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首页> 外文期刊>Paleoceanography >Glacial-interglacial variations in sediment organic carbon accumulation and benthic foraminiferal assemblages on the Bermuda Rise (ODP Site 1063) during MIS 13 to 10
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Glacial-interglacial variations in sediment organic carbon accumulation and benthic foraminiferal assemblages on the Bermuda Rise (ODP Site 1063) during MIS 13 to 10

机译：在MIS 13至10期间百慕大上升（ODP站点1063）上的沉积物有机碳积聚和底栖有孔虫组合的冰河间变化

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摘要

We have determined organic carbon concentrations and isotopic compositions and benthic foraminiferal assemblages in sediments deposited between ～500 and 340 ka at ODP Site 1063 on the northeastern flank of the Bermuda Rise. This time interval includes Marine Isotope Stage (MIS) 11, a particularly warm and long interglacial that was similar to today, and MIS 12, one of the most severe glacials of the last 600 kyr. During MIS 11.3, the peak of interglacial warming, organic carbon accumulation rates are low and benthic foraminiferal assemblages are dominated by Nuttallides umbonifera, a species indicative of oligotrophic environments. Higher accumulation rates during MIS 12 and 10 correspond with elevated sedimentation rates(33-36 cm/kyr). This pattern implies a combination of enhanced delivery and improved preservation of sediment organic matter during these glacial times. Organic δ ~(13)C values are less negative during MIS 12 and MIS 10 than during MIS 11, which is consistent with greater glacial-stage marine productivity. High relative abundances of Oridorsalis umbonatus during glacial intervals probably records a low but sustained flux of highly degraded organic material. Large, recurrent fluctuations in the abundance of Epistominella exigua at the beginnings of the MIS 12 and MIS 10 glaciations suggest a marked increase in local phytoplankton blooms at these times and consequent delivery of phytodetritus to the seafloor. The most likely causes of these variations are changes in the position and strength of the Gulf Stream and its associated cold-ring eddies, combined with increased advection of terrigenous sediments from northerly locations during glacial lowstands.
机译：我们已经确定了百慕大上升沿东北翼ODP站点1063处约500至340 ka之间沉积物中的有机碳浓度，同位素组成和底栖有孔虫组合。此时间间隔包括海洋同位素阶段（MIS）11（与今天类似的特别温暖和长的间冰期）和MIS 12（过去600年来最严重的冰川之一）。在MIS 11.3期间，冰川间变暖的峰值，有机碳的积累速率较低，底栖有孔虫群落主要由Nuttallides umbonifera（一种指示贫营养环境的物种）主导。在MIS 12和MIS 10期间较高的累积速率对应于较高的沉积速率（33-36 cm / kyr）。这种模式意味着在这些冰川时期，增加的输送量和改善的沉积物有机质保存性相结合。 MIS 12和MIS 10期间的有机δ〜（13）C值比MIS 11期间的负值要小，这与更大的冰川期海洋生产力相一致。在冰川间隔期间，乌Or（Oridorsalis umbonatus）的相对丰度较高，可能表明高降解有机物质的通量较低但持续。在MIS 12和MIS 10冰川开始时，埃希氏梭菌大量大量反复出现的波动表明，在这些时期，当地浮游植物的开花显着增加，从而导致植物碎屑向海底的输送。这些变化的最可能原因是墨西哥湾流及其相关的冷圈涡旋的位置和强度的变化，以及冰川低潮期间来自北端的陆源性沉积物的平流增加。

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