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首页> 外文期刊>Geodinamica Acta >Linking the NE Anatolian and Lesser Caucasus ophiolites: evidence for large-scale obduction of oceanic crust and implications for the formation of the Lesser Caucasus-Pontides Arc
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Linking the NE Anatolian and Lesser Caucasus ophiolites: evidence for large-scale obduction of oceanic crust and implications for the formation of the Lesser Caucasus-Pontides Arc

机译：将东北安纳托利亚和小高加索蛇绿岩联系起来：大规模诱变大洋壳的证据及其对小高加索-庞蒂德弧形成的影响

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摘要

In the Lesser Caucasus and NE Anatólia,three domains are distinguished from south to north: (1) Gondwanian-derived continental terranes represented by the South Armenian Block (SAB) and the Tauride-Anatolide Platform (TAP), (2) scattered outcrops of Mesozoic ophiolites,obducted during the Upper Cretaceous times, marking the northern Neotethys suture, and (3) the Eurasian plate, represented by the Eastern Pontides and the Somkheto-Karabagh Arc. At several locations along the northern Neotethyan suture, slivers of preserved unmetamorphozed relics of now-disappeared Northern Neotethys oceanic domain (ophiolite bodies) are obducted over the northern edge of the passive SAB and TAP margins to the south. There is evidence for thrusting of the suture zone ophiolites towards the north; however, we ascribe this to retro-thrusting and accretion onto the active Eurasian margin during the latter stages of obduction. Geodynamic reconstructions of the Lesser Caucasus feature two north dipping subduction zones: (1) one under the Eurasian margin and (2) farther south, an intra-oceanic subduction leading to ophiolite emplacement above the northern margin of SAB. We extend our model for the Lesser Caucasus to NE Anatolia by proposing that the ophiolites of these zones originate from the same oceanic domain, emplaced during a common obduction event. This would correspond to the obduction of nonmetamorphic oceanic domain along a lateral distance of more than 500 km and overthrust up to 80 km of passive continental margin. We infer that the missing volcanic arc, formed above the intra-oceanic subduction, was dragged under the obducting ophiolite through scaling by faulting and tectonic erosion. In this scenario part of the blueschists of Step anavan, the garnet amphibolites of Amasia and the metamorphic arc complex of Erzincan correspond to this missing volcanic arc. Distal outcrops of this exceptional object were preserved from latter collision, concentrated along the suture zones.
机译：在小高加索地区和东北亚纳托利亚地区，从南向北划分为三个区域：（1）以南亚美尼亚地块（SAB）和牛头钉-安纳托利德平台（TAP）为代表的冈瓦纳大陆性地层，（2）散布的露头中生代蛇绿岩，在上白垩世时期形成，标志着新特提斯北部的缝合线，和（3）以东庞德特兹山脉和Somkheto-Karabagh弧为代表的欧亚板块。在北新特提斯缝合线的多个位置，从被动SAB和TAP边缘的北部边缘向南引出了现在消失的北部新特提斯洋域的未变质文物的碎片（蛇绿岩体）。有证据表明缝线蛇纹岩被推向北部。但是，我们将这归因于诱捕后期的逆冲和增生到活跃的欧亚大陆边缘。小高加索地区的地球动力学重建具有两个北倾俯冲带：（1）一个在欧亚大陆边缘之下的俯冲带，和（2）在更南端的一个洋内俯冲带，其将蛇绿岩安置在SAB北边界之上。通过提出这些区域的蛇绿岩起源于同一海洋域，并在一次共同的引诱事件中发生，我们将小高加索地区的模型扩展到安纳托利亚东北部。这将对应于沿超过500 km的横向距离获得非变质的海洋区域，并推翻高达80 km的被动大陆边缘。我们推断，在大洋内部俯冲作用之上形成的缺失火山弧是通过断层和构造侵蚀通过剥蚀作用被拖曳到俯冲蛇绿岩之下的。在这种情况下，Step anavan的blueschist部分，Amasia的石榴石两闪石和Erzincan的变质弧复合体对应于该缺失的火山弧。该异常对象的远端露头被保留，以免随后发生碰撞，并沿缝合线区域集中。

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