Tephrochronology is the study of volcanic ash deposits, combining petrology, geochemistry, and isotopic dating methods. We use tephrochronology, along with other chronostratigraphic techniques, to (1) determine the ages of coincident deposits, and, when multiple tephra layers are present, determine the history of geologic events and rates of geologic processes; and (2) correlate sediments from disparate depositional basins and diverse ecological environments.
Project Mission:
The mission of the Tephrochronology Project is to research, develop, and provide chronostratigraphic information based on studies of volcanic ash layers and tuffs (tephra layers) to various USGS programmatic investigations. The Project also collaborates on a wide range of studies with numerous external agencies (such as universities, and local, state, and other federal agencies).
The Tephrochronology Project provides age and stratigraphic information based on studies of volcanic ash layers and tuffs (tephra layers) to various earth science investigations primarily in the western U.S. The project provides stratigraphic correlation and age control to:
1) studies of faults, earthquake recurrence and hazards mitigation, and neotectonics
2) studies of volcanic hazards, eruption recurrence, and eruptive sources of tephra
3) studies of global change, including correlation and dating of climate-proxy data among depositional basins, and between marine and continental basins
4) topical and regional geologic mapping studies.
Tephra layers are collected at critical locations where age control is required. Then, back in the Tephrochronology Laboratory, the samples are processed and physical characteristics (such as glass shard morphology and mineralogy) of the tephra components are described, and the presence and characteristics of other components (lithic fragments, cements, microfossils1, etc.) are noted. Next, the volcanic glass is separated from the rest of the tephra and analyzed by one or more chemical techniques to determine a compositional "fingerprint." Finally, computer matching software compare this fingerprint with our digital database of approximately 5,900 previously analyzed samples to identify the best matches, and a pool of candidates is generated for correlative samples. The analyzed tephra samples are evaluated in terms of petrographic, stratigraphic, and chronologic criteria to identify the best matches.
These procedures permit correlation of tephra layers at critical sites to other localities where the same tephra layers are present, and often to sites where the ages of the layers have been previously determined by one or more numerical dating methods. New tephra layers are analyzed and dated at those sites where the best materials for dating can be obtained.
The results of our tephrochronologic research are combined with other chronostratigraphic data (for example, isotopic ages, magnetostratigraphy, oxygen-isotope chronostratigraphy, and stratigraphic sequence information) to develop a four-dimensional spatial and temporal chronostratigraphic framework for Neogene sediments and rocks in the western U.S. and the Pacific margin.
1Tephra Project scientists are also capable of providing micropaleontologic support in the forms of Cenozoic planktic and benthic foraminiferal biostratigraphy and analyses of foraminifers and pollen as proxies for shifting paleoenvironmental conditions. These capabilities permit further refinement of preliminary chronostratigraphic frameworks and reconstructions of past climate.
Archive Collections:
In addition to our expansive digital archives of analytical (Electron Microprobe, XRF, INAA, Ion Microprobe (SHRIMP-RG), ICP-MS, etc.), descriptive, and sample locality data, and physical collections of ~7,300 raw outcrop and core samples and finished volcanic glass separates mostly from the western and central regions of the United States, the Tephrochronology Project also is a repository for tephrochronological reference materials from Alaska, New Zealand, Mexico, and Central America, and parts of Europe and Asia. We also hold in our collections Deep Sea Drilling Project (DSDP) and Ocean Drilling Project (ODP) core samples from the northeastern Pacific Ocean, and numerous core samples from many lakes located throughout the western U.S.
Highly important collections include volcanic material collected by then Tephra Project Chief Scientist Andrei Sarna-Wojcicki just prior to, and shortly after the May 18, 1980, eruption of Mount Saint Helens in Washington. Original field notes on the nature and impact of the tephra fallout from that, and subsequent eruptions are also available for reference and study.
Another key reference set consists of 19 discrete Quaternary tephra layers in stratigraphic sequence from the Wilson Creek section of Mono Craters, CA. These tephra samples and the results from our own studies have been and are of very great interest to many investigators working in the region on numerous studies in need of age control. Researchers requesting tephrochronologic support include from scientists from the USGS Long Valley Observatory of the Volcano Hazards Science Center, Geology of Federal Lands in the eastern Sierra Region project, SW Great Basin Project, among many others.
Tephra geochemistry of the Ibex Hollow Tuff, a 12-Ma super-eruption
Below are maps associated with this project.
Geologic map of the Providence Mountains in parts of the Fountain Peak and adjacent 7.5' quadrangles, San Bernardino County, California
Surficial geology and stratigraphy of Pleistocene Lake Manix, San Bernardino County, California
Geologic map and upper Paleozoic stratigraphy of the Marble Canyon area, Cottonwood Canyon quadrangle, Death Valley National Park, Inyo County, California
Below are publications associated with this project.
Ibex Hollow Tuff from ca. 12 Ma supereruption, southern Idaho, identified across North America, eastern Pacific Ocean, and Gulf of Mexico
From saline to freshwater: The diversity of western lakes in space and time
Lake Andrei: A pliocene pluvial lake in Eureka Valley, Eastern California
Born of fire: In search of volcanoes in U.S. national parks, four striking examples
The story of a Yakima fold and how it informs Late Neogene and Quaternary backarc deformation in the Cascadia subduction zone, Manastash anticline, Washington, USA
Geology of the Greenwater Range, and the dawn of Death Valley, California—Field guide for the Death Valley Natural History Conference, 2013
Holocene environmental changes inferred from biological and sedimentological proxies in a high elevation Great Basin lake in the northern Ruby Mountains, Nevada, USA
Quaternary tephrochronology and deposition in the subsurface Sacramento–San Joaquin Delta, California, U.S.A.
Distribution of biologic, anthropogenic, and volcanic constituents as a proxy for sediment transport in the San Francisco Bay Coastal System
Distribution of biologic, anthropogenic, and volcanic constituents as a proxy for sediment transport in the San Francisco Bay Coastal System
Structure and tectonic evolution of the eastern Española Basin, Rio Grande rift, north-central New Mexico
Paleontology and geochronology of the Long Beach core sites and monitoring wells, Long Beach, California
- Overview
Tephrochronology is the study of volcanic ash deposits, combining petrology, geochemistry, and isotopic dating methods. We use tephrochronology, along with other chronostratigraphic techniques, to (1) determine the ages of coincident deposits, and, when multiple tephra layers are present, determine the history of geologic events and rates of geologic processes; and (2) correlate sediments from disparate depositional basins and diverse ecological environments.
Project Mission:
The mission of the Tephrochronology Project is to research, develop, and provide chronostratigraphic information based on studies of volcanic ash layers and tuffs (tephra layers) to various USGS programmatic investigations. The Project also collaborates on a wide range of studies with numerous external agencies (such as universities, and local, state, and other federal agencies).
The Tephrochronology Project provides age and stratigraphic information based on studies of volcanic ash layers and tuffs (tephra layers) to various earth science investigations primarily in the western U.S. The project provides stratigraphic correlation and age control to:
1) studies of faults, earthquake recurrence and hazards mitigation, and neotectonics
2) studies of volcanic hazards, eruption recurrence, and eruptive sources of tephra
3) studies of global change, including correlation and dating of climate-proxy data among depositional basins, and between marine and continental basins
4) topical and regional geologic mapping studies.Tephra layers are collected at critical locations where age control is required. Then, back in the Tephrochronology Laboratory, the samples are processed and physical characteristics (such as glass shard morphology and mineralogy) of the tephra components are described, and the presence and characteristics of other components (lithic fragments, cements, microfossils1, etc.) are noted. Next, the volcanic glass is separated from the rest of the tephra and analyzed by one or more chemical techniques to determine a compositional "fingerprint." Finally, computer matching software compare this fingerprint with our digital database of approximately 5,900 previously analyzed samples to identify the best matches, and a pool of candidates is generated for correlative samples. The analyzed tephra samples are evaluated in terms of petrographic, stratigraphic, and chronologic criteria to identify the best matches.
These procedures permit correlation of tephra layers at critical sites to other localities where the same tephra layers are present, and often to sites where the ages of the layers have been previously determined by one or more numerical dating methods. New tephra layers are analyzed and dated at those sites where the best materials for dating can be obtained.
The results of our tephrochronologic research are combined with other chronostratigraphic data (for example, isotopic ages, magnetostratigraphy, oxygen-isotope chronostratigraphy, and stratigraphic sequence information) to develop a four-dimensional spatial and temporal chronostratigraphic framework for Neogene sediments and rocks in the western U.S. and the Pacific margin.
1Tephra Project scientists are also capable of providing micropaleontologic support in the forms of Cenozoic planktic and benthic foraminiferal biostratigraphy and analyses of foraminifers and pollen as proxies for shifting paleoenvironmental conditions. These capabilities permit further refinement of preliminary chronostratigraphic frameworks and reconstructions of past climate.
Archive Collections:
In addition to our expansive digital archives of analytical (Electron Microprobe, XRF, INAA, Ion Microprobe (SHRIMP-RG), ICP-MS, etc.), descriptive, and sample locality data, and physical collections of ~7,300 raw outcrop and core samples and finished volcanic glass separates mostly from the western and central regions of the United States, the Tephrochronology Project also is a repository for tephrochronological reference materials from Alaska, New Zealand, Mexico, and Central America, and parts of Europe and Asia. We also hold in our collections Deep Sea Drilling Project (DSDP) and Ocean Drilling Project (ODP) core samples from the northeastern Pacific Ocean, and numerous core samples from many lakes located throughout the western U.S.
Highly important collections include volcanic material collected by then Tephra Project Chief Scientist Andrei Sarna-Wojcicki just prior to, and shortly after the May 18, 1980, eruption of Mount Saint Helens in Washington. Original field notes on the nature and impact of the tephra fallout from that, and subsequent eruptions are also available for reference and study.
Another key reference set consists of 19 discrete Quaternary tephra layers in stratigraphic sequence from the Wilson Creek section of Mono Craters, CA. These tephra samples and the results from our own studies have been and are of very great interest to many investigators working in the region on numerous studies in need of age control. Researchers requesting tephrochronologic support include from scientists from the USGS Long Valley Observatory of the Volcano Hazards Science Center, Geology of Federal Lands in the eastern Sierra Region project, SW Great Basin Project, among many others.
- Data
Tephra geochemistry of the Ibex Hollow Tuff, a 12-Ma super-eruption
These tables contain geochemical data collected for tephra samples either correlated with or in the same type section with the Ibex Hollow Tuff. Most samples were collected by Andrei Sarna-Wojcicki and Mike Perkins, but some were submitted to the U.S. Geological Survey Tephrochronology Project for analysis by other persons. Electron microprobe analysis (EMA) was performed at the U.S. Geological Su - Maps
Below are maps associated with this project.
Geologic map of the Providence Mountains in parts of the Fountain Peak and adjacent 7.5' quadrangles, San Bernardino County, California
IntroductionThe Providence Mountains are in the eastern Mojave Desert about 60 km southeast of Baker, San Bernardino County, California. This range, which is noted for its prominent cliffs of Paleozoic limestone, is part of a northeast-trending belt of mountainous terrain more than 100 km long that also includes the Granite Mountains, Mid Hills, and New York Mountains. Providence Mountains State RSurficial geology and stratigraphy of Pleistocene Lake Manix, San Bernardino County, California
Pluvial Lake Manix and its surrounding drainage basin, in the central Mojave Desert of California, has been a focus of paleoclimate, surficial processes, and neotectonic studies by the U.S. Geological Survey (USGS) since about 2004. The USGS initiated studies of Lake Manix deposits to improve understanding of the paleoclimatic record and the shifts in atmospheric circulation that controlled precipGeologic map and upper Paleozoic stratigraphy of the Marble Canyon area, Cottonwood Canyon quadrangle, Death Valley National Park, Inyo County, California
This geologic map and pamphlet focus on the stratigraphy, depositional history, and paleogeographic significance of upper Paleozoic rocks exposed in the Marble Canyon area in Death Valley National Park, California. Bedrock exposed in this area is composed of Mississippian to lower Permian (Cisuralian) marine sedimentary rocks and the Jurassic Hunter Mountain Quartz Monzonite. These units are overl - Publications
Below are publications associated with this project.
Filter Total Items: 16Ibex Hollow Tuff from ca. 12 Ma supereruption, southern Idaho, identified across North America, eastern Pacific Ocean, and Gulf of Mexico
The Ibex Hollow Tuff, 12.08 ± 0.03 Ma (40Ar/39Ar), is a widespread tephra layer erupted from the Bruneau-Jarbidge volcanic field of southern Idaho. Tephra from this eruption was deposited across much of western and central North America and adjacent ocean areas. We identified the Ibex Hollow Tuff at Trapper Creek, Idaho, near its eruption site, and at 15 distal sites, from the Pacific Ocean to theAuthorsAndrei M. Sarna-Wojcicki, Jeffrey R. Knott, John A. Westgate, James R. Budahn, John A. Barron, Colin J. Bray, Greg A. Ludvigson, Charles E. Meyer, David M. Miller, Rick E. Otto, Nicholas J.G. Pearce, Charles C. Smith, Laura Walkup, Elmira Wan, James YountFrom saline to freshwater: The diversity of western lakes in space and time
Beginning with the nineteenth-century territorial surveys, the lakes and lacustrine deposits in what is now the western United States were recognized for their economic value to the expanding nation. In the latter half of the twentieth century, these systems have been acknowledged as outstanding examples of depositional systems serving as models for energy exploration and environmental analysis, mLake Andrei: A pliocene pluvial lake in Eureka Valley, Eastern California
We used geologic mapping, tephrochronology and 40Ar/39Ar dating to describe evidence of a ca. 3.5 Ma pluvial lake in Eureka Valley, eastern California, that we informally name herein Lake Andrei. We identified six different tuffs in the Eureka Valley drainage basin including two previously undescribed tuffs: the 3.509 ± 0.009 Ma tuff of Hanging Rock Canyon and the 3.506 ± 0.010 Ma tuff of Last ChaAuthorsJeffrey R. Knott, Elmira Wan, Alan L. Deino, Mitch Casteel, Marith C. Reheis, Fred Phillips, Laura Walkup, Kyle McCarty, David N. Manoukian, Ernest NuñezBorn of fire: In search of volcanoes in U.S. national parks, four striking examples
Geologic features, particularly volcanic features, have been protected by the National Park Service since its inception. Some volcanic areas were nationally protected even before the National Park Service was established. The first national park, Yellowstone National Park, is one of the most widely known geothermal and volcanic areas in the world. It contains the largest volcanic complex in NorthAuthorsLaura Walkup, Thomas Casadevall, Vincent L. SantucciThe story of a Yakima fold and how it informs Late Neogene and Quaternary backarc deformation in the Cascadia subduction zone, Manastash anticline, Washington, USA
The Yakima folds of central Washington, USA, are prominent anticlines that are the primary tectonic features of the backarc of the northern Cascadia subduction zone. What accounts for their topographic expression and how much strain do they accommodate and over what time period? We investigate Manastash anticline, a north vergent fault propagation fold typical of structures in the fold province. FAuthorsHarvey M. Kelsey, Tyler C. Ladinsky, Lydia M. Staisch, Brian L. Sherrod, Richard J. Blakely, Thomas Pratt, William Stephenson, Jackson K. Odum, Elmira WanGeology of the Greenwater Range, and the dawn of Death Valley, California—Field guide for the Death Valley Natural History Conference, 2013
Much has been written about the age and formation of Death Valley, but that is one—if not the last—chapter in the fascinating geologic history of this area. Igneous and sedimentary rocks in the Greenwater Range, one mountain range east of Death Valley, tell an earlier story that overlaps with the formation of Death Valley proper. This early story has been told by scientists who have studied theseAuthorsJ. P. Calzia, O.T. Rämö, Robert Jachens, Eugene Smith, Jeffrey KnottHolocene environmental changes inferred from biological and sedimentological proxies in a high elevation Great Basin lake in the northern Ruby Mountains, Nevada, USA
Multi-proxy analyses were conducted on a sediment core from Favre Lake, a high elevation cirque lake in the northern Ruby Mountains, Nevada, and provide a ca. 7600 year record of local and regional environmental change. Data indicate that lake levels were lower from 7600-5750 cal yr BP, when local climate was warmer and/or drier than today. Effective moisture increased after 5750 cal yr BP and remAuthorsDavid B. Wahl, Scott W. Starratt, Lysanna Anderson, Jennifer E. Kusler, Christopher C. Fuller, Jason A. Addison, Elmira WanQuaternary tephrochronology and deposition in the subsurface Sacramento–San Joaquin Delta, California, U.S.A.
We document characteristics of tephra, including facies and geochemistry, from 27 subsurface sites in the Sacramento-San Joaquin Delta, California, to obtain stratigraphic constraints in a complex setting. Analyzed discrete tephra deposits are correlative with: 1) an unnamed tephra from the Carlotta Formation near Ferndale, California, herein informally named the ash of Wildcat Grade (<~1.450 - >~AuthorsKatherine L. Maier, Emma Gatti, Elmira Wan, Daniel J. Ponti, Mark Pagenkopp, Scott W. Starratt, Holly A. Olson, John TinsleyDistribution of biologic, anthropogenic, and volcanic constituents as a proxy for sediment transport in the San Francisco Bay Coastal System
Although conventional sediment parameters (mean grain size, sorting, and skewness) and provenance have typically been used to infer sediment transport pathways, most freshwater, brackish, and marine environments are also characterized by abundant sediment constituents of biological, and possibly anthropogenic and volcanic, origin that can provide additional insight into local sedimentary processesAuthorsMary McGann, Li H. Erikson, Elmira Wan, Charles L. Powell, Rosalie F. MaddocksDistribution of biologic, anthropogenic, and volcanic constituents as a proxy for sediment transport in the San Francisco Bay Coastal System
Although conventional sediment parameters (mean grain size, sorting, and skewness) and provenance have typically been used to infer sediment transport pathways, most freshwater, brackish, and marine environments are also characterized by abundant sediment constituents of biological, and possibly anthropogenic and volcanic, origin that can provide additional insight into local sedimentary processesAuthorsMary McGann, Li H. Erikson, Elmira Wan, Charles L. Powell, Rosalie F. MaddocksStructure and tectonic evolution of the eastern Española Basin, Rio Grande rift, north-central New Mexico
We describe the structure of the eastern Española Basin and use stratigraphic and stratal attitude data to interpret its tectonic development. This area consists of a west-dipping half graben in the northern Rio Grande rift that includes several intrabasinal grabens, faults, and folds. The Embudo–Santa Clara–Pajarito fault system, a collection of northeast- and north-striking faults in the centerAuthorsDaniel Koning, V. J. Grauch, Sean D. Connell, J. Ferguson, William McIntosh, Janet L. Slate, Elmira Wan, W. S. BaldridgePaleontology and geochronology of the Long Beach core sites and monitoring wells, Long Beach, California
The U.S. Geological Survey's Focus on Quaternary Stratigraphy in Los Angeles (FOQUS-LA) project was a cooperative coring program between Federal, State, and local agencies. It was designed to provide a better understanding of earthquake potentials and to develop a stratigraphic model of the western Los Angeles Basin in California. The biostratigraphic, geochronologic, and paleoecologic analyses ofAuthorsKristin McDougall, John Hillhouse, Charles Powell, Shannon Mahan, Elmira Wan, Andrei M. Sarna-Wojcicki