Physical Sciences and Mathematics Commons^™

Reevaluating The Geologic Formations Of The Upper Coastal Plain In Chesterfield County, South Carolina, Bradley Aaron Fitzwater

OES Theses and Dissertations

Data from a new geological map of the Patrick, S.C. 7.5 minute quadrangle (1:24,000) and detailed descriptions of two cores collected nearby (Middendorf and Cheraw, S.C.) permit improved interpretation of the geology of this portion of the Carolina Sandhills. Geologic mapping incorporated analyses of outcrops with LiDAR data, soil survey maps, ground-penetrating radar transects, and hand auger borings. Micro- and macrofossil identification and optically-stimulated luminescence (OSL) dating provided age control.

Four distinct mappable units occur throughout the Patrick quadrangle. Resting unconformably on schist of the Paleozoic Persimmons Fork Formation, the Cretaceous Middendorf Formation is more than 85.3 m thick and …

Developing Priority Variables (“Ecosystem Essential Ocean Variables” — Eeovs) For Observing Dynamics And Change In Southern Ocean Ecosystems, Andrew J. Constable, Daniel P. Costa, Oscar Schofield, Louise Newman, Edward R. Urban Jr., Elizabeth A. Fulton, Jessica Melbourne-Thomas, Tosca Ballerini, Philip W. Boyd, Angelika Brandt, Eileen E. Hofmann

CCPO Publications

Reliable statements about variability and change in marine ecosystems and their underlying causes are needed to report on their status and to guide management. Here we use the Framework on Ocean Observing (FOO) to begin developing ecosystem Essential Ocean Variables (eEOVs) for the Southern Ocean Observing System (SOOS). An eEOV is a defined biological or ecological quantity, which is derived from field observations, and which contributes significantly to assessments of Southern Ocean ecosystems. Here, assessments are concerned with estimating status and trends in ecosystem properties, attribution of trends to causes, and predicting future trajectories. eEOVs should be feasible to collect …

Molecular Level Characterization Of Diatom-Associated Biopolymers That Bind 234th, ²³³Pa, ²¹°Pb, And 7be In Seawater: A Case Study With Phaeodactylum Tricornutum, Chia-Ying Chuang, Peter H. Santschi, Chen Xu, Yuelu Jiang, Yi-Fang Ho, Patrick G. Hatcher

Chemistry & Biochemistry Faculty Publications

In order to investigate the importance of biogenic silica associated biopolymers on the scavenging of radionuclides, the diatom Phaeodactylum tricornutum was incubated together with the radionuclides Th-234, Pa-233, Pb-210, and Be-7 during their growth phase. Normalized affinity coefficients were determined for the radionuclides bound with different organic compound classes (i.e., proteins, total carbohydrates, uronic acids) in extracellular (nonattached and attached exopolymeric substances), intracellular (ethylene diamine tetraacetic acid and sodium dodecyl sulfate extractable), and frustule embedded biopolymeric fractions (BF). Results indicated that radionuclides were mostly concentrated in frustule BF. Among three measured organic components, Uronic acids showed the strongest affinities to …

Theoretical Foundation Of Cyclostationary Eof Analysis For Geophysical And Climatic Variables: Concepts And Examples, Kwang-Yul Kim, Benjamin Hamlington, Hanna Na

CCPO Publications

Natural variability is an essential component of observations of all geophysical and climate variables. In principal component analysis (PCA), also called empirical orthogonal function (EOF) analysis, a set of orthogonal eigenfunctions is found from a spatial covariance function. These empirical basis functions often lend useful insights into physical processes in the data and serve as a useful tool for developing statistical methods. The underlying assumption in PCA is the stationarity of the data analyzed; that is, the covariance function does not depend on the origin of time. The stationarity assumption is often not justifiable for geophysical and climate variables even …

Use Of Esi-Fticr-Ms To Characterize Dissolved Organic Matter In Headwater Streams Draining Forest-Dominated And Pasture-Dominated Watersheds, Yuehan Lu, Xiaping Li, Rajaa Mesfioui, James E. Bauer, R. M. Chambers, Elizabeth A. Canuel, Patrick G. Hatcher

Chemistry & Biochemistry Faculty Publications

Electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS) has proven to be a powerful technique revealing complexity and diversity of natural DOM molecules, but its application to DOM analysis in grazing-impacted agricultural systems remains scarce. In the present study, we presented a case study of using ESI-FTICR-MS in analyzing DOM from four headwater streams draining forest-or pasture-dominated watersheds in Virginia, USA. In all samples, most formulas were CHO compounds (71.8-87.9%), with other molecular series (CHOS, CHON, CHONS, and CHOP (N, S)) accounting for only minor fractions. All samples were dominated by molecules falling in the lignin-like region (H/C …

Tropical North Atlantic Subsurface Warming Events As A Fingerprint For Amoc Variability During Marine Isotope Stage 3, Andrew O. Parker, Matthew W. Schmidt, Ping Chang

OES Faculty Publications

The role of Atlantic Meridional Overturning Circulation (AMOC) as the driver of Dansgaard-Oeschger (DO) variability that characterized Marine Isotope Stage 3 (MIS 3) has long been hypothesized. Although there is ample proxy evidence suggesting that DO events were robust features of glacial climate, there is little data supporting a link with AMOC. Recently, modeling studies and subsurface temperature reconstructions have suggested that subsurface warming across the tropical North Atlantic can be used to fingerprint a weakened AMOC during the deglacial because a reduction in the strength of the western boundary current allows warm salinity maximum water of the subtropical gyre …

Crustal Accretion And Mantle Geodynamics At Microplates: Constraints From Gravity Analysis And Numerical Modeling, Katherine Ames

OES Theses and Dissertations

This study investigates crustal accretion and mantle geodynamics at microplates using mantle Bouguer anomaly (MBA) gravity calculations and exploratory numerical models. The Easter and Juan Fernandez microplates are located in the eastern Pacific Ocean along the Pacific, Nazca, and Antarctic plate boundaries. Both microplates formed 3-5 Ma and they are currently rotating clockwise at 15° myr^-1 and 9° myr^-1,respectively [ e.g., Searle et al., 1993]. The study area also encompasses the Easter /Salas y Gomez mantle plume located near the Easter microplate. Both microplates show a difference in average MBA between their west and east ridges, with …

Did A Submarine Landslide Contribute To The 2011 Tohoku Tsunami?, David R. Tappin, Stephan T. Grilli, Jeffrey C. Harris, Robert J. Geller, Timothy Masterlark, James T. Kirby, Fengyan Shi, Gangfeng Ma, K.K.S. Thingbaijam, P. Martin Mai

Civil & Environmental Engineering Faculty Publications

Many studies have modeled the Tohoku tsunami of March 11, 2011 as being due entirely to slip on an earthquake fault, but the following discrepancies suggest that further research is warranted. (1) Published models of tsunami propagation and coastal impact underpredict the observed runup heights of up to 40. m measured along the coast of the Sanriku district in the northeast part of Honshu Island. (2) Published models cannot reproduce the timing and high-frequency content of tsunami waves recorded at three nearshore buoys off Sanriku, nor the timing and dispersion properties of the waveforms at offshore DART buoy #21418. (3) …

Hydrogeologic Variations Across A Barrier Island That Influence Inter-Dune Wetlands False Cape State Park, Virginia, Matthew Collier Richardson

OES Theses and Dissertations

False Cape State Park in southeastern Virginia Beach, Virginia contains a transgressive barrier island complex. Inter-dune swales located on the eastern coast of the barrier island contain soils that experience hydric conditions. However, these swales lack the prolonged presence of hydric soil indicators that are necessary for a site to be officially recognized as a jurisdictional wetland. The appearance and subsequent disappearance of redoximorphic wetland soil features in the young, sandy soils of the inter-dune swales here may stem from changes in the patterns of groundwater recharge and discharge across the island. These soils are being monitored by the Mid …

Distributions Of Particulate Heme B In The Atlantic And Southern Oceans- Implications For Electron Transport In Phytoplankton, Martha Gledhill, Eric P. Achterberg, David J. Honey, Maria C. Nielsdottir, Micha J.A. Rijkenberg

OES Faculty Publications

Concentrations of heme b, the iron-containing component of b-type hemoproteins, ranged from b concentrations were enhanced in the photic zone and decreased with depth. Heme b concentrations correlated positively with chlorophyll a (chl a) in the TNA (r=0.41, pb did not correlate with chl a in the IB or SS. In the IB and SS, stations with high-chlorophyll and low-nutrient (Fe and/or Si) concentrations exhibited low heme bconcentrations relative to particulate organic carbon (< 0.1 μmolmol^-1, and high chl a:heme b ratios (> 500). High chl a:heme b ratios resulted from relative decreases in …

Microbially Induced Sedimentary Structures Recording An Ancient Ecosystem In The Ca. 3.48 Billion-Year-Old Dresser Formation, Pilbara, Western Australia, Nora Noffke, Daniel Christian, David Wacey, Robert M. Hazen

OES Faculty Publications

Microbially induced sedimentary structures (MISS) result from the response of microbial mats to physical sediment dynamics. MISS are cosmopolitan and found in many modern environments, including shelves, tidal flats, lagoons, riverine shores, lakes, interdune areas, and sabkhas. The structures record highly diverse communities of microbial mats and have been reported from numerous intervals in the geological record up to 3.2 billion years (Ga) old. This contribution describes a suite of MISS from some of the oldest well-preserved sedimentary rocks in the geological record, the early Archean (ca. 3.48 Ga) Dresser Formation, Western Australia. Outcrop mapping at the meter to …

Stromatolites And Miss—Differences Between Relatives, N. Noffke, S. M. Awramik

OES Faculty Publications

Benthic microorganisms form highly organized communities called “biofilms.” A biofilm consists of the individual cells plus their extracellular polymeric substances (EPS). In marine and non-marine environments, benthic microbial communities interact with the physical sediment dynamics and other factors in the environment in order to survive. This interaction can produce distinctive sedimentary structures called microbialites. Binding, biostabilization, baffling, and trapping of sediment particles by microorganisms result in the formation of microbially induced sedimentary structures (MISS); however, if carbonate precipitation occurs in EPS, and these processes happen in a repetitive manner, a multilayered build-up can form—stromatolites. Stromatolites and MISS are first found …

Gravity Anomalies Along The East Scotia Ridge: Constraining The Relative Importance Of Magmatic And Tectonic Controls On Crustal Accretion, Briton Lee Nicholson

OES Theses and Dissertations

Similar to regions such as the Lau Basin and the Caribbean Sea, the eastern Scotia Sea is a geologically complex area that involves multiple plate boundary types. This study uses bathymetry and gravity data to infer upper mantle geodynamics in the eastern Scotia Sea region. Beneath this region is an intermediate-rate back-arc spreading center known as the East Scotia Ridge (ESR) that forms the boundary between the Scotia and Sandwich plates. To the east of the ESR are the South Sandwich island arc and the South Sandwich Trench. The ESR is a relatively young feature, with spreading estimated to have …

Could Satellite Altimetry Have Improved Early Detection And Warning Of The 2011 Tohoku Tsunami?, B. D. Hamlington, R. R. Leben, O. A. Godin, E. Gica, V. V. Titov, B. J. Haines, S. D. Desai

CCPO Publications

The 2011 Tohoku tsunami devastated Japan and affected coastal populations all around the Pacific Ocean. Accurate early warning of an impending tsunami requires the detection of the tsunami in the open ocean. While the lead-time was not sufficient for use in warning coastal populations in Japan, satellite altimetry observations of the tsunami could have been used to improve predictions and warnings for other affected areas. By comparing to both model results and historical satellite altimeter data, we use near-real-time satellite altimeter measurements to demonstrate the potential for detecting the 2011 Tohoku tsunami within a few hours of the tsunami being …

The Reduction Of Storm Surge By Vegetation Canopies: Three-Dimensional Simulations, Y. Peter Sheng, Andrew Lapetina, Gangfeng Ma

Civil & Environmental Engineering Faculty Publications

Significant buffering of storm surges by vegetation canopies has been suggested by limited observations and simple numerical studies, particularly following recent Hurricanes Katrina, Rita, and Wilma. Here we simulate storm surge and inundation over idealized topographies using a three-dimensional vegetation-resolving storm surge model coupled to a shallow water wave model and show that a sufficiently wide and tall vegetation canopy reduces inundation on land by 5 to 40 percent, depending upon various storm and canopy parameters. Effectiveness of the vegetation in dissipating storm surge and inundation depends on the intensity and forward speed of the hurricane, as well as the …

Impact Of Abrupt Deglacial Climate Change On Tropical Atlantic Subsurface Temperatures, Matthew W. Schmidt, Ping Chang, Jennifer E. Hertzberg, Theodore R. Them Ii, Link Li, Bette L. Otto-Bliesner

OES Faculty Publications

Both instrumental data analyses and coupled ocean-atmosphere models indicate that Atlantic meridional overturning circulation (AMOC) variability is tightly linked to abrupt tropical North Atlantic (TNA) climate change through both atmospheric and oceanic processes. Although a slowdown of AMOC results in an atmospheric-induced surface cooling in the entire TNA, the subsurface experiences an even larger warming because of rapid reorganizations of ocean circulation patterns at intermediate water depths. Here, we reconstruct high-resolution temperature records using oxygen isotope values and Mg/Ca ratios in both surface- and sub-thermocline-dwelling planktonic foraminifera from a sediment core located in the TNA over the last 22 ky. …

Solar Forcing Of Florida Straits Surface Salinity During The Early Holocene, Matthew W. Schmidt, William A. Weinlein, Franco Marcantonio, Jean Lynch-Stieglitz

OES Faculty Publications

Previous studies showed that sea surface salinity (SSS) in the Florida Straits as well as Florida Current transport covaried with changes in North Atlantic climate over the past two millennia. However, little is known about earlier Holocene hydrographic variability in the Florida Straits. Here, we combine Mg/Ca-paleothermometry and stable oxygen isotope measurements on the planktonic foraminifera Globigerinoides ruber (white variety) from Florida Straits sediment core KNR166-2 JPC 51 (24° 24.70' N, 83° 13.14' W, 198 m deep) to reconstruct a high-resolution (~25 yr/sample) early to mid Holocene record of sea surface temperature and δ¹⁸O_SW)(a …

Deglacial Variability Of Antarctic Intermediate Water Penetration Into The North Atlantic From Authigenic Neodymium Isotope Ratios, Ruifang C. Xie, Franco Marcantonio, Matthew W. Schmidt

OES Faculty Publications

Understanding intermediate water circulation across the last deglacial is critical in assessing the role of oceanic heat transport associated with Atlantic Meridional Overturning Circulation variability across abrupt climate events. However, the links between intermediate water circulation and abrupt climate events such as the Younger Dryas (YD) and Heinrich Event 1 (H1) are still poorly constrained. Here, we reconstruct changes in Antarctic Intermediate Water (AAIW) circulation in the subtropical North Atlantic over the past 25 kyr by measuring authigenic neodymium isotope ratios in sediments from two sites in the Florida Straits. Our authigenic Nd isotope records suggest that there was little …

A New Phase Speciation Leaching Procedure For The Determination Of Metals In Oxic And Anoxic Sediments, Brandon R. Gipson

OES Theses and Dissertations

Toxic trace elements such as cadmium, lead, chromium, and arsenic released by human activities can accumulate in marine and estuarine sediments, where these metals are often sequestered until local environmental changes (e.g., redox, salinity, and/or pH) allow these elements to be reintroduced into the food web. In order to assess the extent of toxic trace element contamination in sediment, numerous leaching schemes have been developed that separate sediment-bound trace metals into operationally defined geochemical phases. These "phase speciation" leaching schemes are typically designed with the purpose of being used on either oxic or anoxic sediments. However, natural sediments often contain …

Florida Straits Deglacial Temperature And Salinity Change: Implications For Tropical Hydrologic Cycle Variability During The Younger Dryas, Matthew W. Schmidt, Jean Lynch-Stieglitz

OES Faculty Publications

The prevailing paradigm of abrupt climate change holds that rapid shifts associated with the most extreme climate swings of the last glacial cycle were forced by changes in the strength and northward extension of Atlantic Meridional Overturning Circulation (AMOC), resulting in an abrupt reorganization of atmospheric circulation patterns with global teleconnections. To determine the timing of tropical Atlantic atmospheric circulation changes over the past 21 ka BP, we reconstruct high resolution sea surface temperature and δ¹⁸O_SW (a proxy for surface salinity) records based on Mg/Ca ratios and oxygen isotope measurements in the planktonic foraminifera Globigerinoides ruber from …

Meridional Shifts In The Marine Itcz And The Tropical Hydrologic Cycle Over The Last Three Glacial Cycles, Matthew W. Schmidt, Howard J. Spero

OES Faculty Publications

Paleoproxy studies show a strong correlation between tropical climate and high-latitude temperature variability recorded in the Greenland ice cores over the last glacial cycle. In particular, abrupt cooling events in the Greenland Ice Sheet Project II δ¹⁸O ice record appear synchronous with a southward migration of the Intertropical Convergence Zone (ITCZ) in the Atlantic, a weakening of the Indian and East Asian monsoon systems, and a strengthening of the South American monsoon system. Because this high-to-low-latitude climate teleconnection significantly alters the tropical hydrologic cycle around the globe, it plays a critical role in regulating global climate on glacial-interglacial …

Evidence From The Florida Straits For Younger Dryas Ocean Circulation Changes, Jean Lynch-Stieglitz, Matthew W. Schmidt, William B. Curry

OES Faculty Publications

The waters passing through the Florida Straits today reflect both the western portion of the wind-driven subtropical gyre and the northward flow of the upper waters which cross the equator, compensating North Atlantic Deep Water export as part of the large-scale Atlantic meridional overturning circulation. It has been postulated from various lines of evidence that the overturning circulation was weaker during the Younger Dryas cold event of the last deglaciation. We show here that the contrast in the oxygen isotopic composition of benthic foraminiferal tests across the Florida Current is reduced during the Younger Dryas. This most likely reflects a …

Comparison Of Ice Core Dissolved Organic Matter From A Greenland Ice Core By Nanospray Fourier Transform Ion Cyclotron Resonance Mass Spectrometry, Joshua Jeremiah Shiloh Marsh

Chemistry & Biochemistry Theses & Dissertations

Recent studies of ice cores have embarked on the task of determining the classes of dissolved organic matter (DOM) present in melt-water from the cores collected in numerous locations in the northern and southern hemispheres. This DOM originally derives from wet precipitation and is thought to reflect atmospheric organic matter derived from anthropogenic and non-anthropogenic sources. Because the amount of DOM is so low, previous studies have necessarily used large sample volumes (greater than 500 mL) to concentrate sufficient ice core DOM necessary for mass spectral analysis. Solid phase extraction (SPE) with C₁₈ resins was followed by evaporative concentration …

Clay Mineral Cycles Identified By Diffuse Spectral Reflectance In Quaternary Sediments From The Northwind Ridge: Implications For Glacial-Interglacial Sedimentation Patterns In The Arctic Ocean, Lyanne N. Yurco, Joseph D. Ortiz, Leonid Polyak, Dennis A. Darby, Kevin A. Crawford

OES Faculty Publications

A Quaternary record of fine-grained sediment composition is used to investigate Arctic Ocean climate variability on glacial-interglacial time scales. Diffuse spectral reflectance data from sediment core P1-92AR-P25 from the Northwind Ridge, north of Alaska, demonstrates cyclic variations in mineralogy. Varimax-rotated R-mode factor analysis of down-core data revealed three major mineralogical assemblages, which were then compared with the content of manganese, a proxy for basin ventilation, and thus glacial-interglacial cycles. Results indicate that factor 1, a smectite + chlorite clay assemblage, was delivered to the core site during interglacials, either by fluvial discharge or sea-ice drift from Siberian rivers or inflow …

Causes Of Tropical Atlantic Paleo-Salinity Variation During Periods Of Reduced Amoc, Xiuquan Wan, Ping Chang, Matthew W. Schmidt

OES Faculty Publications

During periods of reduced Atlantic meridional overturning circulation (AMOC) associated with a freshening of northern North Atlantic surface water, paleo proxy records indicate a corresponding surface salinity increase over the entire tropical Atlantic. Although latitudinal-shifts in the mean position of the Atlantic Intertropical Convergence Zone (ITCZ) can explain certain features of the paleo salinity reconstructions, this mechanism does not offer an explanation for the reconstructed basin-wide paleo-salinity response to AMOC change. Here, we present new results from general circulation model simulations that suggest the sea surface salinity (SSS) increase in the tropical north Atlantic during periods of weakened AMOC is …

A Robust, Multisite Holocene History Of Drift Ice Off Northern Iceland: Implications For North Atlantic Climate, John T. Andrews, Dennis A. Darby, Dennis Eberle, Anne E. Jennings, Matthias Moros, Astrid Ogilvie

OES Faculty Publications

An important indicator of Holocene climate change is provided by evidence for variations in the extent of drift ice. A proxy for drift ice in Iceland waters is provided by the presence of quartz. Quantitative xray diffraction analysis of the < 2 mm sediment fraction was undertaken on 16 cores from around Iceland. The quartz weight (wt.)% estimates from each core were integrated into 250-yr intervals between −0.05 and 11.7 cal. ka BP. Median quartz wt.% varied between 0.2 and 3.4 and maximum values ranged between 2.8 and 11.8 wt.%. High values were attained in the early Holocene and minimum values were reached 6–7 cal. ka BP. Quartz wt.% then rose steadily during the late Holocene. Our data exhibit no correlation with counts on haematite-stained quartz (HSQ) grains from VM129-191 west of Ireland casting doubt on the ice-transport origin. A pilot study on the provenance of Fe oxide grains in two cores that cover the last 1.3 and 6.1 cal. ka BP indicated a large fraction of the grains between 1 and 6 cal. ka BP were from either Icelandic or presently unsampled sources. However, there was a dramatic increase in Canadian and Russian sources from the Arctic Ocean ~1 cal. ka BP. These data may indicate the beginning of an Arctic Oscillation-like climate mode.

Geobiology: Evidence For Early Life On Earth And The Search For Life On Other Planets, Sherry L. Cady, Nora Noffke

OES Faculty Publications

Extensive research efforts in the subdisciplinary field of geobiology have focused on the interactions between Earth and life through time. As a consequence, gaps in our knowledge of Earth’s history are closing, and the search for life beyond Earth is expanding. A few examples of geobiology studies designed to advance our understanding of life on early Earth and to improve the chances of finding life on other planets are provided to highlight recent developments and research areas that are on the verge of new discoveries.

On The Interpretation Of Caribbean Paleo-Temperature Reconstructions During The Younger Dryas, Xiuquan Wan, Ping Chang, R. Saravanan, Rong Zhang, Matthew W. Schmidt

OES Faculty Publications

A conundrum exists regarding whether the sea-surface temperatures decreased or increased over the southern Caribbean and the western Tropical Atlantic region during the Younger Dryas when the North Atlantic cooled substantially and the Atlantic thermohaline circulation was weakened significantly. Despite the proximity of core locations, some proxy reconstructions record a surface cooling, while others indicate a warming. We suggest that this seemingly paradoxical finding may, at least partially, be attributed to the competing physical processes that result in opposing signs of temperature change in the region in response to weakened North Atlantic meridional overturning circulation. Our coupled ocean-atmosphere model experiments …

Microtextures Of Cyanobacterial Mats In Siliciclastic Sedimentary Environments (Modern & Ancient): Applications To The Search For Life On Mars, Dina M. Bower

OES Theses and Dissertations

The current Mars Exploration Rover Program (MER) is one of NASA's most successful missions. The aim of the MER is to explore for possible life on the surface of Mars. My thesis developed new methods of how to detect and to identify microbial mats in siliciclastic sediments (modern and ancient), and to make recommendations on the applicability of MISS as biosignatures. Predominantly, I employed instrumentation portable by future rovers. To search for life on other planets, we need to have information on how this life might look. Most astrobiological studies therefore focus on Earthly analogues of life and its habitats. …

Turbulent Lifestyle: Microbial Mats On Earth’S Sandy Beaches—Today And 3 Billion Years Ago, Nora Noffke

OES Faculty Publications

Archean Earth history is very difficult to reconstruct. Until recently, only bacterial cells preserved in chert, microborings, and stromatolites provided the few clues to ancient life. Now, siliciclastic “microbially induced sedimentary structures” (MISS) are adding to our knowledge of both past life and paleoenvironments. MISS rise from the interaction of photoautotrophic microbial mats with physical sediment dynamics in siliciclastic, shallow-marine settings. Archean MISS can be understood through observations of living microbial mats and modern biotic-physical sedimentary processes. Such geobiological studies are key to the interpretation of the early evolution of prokaryotes. For example, the 2.9 Ga Pongola Supergroup, South Africa, …