1,721,430 research outputs found
Climatic and oceanographic changes in the Azores region during the last 74.7 Ka
No full textIn this study, we reconstruct the complex palaeoclimatic and palaeohydrographic history of the North Atlantic Ocean during the Upper Pleistocene-Holocene, through a high-resolution Globigerinoides ruber - Globigerinoides elongatus plexus study. The studied core (ATA13-OF-KT1) was collected southwest of the Azores islands near the present-day boundary of the Subtropical Gyre/Azores Front Current System (STG/AFCS). Quantitative and stable isotope data of the G. ruber - G. elongatus plexus chromotypes and selected morphotypes showed cyclic oscillations of the STG/AFCS boundary linked to climatic variability at orbital and millennial scales, during the last 74.7 ka
Pulleniatina obliquiloculata Mg/Ca-derived thermocline water temperature records over the last two glacial-interglacial cycles from sediment core MD98-2165 off southern Lombok Strait
No full textWe present a Pulleniatina obliquiloculata Mg/Ca-derived thermocline water temperature record (TWT) covering the last 270,000 years from sediment core MD98-2165 (9.65S, 118.34E) at the south of the Lombok Strait, one of the main exits of the Indonesian Throughflow (ITF) into the Indian Ocean. The sediment core MD98-2165 was retrieved at a water depth of 2100 m during the IMAGES IV cruise of the French R/V Marion Dufresne. For measuring P. obliquiloculata Mg/Ca ratio, Core MD98-2165 was sampled at 4-12 cm interval during the 110-3450 cm depth interval, corresponding to 1.5 – 270 ka. About 30 tests of P. obliquiloculata were picked from the 250-355 µm size fraction. Samples were cleaned without using reductive step. Mg/Ca ratios were converted to temperatures by using calibration equation: Mg/Ca = 0.328 exp (0.09*T). Mg/Ca ratio of P.obliquiloculata vary between 1.6 and 3.1 mmol/mol, corresponding to TWT ranging between 17.8 and 25.1 °C. This reconstructed TWT record from sediment core MD98-2165 is used to study ITF change at orbital and glacial-interglacial timescales
Holocene records of foraminifera oxygen isotope and Mg/Ca-temperatures from MD98-2188
No full textThe Holocene variability in sea surface and thermocline water temperatures (SST and TWT) in the Indo-Pacific Warm Pool (IPWP) has been reconstructed by shell Mg/Ca of two planktonic foraminifera species, the mixed-layer dweller Globigerinoides ruber and the thermocline dweller Pulleniatina obliquiloculata, from sediments of Core MD98-2188 (14.82°N, 123.49°E, 730 m water depth) recovered in the western tropical Philippine Sea. Afterward the Younger Dryas interval (YD), SST warmed gradually till ~10 ka and remained approximately constant afterwards, but TWT rose more rapidly to a peak between ~12 and ~10 ka and then declined by ~1.5°C through the Holocene. The trend of TWT closely followed the boreal summer insolation and could be correlated to tropical climate changes represented by southward movement of the Inter-tropical Convergence Zone (ITCZ) and related changes in East Asian monsoons
Age and sediment geochemical data of MD10-3340, Halmahera Sea
No full textThis data set contains the benthic foraminifera d18O and sediment elemental compositions of core MD10-3340 (00°30.98'S, 128°43.47'E, water depth 1094 m) with a total core length of 34.10 m and covering the last 235,000 years, retrieved from the Halmahera Sea, eastern Indonesia. The elemental compositions were measured by X-ray fluorescence (XRF) core-scanning and analyses of XRF and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) on discrete samples. The original XRF core-scanned results of calcium and titanium are corrected for water content (indicated by the scanning intensity of chlorine) following the method described in the original publication
Colour Scan of sediment core MD01-2382 (top)
No full textProblem with core depth measurement.Consult also Bottom-File of this core and check cruise report for details
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