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Registros recuperados: 9
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Asian dust input in the western Philippine Sea: Evidence from radiogenic Sr and Nd isotopes ArchiMer
Jiang, Fuqing; Li, Tiegang; Xu, Zhaokai; Li, Anchun; Frank, Martin; Chen, Tian-yu.
The radiogenic strontium (Sr) and neodymium (Nd) isotope compositions of the detrital fraction of surface and subsurface sediments have been determined to trace sediment provenance and contributions from Asian dust off the east coast of Luzon Islands in the western Philippine Sea. The Sr and Nd isotope compositions have been very homogenous near the east coast of the Luzon Islands during the latest Quaternary yielding relatively least radiogenic Sr (Sr-87/Sr-86 = 0.70453 to 0.70491) and more radiogenic Nd isotope compositions (epsilon(Nd)(0) = +5.3 to +5.5). These isotope compositions are similar to Luzon rocks and show that these sediments were mainly derived from the Luzon Islands. In contrast, the Sr and Nd isotope compositions of sediments on the...
Tipo: Text Palavras-chave: Asian dust; Luzon Islands; Detrital fraction; Sr isotope; Nd isotope; Western Philippine Sea.
Ano: 2013 URL: https://archimer.ifremer.fr/doc/00264/37537/35824.pdf
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Calcareous nannofossil bioevents and microtektite stratigraphy in the Western Philippine Sea during the Quaternary ArchiMer
Sun, Hanjie; Li, Tiegang; Sun, Rongtao; Yu, Xinke; Chang, Fengming; Tang, Zheng.
Two sediment cores, MD06-3050 and MD06-3047, were analyzed to study the Quaternary calcareous nannofossil and microtektite records. We dated bioevents and the microtektite impact event by calibrating with oxygen isotope stratigraphy. Seven calcareous nannofossil bioevents were identified over the past 2.36 Ma including the last appearance of data for Discoaster brouweri, Calcidiscus macintyrei, large Gephyrocapsa and Pseudoemiliania lacunosa, the first appearance of data for large Gephyrocapsa and Emiliania huxleyi, and the abrupt increase in the abundance of Gephyrocapsa caribbeanica. In addition, we fortunately observed that Australasian microtektites were distributed in core MD06-3050 from 1340 to 1374 cm.
Tipo: Text Palavras-chave: Western Philippine Sea; Quaternary Period; Calcareous nannofossil biostratigraphy; Oxygen isotope stratigraphy; Australasian microtektites.
Ano: 2011 URL: https://archimer.ifremer.fr/doc/00213/32465/30932.pdf
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Comment on "Sr-Nd isotope composition and clay mineral assemblages in Eolian dust from the central Philippine Sea over the last 600kyr: Implications for the transport mechanism of Asian dust" by Seo et al ArchiMer
Xu, Zhaokai; Li, Tiegang; Clift, Peter D.; Wan, Shiming; Cai, Mingjiang; Chen, Hongjin.
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Ano: 2016 URL: https://archimer.ifremer.fr/doc/00421/53202/54943.pdf
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Human impact overwhelms long-term climate control of weathering and erosion in southwest China ArchiMer
Wan, Shiming; Toucanne, Samuel; Clift, Peter D.; Zhao, Debo; Bayon, Germain; Yu, Zhaojie; Cai, Guanqiang; Yin, Xuebo; Revillon, Sidonie; Wang, Dawei; Li, Anchun; Li, Tiegang.
During the Holocene there has been a gradual increase in the influence of humans on Earth systems. High-resolution sedimentary records can help us to assess how erosion and weathering have evolved in response to recent climatic and anthropogenic disturbances. Here we present data from a high-resolution (∼75 cm/k.y.) sedimentary archive from the South China Sea. Provenance data indicate that the sediment was derived from the Red River, and can be used to reconstruct the erosion and/or weathering history in this river basin. Accelerator mass spectrometry 14C dating provides direct age control and reveals coherent variations in clay mineralogy, geochemistry, and terrigenous flux, indicative of strong chemical weathering and physical erosion during the...
Tipo: Text
Ano: 2015 URL: http://archimer.ifremer.fr/doc/00266/37754/37175.pdf
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Paleoproductivity variations in the southern Okinawa Trough since the middle Holocene: Calcareous nannofossil records ArchiMer
Zhao, Jingtao; Li, Tiegang; Li, Jun; Hu, Bangqi.
Based on 17 AMS(14)C age data, we reconstructed high-resolution records of sea surface primary productivity (PP) in the southern Okinawa Trough (MD05-2908) over the last 6.8 ka BP using the calcareous nannofossil carbon isotope and the relative percentage contents of Florisphaera profunda indexes. The underlying mechanism controlling the sea surface PP was then discussed. The sea surface PP, indicated by the coccolith delta C-13 and %Fp conversional equations, decreased with some fluctuations since 6.8 ka BP. This decrease may be connected to the decreased terrigenous input resulting from the reduced East Asian Summer Monsoon (EASM) precipitation. Both the periods of 4-2 ka BP (PME) and 6.8-4.8 ka BP were characterized by relatively higher PP. The former...
Tipo: Text Palavras-chave: Middle Holocene; The southern Okinawa Trough; Primary productivity; Calcareous nannofossil.
Ano: 2012 URL: https://archimer.ifremer.fr/doc/00265/37615/36518.pdf
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Response of the northwestern Pacific upper water delta C-13 to the last deglacial ventilation of the deep Southern Ocean ArchiMer
Chen, Shaungxi; Li, Tiegang; Tang, Zheng; Qiu, Xiaohua; Xiong, Zhifang; Nan, Qingyun; Xu, Zhaokai; Chang, Fengming.
The deglacial delta C-13 minimum events that originated from the ventilation of the deep Southern Ocean around Antarctica, have been recorded in a range of marine sediments from the southern to tropical oceans in late Pleistocene. However, the broad delta C-13 minimum event was also reported as far as to the northern middle latitudes, in northwestern Pacific marginal sea areas, during the last deglaciation. In the northwestern Pacific, forcing from the northern high latitudes is strongly expressed, while the records of influence from the southern high latitudes are few. The Kuroshio Source Region (KSR) forms a boundary between the northwestern Pacific and the southern, tropical Pacific. So, high-resolution planktonic foraminiferal records in core MD06-3054...
Tipo: Text Palavras-chave: Planktonic foraminiferal delta C-13; Ventilation of the deep Southern Ocean; Northwestern Pacific; Last deglaciation; Delta C-13 minimum event.
Ano: 2011 URL: https://archimer.ifremer.fr/doc/00213/32467/30934.pdf
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Sediment provenance and evolution of the East Asian winter monsoon since 700 ka recorded by major elements in the West Philippine Sea ArchiMer
Xu, Zhaokai; Li, Tiegang; Yu, Xinke; Li, Anchun; Tang, Zheng; Choi, Jinyong; Nan, Qingyun.
To synthetically realize the character of major-element compositions as well as its significance for provenance and paleoenvironment recorded in core sediments of the West Philippine Sea over the last 700 ka, grain size and major elements of 221 bulk sediments, together with major-element compositions in the detrital phase of 16 typical samples, in core MD06-3047 collected from the Benham Rise were analyzed. Both discrimination plot and R-mode factor analysis indicate that vertical changes of major elements are mainly controlled by the sedimentation of nearby volcanic matter and the eolian dust input, whereas influences from marine biologic deposition and hydrothermal activity are minor. In particular, Al2O3 and K2O are representative of an eolian dust...
Tipo: Text Palavras-chave: Major elements; Provenance; Eolian dust; East Asian winter monsoon; West Philippine Sea.
Ano: 2013 URL: https://archimer.ifremer.fr/doc/00264/37557/36494.pdf
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Sedimentation rates and provenance analysis in the Southwestern Okinawa Trough since the mid-Holocene ArchiMer
Li, Chuanshun; Jiang, Bo; Li, Anchun; Li, Tiegang; Jiang, Fuqing.
As a high-sedimentation rate depocenter along the path of the Kuroshio Current, the southwesternmost part of the Okinawa Trough is a key area to understand the Kuroshio history and sediments transportation. A 34.17-m-long sediment core was obtained by the advanced piston corer of Marco Polo/IMAGES XII MARION DUFRESNE during the May 2005 from the Southern Okinawa Trough at site MD05-2908. The recovered sediments were analyzed by AMS (14)C dating, coarse size fraction (> 63 mu m) extraction and moisture content determination in order to study its sedimentation flux and provenance. The depth-age relationship of core MD05-2908 was well constrained by 17 (14)C dating points. The sediments span across the mid-Holocene (6.8 ka B.P.) and have remarkablely high...
Tipo: Text Palavras-chave: Southwesternmost Okinawa Trough; Mid-Holocene; Sedimentation rates; Sediment source.
Ano: 2009 URL: https://archimer.ifremer.fr/doc/00207/31842/30287.pdf
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The silicon isotope composition of Ethmodiscus rex laminated diatom mats from the tropical West Pacific: Implications for silicate cycling during the Last Glacial Maximum ArchiMer
Xiong, Zhifang; Li, Tiegang; Algeo, Thomas; Doering, Kristin; Frank, Martin; Brzezinski, Mark A.; Chang, Fengming; Opfergelt, Sophie; Crosta, Xavier; Jiang, Fuqing; Wan, Shiming; Zhai, Bin.
The cause of massive blooms of Ethmodiscus rex laminated diatom mats (LDMs) in the eastern Philippine Sea (EPS) during the Last Glacial Maximum (LGM) remains uncertain. In order to better understand the mechanism of formation of E. rex LDMs from the perspective of dissolved silicon (DSi) utilization, we determined the silicon isotopic composition of single E. rex diatom frustules (delta Si-30(E.rex)) from two sediment cores in the Parece Vela Basin of the EPS. In the study cores, delta Si-30(E.rex) varies from -1.23 parts per thousand to -0.83 parts per thousand (average -1.04 parts per thousand), a range that is atypical of marine diatom delta Si-30 and that corresponds to the lower limit of reported diatom delta Si-30 values of any age. A binary mixing...
Tipo: Text
Ano: 2015 URL: https://archimer.ifremer.fr/doc/00496/60732/65231.pdf
Registros recuperados: 9
Primeira ... 1 ... Última
 

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