| 龙舟,张明洋,来林,张学斌,王然,周长红.内蒙古敖包吐韧性剪切带的厘定与构造属性分析[J].矿产勘查,2025,16(3):453-463 |
| 内蒙古敖包吐韧性剪切带的厘定与构造属性分析 |
| Tectonic property and chronology discussion of Aobaotu Ductile Shear Zone in Inner Mongolia |
| 投稿时间：2024-06-12 |
| DOI：10.20008/j.kckc.202503002 |
| 中文关键词: 韧性剪切带 伸展构造 兴蒙造山带 锆石 U-Pb年龄 早二叠世 |
| 英文关键词: ductile shear zone extensional tectonics Xing’an-Mongolia orogen zircon U-Pb dating Early Permian |
| 基金项目:本文受中国地质调查局项目1∶5万敖如斯台(K49E004013)等六幅区域地质矿产调查(12120114064001)资助。 |
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| 中文摘要: |
| 笔者在内蒙古四子王旗北部敖包吐一带进行 1∶5万区域地质调查时，通过系统性宏观、微观地质调查和室内组构分析，识别出一条大型韧性剪切带。敖包吐韧性剪切带平面呈北东东向面状展布，顺层发育于中—下二叠统大石寨组中。广泛发育透入性糜棱面理、拉伸线理、杆状构造、紧闭褶皱、鞘褶皱等宏观韧性变形，眼球状构造、书斜构造、旋转碎斑及 S-C组构等微观变形也十分发育。定向薄片指示其具有左行剪切的特征；调查中对 300组 C面理和拉伸线理产状进行分区赤平投影，指示其运动方向为 NNW-SSE向，与整体展布方向近于垂直，推测其具有伸展性质；对顺层侵入并发生同步变形的二长花岗岩岩枝进行了锆石 U-Pb定年，年代为(284.2±1.2)Ma，指示敖包吐韧性剪切带形成于早二叠世；该韧性剪切带的发现为解决兴蒙造山带晚古生代构造演化争议提供了新的约束，也为深入理解中亚造山带东段古亚洲洋最终闭合的动力学过程提供了关键线索。 |
| 英文摘要: |
| Aobaotu ductile shear zone is located at the north part of Siziwangqi, Inner Mongolia. According tolarge area surveys, bedding shear is widely developed in the ductile shear zone, L-S type, L>S type and L type tec-tonite are formed. Various macro and micro structures are widely developed such as Shear fold, rodding structure, S-C fabric, domino structure and rotated porphyroclast, etc. Sinistral shearing on the XZ face is concluded by observat-ing directional thin sections. Nearly 300 groups of occurrence of stretching lineation and C foliation were matched measured and stereographic projected by partitioning, which concluded that the shearing direction of Huaaobao-Daqi ductile shear zone is NNW-SSE and perpendicular to the distribution direction. Also concluded that the duc-tile shear zone is of extensional type. Zircon LA-MC-ICP MS U-Pb dating of Syntectonic adamellites apophyseyielded an age of (284.2±1.2) Ma, indicates that Aobaotu ductile shear zone formed in the Early Permian. The dis-covery of this ductile shear zone provides new constraints for resolving the controversy over the Late Paleozoic tec-tonic evolution of the Xingmeng Orogen, and also offers crucial clues for a deeper understanding of the dynamic pro-cess leading to the ultimate closure of the Paleo-Asian Ocean in the eastern segment of the Central Asian Orogen. |
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