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首页> 外文期刊>Journal of Asian earth sciences >Geology and petrology of the Hormuz dolomite, Infra-Cambrian: Implications for the formation of the salt-cored Halul and Shraouh islands, Offshore, State of Qatar
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Geology and petrology of the Hormuz dolomite, Infra-Cambrian: Implications for the formation of the salt-cored Halul and Shraouh islands, Offshore, State of Qatar

机译：寒武纪霍尔木兹白云岩的地质和岩石学：对卡塔尔近海盐芯哈卢尔岛和Shraouh岛形成的影响

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Geological investigations of the Halul and the Shraouh islands, offshore Qatar, indicate that most of their calcareous rocks, which display abundant stromatolitic bedding, belong to the Infra-Cambrian Hormuz Series. Mineralogical, petrological, and geochemical analyses show that these calcareous rocks consist dominantly of dolomite and have formed in a reducing depositional environment. Faint laminations and small streams of organic matter furnish evidence for the involvement of algal mats in their genesis and indicate their formation in an intertidal to supratidal setting. The Halul and Shraouh dolomites experienced extensive recrystallization and sulfatiza-tion during the emplacement of the Halul and Shraouh salt domes that form the cores of the islands. During mobilization and ascent of the salt, the dolomite recrystallized, and its Sr initial ratios were abnormally enhanced by the incorporation of ~(87)Sr from a source, which is more radiogenic than the attendant seawater at the time of the dolomite formation near the Proterozoic-Cambrian boundary. Geochemical analysis show that Si, Al, Ti Zr, and % of insoluble residue are highly correlative, suggesting the presence of detrital minerals such as rutile and zircon. A paleosabkha model may well agree with this chemical signature. However, the Infra-Cambrian age of the Hormuz rocks and the presence of stromatolitic layers containing organic materials in the studied rocks, suggest that organogenic dolomitization could be an alternative dolomitization model.
机译：对卡塔尔近海的Halul和Shraouh岛进行的地质调查表明，它们的大部分钙质岩均显示出丰富的层积层理，属于下寒武纪Hormuz系列。矿物学，岩石学和地球化学分析表明，这些钙质岩主要由白云岩组成，并在还原性沉积环境中形成。薄弱的叠层和少量的有机物流为藻类垫的发生提供了证据，并表明它们在潮间至潮间环境中形成。 Halul和Shraouh白云岩在形成岛屿核心的Halul和Shraouh盐穹顶进入期间经历了广泛的重结晶和硫化作用。在盐的动员和上升过程中，白云石重结晶，其Sr的初始比值通过从某处掺入〜（87）Sr而异常增加，其比在白云石附近形成白云石时所伴随的海水具有更高的放射性。元古代-寒武纪边界。地球化学分析表明，Si，Al，Ti Zr和％的不溶残留物具有高度相关性，表明存在金红石和锆石等碎屑矿物。古生物模型很可能与此化学特征吻合。然而，霍尔木兹岩的寒武纪年龄和研究的岩石中含有有机质的层间岩层的存在表明，器官成因的白云石化作用可能是另一种白云石化作用模型。

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