Jeff Pigati
I study geologic deposits associated with springs and desert wetlands to understand how hydrologic systems in arid environments responded to past episodes of abrupt climate change. I also develop and test innovative methods and materials for radiocarbon dating.
I am also part of an international team of researchers studying ancient human footprints in White Sands National Park. The results of our investigations have shown that humans were in continental North America during the Last Glacial Maximum, between 23,000 and 21,000 years ago, which fundamentally changes our understanding of the peopling of the Americas.
Professional Experience
Research Geologist, U.S. Geological Survey, Geosciences and Environmental Change Science Center, 2007-present
Education and Certifications
Ph.D., University of Arizona. 2004
M.S., University of Arizona. 1996
B.S., Southern Illinois University at Carbondale. 1992
Science and Products
Accumulation of impact markers in desert wetlands and implications for the Younger Dryas impact hypothesis
Radiocarbon ages of terrestrial gastropods extend duration of ice-free conditions at the Two Creeks forest bed, Wisconsin, USA
Late Quaternary sedimentological and climate changes at Lake Bosumtwi Ghana: new constraints from laminae analysis and radiocarbon age modeling
Primary mapping and stratigraphic data and field methods for the Snowmastodon Project
Assessing open-system behavior of 14C in terrestrial gastropod shells
Chronology, sedimentology, and microfauna of groundwater discharge deposits in the central Mojave Desert, Valley Wells, California
Chronology, sedimentology, and microfauna of groundwater discharge deposits in the central Mojave Desert, Valley Wells, California
Extraction of in situ cosmogenic 14C from olivine
A simplified In Situ cosmogenic 14C extraction system
Radiocarbon dating of small terrestrial gastropod shells in North America
Late Pleistocene paleohydrology near the boundary of the Sonoran and Chihuahuan Deserts, southeastern Arizona, USA
A 3000-year record of ground-rupturing earthquakes along the central North Anatolian fault near Lake Ladik, Turkey
Non-USGS Publications**
**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.
Science and Products
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Filter Total Items: 61
Accumulation of impact markers in desert wetlands and implications for the Younger Dryas impact hypothesis
The Younger Dryas impact hypothesis contends that an extraterrestrial object exploded over North America at 12.9 ka, initiating the Younger Dryas cold event, the extinction of many North American megafauna, and the demise of the Clovis archeological culture. Although the exact nature and location of the proposed impact or explosion remain unclear, alleged evidence for the fallout comes from multipAuthorsJeffrey S. Pigati, Claudio Latorre, Jason A. Rech, Julio L. Betancourt, Katherine E. Martinez, James R. BudahnRadiocarbon ages of terrestrial gastropods extend duration of ice-free conditions at the Two Creeks forest bed, Wisconsin, USA
Analysis of terrestrial gastropods that underlie the late Pleistocene Two Creeks forest bed (~ 13,800–13,500 cal yr BP) in eastern Wisconsin, USA provides evidence for a mixed tundra-taiga environment prior to formation of the taiga forest bed. Ten new AMS 14C analyses on terrestrial gastropod shells indicate the mixed tundra-taiga environment persisted from ~ 14,500 to 13,900 cal yr BP. The TwocrAuthorsJason A. Rech, Jeffrey C. Nekola, Jeffrey S. PigatiLate Quaternary sedimentological and climate changes at Lake Bosumtwi Ghana: new constraints from laminae analysis and radiocarbon age modeling
The Lake Bosumtwi sediment record represents one of the longest and highest-resolution terrestrial records of paleoclimate change available from sub-Saharan Africa. Here we report a new sediment age model framework for the last ~ 45 cal kyr of sedimentation using a combination of high-resolution radiocarbon dating, Bayesian age-depth modeling and lamination counting. Our results highlight the pracAuthorsTimothy M. Shanahan, J. Warren Beck, Jonathan T. Overpeck, Nicholas P. McKay, Jeffrey S. Pigati, John A. Peck, Christopher A. Scholz, Clifford W. Heil, John W. KingPrimary mapping and stratigraphic data and field methods for the Snowmastodon Project
During the Snowmastodon Project, many different people collected data for a wide array of purposes under a variety of conditions. Early in the process and in an attempt to provide project-wide consistency, Kirk Johnson appointed Carol Lucking as the project’s data manager both in the field and the lab. She was responsible for using GIS to create maps on an ongoing basis throughout the project. JefAuthorsCarol Lucking, Kirk R. Johnson, Jeffery S. Pigati, Ian MillerAssessing open-system behavior of 14C in terrestrial gastropod shells
In order to assess open-system behavior of radiocarbon in fossil gastropod shells, we measured the 14C activity on 10 aliquots of shell material recovered from Illinoian (~190–130 ka) and pre-Illinoian (~800 ka) loess and lacustrine deposits in the Midwestern USA. Eight of the 10 aliquots yielded measurable 14C activities that ranged from 0.25 to 0.53 percent modern carbon (pMC), corresponding toAuthorsJason A. Rech, Jeffrey S. Pigati, Sophie B. Lehmann, Chelsea N. McGimpsey, David A. Grimley, Jeffrey C. NekolaChronology, sedimentology, and microfauna of groundwater discharge deposits in the central Mojave Desert, Valley Wells, California
During the late Pleistocene, emergent groundwater supported persistent and long-lived desert wetlands in many broad valleys and basins in the American Southwest. When active, these systems provided important food and water sources for local fauna, supported hydrophilic and phreatophytic vegetation, and acted as catchments for eolian and alluvial sediments. Desert wetlands are represented in the geAuthorsJeffrey S. Pigati, David M. Miller, Jordon E. Bright, Shannon Mahan, Jeffrey C. Nekola, James B. PacesChronology, sedimentology, and microfauna of groundwater discharge deposits in the central Mojave Desert, Valley Wells, California
During the late Pleistocene, emergent groundwater supported persistent and long-lived desert wetlands in many broad valleys and basins in the American Southwest. When active, these systems provided important food and water sources for local fauna, supported hydrophilic and phreatophytic vegetation, and acted as catchments for eolian and alluvial sediments. Desert wetlands are represented in the geAuthorsJeffrey S. Pigati, David Miller, J.E. Bright, Shannon A. Mahan, J.C. Nekola, James B. PacesExtraction of in situ cosmogenic 14C from olivine
Chemical pretreatment and extraction techniques have been developed previously to extract in situ cosmogenic radiocarbon (in situ 14C) from quartz and carbonate. These minerals can be found in most environments on Earth, but are usually absent from mafic terrains. To fill this gap, we conducted numerous experiments aimed at extracting in situ 14C from olivine ((Fe,Mg)2SiO4). We were able to extracAuthorsJ.S. Pigati, N.A. Lifton, A.J. Timothy Jull, Jay QuadeA simplified In Situ cosmogenic 14C extraction system
We describe the design, construction, and testing of a new, simplified in situ radiocarbon extraction system at the University of Arizona. Blank levels for the new system are low ((234 ?? 11) ?? 103 atoms (1 ??; n = 7)) and stable. The precision of a given measurement depends on the concentration of 14C, but is typically <5% for concentrations of 100 ?? 103 atoms g-1 or more. The new system is relAuthorsJ.S. Pigati, N.A. Lifton, A.J. Timothy Jull, Jay QuadeRadiocarbon dating of small terrestrial gastropod shells in North America
Fossil shells of small terrestrial gastropods are commonly preserved in wetland, alluvial, loess, and glacial deposits, as well as in sediments at many archeological sites. These shells are composed largely of aragonite (CaCO3) and potentially could be used for radiocarbon dating, but they must meet two criteria before their 14C ages can be considered to be reliable: (1) when gastropods are alive,AuthorsJ.S. Pigati, J.A. Rech, J.C. NekolaLate Pleistocene paleohydrology near the boundary of the Sonoran and Chihuahuan Deserts, southeastern Arizona, USA
Ground-water discharge (GWD) deposits form in arid environments as water tables rise and approach or breach the ground surface during periods of enhanced effective precipitation. Where preserved, these deposits contain information on the timing and elevation of past ground-water fluctuations. Here we report on the investigation of a series of GWD deposits that are exposed in discontinuous outcropsAuthorsJeffery S. Pigati, Jordon E. Bright, Timothy M. Shanahan, Shannon MahanA 3000-year record of ground-rupturing earthquakes along the central North Anatolian fault near Lake Ladik, Turkey
The North Anatolian fault (NAF) is a ???1500 km long, arcuate, dextral strike-slip fault zone in northern Turkey that extends from the Karliova triple junction to the Aegean Sea. East of Bolu, the fault zone exhibits evidence of a sequence of large (Mw >7) earthquakes that occurred during the twentieth century that displayed a migrating earthquake sequence from east to west. Prolonged human occupaAuthorsJ. Fraser, J.S. Pigati, A. Hubert-Ferrari, K. Vanneste, U. Avsar, S. AltinokNon-USGS Publications**
Pigati, J.S. Miller, D.M., 2008, Late Pleistocene wetland deposits at Valley Wells, eastern Mojave Desert, California: initial results. In Trough to trough: the Colorado River and the Salton Sea - 2008 Desert Symposium Field Guide and Proceedings, R.E. Reynolds (Ed.), California State University, Desert Studies Consortium, and LSA Associates, Inc., 138-142.Pigati, J.S., Quade, J., Wilson, J., Jull, A.J.T., Lifton, N.A., 2007, Development of low-background vacuum extraction and graphitization systems for 14C dating of old (40-60 ka) samples. Quaternary International 166, 4-14.Felton, A.A., Russell, J.M., Cohen, A.S., Baker, M.E., Chesley, J., Lezzar, K.E., McGlue, M.M., Pigati, J.S., Quade, J., Stager, J.C., 2007, Paleolimnological evidence for the onset and termination of glacial aridity from Lake Tanganyika, East Tropical Africa. Palaeogeography, Palaeoclimatology, Palaeoecology 252, 405-423.Shanahan, T.S., Overpeck, J.T., Beck, J.W., Wheeler, C.W., Pigati, J.S., Talbot, M.R., Scholz, C.A., Peck, J., King, J.W., 2006, Paleoclimatic variations in West Africa from a record of late Pleistocene and Holocene lake level stands of Lake Bosumtwi, Ghana. Palaeogeography, Palaeoclimatology, Palaeoecology 242 (3-4), 287-302.Shanahan, T.M., Pigati, J.S., Dettman, D.L., Quade, J., 2005, Isotopic variability in the aragonite shells of freshwater gastropods living in springs with nearly constant temperature and isotopic composition. Geochimica et Cosmochimica Acta 69 (16), 3949-3966.Pigati, J.S., Lifton, N.A., 2004, Geomagnetic effects on time-integrated cosmogenic nuclide production with emphasis on in-situ 14C and 10Be. Earth and Planetary Science Letters 226, 193-205. (Elsevier Top 50 Most Cited Papers 2004-2007 Award).Pigati, J.S., Quade, J., Shanahan, T.M., Haynes, C.V. Jr., 2004, Radiocarbon dating of minute gastropods and new constraints on the timing of late Quaternary spring-discharge deposits in southern Arizona, USA. Palaeogeography, Palaeoclimatology, Palaeoecology 204 (1-2), 33-45.Rech, J.A., Pigati, J.S., Quade, J., Betancourt, J.L., 2003, Re-evaluation of mid-Holocene wetland deposits at Quebrada Puripica, northern Chile. Palaeogeography, Palaeoclimatology, Palaeoecology 194, 207-222.Pigati, J.S., 2002, On correcting 14C ages of gastropod shell carbonate for fractionation. Radiocarbon 44(3), 755-760.Stiner, M.C., Achyuthan, H., Arsebuk, G., Howell, F.C., Josephson, S.C., Juell, K.E., Pigati, J.S., Quade, J., 1998, Reconstructing cave bear paleoecology from skeletons: A cross-disciplinary study of middle-Pleistocene bears from Yarimburgaz Cave, Turkey. Paleobiology 24, 74-96.**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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