Marine 187Os/188Os isotope stratigraphy reveals the interaction of volcanism and ocean circulation during Oceanic Anoxic Event 2
Marine 187Os/188Os isotope stratigraphy reveals the interaction of volcanism and ocean circulation during Oceanic Anoxic Event 2
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DOI：
10.1016/j.epsl.2013.12.024
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发表时间：
2014-03-01
影响因子：
5.3
通讯作者：
Voigt, Silke
中科院分区：
文献类型：
--
作者：
Du Vivier, Alice D. C.;Selby, David;Voigt, Silke
高分辨率锇（Os）同位素地层学横跨Cenomanian-Turonian边界间隔从6个部分为四个transcontinental设置产生了海水化学的记录，显示区域变化作为陆地和热液输入的函数，揭示了古环境过程的影响。在每一个部分的Os-187/Os-188配置文件显示了一个可比较的趋势;放射性值在导致海洋缺氧事件2（OAE 2）;突然的非放射性趋势在OAE 2的开始;在OAE 2的第一部分的非放射性间隔;和返回到放射性值接近事件结束时，以上的Cenomanian-Turonian边界。Os-187/Os-188的非放射成因趋势在所有剖面上是同步的。以前的工作表明，加勒比海LIP（大火成岩省）的活动是整个OAE 2的非放射性Os的来源，并可能是海洋缺氧的煽动者。在这里，我们评估这一假设，并考虑活动的影响，从其他LIPs，如高北极LIP.A短暂的转变到高放射性的Os-187/Os-188值发生在OAE 2开始之前，在西部内陆海道。我们评估了这一趋势，并认为多种因素共同在OAE 2的启动中发挥了关键作用;来自大陆和火山源的营养物质的差异输入，加上全球海洋和陆表海的有效古环流，由于更高的营养物质可利用性而提高了生产力，这使得准同期大陆和LIP来源的营养物质向跨赤道盆地输送。(C)2013作者Elsevier B. V.出版，保留所有权利。
High-resolution osmium (Os) isotope stratigraphy across the Cenomanian-Turonian Boundary Interval from 6 sections for four transcontinental settings has produced a record of seawater chemistry that demonstrates regional variability as a function of terrestrial and hydrothermal inputs, revealing the impact of palaeoenvironmental processes. In every section the Os-187/Os-188 profiles show a comparable trend; radiogenic values in the lead up to Oceanic Anoxic Event 2 (OAE 2); an abrupt unradiogenic trend at the onset of OAE 2; an unradiogenic interval during the first part of OAE 2; and a return to radiogenic values towards the end of the event, above the Cenomanian-Turonian boundary. The unradiogenic trend in Os-187/Os-188 is synchronous in all sections. Previous work suggests that activity of the Caribbean LIP (Large Igneous Province) was the source of unradiogenic Os across the OAE 2 and possibly an instigator of anoxia in the oceans. Here we assess this hypothesis and consider the influence of activity from other LIPs; such as the High Arctic LIP.A brief shift to high radiogenic Os-187/Os-188 values occurred in the Western Interior Seaway before the onset of OAE 2. We evaluate this trend and suggest that a combination of factors collectively played critical roles in the initiation of OAE 2; differential input of nutrients from continental and volcanogenic sources, coupled with efficient palaeocirculation of the global ocean and epeiric seas, enhanced productivity due to higher nutrient availability, which permitted penecontemporaneous transport of continental and LIP-derived nutrients to trans-equatorial basins. (C) 2013 The Authors. Published by Elsevier B.V. All rights reserved.