Active simultaneous uplift and margin-normal extension in a forearc high, Crete, Greece
Active simultaneous uplift and margin-normal extension in a forearc high, Crete, Greece
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DOI：
10.1016/j.epsl.2014.04.038
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发表时间：
2014-07-15
影响因子：
5.3
通讯作者：
Fassoulas, C.
中科院分区：
文献类型：
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作者：
Gallen, S. F.;Wegmann, K. W.;Fassoulas, C.
克里特岛位于希腊中部俯冲带的前弧高处，其特点是持续折返、地表隆起和伸展。这里的造山作用和地形发展过程仍然知之甚少。克里特岛南部海岸线的巨大地形起伏（2-6公里）与大型边缘平行断层有关，这些断层形成了被称为希腊海槽的深水深洼地。这些结构被解释为活跃和不活跃的，具有收缩、走滑或伸展运动历史。区分这些不同的结构样式和运动学历史使我们能够探索更通用的模型，以提高我们对同聚合伸展的构造和地球动力学过程的整体理解。我们提出了来自克里特岛中南部海岸线的新观测结果，阐明了这些断层在希腊中部边缘新生代晚期演化中的作用以及控制第四纪地表隆起的过程。更新世海洋阶地与光激发光测年以及与第四纪海平面上升曲线的关联结合使用，以记录海岸隆起并识别活动断层。观察到两条向南倾斜的正断层，它们向近海延伸，抵消了这些海洋阶地沉积物，并表明存在活跃的南北（边缘正断层）延伸。此外，两个断层的下盘和上盘中保存的海洋阶地表明，尽管克里特岛有活跃的伸展作用，但仍在发生区域性净隆起。对陆上活动正断层的现场测绘和几何重建表明，克里特岛中南部的水下山前断层是岸上南倾正断层的综合体。这些发现与希腊弧前上地壳活跃水平缩短的模型不一致。相反，它们与粘性造山楔中前弧的地形生长一致，其中地壳增厚和隆起是物质基底底板作用的结果，伴随着楔形上部的延伸。在这个框架内，提出了希腊弧前新生代晚期垂直构造的新概念模型。 (C) 2014 Elsevier B.V. 保留所有权利。
The island of Crete occupies a forearc high in the central Hellenic subduction zone and is characterized by sustained exhumation, surface uplift and extension. The processes governing orogenesis and topographic development here remain poorly understood. Dramatic topographic relief (2-6 km) astride the southern coastline of Crete is associated with large margin-parallel faults responsible for deep bathymetric depressions known as the Hellenic troughs. These structures have been interpreted as both active and inactive with either contractional, strike-slip, or extensional movement histories. Distinguishing between these different structural styles and kinematic histories here allows us to explore more general models for improving our global understanding of the tectonic and geodynamic processes of syn-convergent extension. We present new observations from the south-central coastline of Crete that clarifies the role of these faults in the late Cenozoic evolution of the central Hellenic margin and the processes controlling Quaternary surface uplift. Pleistocene marine terraces are used in conjunction with optically stimulated luminesce dating and correlation to the Quaternary eustatic curve to document coastal uplift and identify active faults. Two south-dipping normal faults are observed, which extend offshore, offset these marine terrace deposits and indicate active N-S (margin-normal) extension. Further, marine terraces preserved in the footwall and hanging wall of both faults demonstrate that regional net uplift of Crete is occurring despite active extension. Field mapping and geometric reconstructions of an active onshore normal fault reveal that the subaqueous range-front fault of south-central Crete is synthetic to the south-dipping normal faults on shore. These findings are inconsistent with models of active horizontal shortening in the upper crust of the Hellenic forearc. Rather, they are consistent with topographic growth of the forearc in a viscous orogenic wedge, where crustal thickening and uplift are a result of basal underplating of material that is accompanied by extension in the upper portions of the wedge. Within this framework a new conceptual model is presented for the late Cenozoic vertical tectonics of the Hellenic forearc. (C) 2014 Elsevier B.V. All rights reserved.