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Three deep holes, with a maximum penetration of 960 m below sea floor, were drilled into the distal Bengal Fan just south of the equator during ODP Leg 116. The entire section recovered is dominated by sandy silt and mud turbidites derived from the Ganges Delta and from the continental margin of the western Bay of Bengal, interbedded with thin pelagic clays and with biogenic turbidites probably from a local sea mount source. The effects of Hi-Malayan uplift, sea level fluctuations, local tectonics, and fan channel/lobe processes have closely interacted to produce the observed sedimentary record of the past 17 million years since the early Miocene.Coauthors include: James R. Cochran, Lamont-Doherty Geological Observatory (Co-chief scientist); Dorrik A. V. Stow, Nottingham University, England (Co-chief scientist); Christian A. Auroux, Texas A & M University, USA (ODP staff scientist); Kazou Amano, Ibaraki University, Japan; Peter S. Balson, British Geological Survey, Keyworth, Notts, England; Jacques Boulegue, Pierre & Marie Curie University, Paris, France; Garrett W. Brass, University of Miami, Florida, USA; Jeffrey Corrigan, University of Texas, Austin, USA; Stefan Gartner, Texas A & M University, USA; Stuart A. Hall, University of Houston, Texas, USA; Silvia Iaccarino, University of Parma, Italy; Toshio Ishizuka, University of Tokyo, Japan; trena Kacmarska, Mount Allison University, New Brunswick, Canada; Heidemarie Kassens, Kiel University, West Germany; Gregory Leger, Dalhousie University, Halifax, Nova Scotia, Canada; Franca Proto Decima, University of Padova, Italy; C. V. Raman, Andhra University, Visakhapatnam, India; William W. Sager, Texas A & M University, USA; Kozo Takahashi, Woods Hole Oceanographic Institution, USA; Thomas Thompson, 580 Euclid Ave, Boulder, Colo, USA; Jean-Jacques Tiercelin, University of Bretagne, Brest, France; Mark Townsend, University of Nottingham, England; Andreas Wetzel, Tubingen University, West Germany; N. P. Wijayananda, National Aquatatic Resource Agency, Colombo, Sri Lanka; and Colin Williams, Lamont-Doherty Geological Observatory.  相似文献   
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Leg 115 of the Ocean Drilling Program recovered basaltic rocks from four sites along the ancient trail of the Réunion hotspot. The age of volcanism, determined from biostratigraphic data at the four sites, increases to the north and records the motion of India away from the Réunion hotspot through Tertiary time. Hotspot activity began with the eruption of the Deccan flood basalt flows at the time of the Cretaceous/Tertiary boundary. The Réunion hotspot has been stationary with respect to other hotspots in the Atlantic and Indian Ocean basins through Tertiary time. The geochemical compositions of the drilled basalts differ according to the relative contributions of magmas from hotspot and MORB mantle sources.  相似文献   
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旨在探究剥蚀型汇聚板块边缘大地震成因机理的国际综合大洋钻探(IODP)344航次于2012年10月23日至12月11日在中美洲地震频发的哥斯达黎加西部海域实施钻探。介绍了钻探区域的大地构造特征、该航次的主要科学目标、执行情况、所取得的初步成果以及对航次后研究工作的展望等。航次后更多深入细致的研究工作正在进行中,所取得的研究成果将集中在2014年南京召开的航次后学术研讨会上汇报、交流、集成、总结,从而提升对剥蚀型汇聚板块边缘大地震起源机理的认识。  相似文献   
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Fluid flow from pore pressure measurements off La Palma, Canary Islands   总被引:1,自引:0,他引:1  
In situ subseafloor pore pressure results from the western flank of the island of La Palma, Canary Islands, are presented. The data obtained with a Pop Up Pore Pressure Instrument (PUPPI) provide constraints on the fluid circulation and its causes in a very special context: The sediment piles near an intraplate oceanic island built on the continental rise of the Northwest African Margin. The ambient pore pressures estimated from 2 to 4 days long record are negative in almost all cases with values, at depths of a few meters below sea floor, usually on the order of −10 to −70 Pa. Excess pore pressures develop only in the distal most areas. The permeabilities and compressibilities obtained respectively from the decay of the insertion pressures and the amplitude of the tidally induced pore pressure variations range between 2.5×10−18 and 6.6×10−16 m2 and, 6.2×10−9 and 1.5×10−7 Pa−1. According to these permeabilities fluid flow is estimated to be mostly downward and usually on the range between 0 and −0.3 mm y−1. However, from the excess pore pressure profile a complex pattern of fluid circulation is inferred where horizontal fluid motion cannot be neglected. Horizontal flow is probably controlled by significant contrasts in the permeability of the different layers. The prevailing downward fluid flow is abnormal for a classical passive margin. We thus interpret these results as the superposition to the loss of fluids by sediment compaction (on the continental rise), of a large-scale flow system stimulated by thermal buoyancy (100 km wide) related to the volcanic activity on the island of La Palma.  相似文献   
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IODP333航次:科学目标、钻探进展与研究潜力   总被引:1,自引:0,他引:1  
高抒 《地球科学进展》2011,26(12):1290-1299
在“地震带实验项目”(NanTroSEIZE)的总体框架下,IODP333航次的任务是在日本四国岛岸外一条断面的3个站位获取岩芯。钻探于2010年12月12日至2011年1月10日实施,钻取了4个长岩芯,总长达1005m。IODP333航次的主要研究内容是陆坡、海沟底部和海山脊部的第四纪沉积过程,包括沉积层内的孔隙压力...  相似文献   
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Joint inversion of active and passive seismic data in Central Java   总被引:2,自引:0,他引:2  
Seismic and volcanic activities in Central Java, Indonesia, the area of interest of this study, are directly or indirectly related to the subduction of the Indo-Australian plate. In the framework of the MERapi AMphibious EXperiments (MERAMEX), a network consisting of about 130 seismographic stations was installed onshore and offshore in Central Java and operated for more than 150 days. In addition, 3-D active seismic experiments were carried out offshore. In this paper, we present the results of processing combined active and passive seismic data, which contain traveltimes from 292 local earthquakes and additional airgun shots along three offshore profiles. The inversion was performed using the updated LOTOS-06 code that allows processing for active and passive source data. The joint inversion of the active and passive data set considerably improves the resolution of the upper crust, especially in the offshore area in comparison to only passive data. The inversion results are verified using a series of synthetic tests. The resulting images show an exceptionally strong low-velocity anomaly (−30 per cent) in the backarc crust northward of the active volcanoes. In the upper mantle beneath the volcanoes, we observe a low-velocity anomaly inclined towards the slab, which probably reflects the paths of fluids and partially melted materials in the mantle wedge. The crust in the forearc appears to be strongly heterogeneous. The onshore part consists of two high-velocity blocks separated by a narrow low-velocity anomaly, which can be interpreted as a weakened contact zone between two rigid crustal bodies. The recent Java M w= 6.3 earthquake (2006/05/26-UTC) occurred at the lower edge of this zone. Its focal strike slip mechanism is consistent with the orientation of this contact.  相似文献   
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Stable isotopes and element compositions of the fine‐grained matrix were measured for IODP Expedition 307 Hole U1317E drilled from the summit of Challenger Mound in Porcupine Seabight, northeast Atlantic, to explore the palaeoceanographic and palaeoclimatic background to development of the deep‐water coral mound. The 155 m long mound section was divided into two units by an unconformity at 23.6 mbsf: Unit M1 (2.6–1.7 Ma) and Unit M2 (1.0–0.5 Ma). Results from 519 specimens show a difference in δ13C value between Unit M1 (?0.6‰ to ?5.0‰) and Unit M2 (?1.0‰ to 1.0‰), but such a distinct difference was not seen in δ18O values (1.0‰–2.5‰), CaCO3 content (40–60 wt%), Sr/Ca ratio (2.0–8.0 mmol mol?1), and Mg/Ca ratio (10.0–20.0 mmol mol?1) through the mound. Positive δ18O and negative δ13C shifts at the mound base are consistent with the oceanographic changes in the northeast Atlantic at the beginning of the Quaternary. The positive δ13C regression in Unit M2 suggests a linkage to the mid Pleistocene intensified glaciation in the Northern Hemisphere. Warm Mediterranean Upper Core Water of Mediterranean Outflow Water, Eastern North Atlantic Water and cold Labrador Sea Water of North Atlantic Deep Water are key oceanographic features that cause spikes and shifts in stable isotope and element composition. However, the stable isotope values of the sediment matrix could not primarily record the glacial–interglacial eustatic/temperature change, but indirectly indicate current regimes of the intermediate oceanic layer where the coral mound grew. Similarly, elemental ratios and CaCO3 content may not represent the productivity and temperature of surface sea water, respectively, but superpose the fractions from both surface and bottom water. It is concluded that palaeoceanographic change coupled to the Pleistocene glacial/interglacial cycles is a key control on the geochemical stratigraphy of the matrix sediments of the carbonate mound developed in Porcupine Seabight. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   
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