对采自东太平洋 CC 区西部的 WPC1101重力活塞柱样进行了岩石磁学、古地磁极性地层及古生物地层年代学研究工作。等温剩余磁化强度（IRM）、磁滞回线和反向场退磁曲线测试结果表明，沉积物中的磁性矿物主要为磁铁矿，仅在柱状样底部存...对采自东太平洋 CC 区西部的 WPC1101重力活塞柱样进行了岩石磁学、古地磁极性地层及古生物地层年代学研究工作。等温剩余磁化强度（IRM）、磁滞回线和反向场退磁曲线测试结果表明，沉积物中的磁性矿物主要为磁铁矿，仅在柱状样底部存在少量赤铁矿/针铁矿。340~350 cm 发育的埋藏结核层，标志着一处沉积间断的存在；60~336 cm 发育上新世晚期的硅藻化石 Cosinodiscus nodulifer ，但古地磁极性地层缺失上新世第四纪的2r 反极性时；0~60 cm 见第四纪标准化石 Pseudoenuotia doliolus 、Spongaster tetras ，且顶部缺失1正极性时。综合对比古生物地层学、磁性地层学以及邻近区域地层学特征，认为该柱状样记录了从晚渐新世至第四纪的沉积历史，期间存在晚渐新世至早上新世、上新世晚期至第四纪早期及第四纪晚期3个时期的沉积间断，上述沉积间断的形成可能是南极底流的形成与增强、CCD 界面抬升及海底侵蚀作用增强共同控制的结果。展开更多
The impacts of opening the Drake Passage(DP) on the oceanic general circulation are examined.When the DP is open,wind stress at mid-and high latitudes gives rise to a wind-driven gyre,which induces a meridional heat e...The impacts of opening the Drake Passage(DP) on the oceanic general circulation are examined.When the DP is open,wind stress at mid-and high latitudes gives rise to a wind-driven gyre,which induces a meridional heat exchange between mid-and high latitudes in the Southern Ocean.After the opening of the DP,the Antarctic Circumpolar Current(ACC) forms and its associated strong temperature front blocks the heat transport from mid-latitudes to high latitudes.A simple box model is formulated,in which the effects of the wind stress(for the case of DP closed) and the thermal front(for the case of DP open) on the variability of Antarctic Bottom Water(AABW) and North Atlantic Deep Water(NADW) are explored.The sensitivity experiments demonstrate that:(1) When the DP is closed,the enhancement of the wind-driven gyre leads to the decline of AABW formation in the Southern Ocean and the increase of NADW formation in the North Atlantic.As a result,water in high latitudes of the Southern Ocean becomes warmer,so does the bottom water of global ocean.(2) When the DP is open,there is no formation of AABW until the intensity of thermal front along ACC exceeds a threshold value(it is 4.03℃ in our model).Before the formation of AABW,temperature in most of the oceans is higher than that after the formation of AABW,which usually leads to the cooling of high latitudes of the Southern Hemisphere and the bottom water in global ocean.When the strength of the thermal front is lower than the critical value,there is no AABW formation,and temperature in most of the oceans is slightly higher.These results demonstrate that during the opening of the DP,changes in wind stress and the formation of the thermal front in the Southern Ocean can substantially affect the formation of AABW and NADW,thus changing the state of meridional overturning circulation in the global ocean.展开更多
文摘对采自东太平洋 CC 区西部的 WPC1101重力活塞柱样进行了岩石磁学、古地磁极性地层及古生物地层年代学研究工作。等温剩余磁化强度（IRM）、磁滞回线和反向场退磁曲线测试结果表明，沉积物中的磁性矿物主要为磁铁矿，仅在柱状样底部存在少量赤铁矿/针铁矿。340~350 cm 发育的埋藏结核层，标志着一处沉积间断的存在；60~336 cm 发育上新世晚期的硅藻化石 Cosinodiscus nodulifer ，但古地磁极性地层缺失上新世第四纪的2r 反极性时；0~60 cm 见第四纪标准化石 Pseudoenuotia doliolus 、Spongaster tetras ，且顶部缺失1正极性时。综合对比古生物地层学、磁性地层学以及邻近区域地层学特征，认为该柱状样记录了从晚渐新世至第四纪的沉积历史，期间存在晚渐新世至早上新世、上新世晚期至第四纪早期及第四纪晚期3个时期的沉积间断，上述沉积间断的形成可能是南极底流的形成与增强、CCD 界面抬升及海底侵蚀作用增强共同控制的结果。
基金supported by National Basic Research Program of China(Grant No.2012CB957802)the Chinese Polar Environment Comprehensive Investigation & Assessment Programmes(Grant No.CHINARE2012-04-04)+1 种基金Program of International Science and Technology Cooperation(Grant No.S2011GR0348)National Natural Science Foundation of China(Grant No.41176029)
文摘The impacts of opening the Drake Passage(DP) on the oceanic general circulation are examined.When the DP is open,wind stress at mid-and high latitudes gives rise to a wind-driven gyre,which induces a meridional heat exchange between mid-and high latitudes in the Southern Ocean.After the opening of the DP,the Antarctic Circumpolar Current(ACC) forms and its associated strong temperature front blocks the heat transport from mid-latitudes to high latitudes.A simple box model is formulated,in which the effects of the wind stress(for the case of DP closed) and the thermal front(for the case of DP open) on the variability of Antarctic Bottom Water(AABW) and North Atlantic Deep Water(NADW) are explored.The sensitivity experiments demonstrate that:(1) When the DP is closed,the enhancement of the wind-driven gyre leads to the decline of AABW formation in the Southern Ocean and the increase of NADW formation in the North Atlantic.As a result,water in high latitudes of the Southern Ocean becomes warmer,so does the bottom water of global ocean.(2) When the DP is open,there is no formation of AABW until the intensity of thermal front along ACC exceeds a threshold value(it is 4.03℃ in our model).Before the formation of AABW,temperature in most of the oceans is higher than that after the formation of AABW,which usually leads to the cooling of high latitudes of the Southern Hemisphere and the bottom water in global ocean.When the strength of the thermal front is lower than the critical value,there is no AABW formation,and temperature in most of the oceans is slightly higher.These results demonstrate that during the opening of the DP,changes in wind stress and the formation of the thermal front in the Southern Ocean can substantially affect the formation of AABW and NADW,thus changing the state of meridional overturning circulation in the global ocean.
