Physical Sciences and Mathematics Commons^™

Stable Isotope Geochemistry Of Bioapatite, Amanda E. Drewicz

Boise State University Theses and Dissertations

The Cenozoic Era was a time period where dynamic shifts in climate created for both warm-wet greenhouse environments of the mid-Miocene Climatic Optimum (MMCO), and cool-dry, glacial periods of the late Pleistocene. The Cenozoic is close to our own time period, and although past climate reconstructions cannot be used as direct analogs for future climate change, understanding previous environmental responses can help inform policy surrounding future climate change. Presented here are climate reconstructions of the interior western United States, from two different geologic time periods. Each had a different climate, that differed greatly from modern day environments. The use of …

Evaluating Stable Isotope And Geochronologic Techniques For Paleoclimate Reconstruction: Case Study Of The Santa Cruz Formation, Argentina, Robin B. Trayler

Boise State University Theses and Dissertations

Stable isotope analysis has become the method of choice for many studies investigating the paleoecology and paleoclimate of fossil mammal faunas. While organic tissues (collagen, keratins, proteins) persist for < 10⁵ years highly mineralized tooth enamel is resistant to alteration and degradation and faithfully preserves its isotopic composition for millions (> 10⁶) years. Reconstructing past climates from these records relies on both understanding both micro-scale mechanisms of isotope incorporation into individual teeth, and macro-scale changes in isotope compositions over hundreds of thousands or millions of years. In this dissertation I address three questions.

First, how does the geometry and …

Signature Of Obliquity And Eccentricity In Soil Chronosequences, Christopher Shepard, Jon D. Pelletier, Marcel G. Schaap, Craig Rasmussen

Plant and Soil Sciences Faculty Publications

Periodic shifts in Earth's orbit alter incoming solar radiation and drive Quaternary climate cycles. However, unambiguous detection of these orbitally driven climatic changes in records of terrestrial sedimentation and pedogenesis remains poorly defined, limiting our understanding of climate change‐landscape feedbacks, impairing our interpretation of terrestrial paleoclimate proxies, and limiting linkages among pedogenesis, sedimentation, and paleoclimatic change. Using a meta‐analysis, we show that Quaternary soil ages preserved in the modern record have periodicities of 41 and 98 kyr, consistent with orbital cycles. Further, soil ages predominantly date to periods of low rates of climatic change following rapid climate shifts associated with …

Mid-Pliocene To Early Pleistocene Sea Surface And Land Temperature History Of Nw Australia Based On Organic Geochemical Proxies From Site U1463, Rebecca Smith

Masters Theses

Ocean gateways facilitate water circulation between ocean basins, and therefore directly impact thermohaline circulation and global climate. In order to better predict the effects of future climate change, it is critical to constrain past changes in ocean gateway behavior, and corresponding changes in thermohaline circulation, particularly during analogue periods for modern climate change. The Indonesian Throughflow (ITF) is a primary ocean gateway and vital component of the global conveyor that transports water from the Pacific Ocean into the Indian Ocean, however due to a lack of long and continuous sedimentary records from locations under its influence, changes in ITF behavior …

Modern And Paleoecological Perspectives On A Terrestrial-Marine Linkage In The Falkland Islands, Dulcinea V. Groff

Electronic Theses and Dissertations

The Falkland Islands are a biodiversity hotspot in the South Atlantic Ocean, with some of the world’s most important populations of seabirds and seals. The impact of climate change on these marine populations and their coastal breeding habitat in the Falklands is unknown. Coastal grasslands of Poa flabellata (tussac grass) form critical breeding habitat for wildlife, but have been heavily degraded by the introduction of livestock in the 17^th century. This dissertation investigates the impacts of global change (climate change, grazing) on P. flabellata and its sensitivity to the fecal nutrient subsidies provided by marine wildlife. Chapter 1 provides …

Retreat Of The Antarctic Ice Sheet In The Southern Ross Embayment From Records At Amundsen And Liv Glaciers, Southern Transantarctic Mountains, Jillian Pelto

Electronic Theses and Dissertations

The Antarctic Ice Sheet contains ~58 m of global sea-level equivalent and thus its future behavior under global warming is of pressing concern. Examination of past ice-sheet behavior during periods of warming climate can afford insight useful for predicting future sea-level rise. This study focuses on a major unanswered question - namely, the cause of Antarctic Ice Sheet retreat following the last glaciation. Documenting the timing and nature of this deglaciation is crucial to understand the mechanisms behind ice-sheet behavior. Here, I examine how the marine portions of the ice sheet responded to the major warming that occurred at the …

Petrographic And Palynological Investigations Of Sinanpaşa (Afyon) Miocene Coals, Elif Akiska

Bulletin of the Mineral Research and Exploration

In this study, petrographical and palynological analyses of coal samples from two regions (the Kırka region in the south, and the Karacaören region in the north) of the Sinanpaşa (Afyon) Neogene basin were performed. The coal-bearing Neogene sediments indicate the occurrence of fi ve facies: paleosol, matrix-supported conglomerate, coal-bearing mudstone, sandstone-claystone and laminated mudstones. Coal layers are mainly within coal-bearing mudstone facies. In addition, there are various types of coalifi ed materials in matrix-supported conglomerate and sandstone-claystone facies. Based on coal petrography, an interpretation of the coal-forming environment was made. The investigated coals mainly contain a huminite maceral group. From …

Eccentricity Modulation Of Precessional Variation In The Earth’S Climate Response To Astronomical Forcing: A Solution To The 41-Kyr Mystery, Rajarshi Roychowdhury

Doctoral Dissertations

The 41,000-year variability of Earth’s glacial cycles during the late Pliocene-early Pleistocene is usually attributed to variations in Earth’s obliquity (axial tilt). However, a satisfactory explanation for the lack of precessional variation in marine d¹⁸O records, a proxy for ocean temperature and ice-volume, remains contested. Here, a physically based climate model is used to show that the climatic effect of precession is muted in global isotope records due to two different mechanisms, with each dominating as a function of eccentricity. At low eccentricities (e0.019), the time-integrated summer insolation and number of positive degree-days impacting ice sheets varies at …

Monthly Paleostreamflow Reconstruction From Annual Tree-Ring Chronologies, James H. Stagge, David E. Rosenberg, R. J. Derose, Tammy M. Rittenour

Publications

Paleoclimate reconstructions are increasingly used to characterize annual climate variability prior to the instrumental record, to improve estimates of climate extremes, and to provide a baseline for climate-change projections. To date, paleoclimate records have seen limited engineering use to estimate hydrologic risks because water systems models and managers usually require streamflow input at the monthly scale. This study explores the hypothesis that monthly streamflows can be adequately modeled by statistically decomposing annual flow reconstructions. To test this hypothesis, a multiple linear regression model for monthly streamflow reconstruction is presented that expands the set of predictors to include annual streamflow reconstructions, …

Occupational Seasonality And Paleoenvironmental Reconstruction At Quebrada Jaguay 280, Stephanie Melissa Gruver

Graduate Research Theses & Dissertations

Quebrada Jaguay 280 (QJ-280) is one of the oldest maritime archaeological sites in the New World. Previous excavations of the southern Peruvian coastal site have dated occupation from ~13,000-8,000 cal yr BP. These excavations also determined that the occupants of the site used preferential maritime resource procurement strategies and had an interzonal connection to the highlands. In 2017 a new excavation was conducted at QJ-280 and the remains of the marine mollusk Mesodesma donacium were recovered. Geochemical examinations on the shell remains informed on the occupational seasonality of the site and reconstructed sea surface temperatures experienced off the coast of …

Hydrogen, Carbon, And Oxygen Isotopes In Prosopis Sp. Trees: A New Climate Proxy For Holocene Paleoclimate In The Atacama Desert, Chile, Elizabeth Joy Olson

Graduate Research Theses & Dissertations

The spatial ubiquity of trees in terrestrial ecosystems worldwide facilitates the use of stable isotope research in tree-rings to address a wide-range of interdisciplinary questions related to climate, ecology, archaeology, and hydrology. This dissertation focuses on the development and application of Prosopis tamarugo tree-ring stable isotope records as a paleoclimate proxy for the Atacama Desert, Chile. Current paleoclimate proxies from this region lack the spatial and temporal resolution to quantify a causal mechanism for observed Holocene hydroclimate variability. P. tamarugo tree-ring isotopes provide a high-resolution proxy that facilitates the reconstruction of hydroclimate variability at a regional scale. In order to …

From Sea To Lake: The Depositional History Of Saint Albans Bay, Vt, Usa, Matthew Kraft

Graduate College Dissertations and Theses

Sediment accumulated in lakes stores valuable information about past environments and paleoclimatological conditions. Cores previously obtained from Saint Albans Bay, located in the Northeast Arm of Lake Champlain, VT record the transition from the Champlain Sea to Lake Champlain. Belrose (2015) documented the presence of a peat horizon separating the sediments of the Champlain Sea from those of Lake Champlain. Initially, this layer was thought to comprise the transition from the marine environment of the Champlain Sea to a freshwater wetland. However, based on the results from this study, the transition between marine and freshwater conditions is thought to be …

Calcic Paleosols In A Stratigraphic Context From Quaggasfontein, Eastern Cape Province, South Africa: Correlations In The Wapadsberg Pass Area And Implications For Late Permian Climate, Kaci B. Kus

Honors Theses

The Karoo Basin, South Africa, contains a reportedly continuous stratigraphic record spanning the terrestrial vertebrate extinction event equated with the Permian-Triassic boundary (PTB) in the marine record. The current hypothesis links this major loss in biodiversity and vertebrate turnover to a global change in climate towards aridification. Rapid climate change is interpreted to be reflected in continental rocks by a changeover from (1) greenish (Permian) to reddish (Triassic) mudrock, (2) a transition in the river architectures from meandering to braided regimes, and (3) wetland to calcic-bearing paleosols. Here, we present geochemical results on a 1.3-meter calcic paleoVertisol interval found ~34 …

Paleogene-Early Neogene Palynomorphs From The Eastern Equatorial Atlantic And Southeastern Florida, Usa: Biostratigraphy And Paleoenvironmental Implications, Walaa K. Awad

Doctoral Dissertations

"The transition from greenhouse conditions (Paleocene-Eocene Thermal Maximum, PETM) to icehouse conditions (Early Oligocene) is not well documented in tropical-subtropical regions. One hundred and five samples from Ocean Drilling Program (ODP) Site 959 (Hole 959A and Hole 959D) in the Cote d'Ivoire-Ghana Transform Margin, Alo-1 Well in the northern Niger Delta (Anambra) Basin, Nigeria, and W-17001 in southeastern Florida were studied for their palynological contents. Dinoflagellate cysts were mainly utilized for age refinement and to detect subtle changes in paleoenvironment and paleoclimate during the Paleocene-Early Eocene (ODP Hole 959D and Alo-1 Well) and Late Eocene-Early Miocene (ODP Hole 959A and …