerals: implications for the SWEAT correlation. Precambrian Research 94 (3-4), 251-271, doi:10.1016/S0301-9268(98)00118-1.
Cosca, M.A., Arculus, R.J., Pearce, J.A., and Mitchell, J.G., 1998, Inception and early evolution of the Izu-Bonin-Mariana arc system: evidence from 40Ar/39Ar and K-Ar geochronology. The Island Arc, v. 7, p. 579-595.
Cosca, M.A., Mezger, K., and Essene, E.J., 1998, The Baltica-Laurentia connection: Sveconorwegian (Grenvillian) metamorphism, cooling, and unroofing in the Bamble Sector, Norway. Journal of Geology, 106 (5), 539-552, doi:10.1086/516040.
Markley, M.J., Teyssier, C., Cosca, M.A., Caby, R., Hunziker, J.C. and Sartori, M., 1998, Alpine deformation and 40Ar/39Ar geochronology of synkinematic white mica in the Siviez-Mischabel Nappe, western Pennine Alps, Switzerland. Tectonics, v. 17, p. 407-425.
Roberts, D., Cosca, M.A., and Rice, A.H.N., 1998, A 40Ar/39Ar dating study of very low-grade metamorphism from the Rybachi and Sredni Peninsulas, NW Russia-a preliminary report. Norwegian Geological Survey Report, 168, 1-17.
Bill, M., Bussy, F., Cosca, M., Masson, H., and Hunziker, J.C., 1997, High-precision U-Pb and 40Ar/39Ar dating of an Alpine ophiolite (Gets nappe, French Alps). Eclogae Geologicae Helvetiae, 90, 43-54.
Bryant, C.J., Cosca, M.A., and Arculus, R.J., 1997, 40Ar/39Ar ages of Clarence River Supersuite intrusions from the northern portion of the New England Batholith, southern New England Orogen. In Ashley, P.M. and Flood, P.G., eds., Tectonics and Metallogenesis of the New England Orogen, Geological Society of Australia Special Publication, 19, 242-253.
Hoinkes, G., Thöni, M., Lichem, C., Bernhard, F., Kaindl, R., Schweigel, J., Tropper P., and Cosca, M., 1997, Metagranitoids and associated metasediments as indicators for the pre-Alpine magmatic and metamorphic evolution of the western Austroalpine Oetztal Basement (Kaunertal, Tirol). Swiss Bulletin of Mineralogy and Petrology, 77, 299-314.
Moecher, D.M., Cosca, M.A., and Hanson, G.N., 1997, Petrologic and 40Ar/39Ar geochronological constraints on the middle to late Paleozoic thermotectonic history of the southern Connecticut Valley zone, New England Appalachians. Geological Society of America Bulletin, 109 (2), 164-175, doi:10.1130/0016-7606(1997)109<0164:PAAAGC>2.3.CO;2.
Odin, G.S., Amorosi, A., Tateo, F., Coccioni, R., Cosca, M., Negri, A., Pini, G.A., and Hunziker, J.C., 1997, Chapter C2 Integrated stratigraphy (biostratigraphy and geochronology) of the Early Miocene sequence from the Emilian Apennines (Italy). In Montanari, A., Coccioni, R., and Odin, G. S. (eds.) Miocene Integrated Stratigraphic Sequence, p. 221-248. Elsevier, Amsterdam, doi:10.1016/S0920-5446(06)80020-8.
Odin, G.S., Cosca, M., Tateo, F., Negri, A., Vai, G. B., and Hunziker, J.C., 1997, Chapter E2 Integrated stratigraphy of the Late Tortonian Peive di Gesso section (Romagna, Italy). In Montanari, A., Coccioni, R., and Odin, G. S. (eds.) Miocene Integrated Stratigraphic Sequence, p. 449-460. Elsevier, Amsterdam.
Odin, G.S., Cuenca Bescós, G., Canuda, J.J., Cosca, M., and Lago, M., 1997, Chapter C5 Biostratigraphy and geochronology of a Miocene continental volcanoclastic layer from the Ebro basin, Spain. In Montanari, A., Coccioni, R., and Odin, G. S. (eds.) Miocene Integrated Stratigraphic Sequence, p. 297-310. Elsevier, Amsterdam.
Odin, G.S., d’Atri, A., Tateo, F., Cosca, M., and Hunziker, J.C., 1997, Chapter C1 Integrated stratigraphy near the Oligocene-Miocene boundary in the Piedmont basin (Italy): biostratigraphy and geochronology. In Montanari, A., Coccioni, R., and Odin, G. S. (eds.) Miocene Integrated Stratigraphic Sequence, p. 209-220. Elsevier, Amsterdam, doi:10.1016/S0920-5446(06)80019-1.
Odin, G.S., Deino, A., Cosca, M., Laurenzi, M.A., and Montanari, A., 1997, Chapter F1 Miocene geochronology: methods, techniques, and results. In Montanari, A., Coccioni, R., and Odin, G. S. (eds.) Miocene Integrated Stratigraphic Sequence, p. 581-594. Elsevier, Amsterdam.
Odin, G.S., Miculan, P., Cosca, M., Tateo, F., Amorosi, A., and Hunziker, J.C., 1997, Chapter D3Biostratigraphy and geochronology of an Early Serravallian volcanoclastic layer from Sicily. In Montanari, A., Coccioni, R., and Odin, G. S. (eds.) Miocene Integrated Stratigraphic Sequence, p. 351-360. Elsevier, Amsterdam.
Odin, G.S., Ricci Lucchi, F., Tateo, F., Cosca, M., and Hunziker, J.C., 1997, Chapter E7 Integrated stratigraphy of the Maccarone section, Late Messinian (Marche region, Italy). In Montanari, A., Coccioni, R., and Odin, G. S. (eds.) Miocene Integrated Stratigraphic Sequence, p. 529-544. Elsevier, Amsterdam.
Odin, G.S., Takahashi, M., Coccioni, R., and Cosca, M., 1997, Chapter D7 Géochronologie de niveaux situés autour de l’apparition de Globigerina nepenthes au Japon et in Italie: âge de la limite Serravallien/Tortonien. In Montanari, A., Coccioni, R., and Odin, G. S. (eds.) Miocene Integrated Stratigraphic Sequence, p. 393-400. Elsevier, Amsterdam.
Odin, G.S., Vai, G.B., Cosca, M., Tateo, F., and Hunziker, J.C., 1997, Chapter E6 Contribution to the geochronology of the Tortonian/Messinian bundary in the Faenza (Romagna, Italy). In Montanari, A., Coccioni, R., and Odin, G. S. (eds.) Miocene Integrated Stratigraphic Sequence, p. 519-528. Elsevier, Amsterdam, doi:10.1016/S0920-5446(06)80038-5.
Restrepo-Pace, P.A., Ruiz, J., Gehrels, G., and Cosca, M., 1997, Geochronology and Nd isotopic data of Grenville-age rocks in the Colombian Andes: new constraints for Late Proterozoic-Early Paleozoic paleocontinental reconstructions of the Americas. Earth and Planetary Science Letters, 150 (3-4), 427-441, doi:10.1016/S0012-821X(97)00091-5.
Kirschner, D.L., Cosca, M.A., Hunziker, J.C., and Masson, H., 1996, Staircase 40Ar/39Ar spectra of fine-grained white mica: timing and duration of deformation and empirical constraints on argon diffusion. Geology, v. 24, p. 747-750.
Schärer, U., Cosca, M., Hunziker, J., and Steck, A., 1996, Termination of major ductile strike-slip shear and differential cooling along the Insubric line (Central Alps): U/Pb, Rb/Sr and 40Ar/39Ar ages of cross-cutting pegmatites. Earth and Planetary Science Letters, v. 142, p. 331-352.
Cosca, M.A., Essene, E.J., Mezger, K., and van der Pluijm, B.A., 1995, Constraints on the duration of tectonic processes: protracted extension and deep crustal rotation in the Grenville Orogen. Geology, 23 (4), 361-364, doi:10.1130/0091-7613(1995)023<0361:COTDOT>2.3.CO;2.
Crespo-Blanc, A., Masson, H., Sharp, Z., Cosca, M., and Hunziker, J., 1995, A stable and 40Ar/39Ar isotope study of a major thrust in the Helvetic nappes (Swiss Alps): evidence for fluid flow and constraints on nappe kinematics. Geological Society of America Bulletin, 107 (10), 1129-1144, doi:10.1130/0016-7606(1995)107<1129:ASAAAI>2.3.CO;2.
Odin, G.S., Coccioni, R., Cosca, M., and Montanari, A., 1995, 40Ar/39Ar geochronology of biostratigraphically controlled Miocene tuffs from central Japan: Comparison with Italy and age of the Serravallian-Tortonian boundary. Chemical Geology, 125 (1-2), 105-121, doi:10.1016/0009-2541(95)00075-W.
Ruffini, R., Cosca, M.A., d’Atri, A., Hunziker, J.C., and Polino, R., 1995, The volcanic supply of the Taveyanne turbidites (Savoie, France): a riddle for Tertiary Alpine volcanism. In: Polino, R. And Sacchi, R. (eds.) Rapporti Alpi-Appennino e Guide Alle Escursioni, Accademia Nazionale Delle Scienze Detta Dei XL, Roma, p. 359-376.
Schmädicke, E., Mezger, K., Cosca, M.A., and Okrusch, M., 1995, Variscan Sm/Nd and Ar/Ar ages of eclogite-facies rocks from the Erzgebirge, Bohemian Massif. Journal of Metamorphic Geology, 13 (5), 537 - 552, doi:10.1111/j.1525-1314.1995.tb00241.x.
Cosca, M.A. and O'Nions R.K., 1994, A re-examination of the influence of composition on argon retentivity in metamorphic calcic amphiboles. Chemical Geology, 112 (1-2), 39-56, doi:10.1016/0009-2541(94)90103-1.
Odin, G.S., Assorgia, A., Barca, S., Porcu, A., Spano, J., and Cosca, M., 1994, 40Ar/39Ar geochronology of a Burdigalian tuff from central-northern Sardinia. Giornale Geologia, v. 56, p. 185-197.
Odin, G.S., Jelen, B., Drobne, K., Uhan, J., Skaberne, D., PavŠic, J., Cimerman, F.. Cosca, M., and Hunziker, J.C., 1994, Premiers âge géochronologiques de niveaux volcaniclastiques oligocènes de la Région de Zasavje, Slovénie. Giornale Geologia, v. 56, p. 199-212.
van der Pluijm, B.A., Mezger, K., Cosca, M.A., and Essene, E.J., 1994, Determining the significance of high-grade shear zones by using temperature-time paths, with examples from the Grenville Orogen. Geology, 22 (8), 743-746, doi:10.1130/0091-7613(1994)022<0743:DTSOHG>2.3.CO;2.
Spring, L., Bussy, F., Vannay, J.C., Huon, S., and Cosca, M.A., 1993, Early Permian granitic dykes of alkaline affinity in the Indian High Himalaya of Upper Lahul and SE Zanskar: geochemical characterization and geotectonic implications. Geological Society, London, Special Publications, 74, 251-264, doi:10.1144/GSL.SP.1993.074.01.18.
Cosca, M.A., Essene, E.J., Kunk, M.J., and Sutter, J.F., 1992, Differential unroofing within the Central Metasedimentary Belt of the Grenville Orogen: constraints from 40Ar/39Ar thermochronology. Contributions to Mineralogy and Petrology, 110, 211-225, doi:10.1007/BF00310739.
Cosca, M.A., Hunziker, J.C., Huon, S., and Masson, H., 1992, Radiometric age constraints on mineral growth, metamorphism, and tectonism of the Gummfluh Klippe, Briançonnais domain of the Préalpes, Switzerland. Contributions to Mineralogy and Petrology, 112, 439-449, doi:10.1007/BF00310776.
Cosca, M.A., Essene, E.J., and Bowman, J.R., 1991, Complete chemical analyses of metamorphic hornblendes: implications for normalizations, calculated H2O activities and thermobarometry. Contributions to Mineralogy and Petrology, 108, 472-484, doi:10.1007/BF00303451.
Cosca, M.A., Sutter, J.F., and Essene, E.J., 1991, Cooling and inferred uplift/erosion history of the Grenville Orogen, Ontario: constraints from 40Ar/39Ar thermochronology. Tectonics, 10 (5), 959-977, doi:10.1029/91TC00859.
Cosca, M.A., Sutter, J.F., and Essene, E.J., 1990, Comment on "Interpretation of K/Ar mineral dates from the Grenville Orogenic Belt." American Journal of Science, 290 (2), 202-204, doi:10.2475/ajs.290.2.202.
Cosca, M.A., 1989, Cooling and inferred uplift history of the Grenville Orogen, Ontaria: constraints from 40Ar/39Ar thermochronology: PhD thesis University of Michigan, 235 pp.
Cosca, M.A., Essene, E.J., Geissman, J.G., Simmons, W.B., and Coates, D.A., 1989, Pyrometamorphic rocks associated with naturally burned coal beds, Powder River Basin, Wyoming. American Mineralogist, 74 (1-2), 85-100, https://pubs.geoscienceworld.org/ammin/article/74/1-2/85/42195/Pyrometamorphic-rocks-associated-with-naturally.
Cosca, M.A., Rouse, R.C., and Essene, E.J., 1988, Dorrite (Ca2(Mg2 Fe3+4)(Al4Si2)O20), a new member of the aenigmatite group from a pyrometamorphic melt-rock. American Mineralogist, 73 (11-12), 1440-1449, https://pubs.geoscienceworld.org/ammin/article/73/11-12/1440/42089/Dorite-Ca-2-Mg-2-Fe-super-3-4-Al-4-Si-2-O-20-a-new.
Cosca, M.A., and Peacor, D.R., 1987, Chemistry and structure of esseneite (CaFe3+AlSiO6), a new pyroxene produced by pyrometamorphism: American Mineralogist, 72 (1-2), 148-156, https://pubs.geoscienceworld.org/ammin/article/72/1-2/148/41909/Chemistry-and-structure-of-esseneite-CaFe-super-3.
Yau, Y.C., Peacor, D.R., Essene, E.J., Lee, J.H., Kuo, L.C., and Cosca, M.A., 1987, Hydrothermal experiments on candidate packing materials. Clays and Clay Mineralalogy, 35 (4), 241-250, https://pubs.geoscienceworld.org/ccm/article/35/4/241/47021/Hydrothermal-treatment-of-smectite-illite-and.
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
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Argon Geochronology
This project supports the USGS argon geochronology laboratory in Denver. The USGS 40Ar/39Ar geochronology laboratory is a state-of-the-art research facility for determining absolute ages of minerals and rocks. The 40Ar/39Ar laboratory contributes critical geochronology to individual USGS research projects and to partners in academia and other Federal agencies. This laboratory develops methodology...Serving the U.S. Geological Survey’s geochronological data
Geochronological data provide essential information necessary for understanding the timing of geologic processes and events, as well as quantifying rates and timescales key to geologic mapping, mineral and energy resource and hazard assessments. The USGS’s National Geochronological Database (NGDB) contains over 30,000 radiometric ages, but no formal update has occurred in over 20 years. This projGeochronologic Investigations
The present landscape of the Southern Rocky Mountains and surrounding physiographic areas results from time-integrated interaction between the asthenosphere, lithosphere, and hydrosphere. Large-scale phenomena, such as asthenospheric upwelling directly or indirectly affect lithospheric thinning, faulting, basin development, and igneous activity sometimes associated with ore deposits. During the... - Data
Argon and SHRIMP-RG Data for Magmatic Steam Alunite, Sericite, and Zircon from Alunite Ridge and Deer Trail Mountain, Marysvale, Utah
Samples of vein-type magmatic-steam alunite were collected over several field seasons from five mines and prospects (L&N, Mt. Edna, Christmas, upper Mineral Products, and Close In) in the Alunite Ridge and Deer Trail Mountain area, Marysvale, Utah, as well as a sample from the Deer Trail mine workings from which sericite was separated. The magmatic-steam alunite and sericite were analyzed by the 4USGS Geochron: A Database of Geochronological and Thermochronological Dates and Data
USGS Geochron is a database of geochronological and thermochronological dates and data. The data set contains published ages, dates, analytical information, sample metadata including location, and source citations. The following analytical techniques are represented in the data set: 40Ar/39Ar, K-Ar, U-Th-Pb, Sm-Nd, Rb-Sr, Lu-Hf, fission track, and luminescence. This data set incorporates data prevData release for geochronology and geochemistry of volcanic rocks in the Southern Rocky Mountains and Taos Plateau volcanic fields and other Oligocene to Pleistocene volcanic rocks within the southern San Luis Basin and San Juan Mountains, southern Colora
The dataset includes whole-rock geochemistry and 40Ar-39Ar geochronology for Pleistocene to Oligocene volcanic and intrusive rocks. These data support figures and tables in days 2 and 3 of the Field-trip guide to continental arc to rift volcanism of the southern Rocky Mountains-Southern Rocky Mountain, Taos Plateau, and Jemez Mountains volcanic fields of southern Colorado and northern New Mexico (Data to accompany U.S. Geological Survey Data Series 1099: Petrographic, geochemical and geochronologic data for Cenozoic volcanic rocks of the Tonopah, Divide, and Goldfield Mining Districts, Nevada
This dataset is the assembled analytical results of geochemical, petrographic, and geochronologic data for samples, principally those of unmineralized Tertiary volcanic rocks, from the Tonopah, Divide, and Goldfield mining districts of west-central Nevada. Much of the data presented here for the Tonopah and Divide districts are for samples collected by Bonham and Garside (1979) during geologic mapData release of geospatial map database, argon geochronology and geochemistry data for: Geologic map of the San Antonio Mountain area, northern New Mexico and southern Colorado
This dataset accompanies publication "Geologic map of the San Antonio Mountain area, northern New Mexico and southern Colorado". Data presented here include the digital geologic database, 40Ar/39Ar geochronology and major and trace element chemistry from lava flows and an ignimbrite. The geologic database includes spatial feature classes and non-spatial tables that collectively contain the geologiU-Pb SHRIMP and 40Ar/39Ar geochronologic data and backscatter electron (BSE) and panchromatic cathodoluminescent (CL) imagery of sample materials for study of dikes, country rock, and alteration systems, Butte, U.S.A.
These data are for a multidisciplinary study of dikes, country rock, and alteration systems, Butte, U.S.A. Results of the study are described and interpreted in Lund and others (2018). Data included are U-Pb SHRIMP geochronology for quartz porphyry dikes, 40Ar/39Ar thermochronologic data for biotite, hornblende, and K-feldspar from Butte granite country rock, and 40Ar/39Ar thermochronologic data f40Ar/39Ar geochronology of the Tonopah, Divide, and Goldfield districts, Nevada
Ar/Ar data are reported from minerals and rocks that were collected as part of a mineral resource investigation of the Tonopah, Divide, and Goldfield districts in Nevada. Data are reported from 92 samples and associated standards from eight separate neutron irradiations in the Denver USGS TRIGA reactor, including separated mineral grains and whole rocks. Data were collected by infrared laser heatiArgon geochronology data from the Austroalpine-Pennine boundary, Central Alps, Switzerland
Ar/Ar data are reported from eight samples of white mica separated from rock samples collected along the Austroalpine-Pennine boundary in the Central Alps of Switzerland. These samples were collected as part of a Caltech PhD study to examine the tectonic history of this boundary and these argon geochronology data represent one small part of the study. Data are reported from these eight samples togData release of Geologic Map of the Upper Arkansas River Valley Region, North-Central, Colorado
This 1:50,000-scale geologic map represents a compilation of the most recent geologic studies of the upper Arkansas River valley, between Leadville and Salida, Colorado. The valley is structurally controlled by an extensional fault system that forms part of the prominent northern Rio Grande rift, an intra-continental region of crustal extension. This work also incorporates new detailed geologic maArgon data for Poncha Pass Geologic Map
This dataset was collected by Leah E. Morgan and Michael A. Cosca in the Argon Geochronology Laboratory of the USGS in Denver, Colorado in 2015. The dataset contains full raw argon isotopic data for samples presented in: Geologic Map of the Poncha Map Area, Chaffee, Fremont, and Saguache Counties, Colorado. - Maps
Geologic map of the Poncha Pass area, Chaffee, Fremont, and Saguache Counties, Colorado
This report presents a 1:24,000-scale geologic map, cross sections, and descriptive and interpretative text for the Poncha Pass area in central Colorado. The map area is irregular in shape, covering all of one 7 ½' quadrangle (Poncha Pass) and parts of five others (Mount Ouray, Maysville, Salida West, Salida East, and Wellsville). The map boundaries were drawn to cover all of the “Poncha mountainGeologic map of the San Antonio Mountain area, northern New Mexico and southern Colorado
The geologic map of the San Antonio Mountain area in northern New Mexico and southern Colorado is located along the west-central part of the San Luis Valley. The San Luis Valley is the geomorphic expression of the San Luis Basin, an extensional basin associated with the northern Rio Grande rift. Deposits within the map area record volcanic, sedimentary, and tectonic processes over the last ~33 milGeologic map of the upper Arkansas River valley region, north-central Colorado
This 1:50,000-scale U.S. Geological Survey geologic map represents a compilation of the most recent geologic studies of the upper Arkansas River valley between Leadville and Salida, Colorado. The valley is structurally controlled by an extensional fault system that forms part of the prominent northern Rio Grande rift, an intra-continental region of crustal extension. This report also incorporatesGeologic map of the Rio Rico and Nogales 7.5’ quadrangles, Santa Cruz County, Arizona
The Rio Rico and Nogales (Arizona) 1:24,000-scale quadrangles are located in the Basin and Range Province of southern Arizona, and the southern edge of the map is the international border with Sonora, Mexico. The major urban area is Nogales, a bi-national city known as “the gateway to Mexico.” Rocks exposed in the map area range in age from Jurassic through Quaternary. Major physiographic, geolGeologic map of the Alamosa 30’ × 60’ quadrangle, south-central Colorado
The Alamosa 30'× 60' quadrangle is located in the central San Luis Basin of southern Colorado and is bisected by the Rio Grande. The Rio Grande has headwaters in the San Juan Mountains of Colorado and ultimately discharges into the Gulf of Mexico 3,000 kilometers (km) downstream. Alluvial floodplains and associated deposits of the Rio Grande and east-draining tributaries, La Jara Creek and ConejosGeologic map of the Sunshine 7.5' quadrangle, Taos County, New Mexico
The Sunshine 7.5' quadrangle is located in the south-central part of the San Luis Basin of northern New Mexico, in the Rio Grande del Norte National Monument, and contains deposits that record volcanic, tectonic, and associated alluvial and colluvial processes over the past four million years. Sunshine Valley, named for the small locale of Sunshine, is incised by a series of northeast-trending draGeologic map of the Ute Mountain 7.5' quadrangle, Taos County, New Mexico, and Conejos and Costilla Counties, Colorado
The Ute Mountain 7.5' quadrangle is located in the south-central part of the San Luis Basin of northern New Mexico, in the Rio Grande del Norte National Monument, and contains deposits that record volcanic, tectonic, and associated alluvial and colluvial processes over the past four million years. Ute Mountain has the distinction of being one of the largest intermediate composition eruptive centerGeologic map of the Ute Mountain 7.5' quadrangle, Taos County, New Mexico, and Conejos and Costilla Counties, Colorado
The Ute Mountain 7.5' quadrangle is located in the south-central part of the San Luis Basin of northern New Mexico, in the Rio Grande del Norte National Monument, and contains deposits that record volcanic, tectonic, and associated alluvial and colluvial processes over the past four million years. Ute Mountain has the distinction of being one of the largest intermediate composition eruptive centerGeologic map of the Sunshine 7.5' quadrangle, Taos County, New Mexico
The Sunshine 7.5' quadrangle is located in the south-central part of the San Luis Basin of northern New Mexico, in the Rio Grande del Norte National Monument, and contains deposits that record volcanic, tectonic, and associated alluvial and colluvial processes over the past four million years. Sunshine Valley, named for the small locale of Sunshine, is incised by a series of northeast-trending draGeologic map of the Harvard Lakes 7.5' quadrangle, Park and Chaffee Counties, Colorado
The Harvard Lakes 1:24,000-scale quadrangle spans the Arkansas River Valley in central Colorado, and includes the foothills of the Sawatch Range on the west and Mosquito Range on the east. The Arkansas River valley lies in the northern end of the Rio Grande rift and is structurally controlled by Oligocene and younger normal faults mostly along the west side of the valley. Five separate pediment suMineral resource potential map of the Laurel-McGee Roadless Area, Mono County, California
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Constraints on near-ridge magmatism using 40Ar/39Ar geochronology of enriched MORB from the 8°20' N seamount chain
Our understanding of the spatial-temporal-compositional relationships between off-axis magmatism and mid-ocean ridge spreading centers is limited. Determining the 40Ar/39Ar ages of mid-ocean ridge basalt (MORB) lavas erupting near mid-ocean ridges (MOR) has been a challenge due to the characteristically low K2O contents in incompatible element-depleted normal MORB (NMORB). High-precision 40Ar/39ArAuthorsMolly Anderson, Michael Perfit, Leah E. Morgan, Daniel Fornari, Michael A. Cosca, V. Dorsey Wanless40Ar/39Ar geochronology of magmatic-steam alunite from Alunite Ridge and Deer Trail Mountain, Marysvale Volcanic Field, Utah: Timing and duration of miocene hydrothermal activity associated with concealed intrusions
Porphyry and epithermal deposits are important sources of base and precious metals. Most actively mined deposits have been exhumed such that ore bodies are relatively close to the surface and are therefore locatable and economic to extract. Identifying and characterizing concealed deposits, particularly more deeply buried porphyry deposits, represents a far greater challenge for mineral exploratioAuthorsCameron Mark Mercer, M. Cosca, Albert H. Hofstra, Wayne R. Premo, Robert O. Rye, Gary P. LandisTwo-event genesis of Butte lode veins: Geologic and geochronologic evidence from ore veins, dikes, and host plutons
The long-standing ore-genesis model for world-class deposits of the Butte mining district, Montana, is of deep pre-Main Stage porphyry Cu-Mo and overlying Main Stage Ag-Zn-Cu-zoned lode veinsformed from discrete hydrothermal systems related to rhyolite dikes. The lode-specific model describes metals zones that formed in the lode veins as hydrothermal processes diminished in intensity (changing temAuthorsKaren Lund, Ryan J. McAleer, John N. Aleinikoff, Michael CoscaAge and mantle sources of Quaternary basalts associated with “leaky” transform faults of the migrating Anatolia-Arabia-Africa triple junction
The Anatolia (Eurasia), Arabia, and Africa tectonic plates intersect in southeast Turkey, near the Gulf of İskenderun, forming a tectonically active and unstable triple junction (the A3 triple junction). The plate boundaries are marked by broad zones of major, dominantly left-lateral transform faults including the East Anatolian fault zone (the Anatolia-Arabia boundary) and the Dead Sea fault zoAuthorsMichael Cosca, Mary Reid, Jonathan Delph, Gonca Gençalioğlu Kuşcu, Janne Blichert-Toft, Wayne R. Premo, Donna Whitney, Christian Teyssier, Bora RojayCenozoic tectonic evolution of the Ecemiş fault zone and adjacent basins, central Anatolia, Turkey during the transition from Arabia - Eurasia collision to escape tectonics
The effects of Arabia-Eurasia collision are recorded in faults, basins, and exhumed metamorphic massifs across eastern and central Anatolia. These faults and basins also preserve evidence of major changes in deformation and associated sedimentary processes along major suture zones including the Inner Tauride suture where it lies along the southern (Ecemiş) segment of the Central Anatolian fault zoAuthorsPaul J. Umhoefer, Stuart Thompson, Come Lefebre, Michael Cosca, Christian Teyssier, Donna L. WhitneyPetrology of volcanic rocks associated with silver-gold (Ag-Au) epithermal deposits in the Tonopah, Divide, and Goldfield Mining Districts, Nevada
Miocene calc-alkaline volcanic rocks, part of the southern segment of the ancestral Cascades magmatic arc, are spatially, temporally, and likely genetically associated with precious metal epithermal deposits in the Tonopah, Divide, and Goldfield Districts of west-central Nevada. In the Tonopah mining district, volcanic rocks include the Mizpah Trachyte, Fraction Tuff, and Oddie Rhyolite; in the DiAuthorsEdward A. du Bray, David A. John, Joseph Colgan, Peter G. Vikre, Michael A. Cosca, Leah E. MorganPetrographic, geochemical, and geochronologic data for cenozoic volcanic rocks of the Tonopah, Divide, and Goldfield Mining Districts, Nevada
The purpose of this report is to summarize geochemical, petrographic, and geochronologic data for samples, principally those of unmineralized Tertiary volcanic rocks, from the Tonopah, Divide, and Goldfield mining districts of west-central Nevada (fig. 1). Much of the data presented here for the Tonopah and Divide districts are for samples collected by Bonham and Garside (1979) during geologic mapAuthorsEdward A. du Bray, David A. John, Peter G. Vikre, Joseph Colgan, Michael A. Cosca, Leah E. Morgan, Robert J. Fleck, Wayne R. Premo, Christopher S. Holm-DenomaA supervolcano and its sidekicks: A 100 ka eruptive chronology of the Fish Canyon Tuff and associated units of the La Garita magmatic system
Establishing temporal constrains on major volcanic eruptions is limited by the precision of existing geochronometers. Prior work on the La Garita caldera, created by the eruption of the Fish Canyon Tuff, failed to resolve temporal differences between pre-, syn-, and post-collapse eruptive units. Here, we report 40Ar/39Ar geochronologic data supporting a ca. 100 ka eruptive history of the La GaritaAuthorsLeah E. Morgan, Samuel Johnstone, Amy K. Gilmer, Michael A. Cosca, Ren A. ThompsonC–O stable isotope geochemistry and 40Ar/39Ar geochronology of the Bear Lodge carbonatite stockwork, Wyoming, USA
The carbonatite dike swarm and vein stockwork at the center of the Paleogene Bear Lodge alkaline complex (BLAC), Wyoming, USA, is host to diverse REE mineral assemblages that are largely a result of subsolidus modification and REE redistribution. Pseudomorphic replacement of primary burbankite by an assemblage of ancylite, strontianite, and barite is the result of interaction with late-stage hydroAuthorsAllen K. Andersen, Peter B. Larson, Michael A. CoscaTwo-event lode-ore deposition at Butte, USA: 40Ar/39Ar and U-Pb documentation of Ag-Au-polymetallic lodes overprinted by younger stockwork Cu-Mo ores and penecontemporaneous Cu lodes
The ore-genesis model for world-class deposits of the Butte mining district, Montana, USA, is deep pre-Main Stage porphyry Cu-Mo and overlying Main Stage Ag-Zn-Cu zoned-lode deposits, both of which formed from hydrothermal fluids driven by minor volumes of rhyolitic magma. The lode-specific model is that hydrothermal processes diminished in intensity outward from district center along lode veins,
AuthorsKaren Lund, Ryan J. McAleer, John N. Aleinikoff, Michael A. Cosca, Michael J. KunkRapid late Miocene surface uplift of the Central Anatolian Plateau margin
The Central Anatolian Plateau (CAP), Turkey, is bordered to its south by a steep mountain belt that emerged ∼8–7 Ma ago from the Mediterranean Sea. Knowledge of the onset, duration and rate of surface uplift and orographic barrier formation along the plateau margin is crucial for understanding the geodynamic drivers of plateau uplift. We present a new comprehensive data set that includes 12 40Ar/3AuthorsMaud J.M. Meijers, Gilles Y. Brocard, Michael A. Cosca, Tina Lüdecke, Christian Teyssier, Donna L. Whitney, Andreas MulchClimate stability in Central Anatolia during the Messinian Salinity Crisis
Deposition of large amounts of evaporites and erosion of deep canyons within the Mediterranean Basin as a result of reduced basin connectivity with the Atlantic Ocean and the epicontinental Paratethys Sea characterized the Messinian Salinity Crisis (MSC, 5.97–5.33 Ma). The influence of the MSC on Mediterranean environmental conditions within the basin itself has been intensely studied from marineAuthorsMaud J.M. Meijers, Ahmet A Peynircioğlu, Michael A. Cosca, Gilles Y. Brocard, Donna L. Whitney, Cor G. Langereis, Andreas MulchNon-USGS Publications**
Mulch, A., Teyssier, C., Cosca, M A., and Chamberlain, C.P., 2007, Stable isotope paleoaltimetry of Eocene core complexes in the North American Cordillera, Tectonics, 26 (4), TC4001, doi:10.1029/2006TC00199.Zechmeister, M.S., Ferre, E., Cosca, M.A., Geissman, J.W., 2007, Slow and fast deformation in the Dora Maira Massif, Italian Alps: Pseudotachylytes and inferences on exhumation history. Journal of Stuctural Geology, 29 (7), p. 1114-1130, doi:10.1016/j.jsg.2007.03.009.Cosca, M. A., Giorgis, D., Rumble, D., and Liou, J. G. 2006, Limiting effects of UHP metamorphism on length scales of oxygen, hydrogen, and argon isotope exchange: an example from the Qinglongshan UHP ecologites, Sulu Terrain, China: In: Phase relations, high-pressure terranes, P-T-ometry, and plate pushing: a tribute to W. G. Ernst. International Book Series, v. 9, p. 290-323.Keane, S.D., DeWolf, C.P., Essene, E.J., Halliday, A.N., Hall, C.M., Cosca, M.A., 2006, Isotopic Constraints on the Thermal History of the Wind River Range, Wyoming: Implications for Archean Metamorphism. Canadian Journal of Earth Science, 43 (10), 1511-1532, doi:10.1139/e06-090.Manatschal, G., Engström, A., Desmurs, L., Schaltegger, U., Cosca, M., Müntener, O., Bernoulli, D., 2006, What is the tectono-metamorphic evolution of continental break-up: the example of the Tasna ocean-continent transistion. Journal of Structural Geology,28 (10), 1849-1869, doi:10.1016/j.jsg.2006.07.014.Mulch, A., Teyssier, C, Cosca, M.A, and Vennemann, T.W., 2006, Thermomechanical analysis of strain localization in a ductile detachment zone. Journal of Geophysical Research Solid Earth, 111 (B12), doi:10.1029/2005JB004032.Cosca, M.A., Caby, R., and Bussy, F., 2005, Geochemistry and 40Ar/39Ar geochronology of pseudotachylyte associated with UHP whiteschists from the Dora Maira massif, Italy. Tectonophysics, 402 (1-4), 93-110, doi:10.1016/j.tecto.2004.12.033.Cosca, M.A., Giorgis, D., Rumble, D., Liou, J.G., 2005, Limiting effects of UHP metamorphism on length-scales of oxygen, hydrogen, and argon isotope exchange: an example from the Qinglongshan UHP eclogites. International Geology Review, 47 (7), 716-749, doi:10.2747/0020-6814.47.7.716.Mulch, A., Cosca, M.A., Fiebig, J., and Andresen, A., 2005, Time scales of deformation and exhumation in extensional detachment systems determined by high-spatial resolution in situ UV-laser 40Ar/39Ar dating. Earth and Planetary Science Letters, 233 (3-4), 375-390, doi:10.1016/j.epsl.2005.01.042.Putlitz, B., Cosca, M.A., and Schumacher, J., 2005, Prograde mica 40Ar/39Ar growth ages recorded in high pressure rocks (Syros, Cyclades, Greece). Chemical Geology, 214 (1-2), 79-98, doi:10.1016/j.chemgeo.2004.08.056.Haeberlin, Y., Moritz, R., Fontboté, L., and Cosca, M., 2004, Carboniferous orogenic gold deposits at Pataz, Eastern Andean Cordillera, Peru: Geological and structural framework, paragenesis, alteration, and 40Ar/39Ar geochronology. Economic Geology, 99 (1), 73-112, doi:10.2113/gsecongeo.99.1.73.Mulch, A. and Cosca, M.A., 2004, Recrystallization or cooling ages? In situ UV-laser 40Ar/39Ar geochronology of muscovite in mylonitic rocks. Journal of the Geological Society of London, 161 (4), 573-582, doi:10.1144/0016-764903-110.Mulch, A., Teyssier, C., Cosca, M.A., Vanderhaeghe, O., and Vennemann, T., 2004, Reconstructing paleoelevation in eroded orogens. Geology, 32 (6), 525-528, doi:10.1130/G20394.1.Vannay, J-C., Grasemann, B., Rahn, M., Frank, W., Carter, A., Baudraz, V., Cosca, M., 2004, Miocene to Holocene exhumation of metamorphic crustal wedges in the NW Himalaya: evidence for tectonic extrusion coupled to fluvial erosion. Tectonics, 23 (1), doi:10.1029/2002TC001429.Winer, G.S., Feeley, T.C., and Cosca, M.A., 2004, Basaltic volcanism in the Bering Sea: geochronology and volcanic evolution of St. Paul Island, Pribilof Islands, Alaska. Journal of Volcanology and Geothermal Research, 134 (4), 277-301, doi:10.1016/j.jvolgeores.2004.02.003.Bendezú, R., Fontbonté, L., Cosca, M., 2003, Relative age of Cordilleran base metal lode and replacement deposits, and high sulfidation Au-(Ag) epithermal mineralization in the Colquijirca district, central Peru. Mineralium Deposita, 38, 683-694, doi:10.1007/s00126-003-0358-z.Camprubí, A., Ferrari, L., Cosca, M.A., Cardellach, E., Canals, A., 2003, Ages of epithermal deposits in Mexico: regional significance and links with the evolution of Tertiary volcanism. Economic Geology, 98 (5), 1029-1037, doi:10.2113/gsecongeo.98.5.1029.Feeley, T.C., and Cosca, M.A., 2003, Time vs. composition trends of magmatism at Sunlight volcano, Absaroka Volcanic Province, Wyoming. Geological Society of America Bulletin, 115 (6), 714-728, doi:10.1130/0016-7606(2003)115<C0714:TVCTOM>2.0.CO;2.Giorgis, D., Cosca, M.A., Rumble, D., 2003, Pre-metamorphic d18O signatures in morphologically complex zircons from the Qinglongshan UHP meta-granite (Sulu terrain, China). Swiss Bulletin of Mineralogy and Petrology, 83 (2), 133-144, https://www.ingentaconnect.com/content/ssmp/sbmp/2003/00000083/00000002/art00002.Jourdan, F., Marzoli, A., Bertrand, H., Cosca, M., Fontignie, D., 2003, The Northernmost CAMP: 40Ar/39Ar age, petrology and Sr-Nd-Pb isotope geochemistry of the Kerforne dike, Brittany, France. In: Hames, W.C et al. (eds.) The Central Atlantic Magmatic Province: Fragments of Pangea, AGU Geophysical Monograph, 136, 209-226, doi:10.1029/136GM11.Kirschner, D.L., Cosca, M.A., and Masson, H., 2003, An 40Ar/39Ar, Rb/Sr, and stable isotope study of micas in low-grade fold-and-thrust belt: An example from the Swiss Helvetic Alps. Contributions to Mineralogy and Petrology, 145 (4), 460-480, doi:10.1007/s00410-003-0461-2.Kramar, N., Cosca, M.A., Buffat, P.A., and Baumgartner, L.P., 2003, Stacking fault-enhanced argon diffusion in naturally deformed muscovite. In Vance, D., Muller, W., and Villa, I., eds., Geochronology: Linking the Isotopic Record with Petrology and Textures, Geological Society of London. Special Publication, 220, 249-260, doi:10.1144/GSL.SP.2003.220.01.15.Rodríguez Aller, J., Cosca, M. A., Gil Ibarguchi, J. I., and Dallmeyer, R. D., 2003, Strain partitioning and preservation of 40Ar/39Ar ages for the eclogite-facies stage during Variscan exhumation of a subducted crust (Malpica-Tui allochthon, NW Spain) Lithos, 70 (3-4), 111-139, doi:10.1016/S0024-4937(03)00095-1.Schlup, M., Carter, A., Cosca, M., and Steck, A., 2003, Exhumation history of eastern Ladakh revealed by 40Ar/39Ar and fission-track ages: the Indus River-Tso Morari transect, NW Himalaya. Journal of the Geological Society of London, 160, 385-369, doi:10.1144/0016-764902-084.Feeley, T.C., Cosca, M.A., and Lindsay, C.R., 2002, Petrogenesis and implications of calc-alkaline cryptic hybrid magmas from Washburn volcano, Absaroka Volcanic Province, USA. Journal of Petrology, 43 (4), 663-703, doi:10.1093/petrology/43.4.663.Markley, M., Teyssier, C., and Cosca, M., 2002, The relation between grain size and 40Ar/39Ar date for Alpine white mica from the Siviez-Mischabel Nappe, Switzerland. Journal of Stuctural Geology, 24 (12), 1937-1955, doi:10.1016/S0191-8141(02)00006-8.Mulch, A., Cosca, M.A., and Handy, M.R., 2002, In situ UV-laser 40Ar/39Ar geochronology of a micaceous mylonite: an example of defect-enhanced argon loss. Contributions to Mineralogy and Petrology, 142, 738-752, doi:10.1007/s00410-001-0325-6.Solé, J., Cosca, M., Sharp, Z., and Enrique, P, 2002, 40Ar/39Ar geochronolgy and stable isotope geochemistry of late-Hercynian intrusions from north-eastern Iberia with implications for argon loss in K-feldspar. International Journal of Earth Science, 91, 865-881, doi:10.1007/s00531-001-0251-x.Crowe, W.A., Cosca, M.A., Harris, L.B., 2001, 40Ar/39Ar geochronology and Neoproterozoic tectonics along the northern margin of the Eastern Ghats Belt in north Orissa, India. Precambrian Research, 108 (3-4), 237-266, doi:10.1016/S0301-9268(01)00132-2.D’Atri, A., Dela Pierre, Ruffini, R., Novaretti, A., Cosca, M., Hunziker, J.C., 2001, Calcareous plankton biostratigraphy and 40Ar/39Ar dating of Miocene volcanoclastic layers from Monferrato (NW Italy). Eclogae Geologicae Helvetiae, 94 (2), 137-144.de Sigoyer, J., Chavagnac, V., Blichert-Toft, J., Villa, I., Luais, B., Guillot, S., Cosca, M., and Mascle, G., 2001, Dating the Indian continental subduction and collisional thickening in the northwest Himalaya: Multichronology of the Tso Morari eclogites. Comment and Reply, Geology, 29 (2), 192-193, doi:10.1130/0091-7613(2001)029<0192:R>2.0.CO;2.Edel, J-B., Dubois, D., Marchant, R., Hernandez, J., and Cosca, M., 2001, La rotation miocène inférieur du bloc corso-sarde. Nouvelles contraintes paléomagnetiques sur la fin du mouvement. Bulletin Societé Géologique de France, 172 (3), 275-283, doi:10.2113/172.3.275.Janák, M., Plašienka, D., Frey, M., Cosca, M., Schmidt, S., Lupták, B., and Meres, S., 2001, Cretaceous evolution of a metamorphic core complex, the Verporic unit, Western Carpathians (Slovakia): P-T conditions and in situ 40Ar/39Ar UV laser probe dating of metapelites. Journal of Metamorphic Geology, 19 (2), 197-216, doi:10.1046/j.0263-4929.2000.00304.x.Kramar, N., Cosca, M.A., Hunziker, J.C., 2001, Heterogenous 40Ar* distributions in naturally deformed muscovite: in situ UV-laser ablation evidence for microstructurally controlled intragrain diffusion. Earth and Planetary Science Letters, 192 (3), 377-388, doi:10.1016/S0012-821X(01)00456-3.Odin, G.S., Takahashi, M., and Cosca M.A., 2001, 40Ar/39Ar geochronology of Middle Miocene calcareous nannofossil biohorizhons in central Japan. Chemical Geology, 171 (3-4), 239-252, doi:10.1016/S0009-2541(00)00250-3.de Sigoyer, J., Chavagnac, V., Blichert-Toft, J., Villa, I., Luais, B., Guillot, S., Cosca, M., and Mascle, G., 2000, Dating the Indian continental subduction and collisional thickening in the northwest Himalaya: Multichronology of the Tso Morari eclogites. Geology, 28 (6), 487-490, doi:10.1130/0091-7613(2000)28<487:DTICSA>2.0.CO;2.Giorgis, D., Cosca, M.A., Li, S., 2000, Distribution and significance of extraneous argon in UHP eclogite (Sulu terrane, China): insights from in-situ 40Ar/39Ar UV-laser ablation analysis. Earth and Planetary Science Letters, 181 (4), 605-615, doi:10.1016/S0012-821X(00)00221-1.Zeh, A., Cosca, M., Brätz, H., Okrusch, M., and Tichomirova, M., 2000, Simultaneous horst-basin formation and magmatism during Late Variscan transtension: evidence from40Ar/39Ar and 207Pb/206Pb geochronology of the Ruhla Crystalline Complex, International Journal of Earth Science, 89 (1), 52-71, doi:10.1007/s005310050317.Cosca, M.A., Shimron, A., and Caby, R., 1999, Late Precambrian metamorphism and cooling in the Arabian-Nubian Shield: petrology and 40Ar/39Ar geochronology of metamorphic rocks of the Elat area (southern Israel). Precambrian Research, 98 (1-2), 107-127, doi:10.1016/S0301-9268(99)00044-3.Dèzes, P.J., Vannay, J.-C., Steck, A., Bussy, F., and Cosca, M., 1999, Synorogenic extension: quantitative constraints on the age and throw of the Zanskar Shear Zone (NW Himalaya). Geological Society of America Bulletin, 111 (3), 364-374, doi:10.1130/0016-7606(1999)111<0364:SEQCOT>2.3.CO;2.Guillot, S., Cosca, M.A., Allemand, P., and Le Fort, P., 1999, Contrasting metamorphic and geochronologic evolution along the Himalayan Belt. In: Macfarlane, A., Sorkhabi, R.B., Quade, J. (eds) Himalaya and Tibet: Mountain Roots to Mountain Tops. Geological Society of America Special Paper, 328, 117-128, doi:10.1130/0-8137-2328-0.117.Haeberlin, Y., Moritz, R., Fontboté, L., and Cosca, M., 1999, The Pataz gold province (Peru) within the frame of a mesothermal gold and antimony belt of the Eastern Andean Cordillera. In: Stanley, C.J., et al. (eds.) Mineral deposits: processes to processing. Balkema, 2, 1323-326.Jaboyedoff, M., and Cosca, M.A., 1999, Dating incipient metamorphism using 40Ar/39Ar geochronolgy and XRD modeling: a case study from the Swiss Alps. Contributions to Mineralogy and Petrology, 135, 93-113, doi:10.1007/s004100050500.Mezger, K., and Cosca, M.A., 1999, The thermal history of the Eastern Ghats (India) as revealed by U-Pb and 40Ar/39Ar dating of metamorphic and magmatic minerals: implications for the SWEAT correlation. Precambrian Research 94 (3-4), 251-271, doi:10.1016/S0301-9268(98)00118-1.Cosca, M.A., Arculus, R.J., Pearce, J.A., and Mitchell, J.G., 1998, Inception and early evolution of the Izu-Bonin-Mariana arc system: evidence from 40Ar/39Ar and K-Ar geochronology. The Island Arc, v. 7, p. 579-595.Cosca, M.A., Mezger, K., and Essene, E.J., 1998, The Baltica-Laurentia connection: Sveconorwegian (Grenvillian) metamorphism, cooling, and unroofing in the Bamble Sector, Norway. Journal of Geology, 106 (5), 539-552, doi:10.1086/516040.Markley, M.J., Teyssier, C., Cosca, M.A., Caby, R., Hunziker, J.C. and Sartori, M., 1998, Alpine deformation and 40Ar/39Ar geochronology of synkinematic white mica in the Siviez-Mischabel Nappe, western Pennine Alps, Switzerland. Tectonics, v. 17, p. 407-425.Roberts, D., Cosca, M.A., and Rice, A.H.N., 1998, A 40Ar/39Ar dating study of very low-grade metamorphism from the Rybachi and Sredni Peninsulas, NW Russia-a preliminary report. Norwegian Geological Survey Report, 168, 1-17.Bill, M., Bussy, F., Cosca, M., Masson, H., and Hunziker, J.C., 1997, High-precision U-Pb and 40Ar/39Ar dating of an Alpine ophiolite (Gets nappe, French Alps). Eclogae Geologicae Helvetiae, 90, 43-54.Bryant, C.J., Cosca, M.A., and Arculus, R.J., 1997, 40Ar/39Ar ages of Clarence River Supersuite intrusions from the northern portion of the New England Batholith, southern New England Orogen. In Ashley, P.M. and Flood, P.G., eds., Tectonics and Metallogenesis of the New England Orogen, Geological Society of Australia Special Publication, 19, 242-253.Hoinkes, G., Thöni, M., Lichem, C., Bernhard, F., Kaindl, R., Schweigel, J., Tropper P., and Cosca, M., 1997, Metagranitoids and associated metasediments as indicators for the pre-Alpine magmatic and metamorphic evolution of the western Austroalpine Oetztal Basement (Kaunertal, Tirol). Swiss Bulletin of Mineralogy and Petrology, 77, 299-314.Moecher, D.M., Cosca, M.A., and Hanson, G.N., 1997, Petrologic and 40Ar/39Ar geochronological constraints on the middle to late Paleozoic thermotectonic history of the southern Connecticut Valley zone, New England Appalachians. Geological Society of America Bulletin, 109 (2), 164-175, doi:10.1130/0016-7606(1997)109<0164:PAAAGC>2.3.CO;2.Odin, G.S., Amorosi, A., Tateo, F., Coccioni, R., Cosca, M., Negri, A., Pini, G.A., and Hunziker, J.C., 1997, Chapter C2 Integrated stratigraphy (biostratigraphy and geochronology) of the Early Miocene sequence from the Emilian Apennines (Italy). In Montanari, A., Coccioni, R., and Odin, G. S. (eds.) Miocene Integrated Stratigraphic Sequence, p. 221-248. Elsevier, Amsterdam, doi:10.1016/S0920-5446(06)80020-8.Odin, G.S., Cosca, M., Tateo, F., Negri, A., Vai, G. B., and Hunziker, J.C., 1997, Chapter E2 Integrated stratigraphy of the Late Tortonian Peive di Gesso section (Romagna, Italy). In Montanari, A., Coccioni, R., and Odin, G. S. (eds.) Miocene Integrated Stratigraphic Sequence, p. 449-460. Elsevier, Amsterdam.Odin, G.S., Cuenca Bescós, G., Canuda, J.J., Cosca, M., and Lago, M., 1997, Chapter C5 Biostratigraphy and geochronology of a Miocene continental volcanoclastic layer from the Ebro basin, Spain. In Montanari, A., Coccioni, R., and Odin, G. S. (eds.) Miocene Integrated Stratigraphic Sequence, p. 297-310. Elsevier, Amsterdam.Odin, G.S., d’Atri, A., Tateo, F., Cosca, M., and Hunziker, J.C., 1997, Chapter C1 Integrated stratigraphy near the Oligocene-Miocene boundary in the Piedmont basin (Italy): biostratigraphy and geochronology. In Montanari, A., Coccioni, R., and Odin, G. S. (eds.) Miocene Integrated Stratigraphic Sequence, p. 209-220. Elsevier, Amsterdam, doi:10.1016/S0920-5446(06)80019-1.Odin, G.S., Deino, A., Cosca, M., Laurenzi, M.A., and Montanari, A., 1997, Chapter F1 Miocene geochronology: methods, techniques, and results. In Montanari, A., Coccioni, R., and Odin, G. S. (eds.) Miocene Integrated Stratigraphic Sequence, p. 581-594. Elsevier, Amsterdam.Odin, G.S., Miculan, P., Cosca, M., Tateo, F., Amorosi, A., and Hunziker, J.C., 1997, Chapter D3Biostratigraphy and geochronology of an Early Serravallian volcanoclastic layer from Sicily. In Montanari, A., Coccioni, R., and Odin, G. S. (eds.) Miocene Integrated Stratigraphic Sequence, p. 351-360. Elsevier, Amsterdam.Odin, G.S., Ricci Lucchi, F., Tateo, F., Cosca, M., and Hunziker, J.C., 1997, Chapter E7 Integrated stratigraphy of the Maccarone section, Late Messinian (Marche region, Italy). In Montanari, A., Coccioni, R., and Odin, G. S. (eds.) Miocene Integrated Stratigraphic Sequence, p. 529-544. Elsevier, Amsterdam.Odin, G.S., Takahashi, M., Coccioni, R., and Cosca, M., 1997, Chapter D7 Géochronologie de niveaux situés autour de l’apparition de Globigerina nepenthes au Japon et in Italie: âge de la limite Serravallien/Tortonien. In Montanari, A., Coccioni, R., and Odin, G. S. (eds.) Miocene Integrated Stratigraphic Sequence, p. 393-400. Elsevier, Amsterdam.Odin, G.S., Vai, G.B., Cosca, M., Tateo, F., and Hunziker, J.C., 1997, Chapter E6 Contribution to the geochronology of the Tortonian/Messinian bundary in the Faenza (Romagna, Italy). In Montanari, A., Coccioni, R., and Odin, G. S. (eds.) Miocene Integrated Stratigraphic Sequence, p. 519-528. Elsevier, Amsterdam, doi:10.1016/S0920-5446(06)80038-5.Restrepo-Pace, P.A., Ruiz, J., Gehrels, G., and Cosca, M., 1997, Geochronology and Nd isotopic data of Grenville-age rocks in the Colombian Andes: new constraints for Late Proterozoic-Early Paleozoic paleocontinental reconstructions of the Americas. Earth and Planetary Science Letters, 150 (3-4), 427-441, doi:10.1016/S0012-821X(97)00091-5.Kirschner, D.L., Cosca, M.A., Hunziker, J.C., and Masson, H., 1996, Staircase 40Ar/39Ar spectra of fine-grained white mica: timing and duration of deformation and empirical constraints on argon diffusion. Geology, v. 24, p. 747-750.Schärer, U., Cosca, M., Hunziker, J., and Steck, A., 1996, Termination of major ductile strike-slip shear and differential cooling along the Insubric line (Central Alps): U/Pb, Rb/Sr and 40Ar/39Ar ages of cross-cutting pegmatites. Earth and Planetary Science Letters, v. 142, p. 331-352.Cosca, M.A., Essene, E.J., Mezger, K., and van der Pluijm, B.A., 1995, Constraints on the duration of tectonic processes: protracted extension and deep crustal rotation in the Grenville Orogen. Geology, 23 (4), 361-364, doi:10.1130/0091-7613(1995)023<0361:COTDOT>2.3.CO;2.Crespo-Blanc, A., Masson, H., Sharp, Z., Cosca, M., and Hunziker, J., 1995, A stable and 40Ar/39Ar isotope study of a major thrust in the Helvetic nappes (Swiss Alps): evidence for fluid flow and constraints on nappe kinematics. Geological Society of America Bulletin, 107 (10), 1129-1144, doi:10.1130/0016-7606(1995)107<1129:ASAAAI>2.3.CO;2.Odin, G.S., Coccioni, R., Cosca, M., and Montanari, A., 1995, 40Ar/39Ar geochronology of biostratigraphically controlled Miocene tuffs from central Japan: Comparison with Italy and age of the Serravallian-Tortonian boundary. Chemical Geology, 125 (1-2), 105-121, doi:10.1016/0009-2541(95)00075-W.Ruffini, R., Cosca, M.A., d’Atri, A., Hunziker, J.C., and Polino, R., 1995, The volcanic supply of the Taveyanne turbidites (Savoie, France): a riddle for Tertiary Alpine volcanism. In: Polino, R. And Sacchi, R. (eds.) Rapporti Alpi-Appennino e Guide Alle Escursioni, Accademia Nazionale Delle Scienze Detta Dei XL, Roma, p. 359-376.Schmädicke, E., Mezger, K., Cosca, M.A., and Okrusch, M., 1995, Variscan Sm/Nd and Ar/Ar ages of eclogite-facies rocks from the Erzgebirge, Bohemian Massif. Journal of Metamorphic Geology, 13 (5), 537 - 552, doi:10.1111/j.1525-1314.1995.tb00241.x.Cosca, M.A. and O'Nions R.K., 1994, A re-examination of the influence of composition on argon retentivity in metamorphic calcic amphiboles. Chemical Geology, 112 (1-2), 39-56, doi:10.1016/0009-2541(94)90103-1.Odin, G.S., Assorgia, A., Barca, S., Porcu, A., Spano, J., and Cosca, M., 1994, 40Ar/39Ar geochronology of a Burdigalian tuff from central-northern Sardinia. Giornale Geologia, v. 56, p. 185-197.Odin, G.S., Jelen, B., Drobne, K., Uhan, J., Skaberne, D., PavŠic, J., Cimerman, F.. Cosca, M., and Hunziker, J.C., 1994, Premiers âge géochronologiques de niveaux volcaniclastiques oligocènes de la Région de Zasavje, Slovénie. Giornale Geologia, v. 56, p. 199-212.van der Pluijm, B.A., Mezger, K., Cosca, M.A., and Essene, E.J., 1994, Determining the significance of high-grade shear zones by using temperature-time paths, with examples from the Grenville Orogen. Geology, 22 (8), 743-746, doi:10.1130/0091-7613(1994)022<0743:DTSOHG>2.3.CO;2.Spring, L., Bussy, F., Vannay, J.C., Huon, S., and Cosca, M.A., 1993, Early Permian granitic dykes of alkaline affinity in the Indian High Himalaya of Upper Lahul and SE Zanskar: geochemical characterization and geotectonic implications. Geological Society, London, Special Publications, 74, 251-264, doi:10.1144/GSL.SP.1993.074.01.18.Cosca, M.A., Essene, E.J., Kunk, M.J., and Sutter, J.F., 1992, Differential unroofing within the Central Metasedimentary Belt of the Grenville Orogen: constraints from 40Ar/39Ar thermochronology. Contributions to Mineralogy and Petrology, 110, 211-225, doi:10.1007/BF00310739.Cosca, M.A., Hunziker, J.C., Huon, S., and Masson, H., 1992, Radiometric age constraints on mineral growth, metamorphism, and tectonism of the Gummfluh Klippe, Briançonnais domain of the Préalpes, Switzerland. Contributions to Mineralogy and Petrology, 112, 439-449, doi:10.1007/BF00310776.Cosca, M.A., Essene, E.J., and Bowman, J.R., 1991, Complete chemical analyses of metamorphic hornblendes: implications for normalizations, calculated H2O activities and thermobarometry. Contributions to Mineralogy and Petrology, 108, 472-484, doi:10.1007/BF00303451.Cosca, M.A., Sutter, J.F., and Essene, E.J., 1991, Cooling and inferred uplift/erosion history of the Grenville Orogen, Ontario: constraints from 40Ar/39Ar thermochronology. Tectonics, 10 (5), 959-977, doi:10.1029/91TC00859.Cosca, M.A., Sutter, J.F., and Essene, E.J., 1990, Comment on "Interpretation of K/Ar mineral dates from the Grenville Orogenic Belt." American Journal of Science, 290 (2), 202-204, doi:10.2475/ajs.290.2.202.Cosca, M.A., 1989, Cooling and inferred uplift history of the Grenville Orogen, Ontaria: constraints from 40Ar/39Ar thermochronology: PhD thesis University of Michigan, 235 pp.Cosca, M.A., Essene, E.J., Geissman, J.G., Simmons, W.B., and Coates, D.A., 1989, Pyrometamorphic rocks associated with naturally burned coal beds, Powder River Basin, Wyoming. American Mineralogist, 74 (1-2), 85-100, https://pubs.geoscienceworld.org/ammin/article/74/1-2/85/42195/Pyrometamorphic-rocks-associated-with-naturally.Cosca, M.A., Rouse, R.C., and Essene, E.J., 1988, Dorrite (Ca2(Mg2 Fe3+4)(Al4Si2)O20), a new member of the aenigmatite group from a pyrometamorphic melt-rock. American Mineralogist, 73 (11-12), 1440-1449, https://pubs.geoscienceworld.org/ammin/article/73/11-12/1440/42089/Dorite-Ca-2-Mg-2-Fe-super-3-4-Al-4-Si-2-O-20-a-new.Cosca, M.A., and Peacor, D.R., 1987, Chemistry and structure of esseneite (CaFe3+AlSiO6), a new pyroxene produced by pyrometamorphism: American Mineralogist, 72 (1-2), 148-156, https://pubs.geoscienceworld.org/ammin/article/72/1-2/148/41909/Chemistry-and-structure-of-esseneite-CaFe-super-3.Yau, Y.C., Peacor, D.R., Essene, E.J., Lee, J.H., Kuo, L.C., and Cosca, M.A., 1987, Hydrothermal experiments on candidate packing materials. Clays and Clay Mineralalogy, 35 (4), 241-250, https://pubs.geoscienceworld.org/ccm/article/35/4/241/47021/Hydrothermal-treatment-of-smectite-illite-and.**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.