Search

Antarctic continental-scale glaciation is generally assumed to have initiated at the Eocene-Oligocene Transition, yet its subsequent evolution is poorly constrained. We reconstruct changes in bottom water temperature and global ice volume from 0 to 17 Ma using δ18O in conjunction with Mg/Ca records of the infaunal benthic foraminifer, O. umbonatus from Ocean Drilling Program (ODP) Site 806 (equatorial Pacific; ~2500 m). Considering uncertainties in core top calibrations and sensitivity to seawater Mg/Ca (Mg/Ca)sw, we produce a range of Mg/Ca-temperature-Mg/Casw calibrations. Our favored exponential temperature calibration is Mg/Ca = 0.66 ± 0.08 × Mg/Casw0.27±0.06 × e(0.114±0.02 × BWT) and our favored linear temperature calibration is Mg/Ca = (1.21 ± 0.04 + 0.12 ± 0.004 × BWT (bottom water temperature)) × (Mg/Casw−0.003±0.02) (stated errors are 2 s.e.). The equations are obtained by comparing O. umbonatus Mg/Ca for a Paleocene-Eocene section from Ocean Drilling Program (ODP) Site 690 (Weddell Sea) to δ18O temperatures, calculated assuming ice-free conditions during this peak warmth period of the Cenozoic. This procedure suggests negligible effect of Mg/Casw on the Mg distribution coefficient (DMg). Application of the new equations to the Site 806 record leads to the suggestion that global ice volume was greater than today after the Middle Miocene Climate Transition (~14 Ma). ODP Site 806 bottom waters cooled and freshened as the Pacific zonal sea surface temperature gradient increased, and climate cooled through the Pliocene, prior to the Plio-Pleistocene glaciation of the Northern Hemisphere. The records indicate a decoupling of deep water temperatures and global ice volume, demonstrating the importance of thresholds in the evolution of the Antarctic ice sheet.

Trace element incorporation into foraminiferal shells (tests) is governed by physical and chemical conditions of the surrounding marine environment, and therefore foraminiferal geochemistry provides a means of palaeo-oceanographic reconstructions. With the availability of high-spatial-resolution instrumentation with high precision, foraminiferal geochemistry has become a major research topic over recent years. However, reconstructions of past bottom-water oxygenation using foraminiferal tests remain in their infancy. In this study we explore the potential of using Mn / Ca determined by secondary ion mass spectrometry (SIMS) as well as by flow-through inductively coupled plasma optical emission spectroscopy (FT-ICP-OES) in the benthic foraminiferal species Eubuliminella exilis as a proxy for recording changes in bottom-water oxygen conditions in the low-latitude NE Atlantic upwelling system. Furthermore, we compare the SIMS and FT-ICP-OES results with published Mn sediment bulk measurements from the same sediment core. This is the first time that benthic foraminiferal Mn / Ca is directly compared with Mn bulk measurements, which largely agree on the former oxygen conditions. Samples were selected to include different productivity regimes related to Marine Isotope Stage 3 (35–28 ka), the Last Glacial Maximum (28–19 ka), Heinrich Event 1 (18–15.5 ka), Bølling Allerød (15.5–13.5 ka) and the Younger Dryas (13.5–11.5 ka). Foraminiferal Mn / Ca determined by SIMS and FT-ICP-OES is comparable. Mn / Ca was higher during periods with high primary productivity, such as during the Younger Dryas, which indicates low-oxygen conditions. This is further supported by the benthic foraminiferal faunal composition. Our results highlight the proxy potential of Mn / Ca in benthic foraminifera from upwelling systems for reconstructing past variations in oxygen conditions of the sea floor environment as well as the need to use it in combination with other proxy records such as faunal assemblage data., We would like to thank the NORDSIM laboratory (a joint Nordic infrastructure operated under an agreement regulated by NOS-N) for granting analytical time and to Lev Ilyinsky and Kerstin Lindén for their support. This work is NordSIM contribution no. 411.We also thank Mike Hall for foraminiferal test cross-sectioning and also Ed Hathorne and Dave Heslop for flowthrough assistance. This research was funded by the Crafoord Foundation (20100547), the Lund University Centre for Studies of Carbon Cycle and Climate Interactions (LUCCI) and Kungl. Fysiografiska Sällskapet i Lund. H. L. Filipsson and J. Groeneveld acknowledge support from the Swedish Research Council VR (621-2011-5090) as well as funding from the Strategic Research Area Biodiversity and Ecosystem Services in a Changing Climate (BECC). D. Gallego-Torres acknowledges the JAE programme from the CSIC and programme FEDER R5/10FOR/2014 (Junta de Andalucía).

Studying combustion structures, which represent direct evidence of human occupation, can provide insights about the periods and nature of occupation and utilisation of archaeological sites. This research aimed to supplement existing approaches to combustion structures based on typological descriptions of hearths, analysis of fuel residues, and consideration of the frequency of use by thermal characterisation using physical methods. This study deals with the thermal impacts recorded by fired sediment, and the ways in which modifications of both thermoluminescence (TL) and magnetic properties can be used to understand the thermal history of such remains. The laboratory‐site is the cave of Les Fraux (Dordogne, France) which was occupied in the Bronze Age. Archaeologists were wondering about the function and mode of occupation of this cave which exhibits both domestic vestiges (archaeological occupation grounds, hearths, and ceramics) and symbolic remains (rock art and votive ceramic deposition). Considering the significant number of hearths, more than sixty, and their importance in the human occupation, a specific study of the combustion structures was undertaken. Since the cave remained closed since the Bronze Age, the hearths are in an excellent state of preservation, thus offering important opportunities for archaeometric study. The thermal characterisation of hearths from the cave of Les Fraux firstly consisted in investigating the paleothermometric potential of two properties: the thermoluminescence of sedimentary minerals and the magnetism of iron oxides taken from the sediments. A TL paleothermometer was established by comparing TL signals of samples from archaeological hearths and those of thermal references heated in laboratory. Two properties were explored for the magnetic paleothermometer: the unblocking temperatures of remanent magnetisation and the evolution of magnetic signature (mineralogy and grain size) with heating. Paleotemperatures determined for the sediment from the hearths provided initial information about the intensity of their associated fires. Experimental fires were carried on a series simulated hearths to calibrate paleothermometric data relative to the quantities of energy and wood consumed under controlled conditions, to verify the validity of the laboratory thermal reference procedures, and to characterise the process of heat transfer inside the sediment. Finally numerical modeling of heat propagation within idealised sedimentary structures was undertaken, using thermal data recorded from the experimental hearths. The numerical simulations performed in this model allowed the minimal duration of functioning of the combustion structures to be estimated. Combined with the palaeotemperature estimates this allows energy expenditure to be assessed. The combination of thermoluminescence and magnetic characterisation of sedimentary hearth structures from archaeological sites, coupled to numerical analysis of heat transport, provides a novel tool to supplement existing approaches to understanding combustion structures in the past., Les structures de combustion constituent un témoin de la fréquentation humaine et leur étude permet d'appréhender un aspect du mode d'occupation d'un lieu donné. Ainsi, pour compléter les approches classiques qui s'intéressent à la typologie des foyers, à la fréquence des feux, à la nature des combustibles, etc., une caractérisation thermique de ces structures a été proposée. Elle s'appuie sur les impacts thermiques enregistrés par les sédiments soumis aux feux et s'intéresse plus précisément à la manière dont les modifications des propriétés de thermoluminescence (TL) et de magnétisme avec la chauffe pourraient être utilisées pour comprendre l'histoire thermique de ces vestiges. Le site‐laboratoire est celui de la grotte de Fraux (Dordogne), occupée à l'Âge du bronze. Les archéologues s'interrogent sur son statut et son mode d'occupation puisqu'elle présente tant des vestiges domestiques (sols de circulation, foyers, mobiliers) que des vestiges symboliques (manifestations pariétales, dépôts de mobilier). La place importante des foyers parmi ces vestiges a induit une étude spécifique de ces structures. En effet, ce site recèle plus d'une soixantaine de structures de combustion et, aspect important pour notre approche archéométrique, présente un état de conservation exceptionnel puisque la grotte est restée fermée depuis l'occupation de l'Âge du bronze. L'étude de certains foyers de la grotte des Fraux a permis de tester le potentiel de paléothermomètres fondés sur deux propriétés indépendantes : la TL des grains de quartz et le magnétisme des oxydes de fer contenus dans les sédiments. Le paléothermomètre TL a été élaboré en comparant les signaux TL d'échantillons provenant de foyers archéologiques à ceux de références thermiques chauffées en laboratoire. Pour le magnétisme deux pistes ont été exploitées : les températures de déblocage de l'aimantation rémanente et l'évolution de la signature magnétique (minéralogie et taille de grain) avec la chauffe. La détermination des paléotempératures atteintes par les sédiments substrats des structures de combustion apporte une première indication sur leur intensité de chauffe. Afin d'étalonner ces informations paléothermométriques en termes de dépense énergétique, des feux expérimentaux ont été réalisés. Ils ont permis de comparer les impacts thermiques entre feux archéologiques et feux expérimentaux, de construire un échantillonnage d'histoire thermique connue, mais aussi d'estimer les températures atteintes, les épaisseurs de sédiments affectés, les quantités de combustibles consommés pendant un temps donné... Ces expérimentations ont aussi servi de base à une modélisation de la propagation de la chaleur dans les sédiments. Les simulations effectuées dans ce modèle numérique permettent alors d'estimer un temps minimal de fonctionnement des structures de combustion. Combinée avec les paléotempératures, cette information permet une évaluation de l'énergie mise en jeu. Le couplage de la caractérisation TL et magnétique de sédiments des foyers archéologiques ainsi que de la modélisation numérique des transferts de chaleur, fournit un nouvel outil complémentaire des approches existantes pour comprendre les foyers archéologiques.

We have calculated the concentrations of Mg in the bulk and surfaces of aragonite CaCO(3) in equilibrium with aqueous solution, based on molecular dynamics simulations and grand-canonical statistical mechanics. Mg is incorporated in the surfaces, in particular in the (001) terraces, rather than in the bulk of aragonite particles. However, the total Mg content in the bulk and surface of aragonite particles was found to be too small to account for the measured Mg/Ca ratios in corals. We therefore argue that most Mg in corals is either highly metastable in the aragonite lattice, or is located outside the aragonite phase of the coral skeleton, and we discuss the implications of this finding for Mg/Ca paleothermometry.

The modern subarctic North Pacific realm is characterized by a steep vertical gradient in salinity, the permanent halocline. The halocline not only hampers the exchange of gas and heat between the deep ocean and the atmosphere, it also restricts the supply of nutrients from the subsurface into the photic zone, thereby limiting marine productivity. However, for the subarctic North Pacific and its marginal seas it remains unclear whether low glacial productivity was controlled by upper-ocean stratification or by sea-ice dynamics. Recent proxy and modelling studies indicate that the halocline weakened during the last glacial termination. This thesis is based on piston cores recovered from intermediate water levels in the hitherto only poorly studied western Bering Sea, the continental slope off eastern Kamchatka, and the southern Okhotsk Sea. Age models rely on a combination of benthic oxygen isotope stratigraphy, magnetostratigraphy, radiocarbon dating, and intercore correlations via high-resolution core logging data. Millennial-scale changes in marine productivity and terrigenous matter supply were reconstructed over the past 180 kyr applying a geochemical multi-proxy approach in combination with XRF logging data. Special emphasis is given to the last glacial termination, for which high-resolution sea surface temperature (SST), as well as subsurface temperature and salinity-approximating records were produced. These records stem from alkenone-thermometry, and from the combined measurement of stable oxygen isotope and Mg/Ca ratios of the planktonic foraminifera Neogloboquadrina pachyderma (sin.). Direct comparison between both temperature reconstructions allowed to infer oceanographic changes in the mixed layer. Deglacial changes in the ventilation of intermediate and deep waters are inferred from marine radiocarbon ages and stable carbon isotope records. Results point towards low marine productivity but high terrigenous inputs during most of the last glacial-interglacial cycle and Marine Isotope Stage (MIS) 6. Increases in marine productivity occurred during warm stages of MIS5, interglacials, and the last glacial termination. These changes are supposedly controlled by insolation and sea-level changes, thereby influencing the strength of atmospheric pressure systems, seasonal contrasts, and sea-ice rafting. Sea-ice dynamics are thought to drive changes in surface productivity, terrigenous inputs, and upper-ocean stratification. Abrupt environmental changes recorded during the last 180 kyr apply to the deglacial situation and are potentially related to North Atlantic Dansgaard-Oeschger events. During the last glacial termination SST records matched the variability in sea-ice extent, thereby resembling climate oscillations registered in Greenland ice cores. This variability is explained by perturbations of the Atlantic Meridional Overturning Circulation and suggests a quasi-synchronous atmospheric coupling between the North Pacific and the North Atlantic. Subsurface conditions differed on a regional scale, thereby reflecting different sea-ice influence. Deglacial thermocline changes are proposed with reduced thermal stratification of the upper water column during the Heinrich Stadial 1 (H1) and the Younger Dryas cold phases, but strengthened thermal stratification during the Bølling-Allerød warm phase. Moreover, enhanced intermediate water formation in the Bering and Okhotsk seas and according shallow overturning in the subarctic northwest Pacific occurred during H1, supporting the notion of fast atmospheric interactions between the North Pacific and the North Atlantic which are held responsible for this situation. Results for the Holocene surface and subsurface development do not support the hypothesis of the Atlantic–Pacific Seesaw, but imply that modern upper-ocean conditions were established in the early Holocene.

The use of planktonic foraminiferal Mg/Ca ratios to reconstruct past sea surface temperatures (SST) is prevalent in the literature. The perceived simplicity of the underlying chemistry and ease of measurements are alluring. Canonically, temperature is thought to be the primary control on the shell Mg/Ca values. Additionally, an appeal of this proxy is that it can be combined with shell ä18O values to reconstruct changes in the local ä18O of seawater, a proxy for salinity. However, we have identified a salinity effect on the Mg/Ca signal recorded in planktonic foraminifera influencing samples from open ocean locations. This effect causes excess Mg incorporation, higher than predicted by theory, in high salinity regions for the planktonic foraminiferal species, Globigerinoides ruber (white). The shell "excess Mg/Ca" resides within the primary calcite lattice of the shell itself and may be related to the observed cyclic banding of high and low Mg/Ca calcite with the foraminiferal shells. We derive new equations which describe the relationship between shell Mg/Ca, ocean sea surface temperature, salinity, and bottom water ÄCO32-. We also define new equations for ocean temperature and salinity using shell Mg/Ca, ä18O, and bottom water ÄCO32-, which take advantage of the dual sensitivity of shell Mg/Ca and ä18O to temperature and salinity. We apply these results downcore at several locations to assess the influence on paleo-reconstructions. These results are widely applicable to paleoceanographic studies and should allow more accurate reconstructions of both temperature and salinity. Below are brief outlines of the dissertation chapters: 1) A poor correlation between Mg/Ca derived and observed (WOA05) SST was found for 64 coretops in the (sub)tropical Atlantic. Shell-derived SST values from the subtropical gyres were overestimated and the residual "excess Mg/Ca" was well correlated with surface salinity. In this chapter, new calibration equations are developed for the Atlantic Ocean using paired Mg/Ca and ä18O measurements, along with the bottom water ÄCO32-, to predict temperature and salinity. These equations are validated using published coretop data and yield accurate estimates for SST and salinity. 2) The ITCZ is clearly identified in the oceans as the region where temperatures are the highest and salinities are the lowest. These oceanographic fingerprints can be used to track ITCZ variability over the ocean through time. Both canonical equations and the new equations from chapter 1 are used here to reconstruct SST and ä18Oseawater/Salinity gradients since the LGM in the equatorial Atlantic. The marine Atlantic ITCZ migrated in excess of 10° latitude away from its modern position, during both the LGM and early Holocene, supporting climate model results as well as coastal and terrestrial paleohydrological records that document the sensitivity of ITCZ position to both high- and low-latitude forcing. 3) The nature of the excess shell Mg/Ca and the mechanism for incorporation is poorly understood. We investigated excess Mg/Ca using SEM, flow through ICP-MS (FT-ICP-MS) and electron microprobe analyses. SEM and FT-ICP-MS results suggest the excess shell Mg resides within the primary structure of the calcite lattice. Electron microprobe maps of shell Mg/Ca confirm that the excess Mg/Ca lies within the shell itself, likely within the high Mg/Ca calcite bands. These findings suggest the incorporation of shell "excess Mg/Ca" first identified in chapter 1 is not related to post-depositional diagenetic alteration. These results will help elucidate the mechanism responsible for enhanced Mg uptake in high salinity settings. 4) Currently there exist no globally applicable calibration equations relating oceanographic parameters to foraminiferal shell Mg/Ca. In this chapter, we develop new, global calibration equations for G. ruber (white) following the methods of chapter 1. We find that the relationship between shell Mg/Ca and salinity is non-linear, with a threshold value near a salinity of 35, below which there is little influence of salinity on shell Mg/Ca. These equations were validated with published data and appear to be robust. By accounting for the additional influence, alkenone and foraminiferal Mg-Ca derived SST records may be reconciled in for some locations, particularly where there were likely to have been large variations of salinity in the past. These results represent a significant advance for the paleoceanographic community.

The thermal history of the Precordillera terrane of northwestern Argentina has been constrained by the conodont colour alteration index (CAI) in combination with previously published paleothermal data (e.g., illite crystallinity and clay mineral assemblages). The pattern of paleotemperatures displays an increase in paleotemperatures to the west and south of the basin. This configuration shows a gradual and continuous transition from diagenesis to low-grade metamorphism, which is apparently not controlled by any of the morpho-structural subdivisions of the Precordillera (i.e., Western, Central, or Eastern). According to our results, the lower Paleozoic sedimentary burial played a secondary role in the heating of the Precordillera. Instead, the predominant component was loading by thrust sheets, which reflects the effects of the Devonian collision of Chilenia, particularly, in the Western Precordillera. Conversely, our paleothermometric data from the easternmost exposures of the Precordillera do not evidence anomalies referable to any of the accretionary events that contributed to the early Paleozoic building of the southern proto-Andean margin of Gondwana. Instead, the expected thermally altered conodonts from the Cuyania accretion are represented by metamorphosed conodont elements transported to the deeper settings of the west. The CAI data also suggest that overburden depth varied from ca. 3.6 km in the shelf region of the Eastern Precordillera to ca. 12 km in the slope to rise deposits of the Western Precordillera, thus providing constrains for the palinspastic restoration across the orogen. On the other hand, the smooth increase of peak paleotemperatures to the south of the Precordillera is associated with the exposure of deeper crustal levels at that sector, probably related to larger shortening due to stronger collisional effects, or alternatively, a weaker mechanical response of its elastic lithosphere. Fil: Voldman, Gustavo Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; Argentina Fil: Albanesi, Guillermo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; Argentina Fil: Ramos, Victor Alberto. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Geología. Laboratorio de Tectónica Andina; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

International audience; Improving interlaboratory reproducibility (in both precision and accuracy) of Mg/Ca and Sr/Ca determination in marine biogenic carbonates is critical in optimizing their utility as paleothermometers. Coupled with a need for uniform sample cleaning practices, there is a need for more exacting methods and procedures across laboratories using varied instrumentation. Here we employ an intensity ratio/matrix-effect correction methodology to a suite of solution standards and biogenic carbonates (foraminifera tests and a gastropod shell) to investigate short-term and long-term Mg/Ca and Sr/Ca precision and accuracy by different instruments: a magnetic-sector inductively coupled plasma-mass spectrometer (ICP-MS) and a radially viewed inductively coupled plasma-optical emission spectrophotometer (ICP-OES). Over an extended 1.0-24.5 mM Ca concentration range, both instruments have significant Ca matrix effects for Mg/Ca and somewhat less for Sr/Ca. Over our working Ca range (1-8 mM Ca), Mg/Ca matrix effects are significant, requiring correction, and Sr/Ca matrix effects are small to negligible, occasionally requiring correction (linear or logarithmic fit) using a suite of matrix standards for both instruments. The short-term (intrarun) precision for a suite of solution standards is

In core top samples in the Nordic Seas, Mg/Ca ratios of N. pachyderma ( sin.) are generally consistent with previous high-latitude calibration data but do not reflect the modern calcification temperature gradient from 2 degrees C in the northwest to 8 degrees C in the southeast. This is because Mg/Ca ratios in foraminiferal shells from the central Nordic Seas are similar to 0.4 mmol/mol higher than expected from calibrations of Nurnberg ( 1995) and Elderfield and Ganssen ( 2000). The enhanced Mg/Ca ratios are observed in an area with low sedimentation rates (< similar to 5 cm/kyr). Possible factors that may cause this include bioturbation, Holocene variability in old core tops, dissolution, pore water chemistry, occurrence of volcanic ash, and other natural variability. The enhanced foraminiferal Mg/Ca ratios in areas of the Nordic Seas and the northern North Atlantic may also be linked with secondary factors related to the presence of fresher and colder water masses, possibly combined with pore water chemistry in low-sedimentation areas differing from high-sedimentation areas.

In this study we have compared the oxygen isotopic composition of two genera of benthic foraminifera (Uvigerina and Cibicidoides) from core-top samples with modern oxygen isotopic composition of seawater (delta18O). Based on a new relationship between delta18O and salinity for the mid-latitude western South Atlantic, we estimated the isotopic composition of equilibrium calcite (delta18Oeq) using two different equations: (1) O'Neil et al. (1969), modified by McCorkle et al. (1997) and (2) Kim & O'Neil (1997). When using (1), the small difference between delta18Oeq and delta18O of Uvigerina suggests that this genus precipitates its shell close to equilibrium with ambient seawater. The delta18O Cibicidoides data are 0.82 ‰ lower than the predicted (equilibrium) oxygen isotopic composition. Conversely, using (2) the Cibicidoides delta18O data show excellent agreement with the oxygen isotopic composition predicted from delta18O and water temperature while Uvigerina delta18O data are 0.69 ‰ higher than predicted oxygen isotope equilibrium values. Based on the evidences presented here and on the results from previous studies we suggest using the genus Cibicidoides and applying Kim & O'Neil's (1997) equation for down-core paleotemperature investigations. In the absence of enough Cibicidoides specimens we suggest using Uvigerina delta18O data and applying a correction factor of -0.69 ‰.Neste estudo, compara-se a composição de isótopos de oxigênio de dois gêneros de foraminíferos bentônicos (Uvigerina e Cibicidoides) de amostras de topo de testemunho com a composição isotópica moderna da água do mar (delta18O). Baseados em uma nova relação entre delta18O e salinidade para a latitude média do Atlântico Sul ocidental, estimou-se a composição isotópica da calcita em equilíbrio (delta18Oeq) a partir de duas equações diferentes: (1) O'Neil et al. (1969), modificada por McCorkle et al. (1997) e (2) Kim & O'Neil (1997). Utilizando (1), a pequena diferença entre delta18Oeq e delta18O de Uvigerina sugere que este gênero precipita as suas testas próximo ao equilíbrio com a água. Já os dados de delta18O de Cibicidoides são 0,82 ‰ menores que a composição isotópica prevista. Ao contrário, utilizando (2) os dados de delta18O de Cibicidoides mostram uma concordância excelente com a composição isotópica esperada, enquanto que os dados de delta18O de Uvigerina são 0,69 ‰ maiores que os valores de equilíbrio previstos. A partir das evidências apresentadas neste trabalho e em estudos prévios sugerimos a utilização do gênero Cibicidoides e a aplicação da equação de Kim & O'Neil (1997) para pesquisas de paleotemperatura. Na ausência de suficientes espécimens de Cibicidoides sugerimos a utilização de delta18O de Uvigerina aplicando um fator de correção de -0,69 ‰.

The thermal and diagenetic evolution of Carboniferous sandstones in the central Appalachian basin has been resolved using various techniques. Paleothermometers including vitrinite reflectance and fluid inclusions indicate that burial of Lower and Upper Pennsylvanian strata of the Appalachian Plateau in West Virginia exceeded 4.4 km during the late Permian and occurred at a rate of ~100 m/m.y. Exhumation rates of ~10-30 m/m.y. from maximum burial to present depth were constrained using published apatite fission track and radiogenic helium ages. Quartz, lithic and feldspar-rich sandstones from different stratigraphic intervals and locations were sampled from core (95 %) and outcrop (5%) to qualitatively and quantitatively evaluate sandstone diagenesis. A compositional multivariate data set compiled from point counts served as the basis for quantitative analysis of controls on sandstone diagenesis such as framework grain composition, paleoclimate and depositional environment. A priori groups (independent variables) corresponding to the controls were compared using digenetic products (dependent variables). Major conclusions of the analysis are, first, minerals that formed early appear to have been influenced by stratigraphic position. The distribution of siderite and iron-oxide/oxyhydroxide may reflect the second order paleoclimatic signature recognized throughout the Carboniferous, where siderite formed during everwet periods and iron-oxide/oxyhydroxide during semi-arid conditions, reflecting differences in redox. Second, framework grain composition controlled the distribution of diagenetic alterations and quartz cementation in the burial environment. Lithic arenites are deficient in authigenic quartz, yet have undergone various degrees of illitization. The quartz deficiency is attributed to compaction-related loss of primary porosity relatively early, which inhibited flow of silica-bearing fluids. Finally, no correlation can be demonstrated between depositional environment and diagenesis. Anomalously high fluid inclusion homogenization temperatures (> 215 °C) from Upper Pennsylvanian sandstones adjacent to the Alleghany Thrust Front indicate that tectonic setting played an important role in quartz authigenesis. The discrepancy between the fluid inclusion and vitrinite reflectance data imply that warm silica-bearing fluids, likely sourced from low-grade metamorphic reactions, were injected into Pennsylvanian sandstone aquifers during thrust loading associated with the Alleghanian orogeny. Ph. D.

About a decade after its introduction, the field of carbonate clumped isotope thermometry is rapidly expanding because of the large number of possible applications and its potential to solve long‐standing questions in Earth Sciences. Major factors limiting the application of this method are the very high analytical precision required for meaningful interpretations, the relatively complex sample preparation procedures, and the mass spectrometric corrections needed. In this paper we first briefly review the evolution of the analytical and standardization procedures and discuss the major remaining sources of uncertainty. We propose that the use of carbonate standards to project the results to the carbon dioxide equilibrium scale can improve interlaboratory data comparability and help to solve long‐standing discrepancies between laboratories and temperature calibrations. The use of carbonates reduces uncertainties related to gas preparation and cleaning procedures and ensures equal treatment of samples and standards. We present a set of carbonate standards of diverse composition, discuss how they can be used to correct for mass spectrometric biases, and demonstrate that their use significantly improves the comparability among four laboratories. We propose that the use of these standards or of a similar set of carbonate standards will improve the comparability of data across laboratories., Geochemistry, Geophysics, Geosystems, 19 (9), ISSN:1525-2027

About a decade after its introduction, the field of carbonate clumped isotope thermometry is rapidly expanding because of the large number of possible applications and its potential to solve long-standing questions in Earth Sciences. Major factors limiting the application of this method are the very high analytical precision required for meaningful interpretations, the relatively complex sample preparation procedures, and the mass spectrometric corrections needed. In this paper we first briefly review the evolution of the analytical and standardization procedures and discuss the major remaining sources of uncertainty. We propose that the use of carbonate standards to project the results to the carbon dioxide equilibrium scale can improve interlaboratory data comparability and help to solve long-standing discrepancies between laboratories and temperature calibrations. The use of carbonates reduces uncertainties related to gas preparation and cleaning procedures and ensures equal treatment of samples and standards. We present a set of carbonate standards of diverse composition, discuss how they can be used to correct for mass spectrometric biases, and demonstrate that their use significantly improves the comparability among four laboratories. We propose that the use of these standards or of a similar set of carbonate standards will improve the comparability of data across laboratories.