Subduction and obduction: two stages in the Eo-Alpine tectonometamorphic evolution of the Oman Mountains
Subduction and obduction: two stages in the Eo-Alpine tectonometamorphic evolution of the Oman Mountains
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DOI：
10.1144/gsl.sp.1992.049.01.20
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发表时间：
1990
期刊：
影响因子：
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通讯作者：
J. Le Métour;D. Rabu;M. Tegyey;F. Béchennec;M. Beurrier;M. Villey
中科院分区：
文献类型：
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作者：
J. Le Métour;D. Rabu;M. Tegyey;F. Béchennec;M. Beurrier;M. Villey
摘要阿曼山台地单元由陆棚沉积岩和火山岩组成，时代从晚元古代到晚Turonian-Coniacian，主要在多期Eo-Alpine构造运动中变形。晚Turonian-Coniacian期在高压/低温区域变质作用条件下发生NE向（向海）切向剪切变形。这一构造阶段主要是负责的构造和变质分带的平台单位。已确认从Jabal Akhdar南翼（此处出现断裂劈理）到Saih Hatat东部（此处保存片状蓝闪石生态岩）存在从外部到内部区域的西南-东北向梯度。这一构造变质事件与阿拉伯地台东北角向新特提斯洋岩石圈的部分俯冲有关。在坎帕尼亚期，伴随着哈瓦西纳推覆体的逆冲推覆和塞梅尔蛇绿岩的仰冲，出现了具有SW（大陆）聚散的更高级别的剪切变形。这些构造单元分别从阿拉伯大陆边缘的二叠纪-白垩纪盖层和阿尔比-赛诺曼期打开的塞梅尔边缘盆地的洋底向南西西方向迁移。在推覆体向阿拉伯地台推进的过程中，在Jabal Akhdar和Saih Hatat的北方边缘，地台单元内的构造切片和走滑断层形成了正面和侧面斜坡。在变形的第三阶段，可能在Campanian-Maastrichtian，大幅度，长波长，开放，近直立的褶皱伴随着不发达，近垂直，SSW-NNE断裂解理表明适度缩短垂直于早期结构的隆起过程中。由此产生的阿曼山脉的始新世-阿尔卑斯山前陆带部分被海洋碳酸盐沉积物所覆盖，在中马斯特里赫特期至晚马斯特里赫特期或早古近纪期间，在中新世期间受到阿尔卑斯山构造的影响。
Abstract The platform unit of the Oman Mountains is composed of shelf sedimentary and volcanic rocks, ranging in age from late Proterozoic to late Turonian-Coniacian, that were deformed mainly during the polyphase Eo-Alpine tectogenesis. In the late Turonian-Coniacian tangential shearing deformation with NE (oceanward) vergence occurred under HP/LT conditions of regional metamorphism. This tectonic phase was largely responsible for the structural and metamorphic zonation of the platform unit. A SW-NE gradient from external to internal zones has been recognized from the south flank of Jabal Akhdar, where fracture cleavage appears, to the eastern part of Saih Hatat, where schistose glaucophane ecologites are preserved. This tectonometamorphic event was related to partial subduction of the northeast corner of the Arabian platform beneath the neo-Tethyan oceanic lithosphere. A later phase of higher-level shearing deformation with SW (continentward) vergence, during the Campanian, accompanied the thrusting of the Hawasina Nappes and the obduction of the Semail Ophiolite. These tectonic units were transported SSW respectively from the Permian-Cretaceous cover of the Arabian continental margin and from the oceanic floor of the Semail marginal basin that opened during the Albian-Cenomanian. Tectonic slicing and strike-slip faulting within the platform unit, on the northern margins of Jabal Akhdar and Saih Hatat, formed frontal and lateral ramps during the advance of the nappes onto the Arabian Platform. During a third phase of deformation, probably during the Campanian-Maastrichtian, large-amplitude, long-wavelength, open, near-upright folding accompanied by poorly developed, subvertical, SSW-NNE fracture cleavage indicates moderate shortening during uplift perpendicular to the earlier structures. The resulting Eo-Alpine foreland belt of the Oman Mountains was partly covered by marine carbonate deposits during the middle Maastrichtian to late Maastrichtian or early Palaeogene before being affected by Alpine tectonics during the Miocene.