Central Tethyan platform-top hypoxia during Oceanic Anoxic Event 1a
Central Tethyan platform-top hypoxia during Oceanic Anoxic Event 1a
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DOI：
10.5194/cp-15-1327-2019
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发表时间：
2019-01
影响因子：
4.3
通讯作者：
A. Hueter;S. Huck;S. Bodin;U. Heimhofer;S. Weyer;K. Jochum;A. Immenhauser
中科院分区：
文献类型：
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作者：
A. Hueter;S. Huck;S. Bodin;U. Heimhofer;S. Weyer;K. Jochum;A. Immenhauser
抽象的。表层水体的短期缺氧是现代海洋环境中的一种普遍现象，它会导致沿岸海洋生态系统的大量死亡。在这里，我们测试的假设，在早期Aptian，平台顶部缺氧暂时建立在一些广阔的epeiric海中特提斯和造成的，与其他压力相结合，珊瑚礁生态系统的显着变化。潜在的有趣的目标的例子，包括时间间隔的特点是较低的阿普第阶rudist珊瑚群落的消亡和建立microencruster相，如前所述，从特提斯的中部和南部，从原北大西洋域。这些考虑因素是相关的，因为以前的工作主要集中在早期Aptian盆地缺氧的背景下，海洋缺氧事件（OAE）1a，而潜在的扩展的氧气最小区（OMZ）在同时代的浅水环境是underexplored。OAE 1a期间δ 13 C记录中的已知模式允许与先前研究的位置和化学地层段的分配进行充分的时间分辨相关。本文介绍并批判性地讨论了多代理研究的结果（例如，稀土元素（稀土元素，铀同位素，氧化还原敏感的微量元素）应用于下阿普第浅水碳酸盐今天暴露在Kanfanar采石场在伊斯特拉，克罗地亚。这些岩石沉积在一个广泛的，孤立的高在特提斯中部被半远洋盆地包围。值得注意的是，在化学地层段C2，氧化还原敏感的微量元素As，V，Mo，和U在台地碳酸盐，沉积在正常的海洋含氧沃茨，记录的亏损首次发生的盆地，富含有机物的沉积物沉积，这些元素是富集。在C3段期间，海水氧耗尽建立在平台顶部，如Ce/Ce* 和U同位素模式所示。氧化还原敏感性指标的变化与微结壳相的扩展相一致。C4段见证了平台顶部恢复到正常的海洋礁动物群，其特征是正常海洋溶解氧水平的氧化还原敏感代理模式。目前还不清楚，但是，如果平台顶部缺氧导致的盆地，缺氧的水体或空间隔离，浅缺氧水体形成的平台上的扩张和上涌。这里显示的数据是相关的，因为它们揭示了驱动机制，控制知之甚少的动物区系模式，在OAE 1a在浅海领域，并提供证据之间的复杂关系盆地和平台顶部的水团。
Abstract. Short-term hypoxia in epeiric water masses is a common phenomenon of modern marine environments and causes mass mortality in coastal marine ecosystems. Here, we test the hypothesis that during the early Aptian, platform-top hypoxia temporarily established in some of the vast epeiric seas of the central Tethys and caused, combined with other stressors, significant changes in reefal ecosystems. Potentially interesting target examples include time intervals characterized by the demise of lower Aptian rudist–coral communities and the establishment of microencruster facies, as previously described from the central and southern Tethys and from the proto-North Atlantic domain. These considerations are relevant as previous work has predominantly focused on early Aptian basinal anoxia in the context of Oceanic Anoxic Event (OAE) 1a, whereas the potential expansion of the oxygen minimum zone (OMZ) in coeval shallow-water environments is underexplored. Well-known patterns in the δ13C record during OAE 1a allow for a sufficiently time-resolved correlation with previously studied locations and assignment to chemostratigraphic segments. This paper presents and critically discusses the outcome of a multi-proxy study (e.g., rare earth elements (REEs), U isotopes, and redox-sensitive trace elements) applied to lower Aptian shallow-water carbonates today exposed in the Kanfanar quarry in Istria, Croatia. These rocks were deposited on an extensive, isolated high in the central Tethys surrounded by hemipelagic basins. Remarkably, during chemostratigraphic segment C2, the depletion of redox-sensitive trace elements As, V, Mo, and U in platform carbonates, deposited in normal marine oxic waters, record the first occurrence of basinal, organic-rich sediment deposition in which these elements are enriched. During the C3 segment, seawater oxygen depletion established on the platform top as indicated by the patterns in Ce/Ce* and U isotopes. Shifts in redox-sensitive proxies coincide with the expansion of microencruster facies. Segment C4 witnesses the return to normal marine reefal faunas on the platform top and is characterized by patterns in redox-sensitive proxies typical of normal marine dissolved oxygen levels. It remains unclear, however, if platform-top hypoxia resulted from the expansion and upwelling of basinal, oxygen-depleted water masses or if spatially isolated, shallow hypoxic water bodies formed on the platform. Data shown here are relevant as they shed light on the driving mechanisms that control poorly understood faunal patterns during OAE 1a in the neritic realm and provide evidence on the intricate relation between basinal and platform-top water masses.