Browsing by Author "Bird, Broxton"
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Item Characterization of lunar crust with moon mineralogy mapper data(2015-06-09) Sun, Ying; Lin, Li; Bird, Broxton; Johnson, Daniel; Licht, Kathy; Gilhooly, William P.This dissertation has three main focuses: (1) identify the distribution of a new rock type (Mg-spinel lithology) on the Moon and explore the likely petrogenesis of Mg-spinel; (2) investigate the presence of olivine in the crater central peaks and analyze the sources of olivine; (3) determine the compositional variations of lunar crust with depth, and establish a new model to describe the structure of the lunar crust.Item Common Era Midcontinental Hydroclimate Variability Inferred from Iowan Lake Sediments, Usa(2024-02) Goswami, Anusuya; Bird, Broxton; Filippelli, Gabriel; Jacinthe, Pierre-AndréGlobal climate change manifests diverse consequences across the United States, creating distinct challenges in different regions. For example: The Western United States grapples with a notable surge in wildfires and drought events, indicating reduced effective moisture. In contrast, the Eastern part faces severe and frequent flooding events, reflecting higher effective moisture conditions and suggesting an East-West dipole-like climatic pattern. While the current East-West dividing hinge-line sits at 96°W, questions linger about its persistence throughout the late Holocene or whether it has undergone changes over time. Understanding the evolution and stability of this hinge-line is crucial for predicting the impacts of ongoing global warming on various U.S. regions. To address this issue, it is essential to develop additional paleoclimate records from the U.S. Midcontinent, especially those in close proximity to the modern hydroclimate hinge-line. This research focuses on understanding the common era (CE; last 2000 years) hydroclimate variability and its driving mechanisms using lake sediment archives from two hydrologically restricted Iowan kettle lakes, West Lake Okoboji (~1800 years long) and Clear Lake (~2000 years long). The results of multiproxy sedimentological, geochemical, and isotopic analyses reveal a wetter period during the Medieval Climate Anomaly (MCA; 950-1250 CE) and a drier phase during the Little Ice Age (LIA; 1350-1850 CE), aligning with regional patterns in the upper Midwest. Comparisons with regional paleoclimate records suggest that pluvial conditions during the MCA were linked to mean state atmospheric circulation conditions resembling the negative phase of the Pacific-North American (-PNA) teleconnection pattern when Pacific Ocean-atmosphere conditions similarly resembled the negative phase of the Pacific Decadal Oscillation (-PDO). Conversely, drier conditions during the LIA occurred when +PNA-like atmospheric circulation patterns predominated under +PDO-like conditions in the North Pacific Ocean. Comparison with records near the modern hydroclimate hinge-line indicates in-phase relationships with records east of 96˚ W and anti-phased relationships with records west of 96˚ W. This supports idea of the stable hinge line position during the Common Era.Item Determining the Laurentide Ice Sheet and Bedrock Provenance of Midwestern Till by Applying U-Pb Geochronology to Detrital Zircons(2019-10) Mickey, Jeremiah Lee; Licht, Kathy J.; Bird, Broxton; Malone, David; Loope, HenryA broad range of samples were collected from the Huron-Erie Lobe, Lake Michigan Lobe, Saginaw Lobe, and Tipton Till Plain of northern Indiana to determine the provenance of Laurentide Ice Sheet till in the Midwest U.S. during the Illinoian and Wisconsinan glaciations. U-Pb age distributions from approximately 300 detrital zircons (DZ) were used as provenance indicators for each till sample. Till from the Lake Michigan Lobe and was found to be largely homogenized. The distinct lobe DZ age distributions are the Lake Michigan Lobe till with a dominant ~1465 Ma peak, the northern Huron-Erie Lobe till with a dominant ~1060 Ma and a secondary peak at ~1450 Ma, the southern Huron-Erie Lobe till with nearly equal peaks at ~1435 Ma, ~1175 Ma, and ~1065 Ma, and the southern Saginaw Lobe till with a dominant peak at ~1095 Ma. Those four DZ age distributions were treated as endmembers in a nonlinear least-squares mixing model to calculate the contribution of each lobe to till in the Tipton Till Plain. Huron-Erie and Saginaw lobe tills were found to be the primary components of the Tipton Till Plain, and Lake Michigan Lobe till was only found in the western Tipton Till Plain. Zircons from the Saginaw Lobe till increased 39 % in the eastern Tipton Till Plain between the Illinoisan and Wisconsinan glaciations. The mixing model was also applied to relate the DZ age distributions of the lobes to bedrock within and near their flow paths. When comparing nearby bedrock to each lobe’s till, mixing model results, yield an approximate maximum transport distance between 500 and 630 kilometers for the matrix vii fraction of till in the Lake Michigan, Huron-Erie, and Saginaw lobes. Samples for the southern Huron-Erie Lobe indicate that the most of the zircon ages within the southern Huron-Erie Lobe till in Indiana were specifically entrained between Niagara County, New York and east-central Indiana. Within the model’s error, 93 – 100 % of the detrital zircons in each of the three lobes are relatable to nearby Paleozoic and Precambrian sedimentary and metamorphic bedrock formations.Item Effects of American Colonial Settlement and Deforestation on Lacustrine Redox Conditions: Longterm Insights from Martin Lake, Indiana(2020-11) Henke, Alyssa Nicole; Gilhooly, William P., III; Bird, Broxton; Druschel, GregoryColonial settlement of Indiana changed the environment in significant ways; the aim of this study is to quantify the impacts of settlement through the use of geochemical proxies including: % lithics; the carbon (δ13C), nitrogen (δ15N), and sulfur (δ34S) isotope composition of organic matter; the elemental composition of carbon (TOC) and nitrogen (Ntot) in organic matter and their ratio (C/N); the δ34S of mineral sulfides (pyrite and acid volatile sulfides); and iron redox proxies. Lakes are a great recorder of aquatic-terrestrial linkages on both local and global scales. Martin lake’s watershed, in northeastern Indiana, was settled in 1840 by Euro-Americans, and since then clear shifts in lake chemistry are recorded in its sediments. A core spanning roughly the last 300 years taken from Martin Lake is the basis of this study. The impacts of settlement can be seen through the lenses of all the proxies that were used in this study. 1) Post-settlement deforestation increased erosion in Martin Lake’s watershed, increasing sedimentation rates and % lithics. 2) δ13C of organic matter reveals a pattern of deforestation and partial regrowth and agricultural use of land. 3) A pronounced increase in δ15N timed with the change in population at the time of settlement is consistent with the increased input of human or animal waste into Martin Lake. 4) TOC and C/N show an overall increase in the amount of organic matter within the lake caused by deforestation, and that the increased nutrient supply may have stimulated more in-lake productivity. 5) δ34S of mineral sulfides show that deforestation lead to an increase in the available sulfate pool of Martin Lake, which in combination with 6) an increase in FeHR created redox conditions in which pyrite formation was more favorable. These factors culminated in a transition in Martin Lake chemistry and redox cycling within the sediments.Item Introduction to Broxton Bird & His Work(Center for Translating Research Into Practice, IU Indianapolis, 2023-04) Bird, BroxtonProfessor Broxton Bird gives an overview of his paleoclimate research in the midcontinental U.S. that seeks to determine the relationship between past climate change and flooding and how this information can be used to understand how human impacts on the climate and landscape have altered these natural systems and what it means for the future.Item Investigating the Effects of Synoptic-Scale Climatic Processes on Local-Scale Hydrology by Combining Multi-Proxy Analyses of Lacustrine Sediments and Instrumental Records(2022-09) Gibson, Derek Keith; Bird, Broxton; Gilhooly, William, III; Jacinthe, Pierre-André; Licht, Kathy; Wang, XianzhongPaleoclimate records from North and South America were used to develop a holistic understanding of global paleo-hydroclimatic drivers across a range of boundary conditions. Here, geophysical analysis of lacustrine sediment stratigraphy at Lago de Tota, Boyaca, Colombia provided evidence for significant lake-level fluctuations through the late Quaternary and produced a record that potentially spans the last 60 ka. Seismic data revealed a series of off-lap and on-lap sequences in the upper ~20 m of sediments that indicated large amplitude changes in lake-level, driven by variability in the mean latitude of the Intertropical Convergence Zone as controlled by insolation- and ocean circulation-driven hemispheric temperature gradients during glacial/stadial and interglacial/interstadial events. In North America, late Holocene flood recurrence in the Midwest and Holocene changes in the mean latitude of the polar front jet stream were investigated through multi-proxy examinations of sediment cores collected from swale lakes in northern Kentucky and southern Indiana, and a glacially formed kettle lake in northern Indiana. These results showed that the midlatitude jet stream was displaced to the south during the late Holocene, which increased the amount of Midwestern precipitation sourced from the northern Pacific and Arctic, especially during prolonged cool conditions. During these cool periods, when atmospheric flow was meridional and a greater amount of precipitation was delivered from the northerly sources, Ohio River flooding increased. During warm conditions, when clockwise mean-state atmospheric circulation advected southerly moisture from the Gulf of Mexico into the Midwest, flooding on the Ohio River decreased. At present, streamflow in the Midwest is demonstrated here to be generally increasing, despite atmospheric conditions typically associated with reduced streamflow in the paleo-record, due in part to increasing precipitation and modern land-use dynamics. Together, these studies demonstrate the sensitivity and vulnerability of local-scale hydrological processes to synoptic climate change.Item A laminated carbonate record of late holocene precipitation/evaporation from Pretty Lake, Lagrange County, Indiana(2016-11-06) Albert, Ashley Lisbeth; Bird, BroxtonLate Holocene hydroclimate variability in the midcontinental United States is not well understood because there is a lack of high-resolution paleoclimate records constraining historical climate patterns for the region. Here, a 2500-year-long multi proxy lake sediment record from a northern Indiana kettle lake is used to examine spatial and temporal scales of drought and pluvial patterns in the Midwest. Oxygen (18Ocal) isotope analysis of authigenic carbonate and the sedimentary lithic abundance (%lithics) are the primary datasets used to evaluate hydroclimate trends with supporting information from total organic matter, total carbonate and magnetic susceptibility. We additionally derive a record of local evaporation by subtracting the isotopic composition of precipitation (18Oprecip) as characterized by the nearby Martin Lake, IN, record, from the Pretty Lake 18Ocal record. The combined Pretty Lake hydroclimate record documents climate variability during the last 2 millennia and shows that the Midwest has experienced a wide range of evaporative regimes during the late Holocene. We notice a consistent relationship between the Pretty and Martin Lake multi-proxy records; where reduced (increased) evaporative periods and higher (lower) lake levels at Pretty Lake mostly align with increased (decreased) Gulf sourced precipitation and stream erosion with longer (shorter) warm seasons at Martin Lake. Early periods of much drier, and weakened warm-season evaporation patterns dominated from 600 BCE to 900 CE. Evidence of a prolonged period of enhanced warm-season pluvial conditions, with less evaporation and higher lake levels, during the Medieval Climate Anomaly (MCA) between 900 to 1350 CE; and a pronounced century of arid conditions throughout the Little Ice Age (LIA) from 1350 to 1700 CE followed by a gradual decrease in evaporation and rising lake levels starting at 1700 CE and continuing to present. These trends track other Midwest regional hydroclimate climate records, but show an anti-phased relationship with records from the High Plains and western United States regions. This supports the idea that a hydrocilmate dipole exists between the Midwest and western United States driven largely by mean state changes in the Pacific North American teleconnection pattern, but with modification by local and in-lake responses to mean climate states.Item Late Holocene Climate-Flood Relationships on the White River, Indiana, USA(2022-05) Wright, Maxwell N.; Bird, Broxton; Licht, Kathy; Gilhooly, William, III.The frequency and magnitude of floods in the midcontinental United States have increased in recent decades due to changing precipitation patterns as global temperatures rise. These trends pose major social and economic risks to the region, which is home to tens of millions of Americans and a global agricultural center. It is therefore critical to understand if current fluvial dynamics are within the scope of past fluvial-climate relationships, or if they represent a novel response to recent climate and land-use changes. Presented is a 1600-year-long flood frequency record for the moderately sized (~29,400 km2 watershed) White River, Indiana. Flood frequencies were determined using 14C-based sediment accumulation rates at Half Moon Pond, an oxbow lake on the lower White River’s floodplain. Comparison with regional paleoclimate data shows that White River flooding was frequent when atmospheric circulation resembled the negative mode of the Pacific-North American (PNA) teleconnection, particularly during the Medieval Climate Anomaly (950-1250 CE) and the Current Warm Period (last ~150 years). During these times, the regional climate was dominated by warm-season precipitation originating from the Gulf of Mexico. Conversely, White River flooding was less frequent during the Little Ice Age (1250-1800 CE) when cold-season precipitation from the North Pacific/Arctic dominated (+PNA-like conditions). The pre-1790 CE White River flood history was antiphased with reconstructed Ohio River flood frequencies from southern Illinois. This dynamic is consistent with discharge in small to moderate sized watersheds being sensitive to rainstorm runoff and large watersheds being sensitive to snowmelt runoff. After 1790 CE, flooding frequencies of both river systems increased to their highest levels, despite a shift to -PNA-like conditions. This change was likely due to extensive Euro-American land-clearance, which increased runoff/erosion by reducing evapotranspiration, interception, and infiltration. While the White River responded strongly to climatic conditions in the past that were similar to present conditions (-PNA-like conditions), recent land-use practices have amplified the effects of the current hydroclimate. Since a warming climate is expected to increase regional average precipitation and extreme rainfall events, and that landscape modifications have lowered surface resilience to hydroclimate events, flooding will likely become more frequent in the coming decades.Item Meteoric 10Be as a Tracer for Subglacial Chemical Weathering in East Antarctica(2021-12) Arnardóttir, Eiríka Ösp; Licht, Kathy; Graly, Joseph; Bird, Broxton; Gilhooly, WilliamSubglacial chemical processes in Antarctica are potentially significant contributors to global geochemical cycles, but current understanding of their scale and nature is limited. A sequential chemical extraction procedure was developed and tested to investigate the utility of meteoric 10Be as a tracer for chemical weathering processes beneath the East Antarctic Ice Sheet. Subglacial meltwater is widely available under the Antarctic Ice Sheet and chemical constituents within it have the potential to drive geochemical weathering processes in the subglacial environment. Meteoric 10Be is a cosmogenic nuclide with a half-life of 1.39×106 years that is incorporated into glacier ice, therefore its abundance in the subglacial environment in Antarctica is meltwater dependent. It is known to adsorb to fine-grained particles in aqueous solution, precipitate with amorphous oxides, and/or be incorporated into authigenic clay structures during chemical weathering. The presence of 10Be in weathering products derived from beneath the ice therefore indicates chemical weathering processes in the subglacial environment. Freshly emerging subglacial sediments from the Mt. Achernar blue ice moraine were subject to chemical extractions where these weathering phases were isolated and 10Be concentrations therein quantified. Optimization of the phase isolation was developed by examining the effects of each extraction on the sample mineralogy and chemical composition. Experiments on 10Be desorption revealed that pH 3.2-3.5 was optimal for the extraction of adsorbed 10Be. Vigorous disaggregation of the samples before grain size separations and acid extractions is crucial due to the preferential fractionation of the nuclide with clay-sized particles. 10Be concentrations of 2-22×107 atoms g-1 measured in oxides and clay minerals in freshly emerging sediments strongly indicate subglacial chemical weathering in the catchment of the Mt. Achernar moraine. Sediment-meltwater contact in the system was calculated to be on the order of thousands of years, based on total 10Be sample concentrations, local basal melt rates, and 10Be ice concentrations. Strong correlation (R = 0.96) between 10Be and smectite abundance in the sediments indicate authigenic clay formation in the subglacial environment. This study shows that meteoric 10Be is a useful tool to characterize subglacial geochemical weathering processes under the Antarctic Ice Sheet.Item Paleo Perspectives of Climate-Flood Relationships in the Midcontinental U.S.: Using the Past to Inform the Future(Center for Translating Research Into Practice, IU Indianapolis, 2023-04-28) Bird, BroxtonDuring this conversation, Dr. Broxton Bird gives an overview of his paleoclimate research in the midcontinental US that seeks to determine the relationship between past climate change and flooding and how this information can be used to understand how human impacts on the climate and landscape have altered these natural systems and what it means for the future.