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首页> 外文期刊>Palaeogeography, Palaeoclimatology, Palaeoecology: An International Journal for the Geo-Sciences >Pliocene-Holocene evolution of depositional conditions in the eastern Mediterranean: Role of anoxia vs. productivity at time of sapropel deposition
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Pliocene-Holocene evolution of depositional conditions in the eastern Mediterranean: Role of anoxia vs. productivity at time of sapropel deposition

机译：地中海东部沉积条件的上新世-全新世演化：腐质沉积时缺氧与生产力的关系

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A multiproxy geochemical study of nine sapropel layers from ODP Hole 964A, ODP Leg 160 in the eastern Mediterranean spanning the Pliocene-Holocene time interval provides new insights into the evolution of sapropel deposition. Paleoenvironmental proxies were used for reconstruction of productivity (Ba derived from marine barite), oxygen conditions (trace metal ratios) and sedimentary regime (clay minerals, detrital elements). These proxies reveal a significant increase in river runoff relative to decreasing aeolian input during sapropel deposition over the whole time interval. Ba excess supports the argument that a significant increase in export productivity is the main triggering mechanism for sapropel deposition, although preservation also played an important role. Furthermore, major differences exist in depositional conditions, including both oxygenation and productivity since the Pliocene. Productivity fluctuated substantially and was higher during the Pliocene and Pleistocene than during the Holocene; at the same time decreasing oxygen availability parallels the enhanced productivity. Dysoxic to anoxic conditions appear to coincide with marine productivity maxima, thus suggesting that oxygen depletion may be linked to greater consumption rather than restricted circulation. This correspondence supports the hypothesis that productivity fluctuations resulting from climate oscillations were the main cause of enhanced organic matter contents and also a main controlling factor for reduced oxygen availability. (c) 2006 Elsevier B.V. All rights reserved.
机译：对来自地中海东部ODP腿160的ODP孔964A，ODP孔964A的9个腐殖质层进行的多代理地球化学研究，跨越上新世-全新世时间间隔，为腐殖质沉积的演化提供了新见识。古环境代理被用于重建生产力（Ba来源于海洋重晶石），氧气条件（痕量金属比）和沉积体系（粘土矿物，碎屑元素）。这些代理揭示了在整个时间间隔内，相对于在腐泥沉积过程中风沙输入减少而言，河流径流量显着增加。过量的钡支持了这样的论点，即出口生产率的显着提高是腐烂沉积的主要触发机制，尽管保存也起着重要的作用。此外，自上新世以来沉积条件存在重大差异，包括充氧和生产率。在上新世和更新世期间，生产力波动很大，并且比全新世时期高。同时，氧气供应量的减少与生产率的提高平行。从缺氧到缺氧的条件似乎与海洋生产力的最大值相吻合，因此表明耗氧量可能与更大的消耗量而不是限制的循环量有关。这种对应关系支持以下假设：由气候振荡引起的生产率波动是有机物含量增加的主要原因，也是减少氧气供应的主要控制因素。 （c）2006 Elsevier B.V.保留所有权利。

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