Late Jurassic to Cretaceous evolution of the eastern Tethyan Hawasina Basin (Oman Mountains)
Late Jurassic to Cretaceous evolution of the eastern Tethyan Hawasina Basin (Oman Mountains)
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DOI：
10.1111/sed.12326
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发表时间：
2017-01
期刊：
影响因子：
3.5
通讯作者：
S. Wohlwend;R. Celestino;D. Reháková;S. Huck;H. Weissert
中科院分区：
文献类型：
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作者：
S. Wohlwend;R. Celestino;D. Reháková;S. Huck;H. Weissert
今天可以在阿曼山脉的推覆堆中研究中生代大陆边缘的残留物。阿拉伯碳酸盐台地和毗邻的深哈瓦西纳盆地序列保存在该山脉的推覆堆和山脚下。哈瓦西纳盆地侏罗纪-白垩纪沉积序列(苏美尼群和哈姆拉特-杜鲁群)是本次研究的重点。这些盆地档案包含关于东部特提斯赤道海洋系统对白垩纪期间碳循环和气候多重扰动的反应的信息。方解石补偿深度附近形成的浊积型陆坡和盆地层序很难用生物地层学和层序地层学确定年代。现有的哈瓦西纳层序地层格架不足以通过本研究感兴趣的时间窗口追踪古海洋学。因此，现有的层序地层学和生物地层学得到了额外的生物地层学数据和新建立的碳和锶同位素化学地层学的补充。哈瓦西纳盆地受到海平面变化、海洋学变化以及区域构造的影响。海洋学的第一次重大修改发生在侏罗纪末期，当时深海盆地和邻近的海底高地(Huwar组和Sid‘r组下段)积累了远洋Maiolica类型的沉积物。远洋到半远洋的条件一直存在，直到瓦兰吉期，以主要的碳同位素漂移为标志。后来，远洋沉积被豪特里亚到阿普提亚时代的一系列细粒到粗粒的浊积岩所取代。过渡到白垩纪中期的标志是突然转向细粒硅质或硅质岩沉积，当时西特提斯和大西洋积累了富含有机碳的沉积物。在白垩纪早、中期，陆坡和哈瓦西纳盆地似乎都通风良好。硅质石灰岩和硅质岩是混合良好、营养丰富的地表水的标志，而黑色页岩的缺失表明，年轻的、含氧的深水可能来自广阔的阿拉伯地台。这些特殊的海洋条件在海洋缺氧事件1a的极端温室事件开始时最为明显。
Remnants of a Mesozoic continental margin can be studied today in the nappe pile of the Oman Mountains. Successions of the Arabian carbonate platform and the adjacent deep Hawasina Basin are preserved in the nappe pile and in the foothills of this Mountain range. The Jurassic–Cretaceous sediment successions of the Hawasina Basin (Sumeini and Hamrat Duru Group) are focus of this study. These basinal archives contain information on the response of an eastern Tethyan equatorial ocean system to multiple perturbations of the carbon cycle and of climate during the Cretaceous. Turbiditic continental slope and basinal successions formed near the Calcite Compensation Depth are difficult to date with biostratigraphy and sequence stratigraphy. The available stratigraphic framework for the Hawasina successions was not sufficient for tracing palaeoceanography through the time window of interest in this study. Therefore, existing sequence stratigraphy and biostratigraphy are complemented by additional biostratigraphic data and with a newly established carbon and strontium isotope chemostratigraphy. The Hawasina Basin was affected by sea‐level variations, by changes in oceanography and also by regional tectonics. A first major modification of oceanography occurred at the end of the Jurassic when pelagic Maiolica‐type sediments were accumulated in the deep basin and on adjacent submarine highs (Lower Member of Huwar and Sid'r formations). Pelagic to hemipelagic conditions existed until the Valanginian, marked by a major carbon isotope excursion. Pelagic sediments were replaced afterwards by a succession of fine to coarse‐grained turbidites of Hauterivian to Aptian age. The transition into the mid‐Cretaceous is marked by a sudden shift to fine‐grained siliceous or chert deposits, at a time when sediments enriched in organic carbon were accumulated in the western Tethys and Atlantic Oceans. The continental slope as well as the Hawasina Basin seemed to have been well‐ventilated during Early and mid‐Cretaceous time. Siliceous limestones and chert are indicators of well‐mixed and nutrient‐rich surface water, while the absence of black shales suggests young and oxygenated deep water with a possible source on the vast Arabian platform. These peculiar oceanographic conditions were most pronounced during the onset of the extreme greenhouse episodes of the Oceanic Anoxic Event 1a.