Origin, glacial‐interglacial responses, and controlling factors of a cold‐water coral mound in NE Atlantic
Origin, glacial‐interglacial responses, and controlling factors of a cold‐water coral mound in NE Atlantic
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DOI：
10.1029/2008pa001695
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发表时间：
2009-06
期刊：
影响因子：
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通讯作者：
S. Sakai;A. Kano;K. Abe
中科院分区：
文献类型：
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作者：
S. Sakai;A. Kano;K. Abe
[1]最近的深海勘探发现，世界各地的大陆架、斜坡、海山和海脊系统的深水中存在着出乎意料的广泛和多样的珊瑚生态系统。由于缺乏完整的地层剖面，这些冷水珊瑚丘的起源和生长历史知之甚少。在这里，我们显示了高分辨率的氧同位素记录的南极有孔虫从底部到顶部的挑战者丘，西南部的爱尔兰，这是钻在综合大洋钻探计划远征307。挑战者丘在同位素阶段92（224万年前（Ma））开始增长，紧接着北方半球冰川作用的开始和大西洋东北部现代分层的开始。土墩的启动可能是由于重新引入地中海外流水（MOW）和随后的密度梯度与上覆东北大西洋水（NEAW），有机物质很容易被停滞和燃料的珊瑚生态系统的发展。珊瑚的生长持续了11个冰期-间冰期旋回，直到同位素阶段72（1.82马）与冰川siliciconitrile输入从大陆边缘。经过一个长时间的中断，分离的下丘和上丘，珊瑚生长恢复了很短的时间，在同位素阶段19 - 18（0.8 - 0.7马），其中沉积物被侵蚀或不沉积在一个完整的冰期。MOW和NEAW之间的水团界面的发展模式可能发生了变化，因为MOW生产的波动，这是负责在冰量振荡的振幅从低振幅的41 ka周期的低丘上丘的100 ka周期的高振幅。下丘的平均沉降率和CaCO3生产率分别为27 cm/ka和31.1 g/cm 2/ka。
[1] Recent deep-ocean exploration has revealed unexpectedly widespread and diverse coral ecosystems in deep water on continental shelves, slopes, seamounts, and ridge systems around the world. Origin and growth history of these cold-water coral mounds are poorly known, owing to a lack of complete stratigraphic sections through them. Here we show high-resolution oxygen isotope records of planktic foraminifers from the base to the top of Challenger Mound, southwest of Ireland, which was drilled during Integrated Ocean Drilling Program Expedition 307. Challenger Mound began to grow during isotope stage 92 (2.24 million years ago (Ma)), immediately after the onset of Northern Hemisphere glaciation and the initiation of modern stratification in the northeast Atlantic. Mound initiation was likely due to reintroduction of Mediterranean Outflow Water (MOW) and ensuing development of a density gradient with overlying northeastern Atlantic water (NEAW), where organic matter was prone to be stagnated and fueled the coral ecosystem. Coral growth continued for 11 glacial-interglacial cycles until isotopic stage 72 (1.82 Ma) with glacial siliciclastic input from the continental margin. After a long hiatus that separates the lower mound and the upper mound, coral growth restored for a short time in isotope stages 19–18 (0.8–0.7 Ma) in which sediments were either eroded or not deposited during a full glacial stage. The development pattern of the water mass interface between MOW and NEAW might have changed, because of the fluctuations of the MOW production which is responsible for the amplitude in ice volume oscillations from the low-amplitude 41 ka cycles for the lower mound to the high-amplitude 100 ka cycles for the upper mound. The average sedimentation and CaCO3 production rates of the lower mound were evaluated 27 cm/ka and 31.1 g/cm2/ka, respectively.