Paleobiology Commons^™

Paleo-Environmental Change In Deer Lagoon, Whidbey Island Interpreted From Diatoms And Lithology, Lourdes Garcia

All Master's Theses

Puget Sound is a densely populated, tectonically active area that can be affected by earthquakes from local crustal faults and the Cascadia subduction zone capable of producing abrupt coseismic subsidence. Tidal wetlands are particularly sensitive to abrupt changes because they are depositional environments that reside at sea-level and their lithology and ecological communities are strongly controlled by elevation within the tidal frame. As a result, coseismic subsidence can disrupt established environmental gradients and leave distinguishable signatures preserved within the stratigraphy, like tidal mud directly over peat deposits. These preserved records provide an opportunity to reconstruct past earthquakes and associated relative …

Exploring The Morphometrics Of The Diatom Fragilariopsis Kerguelensis As A Proxy For Paleo-Sea Surface Temperature In The Late Pleistocene-Holocene Southern Ocean, Joseph Anthony Ruggiero

Graduate Research Theses & Dissertations

The Southern Ocean has played a large role in moderating global climate since its inception in the Oligocene. With the onset of anthropogenic global warming, it is now more necessary than ever that we understand the world’s climate during periods of rapidly fluctuating temperature in the past. Climatic forecasts are informed by paleoenvironmental conditions of the past during these turbulent periods, which we can examine using proxy data. This thesis assesses a potential proxy for Sea Surface Temperature (SST) through morphometric analysis of the Southern Ocean diatom Fragilariopsis kerguelensis in the Amundsen Sea, West Antarctica. This proxy is based off …

Unearthing The Effects Of European-American Settlement On A Northeast Ohio Kettle Lake Through Diatom Stratigraphy, Justine Paul A. Berina

Senior Independent Study Theses

Recently, wetland conservation has highlighted the necessity for assessing limnological changes following European-American settlement. A prior study at Brown's Lake (northeast Ohio) identified a stratigraphic sequence that shows an abrupt transition from organic-rich muds to several centimeters of a bright loess layer, then a recovery to organic-rich sediments near the top. Based on ²¹⁰Pb dates, the loess deposition occurred before 1846 CE, when a growing population cleared trees and farmed intensively. Likewise, organics had recovered after 1950 CE, when people abandoned farmland and practiced conservation tillage. However, the effects of settlement on limnology are poorly known. Diatoms (microscopic algae; …

Diatom-Inferred Records Of Paleolimnological Variability And Continental Hydrothermal Activity In Yellowstone National Park, Usa, Sabrina Brown

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

Fossil diatoms were used to reconstruct paleoclimatic and hydrothermal conditions in Yellowstone National Park. First, an extensive literature review summarizes the current state of knowledge about eukaryotic organisms characteristic of continental hydrothermal environments. Eukaryotes in hydrothermal systems can live at extremes of acidity (pH 9.0), and at moderately high temperatures (<62 >^○C). Silicate and carbonate precipitation in continental hydrothermal environments is mediated by eukaryotic organisms, which are important members of biofilm communities.

A case study of alkaline-chloride sinter deposits in Yellowstone Lake and the Upper Geyser Basin inferred in-situ diatom growth rather than post-depositional accumulation of valves settling from …

Rapid Fluctuations In Mid-Latitude Siliceous Plankton Production During The Middle Eocene Climatic Optimum (Odp Site 1051, Western North Atlantic), Jakub Witkowski, Steven M. Bohaty, Kirsty M. Edgar, David M. Harwood

ANDRILL Research and Publications

The Middle Eocene Climatic Optimum (MECO; ~ 40 million years ago [Ma]) is one of the most prominent transient global warming events in the Paleogene. Although the event is well documented in geochemical and isotopic proxy records at many locations, the marine biotic response to the MECO remains poorly constrained. We present new high-resolution, quantitative records of siliceous microplankton assemblages from the MECO interval of Ocean Drilling Program (ODP) Site 1051 in the subtropical western North Atlantic Ocean, which are interpreted in the context of published foraminiferal and bulk carbonate stable isotope (δ¹⁸O and δ¹³C) records. …

Diatom Evidence For The Onset Of Pliocene Cooling From And-1b, Mcmurdo Sound, Antarctica, Christina R. Riesselman, Robert B. Dunbar

ANDRILL Research and Publications

The late Pliocene, ~3.3–3.0 Ma, is the most recent interval of sustained global warmth in the geologic past. This window is the focus of climate reconstruction efforts by the U.S. Geological Survey’s Pliocene Research, Interpretation, and Synoptic Mapping (PRISM) Data/Model Cooperative, and may provide a useful climate analog for the coming century. Reconstructions of past surface ocean conditions proximal to the Antarctic continent are essential to understanding the sensitivity of the cryosphere to this key interval in Earth’s climate evolution. An exceptional marine sediment core collected from the southwestern Ross Sea (78° S), Antarctica, during ANDRILL’s McMurdo Ice Shelf Project …