| 张进,曲军峰,赵衡,张北航,赵硕,张义平,惠洁.中亚造山带中部大型韧性走滑双重构造的形成、机制与涵义[J].矿产勘查,2023,14(4):519-540 |
| 中亚造山带中部大型韧性走滑双重构造的形成、机制与涵义 |
| Formation， mechanism and tectonic implication of a large ductile strike-slip duplex in the middle segment of Central Asian Orogenic Belt |
| 投稿时间：2023-03-21 修订日期：2023-03-31 |
| DOI：10.20008/j.kckc.202304001 |
| 中文关键词: 晚古生代—早中生代 韧性走滑双重构造 中亚造山带 阿拉善 陆内变形 构造继承 |
| 英文关键词: late Paleozoic-early Mesozoic ductile strike-slip duplex Central Asian Orogenic Belt Alxa intracontinental deformation structural inheritance |
| 基金项目:本文受中国地质调查局项目（DD20221646， DD20230217）和国家自然科学基金（41972224）联合资助 |
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| 中文摘要: |
| 大型走滑双重构造是造山带中重要构造，它可以发育于造山带演化的不同阶段，同时也是陆内变形的重要方式。大型走滑双重构造的形成具有特殊的边界条件，在不同类型造山带演化过程中起到的作用也不一样，然而目前还缺少足够的认识。中亚造山带是全球显生宙规模最大的增生型造山带，大规模的走滑作用在该造山带的演化中起到了关键作用。目前在该造山带中段的阿拉善地区识别出了一个大型的近东西向的走滑双重构造，该双重构造由7~8条不同方向的次级韧性剪切带组成，东西长约500 km，南北宽约350 km，面积约200000 km2。形成一个巨大的S-C like构造，发育时间为古生代末期—早中生代，区域运动学性质为韧性右行走滑，单条剪切带的走滑位移10~60 km，累积走滑距离250~500 km。它是中亚造山带南缘晚古生代末期—早中生代巨型韧性剪切系统的一部分，也是古亚洲洋关闭后中亚造山带整体变形的一部分。该走滑双重构造分别连接了西侧天山以及东侧兴蒙造山带不同类型的走滑变形，它的形成与较热的岩石圈以及不均一的造山带组成有关，而走滑双重构造的作用也是造成造山带内部结构均一化的过程。结合造山带的类型，一般走滑双重构造多发生在增生型造山带，而碰撞型造山带一般由于较冷的岩石圈而相对缺乏此类构造。阿拉善大型走滑双重构造是中亚造山带中少有报道的大型构造，它是造山带不均一的物质组成、强烈的岩浆作用以及华北克拉通的阻挡而造成的应变集中所导致，它不仅是连接中亚造山带东西的枢纽，而且也是构建中亚造山带结构的重要约束。 |
| 英文摘要: |
| Large strike-slip duplexes are important structures in orogenic belts， which can develop in different evolution stages of orogenic belts and are also important ways of intracontinental deformation. The formation of large-scale strike-slip duplexes has special boundary conditions and plays different roles in the evolution of different types of orogenic belts. However， there is still a lack of sufficient understanding. The Central Asian Orogenic Belt is the largest accretionary orogenic belt in the Phanerozoic era in the world， and large-scale strike slipping has played a key role in the evolution of this orogenic belt. A large near east-west strike-slip duplex has recently been identified in the Alxa in the middle segment of the CAOB， which consists of 7-8 secondary ductile shear zones with different directions， with an overall east-west length of more than 500 km， a north-south width of 350 km， and an area of approximately 200000 km2. This huge S-C like structure was developed from the end of Paleozoic to the early Mesozoic， and was characterized by ductile dextral strike-slipping regionally. The strike-slip displacement of a single shear zone ranges from 10 km and 60 km， and the cumulative displacement of this mega-duplex is between 250 and 500 km. It belongs to the late Paleozoic to early Mesozoic mega-ductile shear system along the southern margin of the CAOB， and represents the overall deformation of the CAOB after the final closure of the Paleo-Asian Ocean. The strike-slip duplex connects different types of strike-slip deformation in the Tianshan to the west and the Xingmeng orogenic belt to the east， and its formation is related to a hotter lithosphere and heterogeneous composition of the orogenic belt. The role of the strike-slip duplexes is also a process of homogenizing the internal structures of orogenic belts. Combined with the types of orogenic belts， strike-slip duplexes generally occur in accretionary orogenic belts， while collision orogenic belts are relatively lacking in such structures due to its cooler lithosphere. The large strike-slip duplex in the Alxa is a rarely reported large-scale structure in the CAOB. It is caused by the combined interplay among heterogeneous composition of the orogenic belt， strong magmatism and strain concentration caused by the blocking of the North China Craton. It is not only a hub connecting the east and west of the CAOB， but also an important constraint for constructing the structure of the CAOB. |
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