Sea‐level related resedimentation processes on the northern slope of Little Bahama Bank (Middle Pleistocene to Holocene)
Sea‐level related resedimentation processes on the northern slope of Little Bahama Bank (Middle Pleistocene to Holocene)
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小巴哈马浅滩北坡（中更新世至全新世）与海平面相关的再沉积过程
DOI：
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发表时间：
2007
期刊：
影响因子：
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通讯作者：
H. Kinkel
中科院分区：
文献类型：
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作者：
H. Lantzsch;S. Roth;J. Reijmer;H. Kinkel
本文介绍了在RV Marion Dufresne号巡航期间，在一个26米长的岩心中观测到的中更新世到全新世的沉积物变化。MD992202岩心取自小巴哈马滩北坡，为中坡沉积环境下的沉积过程提供了一个很好的例子。沉积物组成表明了过去375000年与海平面相关的沉积过程（海洋同位素阶段1至11）。沉积物包括：(i)台地周围软泥（浅水和远洋起源的细粒颗粒），碳酸盐含量、碳酸盐矿物学和粒度变化适中；（ii）层段较粗，胶结碎屑由块状、分选不良、泥浆支撑或碎屑支撑的沉积物组成，高镁方解石含量增加。在间冰期（海洋同位素阶段1、5、7、9和11），台地周围沉积物(i)的特征是文石含量较高，颗粒尺寸更细，有机含量更高，而在冰期（海洋同位素阶段2至4、6、8和10），低镁和高镁方解石值增加，颗粒尺寸更粗，有机含量更低。这些冰期与间冰期在矿物学、粒度分布和有机物含量上的差异清楚地表明，气候控制的海平面波动对小巴哈马滩北坡沉积模式的影响。较粗的沉积物（ii）主要发生在冰期到间冰期和间冰期到冰期的过渡时期，并被解释为再沉积事件，表明沉积物性质（矿物学变化、粒度分布、有机物含量变化）与海平面波动之间存在直接联系。在海平面变化期间，静水压力和波基位置的变化被认为引发了这些大规模的沉积物重新沉积。
Middle Pleistocene to Holocene sediment variations observed in a 26 metre long core taken during a cruise of the RV Marion Dufresne are presented. Core MD992202 was retrieved from the northern slope of Little Bahama Bank and provides an excellent example for sedimentation processes in a mid‐slope depositional environment. The sediment composition indicates sea‐level related deposition processes for the past 375 000 years (marine isotope stages 1 to 11). The sediments consist of: (i) periplatform ooze (fine‐grained particles of shallow‐water and pelagic origin) with moderate variations in carbonate content, carbonate mineralogy and grain‐size; and (ii) coarser intervals with cemented debris consisting of massive, poorly sorted, mud‐supported or clast‐supported deposits with an increased high‐magnesium calcite content. During interglacial stages (marine isotope stages 1, 5, 7, 9 and 11) periplatform oozes (i) are characterized by higher aragonite contents, finer grain‐size and higher organic contents, whereas during glacial stages (marine isotope stages 2 to 4, 6, 8 and 10), increased low‐magnesium and high‐magnesium calcite values, coarser grain‐size and lower organic contents are recorded. These glacial to interglacial differences in mineralogy, grain‐size distribution and organic content clearly show the impact of climatically controlled sea‐level fluctuations on the sedimentation patterns of the northern slope of Little Bahama Bank. The coarser deposits (ii) occur mainly at the transitions from glacial to interglacial and interglacial to glacial stages, and are interpreted as redeposition events, indicating a direct link between sediment properties (changes in mineralogy, grain‐size distribution, variations in organic contents) and sea‐level fluctuations. Changes in hydrostatic pressure and the wave base position during sea‐level changes are proposed to have triggered these large‐scale sediment redepositions.