Deep circulations in the ocean affect the distribution of physical, chemical, and biological properties, and are intimately entwined with the planetary-scale climate. Numerous proxies, including neodymium (Nd) in fossil fish teeth, point to a source region in the South Pacific for much of the low-latitude deep-water during the early Paleogene. We use the MIT general circulation model (MITgcm) to test the sensitivity of deep-water formation to uncertainty in surface boundary conditions in a number of numerical modeling experiments with realistic and idealized bathymetries. Finally, the MITgcm is run with a passive tracer, ENd , for some of the experiments mentioned above and to multiple initial surface distributions of ENd. In our experiments that use idealized basin shapes, appropriate for the early Cenozoic, the formation of North Pacific deep-water occurred in all of our experiments in which we vary the magnitude of the surface density gradient. While the rate of deep-water formation is sensitive to the strength of the surface density gradient, the location of the source regions was not. For our experiments that use realistic bathymetry, the formation of South Pacific deep-water occurred in a majority of our experiments. Here the Southern Ocean has the greatest poleward latitudinal extent, and therefore preference for deep-water formation. When salinity is added into the equation of state we find that this causes an increase in the extent of Southern Ocean deep-water. Lastly, we explore simulations using ENd as a passive tracer. Throughout most of the realistic simulations explored, the densest water occurs in the Southern Ocean. There is a strong sensitivity to where in the Southern Ocean the densest water occurs though, either in the South Pacific or Atlantic. With ENd values different in these regions, various simulations produced different tracer distributions. We found this variability in the sinking region to be very sensitive to runoff and seasonality. The sensitivity to the spatial distribution of surface and interior ENd values was found to have little affect on the final ENd distribution, given that the ENd value in the sinking regions was kept constant.

To better understand the operating mode of the deep oceans during fundamentally warm climate intervals, we present new Nd isotope data from Deep Sea Drilling Project and Ocean Drilling Program sites in the North Pacific to expand the reconstruction of water mass composition and structure during the early Cenozoic. Fossil fish debris from Sites 192, 464, 465, 883, 884 and 1208 (paleowater depths spanning 900 to 4000 m) were used to reconstruct the water mass composition from ~85 to 30 Ma. The fish debris is shown to not be overprinted as there was no systematic offset between the detrital silicate and the fish debris composition. Cleaned and uncleaned fish debris were both included in the reconstruction of water mass composition as they were found to record the same Nd isotope composition. North Pacific deep water convection occurred from ~67 to 45 Ma, the peak in production is recorded by broadly coincident trends at Sites 192, 464 and 883. Further support for North Pacific deep-water convection during the early Paleogene are the geographic trends in detrital silicate versus fish debris composition, greater separation at the more northerly Emperor Seamount sites, and the location of the most radiogenic detrital values at the Emperor Seamount sites. The Emperor Seamount chain likely played a major role in the flow of the North Pacific deep-water mass as it acted as a physical barrier to flow at deep-water sites compared to shallow depths (albeit still deep-water). εNd values indicate the timing of the cessation of major, deep convection in the North Pacific occurred much earlier, ~52 Ma than the timing obtained from shallower Shatsky Rise sites, ~45 Ma. Convection in the North Pacific likely produced a dense water mass that influenced the deeper sites in this study more than the shallower sites until ~52 Ma when convection was not as intense or the waters were not sufficiently dense to impact the deeper sites. Deep water convection was most intense during the relatively “cool” portion of the Late Cretaceous and Early Paleocene.

Thick Paleogene sequences occur in the southern deformed fold and thrust belt of the Himalayas. In this thesis I describe detailed litho- and biostratigraphy from ten key stratigraphic sections in the Kohat Basin, the Potwar Basin and the Trans Indus Ranges (TIR). These stratigraphies combined with microfacies analysis resulted in a new interpretation of the tectono-stratigraphic history of the area, which is dominated by India-Asia collision but where eustatatic effects can also be identified. Of particular interest is documenting the timing of the final closure of the northern rim of the Tethys caused by this collision. The Kohat and Potwar Basins represent foreland basins within the collision zone. Their stratigraphies document effects of local tectonics and eustatic sea level. The biostratigraphy is based on occurrences of larger benthic foraminifera. Taxonomy of the species is included in the thesis. The Paleogene rocks of the study area are divided into local larger benthic forminiferal biozones: BFZK 1- BFZK 6 in the Kohat Basin and BFZP 1-BFZP 3 in the Potwar Basin and the TIR. These local biozones are correlated to the global standard biozonation schemes of Höttinger (1960), Schaub (1981), and Serra Kiel et al. (1998). The ages of the sequences are Late Paleocene (Thanitian) to Middle Eocene (Upper Lutetian) in the Kohat Basin, and Late Paleocene (Thanitian) to Early Eocene (Middle Cuisian) in the Potwar Basin and the TIR. The sediments were deposited along a carbonate ramp platform in both areas (sensu Read, 1982, 1985). The sequence stratigraphic histories of the two basins are described as follows. In the Kohat Basin, Thanitian to Middle Cuisian strata record the first Transgressive-Regressive cycle (TRK 1). The first sequence boundary (SBK 1) is followed by Middle Cuisian-Upper Cuisian lowstand progradational deposition that marks the end of TRK 1 cycle. Middle Lutetian 1-Upper Lutetian strata represent the second Transgressive-Regressive cycle (TRK 2). The second sequence boundary (SBK 2) ends TRK 2 deposition, after which no more deposition took place. In the Potwar Basin and the TIR, Thanitian strata comprise the first Transgressive- Regressive cycle (TRP 1), whilst Lower Lllerdian-Middle Lllerdian 1 strata constitute the second Transgressive-Regressive cycle (TRP 2). Middle Lllerdian 2 to Middle Cuisian strata mark the third Transgressive-Regressive cycle (TRP 3). Three sequence boundaries (the SBP 1, the SBP 2 and the SBP 3), marked by exposure surfaces, separate the three depositional cycles. The SBP 1 and SBP 2 sequence boundaries are controlled by local tectonics. In contrast the SBP 3 and SBK 1 sequence boundaries are synchronous at 49.5 Ma, and represent a phase of significant relative sea level fall, possibly driven by the combined effect of uplift (collision tectonics) and eustatic sea level fall (e.g. Haq et al., 1987). This implies that proto-closure of the northern rim of the Tethys occurred around 49.5 Ma. Reestablishment of marine conditions in the Kohat Basin occurred in the Middle Lutetian 1 around 45.8 Ma, possibly caused by a combination of flexural loading of the Indian plate (Pivinik & Wells, 1996) and eustatic sea-level rise (e.g. Haq et al., 1987). The final closure of the Tethys, marked by the end of marine sedimentation in the Kohat Basin, occurred in the Upper Lutetian (41.2 Ma). Finally, Himalayan foreland molasses sedimentation occurred during Miocene to Pliocene.

Tectonic development of the Andean Cordillera has profoundly changed the topography, climate, and vegetation patterns of the southern central Andes. The Cenozoic Bermejo Basin in Argentina (30 degrees S) provides a key record of thrust belt kinematics and paleoclimate south of the high-elevation Puna Plateau. Ongoing debate regarding the timing of initiation of upper plate shortening and Andean uplift persists, precluding a thorough understanding of the earlier tectonic and climatic controls on basin evolution. We present new sedimentology, detrital geochronology, sandstone petrography, and subsidence analysis from the Bermejo Basin that reveal siliciclastic-evaporative fluvial and lacustrine environments prior to the main documented phase of Oligocene-Miocene shortening of the Frontal Cordillera and Argentine Precordillera. We report the first radiometric dates from detrital zircons collected in the Cienaga del Rio Huaco Formation, previously mapped as Permian, that constrain a Late Cretaceous (95-93Ma) maximum depositional age. Provenance and paleocurrent data from these strata indicate that detritus was derived from dissected arc and cratonic sources in the north and northeast. Detrital zircon U-Pb ages of 37Ma from the overlying red beds suggest that foredeep sedimentation began by at least the late Eocene. At this time, sediment dispersal shifted from axial southward to transversal eastward from the Andean Arc and Frontal Cordillera. Subsidence analysis of the basin fill is compatible with increasing tectonic deformation beginning in Eocene time, suggesting that a distal foredeep maintained fluvial connectivity to the hinterland during topographic uplift and unroofing of the Frontal Cordillera, prior to Oligocene-Miocene deformation across the Precordillera.

The latitudinal motion of the Tibetan Himalayathe northernmost continental unit of the Indian plateis a key component in testing paleogeographic reconstructions of the Indian plate before the India-Asia collision. Paleomagnetic studies of sedimentary rocks (mostly carbonate rocks) from the Tibetan Himalaya are complicated by potentially pervasive yet cryptic remagnetization. Although traditional paleomagnetic field tests reveal some of this remagnetization, secondary remanence acquired prior to folding or tilting easily escapes detection. Here we describe comprehensive rock magnetic and petrographic investigations of Jurassic to Paleocene carbonate and volcaniclastic rocks from Tibetan Himalayan strata (Tingri and Gamba areas). These units have been the focus of several key paleomagnetic studies for Greater Indian paleogeography. Our results reveal that while the dominant magnetic carrier in both carbonate and volcaniclastic rocks is magnetite, their magnetic and petrographic characteristics are distinctly different. Carbonate rocks have wasp-waisted hysteresis loops, suppressed Verwey transitions, extremely fine grain sizes (superparamagnetic), and strong frequency-dependent magnetic susceptibility. Volcaniclastic rocks exhibit pot-bellied hysteresis loops and distinct Verwey transitions. Electron microscopy reveals that magnetite grains in carbonate rocks are pseudomorphs of early diagenetic pyrite, whereas detrital magnetite is abundant and pyrite is rarely oxidized in the volcaniclastic rocks. We suggest that the volcaniclastic rocks retain a primary remanence, but oxidation of early diagenetic iron sulfide to fine-grained magnetite has likely caused widespread chemical remagnetization of the carbonate units. We recommend that thorough rock magnetic and petrographic investigations are prerequisites for paleomagnetic studies throughout southern Tibet and everywhere in general.

The fossil flora and depositional setting of the early Eocene Falkland site in the southern interior of British Columbia, Canada is reported here in detail for the first time. Falkland is part of a series of fossil localities that occur in a region known as the Okanagan Highlands. These sites represent relatively cool upland environments in the greenhouse world of the early Eocene. Macrofossil collections were obtained from Falkland using an unbiased census approach with systematic sampling through three informal units in the exposed outcrop. A stratigraphic log reveals a lacustrine sequence dominated by finely laminated mudstone or shale with periodic influx of coarser material, punctuated by thin volcanic ash layers. Paleoelevation of the site is estimated based on paleobotanical evidence to have been similar to or slightly higher than modern levels (¡Ý1.3 km) during the early Eocene.<p> Paleoclimate is assessed using both physiognomic and floristic approaches as applied to the Falkland flora. Physiognomic approaches correlate aspects of leaf morphology with climate, while floristic approaches use the tolerances of modern nearest living relatives to infer a climate envelope for the fossil flora. Overall, the different methods give broadly consistent results, with an identifiable zone of overlap in the estimates for mean annual temperature at ~10.5¡ãC, cold month mean temperature at 2.3¨C6.3¡ãC, warm month mean temperature at 20.2¨C23.7¡ãC, and a minimum mean annual precipitation of 82¨C120 cm/yr. Assessment of paleoclimate for the three individual units indicates a cooling trend over time, consistent with a radiometric date of 50.61¡À0.16 Ma that places the site in the waning phase of the Early Eocene Climatic Optimum (EECO).<p> The stomatal frequency of fossil Ginkgo adiantoides from Falkland is used to estimate paleoatmospheric carbon dioxide (pCO2). Results from Falkland indicate that pCO2 was significantly higher than modern (>2x) in the early Eocene, although the upper limit of the estimate is unconstrained due to limitations with modern calibration datasets. Analysis of specimens from the three units indicates that climate and pCO2 were coupled during the EECO. Examination of modern Ginkgo biloba leaves suggests that stomatal density is more likely to be accurately measured than stomatal index. In addition, there is a significant difference between stomatal frequencies of long- and short-shoot leaves, suggesting that this factor needs to be taken into account in modern calibration datasets.<p> The Falkland flora was described in two phases. In the first phase, specimens were assigned to morphotypes, informal categories that ideally correspond to species-level organization. In total, 1561 specimens were assigned to 138 morphotypes encompassing foliage and reproductive structures. The taxonomic literature was then investigated and morphotypes were assigned to formal taxa wherever possible. Gymnosperms are dominated by taxa in Cupressaceae, Pinaceae, and Ginkgoaceae, and there is a diverse angiosperm flora particularly rich in taxa belonging to Rosaceae, Betulaceae, and Sapindaceae. Rarefaction analysis shows Falkland as having diversity comparable to that of the hyper-diverse Laguna del Hunco site in Argentina. These data are consistent with an emerging understanding of high diversity in early Eocene forest communities associated with mild but equable climates. The Falkland flora retains a foundation of common taxa through all three units, including Metasequoia, Ginkgo, and Alnus; however, there is a distinct plant community in the upper unit as angiosperms become more abundant and the assemblage more diverse. Patterns in plant diversity are assessed within a context of changing climate and an active disturbance regime at the Falkland site.

The fossil flora and depositional setting of the early Eocene Falkland site in the southern interior of British Columbia, Canada is reported here in detail for the first time. Falkland is part of a series of fossil localities that occur in a region known as the Okanagan Highlands. These sites represent relatively cool upland environments in the greenhouse world of the early Eocene. Macrofossil collections were obtained from Falkland using an unbiased census approach with systematic sampling through three informal units in the exposed outcrop. A stratigraphic log reveals a lacustrine sequence dominated by finely laminated mudstone or shale with periodic influx of coarser material, punctuated by thin volcanic ash layers. Paleoelevation of the site is estimated based on paleobotanical evidence to have been similar to or slightly higher than modern levels (¡Ý1.3 km) during the early Eocene.<p> Paleoclimate is assessed using both physiognomic and floristic approaches as applied to the Falkland flora. Physiognomic approaches correlate aspects of leaf morphology with climate, while floristic approaches use the tolerances of modern nearest living relatives to infer a climate envelope for the fossil flora. Overall, the different methods give broadly consistent results, with an identifiable zone of overlap in the estimates for mean annual temperature at ~10.5¡ãC, cold month mean temperature at 2.3¨C6.3¡ãC, warm month mean temperature at 20.2¨C23.7¡ãC, and a minimum mean annual precipitation of 82¨C120 cm/yr. Assessment of paleoclimate for the three individual units indicates a cooling trend over time, consistent with a radiometric date of 50.61¡À0.16 Ma that places the site in the waning phase of the Early Eocene Climatic Optimum (EECO).<p> The stomatal frequency of fossil Ginkgo adiantoides from Falkland is used to estimate paleoatmospheric carbon dioxide (pCO2). Results from Falkland indicate that pCO2 was significantly higher than modern (>2x) in the early Eocene, although the upper limit of the estimate is unconstrained due to limitations with modern calibration datasets. Analysis of specimens from the three units indicates that climate and pCO2 were coupled during the EECO. Examination of modern Ginkgo biloba leaves suggests that stomatal density is more likely to be accurately measured than stomatal index. In addition, there is a significant difference between stomatal frequencies of long- and short-shoot leaves, suggesting that this factor needs to be taken into account in modern calibration datasets.<p> The Falkland flora was described in two phases. In the first phase, specimens were assigned to morphotypes, informal categories that ideally correspond to species-level organization. In total, 1561 specimens were assigned to 138 morphotypes encompassing foliage and reproductive structures. The taxonomic literature was then investigated and morphotypes were assigned to formal taxa wherever possible. Gymnosperms are dominated by taxa in Cupressaceae, Pinaceae, and Ginkgoaceae, and there is a diverse angiosperm flora particularly rich in taxa belonging to Rosaceae, Betulaceae, and Sapindaceae. Rarefaction analysis shows Falkland as having diversity comparable to that of the hyper-diverse Laguna del Hunco site in Argentina. These data are consistent with an emerging understanding of high diversity in early Eocene forest communities associated with mild but equable climates. The Falkland flora retains a foundation of common taxa through all three units, including Metasequoia, Ginkgo, and Alnus; however, there is a distinct plant community in the upper unit as angiosperms become more abundant and the assemblage more diverse. Patterns in plant diversity are assessed within a context of changing climate and an active disturbance regime at the Falkland site.

Many scientific studies have been conducted on the Cretaceous-Paleogene boundary (KTB) in the Gulf coast region and, in particular, the Brazos River section in Falls County, Texas. Despite this, there remains much to be learned about the KTB and its depositional environment. Study of the KTB has been multidisciplinary, primarily in the fields of sedimentology and paleontology. Some researchers in these disciplines have questioned the consensus view of the placement of the KTB and subsequent interpretation of the timing of depositional events and mass extinction events. Geophysical methods have potential to provide additional understanding of the physical properties of the KTB. To date, study of the KTB has relied on point data and borehole information to create cross sections of the complex. Seismic refraction surveys can provide spatially continuous information on susburface horizons located adjacent to the KTB. In this study, seismic first-arrival traveltimes are processed with a tomographic modeling program to map the top of the hummocky cross-bedded sandstone (HCS), which is a key indicator of the deposition environment at the time of KTB boundary complex placement. The survey area is located at Cottonmouth Creek, a tributary of the Brazos River. Three seismic lines were surveyed, one across Cottonmouth Creek, and two parallel to the creek on either side. The data from the two parallel lines were processed using the 2-D seismic refraction tomography algorithm of Zelt and Smith. The reconstructed depth to the HCS in the survey area is approximately 6 m, with layer seismic velocities of 364, 1800, and 2200 m/s, respectively. Seismic tomography successfully mapped the HCS layer and reveals approximately 1 m amplitude undulations vertically and undulations on the order of several m horizontally. These variations are consistent with exposed surfaces of the HCS in the creek bed. Seismic refraction has been utilized successfully herein to map a key buried indicator, namely the top of the HCS layer, associated with the KTB complex. A detailed 3-D seismic refraction survey at this site is recommended to generate a high-resolution 2-D terrain map of the top of the HCS layer.

abstract: The earliest Eocene marked the appearance of the first North American euprimates (adapids, omomyids). Despite the fact that leading hypotheses assert that traits involved in food acquisition underlie euprimate origination and early diversification, the precise role that dietary competition played in establishing euprimates as successful members of mammalian communities is unclear. This is because the degree of niche overlap between euprimates and all likely mammalian dietary competitors ("the euprimate competitive guild") is unknown. This research determined which of three major competition hypotheses - non-competition, strong competition, and weak competition - characterized the late Paleocene-early Eocene euprimate competitive guild. Each of these hypotheses is defined by a unique temporal pattern of niche overlap between euprimates and their non-euprimate competitors, allowing an evaluation of the nature of dietary competitive interactions surrounding the earliest euprimates in North America. Dietary niches were reconstructed for taxa within the fossil euprimate competitive guild using molar morphological measures determined to discriminate dietary regimes in two extant mammalian guilds. The degree of dietary niche separation among taxa was then evaluated across a series of fossil samples from the Bighorn Basin, Wyoming just prior to, during, and after euprimate origination. Statistical overlap between each pair of euprimate and non-euprimate dietary niches was determined using modified multivariate pairwise comparisons using distances in a multidimensional principal component "niche" space. Results indicate that euprimate origination and diversification in North America was generally characterized by the absence of dietary competition. This lack of competition with non-euprimates is consistent with an increase in the abundance and diversity of euprimates during the early Eocene, signifying that the "success" of euprimates may not be the result of direct biotic interactions between euprimates and other mammals. An examination of the euprimate dietary niche itself determined that adapids and omomyids occupied distinct niches and did not engage in dietary competition during the early Eocene. Furthermore, changes in euprimate dietary niche size over time parallel major climatic shifts. Reconstructing how both biotic and abiotic mechanisms affected Eocene euprimates has the potential to enhance our understanding of these influences on modern primate communities. / Dissertation/Thesis / Ph.D. Anthropology 2014

Fossil plants are regard to be excellent proxies to trace paleoclimatic and paleoatmospheric changes. The vegetational response to changing paleoclimate and paleoatmospheric conditions has already been known for a long time and is well documented for the Paleogene of central Europe. Methods such as the Coexistence Approach (CA) and the Climate Leaf Analyses Multivariate Program (CLAMP) analyze the composition of fossil plant assemblages. Changes in paleoclimate and CO2 through time can be tracked also via changes in morphometric parameters such as leaf area, leaf size and leaf shape or epidermal (cuticular) parameters as for instance stomata density (SD), stomata index (SI) and stomata size. The multivariate gas exchange model combines morphometric and cuticular parameters, together with assumed paleoclimate conditions and physiological data of nearest living equivalents to determine paleo-CO2. Plants show differences in morphological, morphometric and cuticular parameters, not only in response to overall changes in CO2 and climate, but also due to their immobility and dependency on light intensity, water availability and soil conditions at the respective site. In this study leaf traits of both Rhodomyrtophyllum reticulosum and Platanus neptuni from 23 sites in Germany, Austria and the Czech Republic covering a time span from the late early Eocene to the early Miocene of central Europe are investigated. Alongside the stratigraphic range of the data set, which allows for tracing long-term variations in the respective parameters, sites of different depositional facies types (maar deposits, marine deposits and fluvial-lacustrine deposits) were included. It has been proven that the investigation of single species and their correspondence to global and regional paleoclimatic and paleoatmospheric shifts has to be done considering differences in the respective depositional setting and thus habitat. Regional effects influence the peculiarity of leaf traits greatly which implies that regional and site related patterns partly overweigh global correspondences. The weak correlation of leaf trait changes to global changes in paleoclimate and CO2 implies that the long-lived species Rhodomyrtophyllum reticulosum and Platanus neptuni are not suitable to track these changes due their high plasticity and adaptability. The long stratigraphic range of the investigated species therefore point out the high adaption potential which by implication leads to a lower correspondence to global paleoclimatic changes. The determination of crucial leaf traits and their response to overall changes in paleoclimate and CO2 hampers the fact that the fossil record bears mainly elements present in azonal vegetation which is caused by predominantly burial of fossils in aquatic bodies. Hence, long-lived species could have been survived these remarkable changes in climate from the end of the Early Eocene Climatic Optimum to the Oligocene icehouse world due to their occurrence in azonal assemblages, buffering global effects in climate variability to a certain degree. The investigation of long-lived fossil species therefore has to be done by coincident consideration of the composition of the whole plant assemblage, which reflects both azonal and partly zonal vegetation of the respective time interval.