...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Paleoceanography >Miocene to Pleistocene osmium isotopic records of the Mediterranean sediments
【24h】

Miocene to Pleistocene osmium isotopic records of the Mediterranean sediments

机译：地中海沉积物的中新世至更新世同位素记录

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

In the late Miocene the Mediterranean Sea experienced a salinity crisis and thick sequences of evaporites precipitated across the deep and marginal basins. In this study we report Os isotopic records from Deep Sea Drilling Project and Ocean Drilling Project cores in the Mediterranean: the Balearic Sea (Site 372), the Tyrrhenian Sea (Site 654), the Ionian Basin (Site 374), and the Florence Rise (Sites 375-376), as well as Integrated Ocean Drilling Project Site U1387 in Gulf of Cadiz, North Atlantic. Pliocene-Pleistocene sediments at all sites show Os-187/Os-188 values close to that of the coeval ocean water, indicating that the Mediterranean was connected to the North Atlantic. Evaporitic sediments deposited during the latest Miocene, however, have Os-187/Os-188 values significantly lower than coeval ocean water values. The offset of the Mediterranean evaporite Os-187/Os-188 is attributed to limited exchange with the North Atlantic during the Messinian salinity crisis. The source of unradiogenic Os is likely to be weathering of ultramafic rocks (ophiolites) cropping out in the Mediterranean's drainage basins. Based on a box model we estimated the amount of unradiogenic Os and the Atlantic-Mediterranean exchange rate to explain this offset. Os isotopic ratios of the pre-evaporite sediments in the western Mediterranean are almost identical to that of the coeval ocean water. In contrast, equivalent sediments from the Florence Rise have significantly lower Os-187/Os-188 values. The offset in the Os isotopic ratio on the Florence Rise is attributed either to limited water exchange between eastern and western Mediterranean or to local effects associated with exhumation of the Troodos ophiolites (Cyprus).
机译：在中新世晚期，地中海经历了盐度危机，并且在深部和边缘盆地沉积了浓厚的蒸发岩层。在这项研究中，我们报告了地中海深海钻探项目和海洋钻探项目核心的Os同位素记录：巴利阿里海（Site 372），第勒尼安海（Site 654），爱奥尼亚海盆（Site 374）和佛罗伦萨高地（站点375-376），以及北大西洋加的斯湾的综合海洋钻探项目站点U1387。在所有地点的上新世-更新世沉积物的Os-187 / Os-188值都接近中世纪的海水，表明地中海与北大西洋相连。然而，在最近的中新世期间沉积的蒸发沉积物的Os-187 / Os-188值明显低于同期的海洋水值。地中海蒸发岩Os-187 / Os-188的偏移归因于在墨西尼盐度危机期间与北大西洋的有限交换。非放射源Os的来源可能是地中海流域中种植的超镁铁质岩石（蛇绿岩）的风化作用。基于盒模型，我们估计了非放射源Os的数量和大西洋与地中海的汇率，以解释这一偏移量。地中海西部的蒸发前沉积物的Os同位素比几乎与同期海水的Os同位素比相同。相反，佛罗伦萨河谷的同等沉积物的Os-187 / Os-188值要低得多。佛罗伦萨上升区Os同位素比的偏移归因于东地中海和西地中海之间有限的水交换，或归因于Troodos蛇绿岩（塞浦路斯）挖掘出的局部效应。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号