A5044186752- Geology and Paleoclimatology Research
- Isotope Analysis in Ecology
- Groundwater and Isotope Geochemistry
- Atmospheric and Environmental Gas Dynamics
- Methane Hydrates and Related Phenomena
- Geological formations and processes
- Paleontology and Stratigraphy of Fossils
- Evolution and Paleontology Studies
- Hydrocarbon exploration and reservoir analysis
- Geological Studies and Exploration
- CO2 Sequestration and Geologic Interactions
- Amazonian Archaeology and Ethnohistory
- Climate variability and models
- Ecology and Vegetation Dynamics Studies
- Astro and Planetary Science
- Geomagnetism and Paleomagnetism Studies
- Marine and coastal ecosystems
- Geochemistry and Geologic Mapping
- Karst Systems and Hydrogeology
- Geochemistry and Elemental Analysis
- Climate change and permafrost
- Geological and Geochemical Analysis
- Microbial Community Ecology and Physiology
- Water-Energy-Food Nexus Studies
- Atmospheric Ozone and Climate
University of Washington
2024-2025
Oregon State University
2024-2025
Colorado State University
2022-2024
New Mexico Consortium
2024
Los Alamos National Laboratory
2024
Carbon180
2024
Stanford University
2019-2023
Brown University
2022
Abstract In the Miocene (23–5 Ma), a large wetland known as Pebas System characterized western Amazonia. During Middle Climatic Optimum (c. 17–15 this system reached its maximum extent and was episodically connected to Caribbean Sea, while receiving sediment input from Andes in west, craton (continental core) east. Towards late 10 Ma) transitioned into fluvial-dominated system. biogeographic models, is often considered two contexts: one describing cradle of speciation for aquatic or...
Abstract The shift from denser forests to open, grass‐dominated vegetation in west‐central North America between 26 and 15 million years ago is a major ecological transition with no clear driving force. This open habitat (OHT) considered by some be evidence for drier summers, more seasonal precipitation, or cooler climate, but others have proposed that wetter conditions and/or warming initiated the OHT. Here, we use published ( n = 2,065) new 173) oxygen isotope measurements δ 18 O )...
Abstract Terrestrial gradients in the oxygen isotopic composition of meteoric water ( δ 18 O ), as reconstructed through proxies, reflect characteristics ancient hydrologic conditions. These are primarily influenced by atmospheric transport vapor and balance precipitation evapotranspiration, which linked to climate topography. We incorporate these effects into a one‐dimensional model that predicts spatial evolution based on local topography regional water‐energy budget. Specifically, we...
In the Miocene, a large wetland system extended from Andean foothills into western Amazonia. This has no modern analogue and driving mechanisms are not yet fully understood. Dynamic topography uplift thought to have controlled deposition, with allocyclic base level changes driven by eustasy orbital forcing also playing role. this study we investigate presumed cyclicity that sediment while assessing source biomes in Miocene wetland. We do integrating lithological, palynological, malacological...
Abstract Several mechanisms have been proposed to explain why the isotope ratios of precipitation vary in space and time they correlate with other climate variables like temperature precipitation. Here we argue that this behavior is best understood through lens radiative transfer, which treats depletion atmospheric vapor transport by as analogous attenuation light absorption or scattering. Building on earlier work Siler et al. (2021), introduce a simple model uses equations transfer...
Triple oxygen isotope measurements are an emerging tool in paleoclimate reconstructions. In this contribution we develop the application of triple to lacustrine sediments reconstruct past elevations. We focus on a well-constrained sample set from Eocene North American Cordillera (Cherty Limestone Formation, Elko Basin, NV, United States, 42–43.5 Ma) east side elevated Nevadaplano. present freshwater chert samples Cherty Formation. Across evaporation trend spanning 6.5‰ δ 18 O values observe...
The John Day region of central Oregon, United States contains ∼50 million years near-continuous, fossiliferous sedimentation, representing one the world’s richest archives Cenozoic terrestrial ecosystems and climate. Stable isotope proxy data from this are commonly used to infer elevation history Cascades, which intercept westerly moisture in transit region. However, Blue Mountains, accreted Mesozoic, create a local high topography that can confound signals Cascades uplift. deposits,...
Quantum diamond microscope (QDM) magnetic field imaging is a recently developed technique capable of mapping sources in geologic samples at 1 micrometer resolution. Applying QDM to speleothems can provide high‐resolution time series detrital input into the cave environment, which, turn, yield useful paleoenvironmental information. Here we map over speleothem from midwest Brazil 174 year timespan with annual sub-annual resolution and perform backfield remanence acquisition experiments...
Abstract. The Great Plains of North America host a stark climatic gradient, separating the humid and well-watered eastern US from semi-arid arid western US, this gradient shapes region's water availability, its ecosystems, economies. This boundary is largely set by influence two competing atmospheric circulation systems that meet over – wintertime westerlies bring dominantly dry air gives way to moist, southerly transported low-level jet in warmer months. Climate model simulations suggest...
We use triple oxygen isotopes of altered granitic rocks to determine the isotope composition meteoric waters in a fossil hydrothermal system, low δ 18 O Eocene Idaho Batholith, originally studied by Criss and Taylor (1983).In doing so we: 1) test whether water values estimated from previous δD analyses on quartz, feldspar biotite are robust 2) palaeoelevation highlands that presently constrained primarily paired muscovite quartz core complexes granites.Our calculated higher than estimates...
The timing of surface uplift the Altai Mountains in northern Central Asia—and climatic consequences—remains controversial. Today, cast a substantial rain shadow, effectively separating western Gobi Desert and steppe from Siberian Taiga. We take advantage this stark gradient to trace interaction climate topography lee Altai. First, we present new water stable isotope data that demonstrate that—along with gradient—the modify δ<sup>18</sup>O precipitation via rainout on leeward side range....
Abstract Speleothem oxygen isotope records (δ 18 O) of tropical South American rainfall in the late Quaternary show a zonal “South Precipitation Dipole” (SAPD). The dipole is characterized by opposing east‐west precipitation anomalies compared to present—wetter east and drier west at mid‐Holocene (∼7 ka), wetter Last Glacial Maximum (∼21 ka). However, SAPD remains enigmatic because it expressed differently western versus eastern δ O isotope‐enabled climate model simulations usually...
In the tropics, oxygen isotope signals of past climate change range from less than 1‰ to upwards 7‰ or more. Regardless amplitude, these are often interpreted reflect changes in local rainout. However, stable isotopes precipitation can carry information about rainout across thousands kilometers, making it hard parse and non-local effects. Here, we present a framework that links amplitude tropical spatial patterns cause them. Using three models varying complexity, show largest require...
Solar cycles are important moderators of the Earth's global climate system. Although modern-day solar well known, they have been less studied over geological time. High-resolution records such as varves previously used for reconstructing from Paleoproterozoic through Quaternary. In this paper, very fine (<1 mm) sedimentary laminations Early Cretaceous Yixian Formation in Xiushui Basin were Northern Liaoning Province, North China. Two different microfacies striped shale Third Member...
Triple oxygen isotopes of hydrothermally altered minerals from crystalline rocks can be used to determine past elevations mountain ranges. This method uses all three ( 16 O, 17 and 18 O) create arrays that extrapolated back the meteoric water line. One advantage this technique is it relies only on in contrast previous studies use hydrogen isotopic composition waters. Our analysis suggests may exchange with ambient fluids. provide an independent check reliability isotope studies.
In the last two decades, analytical advances and a growing interest in relevant research questions has brought rapid increase amount of stable isotope data used for reconstructing terrestrial paleoclimates environments. As spatial temporal resolution proxy continues to improve, quantitative interpretation these is becoming increasingly common. These theory bring opportunities multi-proxy comparisons, synthesis modeling large datasets, integration with paleoecological improved climate model...
Abstract. The Great Plains of North America host a stark climatic gradient, separating the humid and well-watered eastern US from semi-arid arid western US. First studied in detail by John Wesley Powell, this gradient shapes region’s ecosystems, economies, availability water across landscape. This is largely set influence two competing atmospheric circulation systems that meet over – wintertime westerlies bring dominantly dry air gives way to moist, southerly transported Low-Level Jet warmer...
&lt;p&gt;The Poaceae (the grass family) includes over 11000 species and covers large part of the Earth land surfaces. Their history is rooted in Cretaceous, but this group only expanded fully globe during late Miocene. In Amazon drainage basin (ADB) grasses were at core a heated debate, which it was hypothesized that Pleistocene glacial periods replaced vast extents rainforest. Although hypothesis now rejected, ADB still remains to be resolved. paper we propose 3-staged model for...