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首页> 外文期刊>Palaeogeography, Palaeoclimatology, Palaeoecology: An International Journal for the Geo-Sciences >Trace element indicators of increased primary production and decreased water-column ventilation during deposition of latest Pliocene sapropels at five locations across the Mediterranean Sea
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Trace element indicators of increased primary production and decreased water-column ventilation during deposition of latest Pliocene sapropels at five locations across the Mediterranean Sea

机译：微量元素指示物在地中海上五个位置沉积最新的上新世腐殖土期间增加初级产量并减少水柱通风

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摘要

Compositions of productivity- and redox-sensitive trace-metals in two Upper Pliocene sapropel sequences from western Mediterranean ODP Sites 974 and 975 and eastern Mediterranean Sites 964, 969, and 967 provide information about the conditions leading to sapropel deposition. Except at Site 975, closest to the Atlantic Ocean, all sapropels display elevated element/Al ratios for Ba, Re, Cd, Mo, U, Cr, Cu, V, and Zn. High total organic carbon (TOC) concentrations and Ba/Al ratios point to increased primary productivity during sapropel deposition. Enrichments of redox-sensitive trace elements and elevated Re/Mo ratios indicate water-column oxygen depletion during sapropel formation. Anoxia likely was caused by increased fluxes of organic matter to the seafloor that would have enhanced oxygen demand at depth. One of the sapropel sequences investigated in this study, insolation-cycle 178, contains a zone having low TOC, low Ba/Al ratios, and low trace-metal contents. These features identify this interval as an interruption of the increased productivity associated with sapropels and of the sub-oxic/anoxic conditions that are fully-developed in the upper half of this sapropel layer. Significant differences in trace-metal enrichments between the eastern and western Mediterranean indicate that the eastern basin was a focal point for sapropel initiation. In contrast, Site 975 appears to have been heavily influenced by the Atlantic Ocean during i-cycles 178 and 180 and was not strongly influenced by the paleoceanographic changes affecting the rest of the Mediterranean. (c) 2007 Elsevier B.V. All rights reserved.
机译：来自地中海西部ODP站点974和975和地中海东部964、969和967站点的两个上新世上层腐殖质序列中对生产力和氧化还原敏感的痕量金属的组成提供了导致腐烂沉积条件的信息。除最靠近大西洋的975号站点外，所有腐泥中Ba，Re，Cd，Mo，U，Cr，Cu，V和Zn的元素铝比均升高。较高的总有机碳（TOC）浓度和Ba / Al比率表明在sa石沉积过程中初级生产率提高。氧化还原敏感的痕量元素的富集和升高的Re / Mo比值表明在腐草酸形成过程中水柱中的氧耗竭。缺氧可能是由于有机物质通向海底的通量增加而引起的，这将增加深处的氧气需求。在这项研究中研究的腐腐岩序列之一，日晒周期178，包含一个具有低TOC，低Ba / Al比和低痕量金属含量的区域。这些特征将这个间隔确定为与腐殖质相关的生产率提高以及该腐殖质层上半部分完全发育的亚缺氧/缺氧条件的中断。地中海东部和西部之间痕量金属富集的显着差异表明，东部盆地是腐殖质萌发的重点。相比之下，Site 975似乎在178和180周期i周期受到大西洋的强烈影响，而不受影响地中海其他地区的古海洋学变化的强烈影响。 （c）2007 Elsevier B.V.保留所有权利。

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