Research and Publications - Department of Geological Sciences
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Item Oxygen isotope composition of teeth suggests endothermy and possible migration in some Late Cretaceous shark taxa from the Gulf Coastal Plain, USA(Cambridge University Press, 2025-01-02) Comans, Chelsea M.; Tobin, Thomas S.; Totten, Rebecca L.We analyzed the oxygen isotope composition of biogenic apatite phosphate (δ18Op) in fossil tooth enameloid to investigate the paleoecology of Late Cretaceous sharks in the Gulf Coastal Plain of Alabama, USA. We analyzed six different shark taxa from both the Mooreville Chalk and the Blufftown Formation. We compared shark δ18Op with the δ18Op of a co-occurring poikilothermic bony fish Enchodus petrosus as a reference for ambient conditions. Enchodus petrosus tooth enamel δ18Op values are similar between formations (21.3‰ and 21.4‰ Vienna Standard Mean Ocean Water [VSMOW], respectively), suggesting minimal differences in water δ18O between formations. Most shark taxa in this study are characterized by δ18Op values that overlap with E. petrosus values, indicating they likely lived in similar hab itats and were also poikilothermic. Ptychodus mortoni and Cretoxyrhina mantelli exhibit sig nificantly lower δ18Op values than co-occurring E. petrosus (P. mortoni δ18Op is 19.1‰ VSMOW in the Mooreville Chalk; C mantelli δ18Op is 20.2‰ VSMOW in the Mooreville Chalk and 18.1‰ VSMOW in the Blufftown Formation). Excursions into brackish or fresh water habitats and thermal water-depth gradients are unlikely explanations for the lower P. mortoni and C. mantelli δ18Op values. The low P. mortoni δ18Op value is best explained by higher body temperature relative to surrounding temperatures due to active heating (e.g., mesothermy) or passive heating due to its large body size (e.g., gigantothermy). The low C. mantelli δ18Op values are best explained by a combination of mesothermy (e.g., active heating) and migration (e.g., from the Western Interior Seaway, low-latitude warmer waters, or the paleo–Gulf Stream), supporting the hypothesis that mesothermy evolved in lamniform shark taxa during the Late Cretaceous. If the anomalous P. mortoni δ18Op values are also driven by active thermoregulation, this suggests that mesothermy evolved independently in multiple families of Late Cretaceous sharks.Item Archaeological climate proxies and the complexities of reconstructing Holocene El Niño in coastal Peru.Sandweiss, Daniel S.; Andrus, C. Fred. T.; Kelley, Alice R.; Maasch, Kirk A.; Reitz, Elizabeth J.; Roscoe, Paul B.Item Examining the potential of Pacific abalone as a novel high-resolution archive of upwelling in the California Current.Bassett, Christine N.; Andrus, C. Fred. T.Item Skeletal growth controls on Mg/Ca and P/Ca ratios in tropical Eastern Pacific rhodoliths (coralline red algae).Sletten, Hillary R.; Gillikin, David P.; Halfar, Jochen; Andrus, C. Fred. T.; Guzman, HectorItem A 7,000-year record of floods and ecological feedbacks in Weeks Bay, Alabama, USA.Minzoni, Rebecca T.; Parker, Lauren E.; Wallace, Davin J.; Lambert, William J.; Elliot, Emily A.; Andrus, C. Fred. T.Item Fundamental questions and applications of sclerochronology: community-defined research priorities.Trofimova, T.; Alexandroff, S.; Mette, M.; Tray, E; Butler, P.; Campana, S.; Harper, E.; Johnson, A.; Morrongiello, J.; Peharda Uljevic, M.; Schöne, B. R.; Andersson, C.; Andrus, C. Fred. T.; Black, B.; Buechell, M.; Carroll, M.; DeLong, K.; Gillanders, B.; Grønkjær, P.; Killam, D.; Pendergrast, A.; Reynolds, D.; Scourse, J.; Shirai, K.; Thebault, J.; Trueman, C.; de Winter, N. J.Item Subseasonal variations in marine radiocarbon reservoir age from pre-bomb Donax obesulus and Protothaca asperrima shell carbonate.Etayo-Cadavid, Miguel F.; Andrus, C. Fred. T.; Jones, Kevin B.; Hodgins, Gregory W. L.Item Sclerochronological basis for growth increment counting: a reliable technique for life-span determination of Crassostrea virginica from the Mid-Atlantic United States.Zimmt, J. B.; Lockwood, Rowan; Andrus, C. Fred. T.; Herbert, G. S.Item Gneiss Domes, Vertical and Horizontal Mass Transfer, and the Initiation of Extension in the Hot Lower-Crustal Root of a Continental Arc, Fiordland, New ZealandKepeis, Keith A.; Schwartz, Joshua; Stowell, Harold; Tulloch, AndrewItem The Farnham Peat Collection: A Subject Catalog of the Peat Research Materials in the Natural Resources Library(1990-08-04) Sandy, John H.; Hauck, Barbara H.; Hendrickson, Susan R.; Weber, Frances A.Item NRRI Library to House Materials Related to Copper-Nickel Study(1989-03-10) Sandy, John H.; Miller, PatriciaItem The Elusive Evidence of Volcanic Lightning(Nature Portfolio, 2017) Genareau, K.; Gharghabi, P.; Gafford, J.; Mazzola, M.; University of Alabama Tuscaloosa; Mississippi State UniversityLightning strikes are known to morphologically alter and chemically reduce geologic formations and deposits, forming fulgurites. A similar process occurs as the result of volcanic lightning discharge, when airborne volcanic ash is transformed into lightning-induced volcanic spherules (LIVS). Here, we adapt the calculations used in previous studies of lightning-induced damage to infrastructure materials to determine the effects on pseudo-ash samples of simplified composition. Using laboratory high-current impulse experiments, this research shows that within the lightning discharge channel there is an ideal melting zone that represents roughly 10% or less of the total channel radius at which temperatures are sufficient to melt the ash, regardless of peak current. The melted ash is simultaneously expelled from the channel by the heated, expanding air, permitting particles to cool during atmospheric transport before coming to rest in ash fall deposits. The limited size of this ideal melting zone explains the low number of LIVS typically observed in volcanic ash despite the frequent occurrence of lightning during explosive eruptions.Item Use of ESI-FTICR-MS to Characterize Dissolved Organic Matter in Headwater Streams Draining Forest-Dominated and Pasture-Dominated Watersheds(PLOS, 2015) Lu, YueHan; Li, Xiaping; Mesfioui, Rajaa; Bauer, James E.; Chambers, R. M.; Canuel, Elizabeth A.; Hatcher, Patrick G.; University of Alabama Tuscaloosa; Old Dominion University; Ohio State University; William & Mary; Virginia Institute of Marine ScienceElectrospray 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 = 0.7-1.5, O/C = 0.1-0.67), suggesting the predominance of allochthonous, terrestrial plant-derived DOM. Relative to the two pasture streams, DOM formulas in the two forest streams were more similar, based on Jaccard similarity coefficients and nonmetric multidimensional scaling calculated from Bray-Curtis distance. Formulas from the pasture streams were characterized by lower proportions of aromatic formulas and lower unsaturation, suggesting that the allochthonous versus autochthonous contributions of organic matter to streams were modified by pasture land use. The number of condensed aromatic structures (CAS) was higher for the forest streams, which is possibly due to the controlled burning in the forest-dominated watersheds and suggests that black carbon was mobilized from soils to streams. During 15-day biodegradation experiments, DOM from the two pasture streams was altered to a greater extent than DOM from the forest streams, with formulas with H/C and O/C ranges similar to protein (H/C = 1.5-2.2, O/C = 0.3-0.67), lipid (H/C = 1.5-2.0, O/C = 0-0.3), and unsaturated hydrocarbon (H/C = 0.7-1.5, O/C = 0-0.1) being the most bioreactive groups. Aromatic compound formulas including CAS were preferentially removed during combined light+bacterial incubations, supporting the contention that black carbon is labile to light alterations. Collectively, our data demonstrate that head-water DOM composition contains integrative information on watershed sources and processes, and the application of ESI-FTICR-MS technique offers additional insights into compound composition and reactivity unrevealed by fluorescence and stable carbon isotopic measurements.Item Recognition of a likely two phased extinction at the K-Pg boundary in Antarctica(Nature Portfolio, 2017) Tobin, Thomas S.; University of Alabama TuscaloosaThe southernmost Cretaceous-Paleogene (K-Pg) outcrop exposure is the well-studied exposure on Seymour Island, Antarctica. Deposition across the K-Pg boundary there is uninterrupted, and as a consequence the ammonite fossil record is commonly used to test statistical methods of evaluating mass extinctions to account for the incompleteness of the fossil record. Numerous detailed fossil data sets from Seymour Island, comprised dominantly of mollusks, have been published over the last 30 years, but in most cases have not received statistical treatment. Here a previously published statistical technique is modified, automated, and applied to all published macrofossil data sets available from Seymour Island. All data sets reveal likely evidence of two separate multi-species extinctions, one synchronous with bolide impact evidence at the K-Pg boundary, and another 45 +/- 15 meters (similar to 140-290 ky) below the boundary. The apparent earlier extinction primarily affects benthic mollusks, while the boundary extinction primarily affects ammonites. While there is no unique sedimentological change over the interval where the earlier extinction is identified, it is impossible to exclude the possibility that this pattern is stratigraphically controlled. The automation of this technique allows it to be applied easily to other large fossil data sets.Item Fractal nature of groundwater level fluctuations affected by riparian zone vegetation water use and river stage variations(Nature Portfolio, 2019) Sun, HongGuang; Gu, Xiufen; Zhu, Jianting; Yu, Zhongbo; Zhang, Yong; Hohai University; University of Wyoming; University of Alabama TuscaloosaGroundwater systems affected by various factors can exhibit complex fractal behaviors, whose reliable characterization however is not straightforward. This study explores the fractal scaling behavior of the groundwater systems affected by plant water use and river stage fluctuations in the riparian zone, using multifractal detrended fluctuation analysis (MFDFA). The multifractal spectrum based on the local Hurst exponent is used to quantify the complexity of fractal nature. Results show that the water level variations at the riparian zone of the Colorado River, USA, exhibit multifractal characteristics mainly caused by the memory of time series of the water level fluctuations. The groundwater level at the monitoring well close to the river characterizes the season-dependent scaling behavior, including persistence from December to February and anti-persistence from March to November. For the site with high-density plants (Tamarisk ramosissima, which requires direct access to groundwater as its source of water), the groundwater level fluctuation becomes persistent in spring and summer, since the plants have the most significant and sustained influence on the groundwater in these seasons, which can result in stronger memory of the water level fluctuation. Results also show that the high-density plants weaken the complexity of the multifractal property of the groundwater system. In addition, the groundwater level variations at the site close to the river exhibit the most complex multifractality due to the influence of the river stage fluctuation.Item Effects of Lightning on the Magnetic Properties of Volcanic Ash(Nature Portfolio, 2019) Genareau, Kimberly; Hong, Yang-Ki; Lee, Woncheol; Choi, Minyeong; Rostaghi-Chalaki, Mojtaba; Gharghabi, Pedram; Gafford, James; Kluss, Joni; University of Alabama Tuscaloosa; Mississippi State University; University of North Carolina; University of North Carolina CharlotteHigh-current impulse experiments were performed on volcanic ash samples to determine the magnetic effects that may result from the occurrence of volcanic lightning during explosive eruptions. Pseudo-ash was manufactured through milling and sieving of eruptive deposits with different bulk compositions and mineral contents. By comparing pre- and post-experimental samples, it was found that the saturation (i.e., maximum possible) magnetization increased, and coercivity (i.e., ability to withstand demagnetization) decreased. The increase in saturation magnetization was greater for compositionally evolved samples compared to more primitive samples subjected to equivalent currents. Changes in remanent (i.e., residual) magnetization do not correlate with composition, and show wide variability. Variations in magnetic properties were generally more significant when samples were subjected to higher peak currents as higher currents affect a greater proportion of the subjected sample. The electrons introduced by the current impulse cause reduction and devolatilization of the ash grains, changing their structural, mineralogical, and magnetic properties.Item Two-step extinction of Late Cretaceous marine vertebrates in northern Gulf of Mexico prolonged biodiversity loss prior to the Chicxulub impact(Nature Portfolio, 2020) Ikejiri, Takehito; Lu, YueHan; Zhang, Bo; University of Alabama TuscaloosaRecent studies on mass extinctions are often based on the global fossil record, but data from selected paleogeographic regions under a relatively constant paleoenvironmental setting can also provide important information. Eighty-nine marine vertebrate species, including cartilaginous and bony fish and marine reptiles, from northern Gulf of Mexico - located about 500km from the Chicxulub crater - offer a unique opportunity to determine an extinction process during the last 20 million years of the Late Cretaceous. Our diversity data show two separate extinction events: (i) the 'Middle Campanian Crisis' (about 77 Mya) and (ii) the end-Maastrichtian (66 Mya) events. Whether this stepwise pattern of extinctions occurred locally or globally cannot be determined at present due to the lack of a dataset of the marine vertebrate record for reliable comparison. However, this stepwise pattern including the Middle Campanian and end-Maastrichtian events for, at least, a 13 million-year interval indicates long-term global marine environmental changes (e.g., regression, ocean water chemistry change). Because most Cretaceous marine vertebrates already disappeared in the Gulf of Mexico prior to the latest Maastrichtian, the Chicxulub Impact may not be considered as the most devastating extinction event for the community.Item Effects of nitrogen fertilization and bioenergy crop type on topsoil organic carbon and total Nitrogen contents in middle Tennessee USA(PLOS, 2020) Li, Jianwei; Jian, Siyang; Lane, Chad S.; Lu, YueHan; He, Xiaorui; Wang, Gangsheng; Mayes, Melanie A.; Dzantor, Kudjo E.; Hui, Dafeng; Tennessee State University; University of North Carolina; University of North Carolina Wilmington; University of Alabama Tuscaloosa; University of Oklahoma - Norman; United States Department of Energy (DOE); Oak Ridge National LaboratoryNitrogen (N) fertilization affects bioenergy crop growth and productivity and consequently carbon (C) and N contents in soil, it however remains unclear whether N fertilization and crop type individually or interactively influence soil organic carbon (SOC) and total N (TN). In a three-year long fertilization experiment in switchgrass (SG: Panicum virgatum L.) and gamagrass (GG: Tripsacum dactyloides L.) croplands in Middle Tennessee USA, soil samples (0-15cm) were collected in plots with no N input (NN), low N input (LN: 84 kg N ha(-1) yr(-1) in urea) and high N input (HN: 168 kg N ha(-1) yr(-1) in urea). Besides SOC and TN, the aboveground plant biomass was also quantified. In addition to a summary of published root morphology data based on a separated mesocosm experiment, the root leachable dissolved organic matter (DOM) of both crops was also measured using archived samples. Results showed no significant interaction of N fertilization and crop type on SOC, TN or plant aboveground biomass (ABG). Relative to NN, HN (not LN) significantly increased SOC and TN in both crops. Though SG showed a 15-68% significantly higher ABG than GG, GG showed a 9.3-12% significantly higher SOC and TN than SG. The positive linear relationships of SOC or TN with ABG were identified for SG. However, GG showed structurally more complex and less readily decomposed root DOM, a larger root volume, total root length and surface area than SG. Collectively, these suggested that intensive N fertilization could increase C and N stocks in bioenergy cropland soils but these effects may be more likely mediated by the aboveground biomass in SG and root chemistry and morphology in GG. Future studies are expected to examine the root characteristics in different bioenergy croplands under the field fertilization experiment.Item Nitrogen Fertilization Restructured Spatial Patterns of Soil Organic Carbon and Total Nitrogen in Switchgrass and Gamagrass Croplands in Tennessee USA(Nature Portfolio, 2020) Li, Jianwei; Jian, Siyang; Lane, Chad S.; Guo, Chunlan; Lu, YueHan; Deng, Qi; Mayes, Melanie A.; Dzantor, Kudjo E.; Hui, Dafeng; Tennessee State University; University of North Carolina; University of North Carolina Wilmington; Jiangxi Agricultural University; University of Alabama Tuscaloosa; Chinese Academy of Sciences; South China Botanical Garden, CAS; United States Department of Energy (DOE); Oak Ridge National LaboratoryNitrogen (N) fertilizers can potentially alter spatial distribution of soil organic carbon (SOC) and total nitrogen (TN) concentrations in croplands such as switchgrass (SG: Panicum virgatum L.) and gamagrass (GG: Tripsacum dactyloides L.), but it remains unclear whether these effects are the same between crops and under different rates of fertilization. C-13 and N-15 are two important proxy measures of soil biogeochemistry, but they were rarely examined as to their spatial distributions in soil. Based on a three-year long fertilization experiment in Middle Tennessee, USA, the top mineral horizon soils (0-15cm) were collected using a spatially explicit design within two 15-m(2) plots under three fertilization treatments in SG and GG croplands. A total of 288 samples were collected based on 12 plots and 24 samples in each plot. The fertilization treatments were no N input (NN), low N input (LN: 84kgN ha(-1) in urea) and high N input (HN: 168kgN ha(-1) in urea). The SOC, TN, SOC/TN (C: N), delta C-13 and delta N-15 were quantified and their within-plot variations and spatial distributions were achieved via descriptive and geostatistical methods. Results showed that SG generally displayed 10 similar to 120% higher plot-level variations in all variables than GG, and the plot-level variations were 20 similar to 77% higher in NN plots than LN and HN plots in SG but they were comparable in unfertilized and fertilized plots in GG. Relative to NN, LN and HN showed more significant surface trends and spatial structures in SOC and TN in both croplands, and the fertilization effect appeared more pronounced in SG. Spatial patterns in C: N, delta C-13 and delta N-15 were comparable among different fertilization treatments in both croplands. The descending within-plot variations were also identified among variables (SOC>TN>delta N-15>C: N>delta C-13). This study demonstrated that N fertilizations generally reduced the plot-level variance and simultaneously re-established spatial structures of SOC and TN in bioenergy croplands, which little varied with fertilization rate but was more responsive in switchgrass cropland.