Research and Publications - Department of Geological Sciences
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Item Tertiary Phosphates in Alabama(American Association for the Advancement of Science., 1885-05-08) Smith, Eugene A.Item Underthrust Folds and Faults(American Journal of Science, 1893) Smith, Eugene A.Item On Some Post-Eocene and Other Formations of the Gulf Region of the United States(The American Association for the Advancement of Science, 1906-03-30) Smith, Eugene A.Item NRRI Library to House Materials Related to Copper-Nickel Study(1989-03-10) Sandy, John H.; Miller, PatriciaItem 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 Revised classification and terminology of Palaeozoic stromatoporoids(Institute of Paleobiology, 1999) Stearn, Colin W.; Webby, Barry D.; Nestor, Heldur; Stock, Carl W.Palaeozoic stromatoporoids comprise an extinct class of non-spiculate poriferans that are represented as fossils by their basal carbonate skeleton. A revised terminology for the description of these fossils is presented. Seven orders (Labechiida, Clathrodictyida, Actinostromatida, Stromatoporellida, Stromatoporida, Syringostromatida, Amphiporida) are recognized. The following is recorded for each genus: (1) type species, catalogue number and depository of the primary holotype; (2) synonyms and their type species; (3) diagnosis; (4) stratigraphic range; (5) estimate of the number of species assigned to the genus; (6) stratigraphic and geographic distribution of the genus. Problems in the definition and recognition of the genus are briefly discussed in annotations. One hundred and nine genera are considered valid, or doubtfully valid. Fifty three genera are placed in synonymy. An additional 14 genera are considered to be of uncertain placement in the classification.Item Oxygen isotope record of the 1997-1998 El Nino in Peruvian sea catfish (Galeichthys peruvianus) otoliths(American Geophysical Union, 2002-10-11) Andrus, CFT; Crowe, DE; Romanek, CS; University System of Georgia; University of Georgia; United States Department of Energy (DOE); Savannah River Ecology Laboratory; University of Alabama Tuscaloosa[1] Sagittal otoliths of the Peruvian sea catfish Galeichthys peruvianus were collected from the north coast of Peru during and after the 1997-1998 El Nino. The otoliths were analyzed via laser microprobe and micromilling techniques for oxygen isotope composition through ontogeny to document their use as an El Nino-Southern Oscillation (ENSO) proxy. Results were compared to theoretical calculations for the delta(18)O of otolith aragonite using measured sea surface temperatures (SST) and delta(18)O values for local seawater assuming equilibrium oxygen isotope fractionation was achieved. All otoliths recorded the 1997-1998 El Nino event as well as seasonal temperature variations. These ENSO events were recorded in otolith aragonite as significant negative excursions in delta(18)O that reflected the increased temperature of local marine waters. The combined otolith data were used to create a 10-year SST record, including ENSO events and local seasonal temperature variation, validating the use of otolith delta(18)O as a temperature proxy.Item Seasonal Shell Growth and Longevity in Donax Variabilis from Northeastern Florida: Evidence from Oxygen Isotopes(2004) Jones, Douglas S.; Quitmyer, Irvy R.; Andrus, C. Fred T.; University of Alabama TuscaloosaThe variable coquina clam, Donax variabilis, is one of the most common inhabitants of exposed sandy beach intertidal and shallow subtidal zones in the southeastern United States. Its exceptional burrowing and migratory behaviors are well documented, as are its biogeograpbic distribution and phylogenetic relationships. However, basic life history parameters such as season and rate of shell growth and longevity are poorly constrained for this species, usually estimated from size-frequency analyses of sample populations. High-resolution sampling of individual D. variabilis shells, and analysis of the oxygen isotopic variation in these samples, provides an alternate method of assessing shell growth and longevity in this species with a high degree of precision. Comparison of isotopic paleotemperature profiles with local seawater temperatures in the northeastern Florida study region indicates rapid shell growth (>4 mm/month) during a life span of 3 to 5 months, substantially shorter than most previous estimates. Detailed analysis of two modern shells indicates growth during spring and summer whereas four Archaic period archaeological shells revealed a summer-autumn growth record. In all cases the largest archaeological shells were substantially bigger than the largest modern shells, reflecting a greater longevity by about 2 months. Although recruitment can be fairly continuous throughout the year, size-frequency analyses of D. variabilis in separate years at the same locality reveal substantial interannual differences in population dynamics.Item Seismic velocity structure and depth-dependence of anisotropy in the Red Sea and Arabian shield from surface wave analysis(American Geophysical Union, 2008-10-14) Hansen, Samantha E.; Gaherty, James B.; Schwartz, Susan Y.; Rodgers, Arthur J.; Al-Amri, Abdullah M. S.; King Saud University; Columbia University; United States Department of Energy (DOE); Lawrence Livermore National Laboratory; University of California System; University of California Santa Cruz; University of Alabama TuscaloosaWe investigate the lithospheric and upper mantle shear wave velocity structure and the depth-dependence of anisotropy along the Red Sea and beneath the Arabian Peninsula using receiver function constraints and phase velocities of surface waves traversing two transects of stations from the Saudi Arabian National Digital Seismic Network. Frequency-dependent phase delays of fundamental-mode Love and Rayleigh waves, measured using a cross-correlation procedure, require very slow shear velocities and the presence of anisotropy to depths of at least 180 km in the upper mantle. Linearized inversion of these data produce path-averaged 1D radially anisotropic models with similar to 4% anisotropy in the lithosphere and across the lithosphere-asthenosphere boundary (LAB). Models with reasonable crustal velocities in which the mantle lithosphere is isotropic cannot satisfy the data. The lithosphere, which ranges in thickness from about 70 km near the Red Sea coast to about 90 km beneath the Arabian Shield, is underlain by a pronounced low-velocity zone with shear velocities as low as 4.1 km/s. Forward models of azimuthal anisotropy, which are constructed from previously determined shear wave splitting estimates, can reconcile surface and body wave observations of anisotropy. The low shear velocities extend to greater depth than those observed in other continental rift and oceanic ridge environments. The depth extent of these low velocities combined with the sharp velocity contrast across the LAB may indicate the influence of the Afar hot spot and the presence of partial melt beneath Arabia. The anisotropic signature primarily reflects a combination of plate- and density-driven flow associated with rifting processes in the Red Sea.Item Using S wave receiver functions to estimate crustal structure beneath ice sheets: An application to the Transantarctic Mountains and East Antarctic craton(American Geophysical Union, 2009) Hansen, Samantha E.; Julia, Jordi; Nyblade, Andrew A.; Pyle, Moira L.; Wiens, Douglas A.; Anandakrishnan, Sridhar; Pennsylvania Commonwealth System of Higher Education (PCSHE); Pennsylvania State University; Pennsylvania State University - University Park; Washington University (WUSTL); University of Alabama TuscaloosaFor seismic stations deployed on ice sheets, determining crustal structure using P wave receiver functions can be difficult since ice reverberations may mask P-to-S (Ps) conversions from the crust-mantle boundary (Moho). In this study, we assess the usefulness of S wave receiver functions (SRFs), which are not affected by ice multiples, for investigating crustal structure beneath ice sheets by analyzing broadband seismic data recorded across the Transantarctic Mountains (TAMs) and the East Antarctic (EA) craton. Clear S-to-P (Sp) conversions from the Moho are obtained using standard SRF processing methods and are easier to interpret than the corresponding Ps conversion on PRFs. When the Sp-S times are modeled together with 16-20 s Rayleigh wave group velocities, we obtain Moho depth estimates of similar to 40-45 km for the EA craton, consistent with average Precambrian crustal thickness found globally but similar to 9 km thicker than previously reported estimates. A somewhat thinner crust (similar to 35-40 km) is obtained beneath the TAMs, suggesting that crustal buoyancy is at most a minor contributor to the uplift of the mountain range in this region.Item Upper-mantle low-velocity zone structure beneath the Kaapvaal craton from S-wave receiver functions(Oxford University Press, 2009) Hansen, Samantha E.; Nyblade, Andrew A.; Julia, Jordi; Dirks, Paul H. G. M.; Durrheim, Raymond J.; Pennsylvania Commonwealth System of Higher Education (PCSHE); Pennsylvania State University; Pennsylvania State University - University Park; University of Witwatersrand; University of Alabama TuscaloosaP>The southern African Plateau is marked by anomalously high elevations, reaching 1-2 km above sea level, and there is much debate as to whether this topography is compensated by a lower mantle source or by elevated temperatures in the upper mantle. In this study, we use S-wave receiver functions (SRFs) to estimate the lithospheric thickness and sublithospheric mantle velocity structure beneath the Kaapvaal craton, which forms the core of the Plateau. To fit the SRF data, a low-velocity zone (LVZ) is required below a similar to 160-km-thick lithospheric lid, but the LVZ is no thicker than similar to 90 km. Although the lid thickness obtained is thinner than that reported in previous SRF studies, neither the lid thickness nor the shear velocity decrease (similar to 4.5%) associated with the LVZ is anomalous compared to other cratonic environments. Therefore, we conclude that elevated temperatures in the sublithospheric upper mantle contribute little support to the high elevations in this region of southern Africa.Item Vital Effects in the Context of Biomineralization(2010) Pérez-Huerta, Alberto; Andrus, C. Fred T.; University of Alabama TuscaloosaVital effects can be defined as biological processes overriding environmental signals, as recorded in geochemical signatures in biominerals. The nature and influence of these vital effects are poorly understood, particularly related to biogenic mineral formation. The aim of this review article is to highlight the complexity of the study of vital effects in the context of biomineralization. Improving our knowledge of vital effects will greatly contribute to a better interpretation of biogeochemical proxies for paleoenvironmental and paleoclimatic reconstructions, and the fundamental understanding of biomineralization itself.Item Hydrologic response to precipitation pulses under and between shrubs in the Chihuahuan Desert, Arizona(American Geophysical Union, 2010-10-08) Moran, M. S.; Hamerlynck, E. P.; Scott, R. L.; Stone, J. J.; Collins, C. D. Holifield; Keefer, T. O.; Bryant, R.; DeYoung, L.; Nearing, G. S.; Sugg, Z.; Hymer, D. C.; United States Department of Agriculture (USDA); University of Arizona; National Aeronautics & Space Administration (NASA); NASA Goddard Space Flight Center; University of Alabama TuscaloosaObservations of the temporal and spatial distribution of poststorm soil moisture in open shrublands and savannas are limited, yet they are critical to understanding the interaction and feedback between moisture distribution and canopies. The objective of this analysis was to study the hydrologic impacts of precipitation pulses on the upper layer of soils under and between shrubs. The study was based on measurements of precipitation, runoff, and under-and between-shrub soil moisture over a period of 20 years (1990-2009) at a shrub-dominated site in the Walnut Gulch Experimental Watershed (WGEW) near Tombstone, Arizona. Within much of the root zone (to 30 cm depth), infiltration was not significantly different under versus between shrubs, and the under: between infiltration ratio was not related to pulse size or intensity. However, root-zone soil moisture was significantly higher between shrubs than under shrubs. The soil moisture measured at the surface (at 5 cm depth) was not consistently different under and between shrubs, but the soil moisture measured at depths of 15 and 30 cm were both significantly higher between shrubs than under shrubs. Considering mechanisms that explain the interaction between plants and soil moisture, we found no differences in infiltration, evaporative losses, and surface soil moisture in locations under and between shrubs. This led to the conclusion that lower root-zone soil moisture under shrubs was due largely to greater root density under shrubs than between shrubs. This study adds to the understanding of the impact of precipitation patterns on infiltration and soil moisture in shrub-dominated sites and the potential for vegetation change in arid and semiarid lands.Item EVALUATING MOBILITY, MONUMENTALITY, AND FEASTING AT THE SAPELO ISLAND SHELL RING COMPLEX(Cambridge University Press, 2011) Thompson, Victor D.; Andrus, C. Fred T.; University System of Ohio; Ohio State University; University of Alabama TuscaloosaTwo of the most salient anthropological questions regarding southeastern shell ring sites are related to the season(s) that they were occupied and whether or not the deposits represent monumental constructions and/or feasting remains. This paper addresses these questions through the analysis of growth band of clams (Mercenaria spp.) (N = 620) and stable oxygen isotope ratios of clam and oyster shells (Crassostrea virginica) (N = 58) at the Sapelo Island Shell Ring complex located on the Georgia coast, USA. The season of death and the samples' position in the shell matrix at Sapelo provide important information on the rate of shell deposition and the season(s) the site was occupied. These data support the view that at least some portion of the human population at Sapelo occupied the site year-round. Additionally, while it appears that two shell rings at the site formed through the gradual deposition and accumulation of daily subsistence, other areas evidence short term, large-scale, shellfish processing and may lend credence to the view that at some point shell rings become monuments, commemorating rituals and gatherings.Item Treatise Online, no. 2, Part E, Revised, Volume 4, Chapter 5: A list of Upper Paleozoic–Mesozoic stromatoporoid-like genera; and excluded taxa(Paleontological Institute, 2011-01-18) Stearn, Colin W.; Stock, Carl W.Item Assimilating remote sensing observations of leaf area index and soil moisture for wheat yield estimates: An observing system simulation experiment(American Geophysical Union, 2012-05-17) Nearing, G. S.; Crow, W. T.; Thorp, K. R.; Moran, M. S.; Reichle, R. H.; Gupta, H. V.; University of Arizona; United States Department of Agriculture (USDA); National Aeronautics & Space Administration (NASA); NASA Goddard Space Flight Center; University of Alabama TuscaloosaObserving system simulation experiments were used to investigate ensemble Bayesian state-updating data assimilation of observations of leaf area index (LAI) and soil moisture (theta) for the purpose of improving single-season wheat yield estimates with the Decision Support System for Agrotechnology Transfer (DSSAT) CropSim-Ceres model. Assimilation was conducted in an energy-limited environment and a water-limited environment. Modeling uncertainty was prescribed to weather inputs, soil parameters and initial conditions, and cultivar parameters and through perturbations to model state transition equations. The ensemble Kalman filter and the sequential importance resampling filter were tested for the ability to attenuate effects of these types of uncertainty on yield estimates. LAI and theta observations were synthesized according to characteristics of existing remote sensing data, and effects of observation error were tested. Results indicate that the potential for assimilation to improve end-of-season yield estimates is low. Limitations are due to a lack of root zone soil moisture information, error in LAI observations, and a lack of correlation between leaf and grain growth.Item El Nino Impact on Mollusk Biomineralization-Implications for Trace Element Proxy Reconstructions and the Paleo-Archeological Record(PLOS, 2013-02-06) Perez-Huerta, Alberto; Etayo-Cadavid, Miguel F.; Andrus, C. Fred T.; Jeffries, Teresa E.; Watkins, Clifton; Street, Shane C.; Sandweiss, Daniel H.; University of Alabama Tuscaloosa; Natural History Museum London; University of Maine System; University of Maine OronoMarine macroinvertebrates are ideal sentinel organisms to monitor rapid environmental changes associated with climatic phenomena. These organisms build up protective exoskeletons incrementally by biologically-controlled mineralization, which is deeply rooted in long-term evolutionary processes. Recent studies relating potential rapid environmental fluctuations to climate change, such as ocean acidification, suggest modifications on carbonate biominerals of marine invertebrates. However, the influence of known, and recurrent, climatic events on these biological processes during active mineralization is still insufficiently understood. Analysis of Peruvian cockles from the 1982-83 large magnitude El Nino event shows significant alterations of the chemico-structure of carbonate biominerals. Here, we show that bivalves modify the main biomineralization mechanism during the event to continue shell secretion. As a result, magnesium content increases to stabilize amorphous calcium carbonate (ACC), inducing a rise in Mg/Ca unrelated to the associated increase in sea-surface temperature. Analysis of variations in Sr/Ca also suggests that this proxy should not be used in these bivalves to detect the temperature anomaly, while Ba/Ca peaks are recorded in shells in response to an increase in productivity, or dissolved barium in seawater, after the event. Presented data contribute to a better understanding of the effects of abrupt climate change on shell biomineralization, while also offering an alternative view of bivalve elemental proxy reconstructions. Furthermore, biomineralization changes in mollusk shells can be used as a novel potential proxy to provide a more nuanced historical record of El Nino and similar rapid environmental change events.Item Upper mantle seismic structure beneath central East Antarctica from body wave tomography: Implications for the origin of the Gamburtsev Subglacial Mountains(American Geophysical Union, 2013-04-17) Lloyd, Andrew J.; Nyblade, Andrew A.; Wiens, Douglas A.; Shore, Patrick J.; Hansen, Samantha E.; Kanao, Masaki; Zhao, Dapeng; Pennsylvania Commonwealth System of Higher Education (PCSHE); Pennsylvania State University; Pennsylvania State University - University Park; Washington University (WUSTL); University of Alabama Tuscaloosa; Research Organization of Information & Systems (ROIS); National Institute of Polar Research (NIPR) - Japan; Tohoku UniversityThe Gamburtsev Subglacial Mountains (GSM), located near the center of East Antarctica, are the highest feature within the East Antarctic highlands and have been investigated seismically for the first time during the 2007/2008 International Polar Year by the Gamburtsev Mountains Seismic Experiment. Using data from a network of 26 broadband seismic stations and body wave tomography, the P and S wave velocity structure of the upper mantle beneath the GSM and adjacent regions has been examined. Tomographic images produced from teleseismic P and S phases reveal several large-scale, small amplitude anomalies (Vp=1.0%, Vs=2.0%) in the upper 250 km of the mantle. The lateral distributions of these large-scale anomalies are similar in both the P and S wave velocity models and resolution tests show that they are well resolved. Velocity anomalies indicate slower, thinner lithosphere beneath the likely Meso- or Neoproterozoic Polar Subglacial Basin and faster, thicker lithosphere beneath the likely Archean/Paleoproterozoic East Antarctic highlands. Within the region of faster, thicker lithosphere, a lower amplitude (Vp=0.5%, Vs=1.0%) slow to fast velocity pattern is observed beneath the western flank of the GSM, suggesting a suture between two lithospheric blocks possibly of similar age. These findings point to a Precambrian origin for the high topography of the GSM, corroborating other studies invoking a long-lived highland landscape in central East Antarctica, as opposed to uplift caused by Permian/Cretaceous rifting or Cenozoic magmatism. The longevity of the GSM makes them geologically unusual; however, plausible analogs exist, such as the 550 Ma Petermann Ranges in central Australia. Additional uplift may have occurred by the reactivation of pre-existing faults, for example, during the Carboniferous-Permian collision of Gondwana and Laurussia.Item An approach to quantifying the efficiency of a Bayesian filter(American Geophysical Union, 2013-04-26) Nearing, Grey S.; Gupta, Hoshin V.; Crow, Wade T.; Gong, Wei; University of Arizona; United States Department of Agriculture (USDA); Beijing Normal University; University of Alabama TuscaloosaData assimilation is the Bayesian conditioning of uncertain model simulations on observations to reduce uncertainty about model states. In practice, it is common to make simplifying assumptions about the prior and posterior state distributions, and to employ approximations of the likelihood function, which can reduce the efficiency of the filter. We propose metrics that quantify how much of the uncertainty in a Bayesian posterior state distribution is due to (i) the observation operator, (ii) observation error, and (iii) approximations of Bayes' Law. Our approach uses discrete Shannon entropy to quantify uncertainty, and we define the utility of an observation (for reducing uncertainty about a model state) as the ratio of the mutual information between the state and observation to the entropy of the state prior. These metrics make it possible to analyze the efficiency of a proposed observation system and data assimilation strategy, and provide a way to examine the propagation of information through the dynamic system model. We demonstrate the procedure on the problem of estimating profile soil moisture from observations at the surface (top 5 cm). The results show that when synthetic observations of 5 cm soil moisture are assimilated into a three-layer model of soil hydrology, the ensemble Kalman filter does not use all of the information available in observations.Item Rayleigh wave constraints on the structure and tectonic history of the Gamburtsev Subglacial Mountains, East Antarctica(American Geophysical Union, 2013-05-10) Heeszel, David S.; Wiens, Douglas A.; Nyblade, Andrew A.; Hansen, Samantha E.; Kanao, Masaki; An, Meijan; Zhao, Yue; Washington University (WUSTL); University of California System; University of California San Diego; Scripps Institution of Oceanography; Pennsylvania Commonwealth System of Higher Education (PCSHE); Pennsylvania State University; Pennsylvania State University - University Park; University of Alabama Tuscaloosa; Research Organization of Information & Systems (ROIS); National Institute of Polar Research (NIPR) - Japan; Chinese Academy of Geological SciencesThe Gamburtsev Subglacial Mountains (GSM), located near the center of East Antarctica, remain one of the most enigmatic mountain ranges on Earth. A lack of direct geologic samples renders their tectonic history almost totally unconstrained. We utilize teleseismic Rayleigh wave data from a 2 year deployment of broadband seismic stations across the region to image shear velocity structure and analyze the lithospheric age of the GSM and surrounding regions. We solve for 2-D phase velocities and invert these results for 3-D shear velocity structure. We perform a Monte Carlo simulation to improve constraints of crustal thickness and shear velocity structure. Beneath the core of the GSM, we find crustal thickness in excess of 55km. Mantle shear velocities remain faster than global average models to a depth of approximately 250km, indicating a thick lithospheric root. Thinner crust and slower upper mantle velocities are observed beneath the Lambert Rift System and the Polar Subglacial Basin. When compared with phase velocity curves corresponding to specific tectonothermal ages elsewhere in the world, average phase velocity results for the GSM are consistent with regions of Archean-Paleoproterozoic origin. Combined with radiometric ages of detrital zircons found offshore, these results indicate a region of old crust that has undergone repeated periods of uplift and erosion, most recently during the Mesozoic breakup of Gondwana. Lower crustal seismic velocities imply a moderately dense lower crust beneath the core of the GSM, but with lower density than suggested by recent gravity models.