Publications
Filter Total Items: 890
40Ar/39Ar thermochronology and Alleghanian development of the southernmost Appalachian Piedmont, Alabama and southwest Georgia 40Ar/39Ar thermochronology and Alleghanian development of the southernmost Appalachian Piedmont, Alabama and southwest Georgia
40Ar/39Ar age spectra of hornblende, muscovite, and microcline, and total fusion ages of biotite from metamorphic rocks of the Inner Piedmont, Pine Mountain, and Uchee belts are reported. Mineral cooling ages from the eastern part of the Inner Piedmont are as follows: hornblende, 320 Ma; muscovite, 296 Ma; biotite, 293 Ma; and microcline (diffusional release patterns) Tmax = 267 Ma, Tmin...
Authors
Mark G. Steltenpohl, Michael J. Kunk
Exhumation of eclogitized continental basement during Variscan lithospheric delamination and gravitational collapse, Sudety Mountains, Poland Exhumation of eclogitized continental basement during Variscan lithospheric delamination and gravitational collapse, Sudety Mountains, Poland
A Variscan,deep-crustal-level (eclogite-facies),continental basement massif in western Poland, the Snieznik complex, was tectonically exhumed. Crustal-penetrating mylonite zones record three main kinematic events: early top-to-the-north-directed thrusting, right-slip transpression-tension, and late top-to-the-south and -east normal faulting. Thrusting resulted in extreme crustal...
Authors
Mark G. Steltenpohl, Zbignew Cymerman, E.J. Krogh, Michael J. Kunk
Middle Eocene intrusive igneous rocks of the central Appalachian Valley and Ridge province - Setting, chemistry, and implications for crustal structure Middle Eocene intrusive igneous rocks of the central Appalachian Valley and Ridge province - Setting, chemistry, and implications for crustal structure
No abstract available.
Authors
C. Scott Southworth, Karen J. Gray, John F. Sutter
A detailed taxonomy of Upper Cretaceous and lower Tertiary Crassatellidae in the eastern United States: An example of the nature of extinction at the boundary A detailed taxonomy of Upper Cretaceous and lower Tertiary Crassatellidae in the eastern United States: An example of the nature of extinction at the boundary
Current theories on the causes of extinction at the Cretaceous-Tertiary boundary have been based on previously published data; however, few workers have stopped to ask the question, 'How good is the basic data set?' To test the accuracy of the published record, a quantitative and qualitative analysis of the Crassatellidae (Mollusca, Bivalvia) of the Gulf and Mid-Atlantic Coastal Plains...
Authors
G. Lynn Wingard
Paleozoic and Mesozoic rocks of Mount Ichabod and Dorsey Canyon, Elko County, Nevada: Evidence for post-Early Triassic emplacement of the Roberts Mountains and Golconda allochthons Paleozoic and Mesozoic rocks of Mount Ichabod and Dorsey Canyon, Elko County, Nevada: Evidence for post-Early Triassic emplacement of the Roberts Mountains and Golconda allochthons
No abstract available.
Authors
Keith B. Ketner, Benita L. Murchey, Robert G. Stamm, Bruce R. Wardlaw
Contrasting P‐T‐t paths: Thermochronologic evidence for a Late Paleozoic final assembly of the Avalon Composite Terrane in the New England Appalachians Contrasting P‐T‐t paths: Thermochronologic evidence for a Late Paleozoic final assembly of the Avalon Composite Terrane in the New England Appalachians
Strongly contrasting pressure‐temperature‐time paths for the Avalon composite terrane and the structurally overlying Putnam‐Nashoba zone in eastern New England obtained from thermochronologic and thermobarometric data are best explained by a late Paleozoic underthrusting of cover rocks by the Avalon composite terrane. We present new Ar and U‐Pb thermochronologic data that show that in...
Authors
R. P. Wintsch, J. F. Sutter, Michael J. Kunk, John N. Aleinikoff, Michael J. Dorais
High resolution late Pliocene sea-surface temperature record from the northeast Atlantic Ocean High resolution late Pliocene sea-surface temperature record from the northeast Atlantic Ocean
Application of quantitative micropaleontologic methods of sea-surface temperature (SST) estimation to the planktic foraminiferal faunas at Hole 548 in the northeast Atlantic between 3.5 and 2.0 Ma provide a detailed record of Pliocene surface temperature changes during the onset of major Northern Hemisphere glaciation. SST estimates indicate a relatively warm interval of “enhanced...
Authors
Harry J. Dowsett, P. Loubere
Closure of the Isthmus of Panama: The near-shore marine record of Costa Rica and western Panama Closure of the Isthmus of Panama: The near-shore marine record of Costa Rica and western Panama
The final closure of the Isthmus of Panama at ∼3.5 Ma divided the American tropical ocean into two separate and different oceanographic regions. Consequences for the marine biota were profound, but, hitherto, correlation of the Pacific and Caribbean coastal sections has not been precise enough to track biologic patterns. We present here a correlation of 31 sections from the Pacific and...
Authors
Anthony G. Coates, Jeremy B. C. Jackson, Laurel S. Collins, Thomas M. Cronin, Harry J. Dowsett, Laurel M. Bybell, Peter Jung, Jorge Obando
Alleghanian development of the Goat Rock fault zone, southernmost Appalachians: Temporal compatibility with the master decollement Alleghanian development of the Goat Rock fault zone, southernmost Appalachians: Temporal compatibility with the master decollement
The Goat Rock and associated Bartletts Ferry fault zones, which mark the eastern margin of the Pine Mountain Grenville basement massif, are controversial due to the suggestion that they are rare exposed segments of the late Paleozoic southern Appalachian master decollement. The controversy in part stems from reported middle Paleozoic (Acadian) radiometric dates postulated as the time of...
Authors
Mark G. Steltenpohl, S. Goldberg, T.B. Hanley, Michael J. Kunk
Calibration of the latest Eocene-Oligocene geomagnetic polarity time scale using 40 Ar/ 39 Ar dated ignimbrites Calibration of the latest Eocene-Oligocene geomagnetic polarity time scale using 40 Ar/ 39 Ar dated ignimbrites
A discontinuous record of late Eocene-Oligocene geomagnetic polarity has been determined using high-precision (±
Authors
W. C. McIntosh, J. W. Geissman, C.E. Chapin, Michael J. Kunk, Christopher D. Henry
Hydrogeology of thick till deposits in Connecticut Hydrogeology of thick till deposits in Connecticut
No abstract available.
Authors
Robert L. Melvin, Byron D. Stone, J. R. Stone, N.J. Trask