A5016536362- Geology and Paleoclimatology Research
- Isotope Analysis in Ecology
- Geological formations and processes
- Pleistocene-Era Hominins and Archaeology
- Archaeology and ancient environmental studies
- Hydrology and Sediment Transport Processes
- Water Quality and Resources Studies
- Geochemistry and Geologic Mapping
- Groundwater and Isotope Geochemistry
- Evolution and Paleontology Studies
- Methane Hydrates and Related Phenomena
- Coastal wetland ecosystem dynamics
- Fish Ecology and Management Studies
- Tree-ring climate responses
- Paleontology and Stratigraphy of Fossils
- Marine Biology and Ecology Research
- Archaeological and Geological Studies
- Geological and Geophysical Studies Worldwide
- Fish Biology and Ecology Studies
- Marine and fisheries research
- Archaeology and Natural History
- Botany, Ecology, and Taxonomy Studies
- Peatlands and Wetlands Ecology
- Hydrocarbon exploration and reservoir analysis
- Geological and Tectonic Studies in Latin America
Northern Arizona University
2007-2024
University of Arizona
2011-2024
Institut de l'Information Scientifique et Technique
2021
University of Debrecen
2021
Environmental Education Exchange
2018
Although climate change is considered to have been a large-scale driver of African human evolution, landscape-scale shifts in ecological resources that may shaped novel hominin adaptations are rarely investigated. We use well-dated, high-resolution, drill-core datasets understand dynamics associated with major adaptive transition the archeological record ~24 km from coring site. Outcrops preserve evidence replacement Acheulean by Middle Stone Age (MSA) technological, cognitive, and social...
Initial interpretation of the sediments from Burmester core (Eardley et al. (1973). Geological Society America Bulletin 84, 211–216) indicated that 17 deep-lake cycles, separated by shallow-lake and soil-forming intervals, occurred in Bonneville basin during Brunhes Chron (the last 780 × 10 3 yr). Our re-examination core, along with new sedimentological, geochronological, paleontological data, indicate only four cycles this period, apparently correlative marine oxygen-isotope stages 2, 6,...
In this study, we demonstrate the utility of amino acid geochronology based on single‐foraminiferal tests in Quaternary sediment cores from Queensland margin, Australia. The large planktonic foraminifer Pulleniatina obliquiloculata is ubiquitous shelf, slope, and basin sediments north as well pantropical oceans. Fossil are resistant to dissolution, retain substantial concentrations acids (2–4 nmol mg −1 shell) over hundreds thousands years. Amino D L isomers aspartic (Asp) glutamic (Glu)...
ABSTRACT The direct carbonate procedure for accelerator mass spectrometry radiocarbon (AMS 14 C) dating of submilligram samples biogenic without graphitization is becoming widely used in a variety studies. We compare the results 153 paired and standard graphite C determinations on single specimens an assortment carbonates. A reduced major axis regression shows strong relationship between percent Modern Carbon (pMC) values (m = 0.996; 95% CI [0.991–1.001]). An analysis differences confidence...
Research Article| November 01, 2011 Chronology, sedimentology, and microfauna of groundwater discharge deposits in the central Mojave Desert, Valley Wells, California Jeffrey S. Pigati; Pigati † 1U.S. Geological Survey, Denver Federal Center, Box 25046, MS-980, Denver, Colorado 80225, USA †E-mail: jpigati@usgs.gov Search for other works by this author on: GSW Google Scholar David M. Miller; Miller 2U.S. 345 Middlefield Road, MS-973, Menlo Park, 94025, Jordon E. Bright; Bright § 3School Earth...
Geological indicators of past relative sea level changes are fundamental to reconstruct the extent former ice sheet during interglacials, which considered analogs for future climate conditions.Four dating from Holocene Pliocene, have left sea-level imprints in proximity coastal town Camarones Central Patagonia, Argentina.Sea-level index points were preserved as beach ridges deposited by storm waves above modern level.We used highly accurate survey techniques measure elevation these...
Abstract An outcrop-based lake-level curve, constrained by ~ 70 calibrated 14 C ages on Anodonta shells, indicates at least 8 highstands between 45 and 25 cal ka BP within 10 m of the 543-m upper threshold Lake Manix in Mojave Desert southern California. Correlations with ice, marine, speleothem records suggest that youngest three coincide Dansgaard–Oeschger (D–O) stadials Heinrich events 3 4. The record is consistent results from studies Southwest indicate cool wet conditions during D–O...
Abstract The southern Bouse Formation (late Miocene–early Pliocene) in Blythe basin, CA-AZ, contains a controversial record of the events that preceded integration developing Colorado River with Gulf California. High resolution microfaunal and stable isotope (δ18O, δ13C; VPDB) data from key outcrop marl claystone an abrupt change water chemistry we interpret to be result catastrophic sill breach. Basal mix brackish-water ostracodes marine foraminifers. Ostracode δ18O values are slightly...
Abstract Accurate reconstruction of the paleo-Mojave River and pluvial lake (Harper, Manix, Cronese, Mojave) system southern California is critical to understanding paleoclimate North American polar jet stream position over last 500 ka. Previous studies inferred a south 35°N at 18 ka ~ 40°N 17–14 Highstand sediments Harper Lake, upstream-most along Mojave River, have yielded uncalibrated radiocarbon ages ranging from 24,000 > 30,000 14 C yr BP. Based on geologic mapping, optically...
Abstract Luminescence geochronology, especially infrared stimulated luminescence analyses on marsh mud, shows that a relatively deep lake reached its peak (∼1340 m above sea level) in the Bonneville basin 59,000±5000 yr ago. The age is consistent with nonfinite 14 C ages and amino acid geochronology ostracodes. Cutler Dam Alloformation was deposited during this cycle, which, like subsequent appears to have maximum highstand following of global glacial stage (marine oxygen-isotope 4) but at...
Limestone beds underlain and overlain by alluvial fan conglomerate near Amboy, California, are very similar in many respects to parts of the Bouse Formation, suggesting that an arm Pliocene water body extended across a wide part southern Mojave Desert. The deposits north town Amboy at below elevation 290 m, along northern piedmont Bristol "dry" Lake basin. outcrops contain Lawlor Tuff (4.83 Ma), which is also found outcrop Formation Blythe basin Buzzards Peak Chocolate Mountains, 180 km...
Uncertainty over the depositional environment of late Miocene and early Pliocene Bouse Formation hinders our understanding evolution lower Colorado River corridor. Competing marine lacustrine models for origin southern remain extremely difficult to reconcile after nearly 60 yr study. This paper compares new microfossil data, inorganic biologic carbonate δ18O δ13C values (relative Vienna Pee Dee Belemnite), fish bone 87Sr/86Sr ratios from northern outcrops Formation. The contested share a...
Abstract In North America, terrestrial records of biodiversity and climate change that span Marine Oxygen Isotope Stage (MIS) 5 are rare. Where found, they provide insight into how the coupling ocean–atmosphere system is manifested in biotic environmental biosphere responds to change. 2010–2011, construction at Ziegler Reservoir near Snowmass Village, Colorado (USA) revealed a nearly continuous, lacustrine/wetland sedimentary sequence preserved evidence past plant communities between ~140 55...