Genesis of the Batinah mélange above the Semail ophiolite, Oman
Genesis of the Batinah mélange above the Semail ophiolite, Oman
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DOI：
10.1016/0191-8141(83)90003-2
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发表时间：
1983
影响因子：
3.1
通讯作者：
A. Robertson;N. Woodcock
中科院分区：
文献类型：
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作者：
A. Robertson;N. Woodcock
阿曼山脉北部晚白垩世塞梅尔蛇绿岩上覆的Batinah msamulange主要由深水相沉积岩、碱性熔岩和侵入岩组成，具有大陆边缘亲缘关系，还有少量塞梅尔蛇绿岩和变质岩。可以识别出四种跨界结构类型。表混色有大量(> 1公里)完整的表很少干涉矩阵或其他类型的混色,和一个组织表取向织物。厚板的结构更细（约100米），更容易断裂。块混色与一些较小的(>米)块矩阵和疲软的随机块织物。碎屑岩为基质支撑的粗晶岩，具有较弱的沉积碎屑结构。构造关系，特别是构造组构的缺失，破碎组构强度随破碎程度的增加而降低，以及脆性破碎的丰富，表明这些岩体类型是由重力驱动的沉积过程或单个岩板的表面滑动或逆冲形成的。在板岩中，可以将长序列拼凑在一起，从上三叠统基性海底挤出物和沉积物到放射虫质燧石，半深海和再沉积的石灰石，并终止于非钙质放射物与早白垩世的锰矿床。魔术技能数不胜数。这些层序可以与目前在断裂带中暴露的亚蛇绿岩相匹配。这些序列在走廊上逐渐被打乱，并可以连续地追踪到覆盖的msamange，然后从走廊上变薄。我们认为，在阿拉伯边缘晚白垩世侵位期间，活动断层走廊分裂了塞梅尔板块，并充当了亚蛇绿岩向蛇绿岩表面供应的管道。在那里，岩石通过表面作用重新分布。
The Batinah mélange which overlies the late Cretaceous Semail ophiolite in the northern Oman Mountains comprises mostly sedimentary rocks of deep-water facies, alkalic lavas and intrusives, all of continental margin affinities, together with smaller volumes of Semail ophiolitic and metamorphic rocks. Four intergradational textural types of mélange can be recognized. Sheet mélange has large (>1 km) intact sheets either with little intervening matrix or set in other mélange types, and with an organised sheet orientation fabric. Slab mélange is finer textured (>100 m) and more disrupted. Block mélange has smaller (> m) blocks with some matrix and a weak to random block fabric. Clast mélange is matrix-supported rudite with a weak depositional clast fabric. Structural relationships, particularly the absence of tectonic fabrics, the decreasing strength of fragment fabrics with increasing fragmentation, and the abundance of brittle fragmentation, suggest that these mélange types formed by either gravity-driven sedimentary processes or superficial sliding or thrusting of individual rock slabs.In the slab mélange, long sequences can be pieced together, passing up from Upper Triassic mafic sub-marine extrusives and sediments into radiolarian cherts, hemipelagic and redeposited limestones, and terminating in non-calcareous radiolarities with Mn-deposits of early Cretaceous age. Mafic sills are numerous. These sequences can be matched with sub-ophiolite rocks now exposed in fault corridors through the Semail. These sequences become progressively disrupted upwards in the corridors and can be traced continuously into overlying mélange, which then thins away from the corridors.We argue that, during late Cretaceous emplacement over the Arabian margin, active fault corridors split the Semail slab and acted as conduits up which sub-ophiolite rocks were supplied to the ophiolite surface. There the rocks were redisributed by superficial processes.