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  • Abstract: Stable isotopic measurements of G. sacculifer and C. wuellerstorfi in a core from the western equatorial Atlantic imply that there are parallel, suborbital oscillations in surface water hydrography and deep water circulation occurring during oxygen isotope stages 2 and 3. Low values of G. sacculifer delta18O accompany high values of C. wuellerstorfi delta13C, linking warmer sea surface temperatures (SSTs) in the tropics with increased production of lower North Atlantic Deep Water (NADW). The amplitude of the delta18O oscillations is 0.6 per mil (or 2°-3°C), which is superimposed on a glacial/interglacial amplitude of about 2.1per mil. Using the G. sacculifer delta18O data, we calculate that surface waters were colder during stage 2 than calculated by CLIMAP [1976, 1981]. The longer-period (>2 kyr) oscillations in air temperature recorded in the Greenland and Antarctic ice cores appear to correlate with oscillations in sea surface temperature in the equatorial Atlantic. The magnitude of these oscillations in tropical SST is too large to have resulted from changes in meridional heat transport caused by the global conveyor alone. The apparent synchroneity of equatorial SST and polar air temperature changes, as well as the amplitude of the SST changes at the equator, are consistent with the climate effects expected from changes in the atmosphere's greenhouse gas content (H2Ovapor, CO2, and CH4). Category: geoscientificInformation Source: Supplement to: Curry, William B; Oppo, Delia W (1997): Synchronous, high-frequency oscillations in tropical sea surface temperatures and North Atlantic Deep Water productivity during the last glacial cycle. Paleoceanography, 12(1), 1-14, https://doi.org/10.1029/96PA02413 Supplemental Information: Not Availble Coverage: EVENT LABEL: * LATITUDE: 5.906700 * LONGITUDE: -44.195000 * ELEVATION START: -4056.0 m * ELEVATION END: 0.0 m * Recovery: 6 m * METHOD|DEVICE: Piston corer
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  • Abstract: This paper presents physical and nutrient results from the Etude du Broutage en Zone Equatoriale cruise, conducted in the equatorial Pacific along the 180° meridian from 8°S to 8°N. Cold conditions of the El Niño-Southern Oscillation cycle were evident during the cruise (October-November 1996), and the equatorial upwelling was in its far western extension. Along the sampled section the nutrient-enriched area was asymmetric around the equator, and a zone of high remineralization was found from 6° to 3°S. Intensive sampling at two 5-day time series stations (3°S and 0°) provided some insight on high-frequency variability. At 3°S a deep density mixed layer showed only small fluctuations in nutrients. On the equator a rapid reduction of surface nutrients during the time series station was attributed to advection of a different water mass from the northeast, in the southward branch of a Tropical Instability Wave (TIW). Measurements from the Tropical Atmosphere-Ocean (TAO) array in the area confirmed significant contemporaneous TIW activity, which was linked to the cold conditions. Thus, in contrast to previous observations, it is shown that TIWs can contribute to relative decrease of nutrients at the equator. During the two time series sampling efforts, variability at diurnal and semidiurnal periods were found in physical parameters, originating from surface atmospheric forcing and internal wave activity at tidal frequency, respectively. In the 0-150 m layer, where intensive sampling of nutrients was performed, high-frequency variability did not seem to modify nutrient distribution significantly and physical influences dominated over biology. Category: geoscientificInformation Source: Supplement to: Eldin, Gérard; Rodier, Martine (2003): Ocean physics and nutrient fields along 180° during an El Niño-Southern Oscillation cold phase. Journal of Geophysical Research: Oceans, 108(C12), 8137, https://doi.org/10.1029/2000JC000746 Supplemental Information: Not Availble Coverage: Not Available
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  • Abstract: Transport studies that employ column experiments in closed-flow mode complement classical approaches by providing new characteristic features observed in the breakthrough behavior and an equilibrium between liquid and solid phase. Specific to the closed-flow mode is the recirculation of the column effluent to the inflow via a mixing vessel. Depending on the ratio of volume of the water-filled pore space to the volume of the mixing vessel, a damped oscillating solute concentration emerges in effluent and mixing vessel. Oscillation frequency, extent of damping and amplitude are thereby governed by the transport properties of the porous medium. These characteristics allow for the analysis of transport processes in soils in a similar fashion as known for classical open-flow column experiments. However, the experimental design considers feedbacks of liquid solid interactions by connecting the effluent solution with the inflow. In this way, solute and porous medium can equilibrate with respect to all physicochemical parameters, thereby permitting a convenient consideration of mass balances. With this paper, the features emerging in the breakthrough of column experiments run in closed-flow mode and methods of evaluation are illustrated under experimental boundary conditions forcing the appearance of these oscillations. Additionally, the effect of flow velocity and mixing vessel volume on the breakthrough is investigated. We demonstrate that the water content of the porous medium and the pumping rate can be determined from a conservative tracer breakthrough curve. In this way, external preconditioning of the soil material, e.g., drying, can be avoided. This renders the closed-flow column approach especially interesting for the study of porous media with diverse mineral content and bacterial community that react strongly on changes in the water content. Furthermore, the basis for the modeling of closed-flow experiments is given by the derivation of constitutive equations and numerical implementation, validated by the presented experiments. Category: geoscientificInformation Source: Supplement to: Ritschel, Thomas; Totsche, Kai Uwe (2016): Closed-flow column experiments - insights into solute transport provided by a damped oscillating breakthrough behavior. Water Resources Research, 52(3), 2206-2221, https://doi.org/10.1002/2015WR018317 Supplemental Information: Not Availble Coverage: Not Available
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  • Abstract: The R codes provide Bayesian model fitting procedures for AAR-^14^C datasets. These codes are updated versions of the analytical scripts published by Allen et al. (2013). Based on the ages derived from the models fitted, it is possible then to account for the time-averaging (temporal resolution of the fossil record). The time-averaging estimates are based on empirical posterior distributions, accounting for dating uncertainty, as in Ritter et al. (2017). In addition, the R codes implements the figures produced both the cited dissertation and its derived manuscripts, like the best models fitted, age-frequency distribuitions (Histograms), its relations with sea-level oscilation in the Southern Brazilian shelf etc. Category: geoscientificInformation Source: Not Available Supplemental Information: Not Availble Coverage: Not Available
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  • Abstract: We report 150 kyr records of U37K' sea-surface temperature (SST) and carbonate content with 150-200-year sampling resolution from the southern South China Sea (SCS) in the northern margin of the Western Pacific Warm Pool (WPWP) using IMAGES Core MD972151. The glacial/interglacial SST change is about 5 °C for Termination II (23.5 to 28.5°C) and 4°C for Termination I (24 to 28°C). The simultaneous rise of sea level and U37K' SST during Termination I suggests that sea-level change has played an important role in the SCS SST variability by influencing the exchange of tropical ocean warm surface water with the SCS through the Sunda Shelf region (sill depth 30-50 m). When sea-level drop was less than 30 m relative to today's, MD972151 SST was constantly above 27 °C, a situation which occurred during MIS 5e, part of MIS5c and 5a, and over the last 11 kyr. Sea-level change was also the main control on carbonate content in the SCS; this was lower during low sea-level stands due to the dilution effect of enhanced terrigenous inputs. Within the limitations of our age model, millennial-scale SST oscillations (1.5°C over a few hundred years) occurred frequently during the entire glacial period, correlating reasonably well with the Hulu monsoon record from eastern China and the Dansgaard-Oeschger (D-O) cycles recorded for high-latitude regions in the Northern Hemisphere. Such correlations suggest a possible teleconnection between higher latitude atmospheric forcing and low-latitude climate oscillations in the western Pacific tropical region via the Asian monsoon system. Carbonate content also reveals millennial-scale oscillations during the glacial period, with higher content correlated with higher SST. Millennial-scale fluctuations of SST and carbonate contents at this low-latitude SCS provide additional evidence that high-frequency climate changes are global phenomena. Category: geoscientificInformation Source: Supplement to: Zhao, Meixun; Huang, Chi-Yue; Wang, Chia-Chun; Wei, Ganjian (2006): A millennial-scale U37K' sea-surface temperature record from the South China Sea (8°N) over the last 150 kyr: Monsoon and sea-level influence. Palaeogeography, Palaeoclimatology, Palaeoecology, 236(1-2), 39-55, https://doi.org/10.1016/j.palaeo.2005.11.033 Supplemental Information: Not Availble Coverage: EVENT LABEL: (MD972151) * LATITUDE: 8.728000 * LONGITUDE: 109.869000 * ELEVATION: -1598.0 m * Recovery: 26.72 m * LOCATION: South China Sea * CAMPAIGN: MD106 * BASIS: Marion Dufresne (1995) * METHOD/DEVICE: Calypso Corer
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  • Abstract: The long-term record of glacial/interglacial cycles indicates three major paleoceanographic regimes in the Norwegian Sea. The period since the first major glaciation over Scandinavia at 2.56 Ma is characterized by high-frequency, low-amplitude oscillations of ice-rafted debris inputs, a lowered salinity, and decreased carbonate shell production in surface waters as well as overall strong carbonate dissolution at the sea floor. These conditions indicate a more zonal circulation pattern in the Northern Hemisphere and a relative isolation of surface and bottom waters in the Norwegian Sea. The generally temperate glacial climate was only interrupted by episodic weak intrusions of warm Atlantic waters. These intrusions have been detected in considerable magnitude only at Site 644, and thus are restricted to areas much closer to the Norwegian shelf than during earlier periods. The interval from 1.2 to 0.6 Ma is characterized by an increase in carbonate shell production and a better preservation, as well as a change in frequency patterns of ice-rafted debris inputs. This pattern reflects increasing meridionality in circulation-strengthening contrasts in the Norwegian Sea between strong glaciations and warm interglacials. The past 0.6 Ma reveal high-amplitude oscillations in carbonate records that are dominated by the 100-k.y. frequency pattern. Glacial/interglacial sedimentary cycles in the ODP Leg 104 drill sites reveal a variety of specific dark lithofacies. These dark diamictons reflect intense iceberg rafting in surface waters fed by surges along the front of marine-based parts of the continental ice sheets in the southeastern sector of the Norwegian Sea and are associated with resuspension of reworked fossil organic carbon and strong dissolution at the sea floor. Piling up of huge iceberg barriers along the Iceland-Faeroe-Scotland Ridge might have partially blocked off surface water connections with the North Atlantic during these periods Category: geoscientificInformation Source: Supplement to: Henrich, Rüdiger (1989): Glacial/interglacial cycles in the Norwegian Sea: sedimentology, paleoceanography, and evolution of late Pliocene to Quaternary northern hemisphere climate. In: Eldholm, O; Thiede, J; Taylor, E; et al. (eds.), Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 104, 189-232, https://doi.org/10.2973/odp.proc.sr.104.116.1989 Supplemental Information: Not Availble Coverage: EVENT LABEL: * LATITUDE: 67.225000 * LONGITUDE: 2.928300 * DATE/TIME START: 1985-06-28T14:40:00 * DATE/TIME END: 1985-06-29T20:15:00 * ELEVATION: -1294.0 m * Penetration: 221.1 m * Recovery: 214.61 m * LOCATION: Norwegian Sea * CAMPAIGN: Leg104 * BASIS: Joides Resolution * METHOD|DEVICE: Drilling/drill rig EVENT LABEL: * LATITUDE: 67.220000 * LONGITUDE: 2.930000 * DATE/TIME START: 1985-06-29T20:15:00 * DATE/TIME END: 1985-07-01T15:00:00 * ELEVATION: -1292.0 m * Penetration: 199.6 m * Recovery: 194.93 m * LOCATION: Norwegian Sea * CAMPAIGN: Leg104 * BASIS: Joides Resolution * METHOD|DEVICE: Drilling/drill rig EVENT LABEL: * LATITUDE: 67.715000 * LONGITUDE: 1.033300 * DATE/TIME START: 1985-08-03T06:07:00 * DATE/TIME END: 1985-08-08T01:45:00 * ELEVATION: -2780.0 m * Penetration: 565.2 m * Recovery: 458.29 m * LOCATION: Norwegian Sea * CAMPAIGN: Leg104 * BASIS: Joides Resolution * METHOD|DEVICE: Drilling/drill rig
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  • Abstract: The Mesozoic Era experienced several instances of abrupt environmental change that are associated with instabilities in the climate, reorganizations of the global carbon cycle, and elevated extinction rates. Often during these perturbations, oxygen-deficient conditions developed in the oceans resulting in the widespread deposition of organic-rich sediments - these events are referred to as Oceanic Anoxic Events or OAEs. Such events have been linked to massive injections of greenhouse gases into the ocean- atmosphere system by transient episodes of voluminous volcanism and the destabilization of methane clathrates within marine environments. Nevertheless, uncertainty surrounds the specific environmental drivers and feedbacks that occurred during the OAEs that caused perturbations in the carbon cycle; this is particularly true of the Early Jurassic Toarcian OAE (ca. 183.1 Ma). Here, we present biostratigraphically constrained carbon isotope data from western North America (Alberta and British Columbia, Canada) to better assess the global extent of the carbon cycle perturbations. We identify the large negative carbon isotope excursion associated with the OAE along with high-frequency oscillations and steps within the onset of this excursion. We propose that these high-frequency carbon isotope excursions reflect changes to the global carbon cycle and also that they are related to the production and release of greenhouse gases from terrestrial environments on astronomical timescales. Furthermore, increased terrestrial methanogenesis should be considered an important climatic feedback during Ocean Anoxic Events and other similar events in Earth history after the proliferation of land plants. Category: geoscientificInformation Source: Supplement to: Them II, Theodore R; Gill, Benjamin C; Gröcke, Darren R; Tulsky, E T; Martindale, Rowan C; Poulton, T P; Smith, P L (2017): High-resolution carbon isotope records of the Toarcian Oceanic Anoxic Event (Early Jurassic) from North America and implications for the global drivers of the Toarcian carbon cycle. Earth and Planetary Science Letters, 459, 118-126, https://doi.org/10.1016/j.epsl.2016.11.021 Supplemental Information: Not Availble Coverage: Not Available
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  • Abstract: A geochemical study of sediments from Ocean Drilling Program Site 983 was conducted to examine low-frequency variations in carbonate content as expressed by blue-band reflectance (450-500 nm) over the last 1.2 Ma. Sedimentary percent organic carbon, percent carbonate, and excess barium (Ba[ex]) were used as the primary tools to evaluate the factors responsible for these long-term changes. We observe positive correlation between the mass-accumulation rate of various biogenic components and the mass-accumulation rate of Ba(ex), especially in sediments younger than ~600 ka. Deeper in the section (~600-1200 ka), the correlation between Ba(ex) and the other biogenic tracers is weak. The lack of correlation between Ba(ex) and biogenic carbonate likely results either from a higher supply of terrigenous material at that time (which confounds Ba[ex] estimation), or remobilization of Ba resulting from low pore-water sulfate ion concentrations, or both. Nonbiogenic sediments at Site 983, represented by Th, K2O, and the molar Ti/Al ratio, exhibit cyclic variations that represent mixing between continental and oceanic (i.e., basaltic) terrigenous sources. The timing of these cycles matches that of the major glacial-interglacial cycles, which suggests that they result from the supply of continental material as ice-rafted debris during glacial periods and fine-grained basaltic material by bottom currents during interglacial periods. Given these observations, the most likely causes for the low-frequency carbonate variations observed in the Site 983 sediments are shifts in surface productivity and, to a lesser extent, dilution by the input of terrigenous material. Category: geoscientificInformation Source: Supplement to: Hyun, Sangmin; Ortiz, Joseph D; Raymo, Maureen E; Taira, Asahiko (1999): Low-frequency oscillations in Site 983 sediments: relationships between carbonate and productivity proxies. In: Raymo, ME; Jansen, E; Blum, P; Herbert, TD (eds.) Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 162, 1-11, https://doi.org/10.2973/odp.proc.sr.162.019.1999 Supplemental Information: Not Availble Coverage: EVENT LABEL: * LATITUDE: 60.403500 * LONGITUDE: -23.640667 * DATE/TIME START: 1995-07-21T00:00:00 * DATE/TIME END: 1995-07-24T00:00:00 * ELEVATION: -1983.7 m * Penetration: 766.5 m * Recovery: 798 m * LOCATION: North Atlantic Ocean * CAMPAIGN: Leg162 * BASIS: Joides Resolution * METHOD|DEVICE: Composite Core
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  • Abstract: Two expeditions to Dorado Outcrop on the eastern flank of the East Pacific Rise and west of the Middle America Trench collected images, video, rocks, and sediment samples and measured temperature and fluid discharge rates to document the physical and biogeochemical characteristics of a regional, low‐temperature (~15 °C) hydrothermal system. Analysis of video and images identified lava morphologies: pillow, lobate, and sheet flows. Glasses from collected lavas were consistent with an off‐axis formation. Hydrothermal discharge generally occurs through pillow lavas but is patchy, sporadic, and sometimes ceases at particular sites of discharge. Yearlong temperature measurements at five of these discharge sites show daily ranges that oscillate with tidal frequencies by 6 °C or more. Instantaneous fluid discharge rates (0.16 to 0.19 L/s) were determined resulting in a calculated discharge of ~200 L/s when integrated over the area defined by the most robust fluid discharge. Such discharge has a power output of 10-12 MW. Hydrothermal seepage through thin sediment adjacent to the outcrop accounts for <3% of this discharge, but seepage may support an oxic sediment column. High extractable Mn concentrations and depleted δ13C in the low but variable organic solid phase suggest that hydrothermal fluids provide a source for manganese accumulation and likely enhance the oxidation of organic carbon. Comparisons of the physical and geochemical characteristics at Dorado and Baby Bare Outcrops, the latter being the only other site of ridge‐flank hydrothermal discharge that has been sampled directly, suggest commonalities and differences that have implications for future discoveries. Category: geoscientificInformation Source: Supplement to: Wheat, C Geoffrey; Hartwell, Anne M; McManus, James; Fisher, Andrew T; Orcutt, Beth N; Schlicht, Lucy E M; Niedenzu, Sara; Bach, Wolfgang (2019): Geology and fluid discharge at Dorado Outcrop, a low temperature ridge-flank hydrothermal system. Geochemistry, Geophysics, Geosystems, 20(1), 487-504, https://doi.org/10.1029/2018GC007933 Supplemental Information: Not Availble Coverage: Not Available
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  • Abstract: Date-32 is a fast and easily used computer program developed to date Quaternary deep-sea cores by associating variations in the earth's orbit with recurring oscillations in core properties, such as carbonate content or isotope composition. Starting with known top and bottom dates, distortions in the periodicities of the core properties due to varying sedimentation rates are realigned by fast Fourier analysis so as to maximise the spectral energy density at the orbital frequencies. This allows age interpolation to all parts of the core to an accuracy of 10 kyrs, or about 1.5% of the record duration for a typical Brunhes sequence. The influence of astronomical forcing is examined and the method is applied to provide preliminary dates in a high-resolution Brunhes record from DSDP Site 594 off southeastern New Zealand. Category: geoscientificInformation Source: Supplement to: Black, Kerry P; Nelson, Campbell S; Hendy, Chris H (1988): A spectral analysis procedure for dating Quaternary deep-sea cores and its application to a high-resolution Brunhes record from the Southwest Pacific. Marine Geology, 83(1-4), 21-30, https://doi.org/10.1016/0025-3227(88)90049-7 Supplemental Information: Not Availble Coverage: EVENT LABEL: * LATITUDE: -45.523500 * LONGITUDE: 174.948000 * DATE/TIME: 1983-01-03T00:00:00 * ELEVATION: -1204.0 m * Penetration: 505.1 m * Recovery: 300.7 m * LOCATION: South Pacific/CONT RISE * CAMPAIGN: Leg90 * BASIS: Glomar Challenger * METHOD|DEVICE: Drilling/drill rig
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