Magma generation by slab steepening and breakoff beneath a subduction-accretion complex: An alternative model for collision-related volcanism in Eastern Anatolia, Turkey
Magma generation by slab steepening and breakoff beneath a subduction-accretion complex: An alternative model for collision-related volcanism in Eastern Anatolia, Turkey
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DOI：
10.1029/2003gl018019
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发表时间：
2003-11-14
影响因子：
5.2
通讯作者：
Keskin, M
中科院分区：
文献类型：
--
作者：
Keskin, M
东安纳托利亚被认为是大陆碰撞的最好例子之一，以2公里高的高原为代表。它显示出浅层和弥散的地震活动，表明地壳仍在积极变形。东安纳托利亚最引人注目的方面可能是新近纪和第四纪期间爆发的与碰撞有关的火山产物的体积和成分变化。对于该地区火山活动的成因，已经提出了一些模型。然而，最近的地球物理研究表明，地幔岩石圈几乎是完全不存在下的大部分地区，这使我们质疑以前的模型的有效性。在本文中，我们提出了一个新的岩浆成因模式：板片变陡和大型俯冲-增生杂岩下的断裂。该模型认为，一个向北俯冲的海洋岩石圈下的东安纳托利亚增生棱镜变陡，并最终脱离大陆岩石圈的Bitlis-Poturge地块，大陆增生复杂的碰撞。这使得软流圈地幔与浅部的增生复合体接触（例如，约50公里），导致快速的区域隆起和大规模的熔融，导致碰撞火山作用。
Eastern Anatolia is regarded as one of the best examples of continental collision, represented by a 2 km high plateau. It displays shallow and diffuse seismicity, indicating that the crust is still being actively deformed. Perhaps the most striking aspect of Eastern Anatolia is the volume and compositional variability of collision-related volcanic products erupted during the Neogene and Quaternary time. A number of models have been proposed for the genesis of this volcanism in the region. However, recent geophysical studies have revealed that a mantle lithosphere is almost completely absent beneath a greater portion of the region, which makes us question the validity of the previous models. In this paper, we propose a new model for magma genesis: slab steepening and breakoff beneath a large subduction-accretion complex. This model holds that a northward subducting oceanic lithosphere beneath the Eastern Anatolia Accretionary Prism gets steepened and eventually detached from the continental lithosphere of the Bitlis-Poturge Massif, following the continent-accretionary complex collision. This brings the asthenospheric mantle in contact with the accretionary complex at shallow depths (e.g., around 50 km), resulting in rapid regional uplift and extensive melting which leads to collisional volcanism.