郯庐断裂带北段构造特征及构造演化序列

根据大量野外地质调查和盆地地震资料分析,认为郯庐断裂北段在中-新生代发生多期不同性质的活动,形成各具特色的构造变形现象。密山县知一镇敦密断裂韧性剪切带具有左旋走滑特征,其中黑云母~(40)Ar/~(36)Ar-~(39)Ar/~(36)Ar等时线年龄为161±3Ma,是郯庐断裂带被利用发生第二期左旋走滑运动并向北扩展到中国东北-俄罗斯远东地区的产物。四平市叶赫乡佳伊断裂带中负花状断裂形成于早白垩世早中期,是郯庐断裂北段在早白垩世遭受左旋走滑-拉张作用的典型代表。四平市石岭镇佳伊断裂大型走滑-逆冲断褶带、桦甸县敦密断裂"逆地堑"、沈阳-哈尔滨逆冲断裂形成于晚白垩世嫩江运动-晚白垩世末期,这一时期脆性右旋走滑-逆冲事件规模大,影响范围广,导致整个郯庐断裂北段遭受到强烈改造。佳伊断裂带和敦密断裂带中古近纪盆地在横剖面上呈不对称地堑,并且不对称地堑沿断裂带走向发生断、超方向左右变位,是郯庐断裂带北段在古近纪时受右旋走滑、伸展双重机制控制的产物。根据郯庐断裂带北段中-新生代不同地质时期变形特征,建立了郯庐断裂北段构造演化序列。即郯庐断裂北段构造演化分为左旋韧性剪切(J_2末期)、左旋张扭(K_1早中期)、右旋压扭(K_2晚期-末期)、右旋走滑断陷(E)和构造反转(E_3末期)五个阶段。其演化历史主要受控于环太平洋构造域的构造作用。

The structural feature and evolutionary series in the northern segment of Tancheng-Lujiang fault zone

According to the plenty of field geological survey and basin earthquake data analysis, the author believed that multiperiodie and diversely characteristic activities happened and the tectonic deformed phenomena with characteristics were formed in the northern segment of Tancheng-Lujiang fault zone in Mesozoic-Cenozoic era. Sinistral strike-slip is characteristic of Dunhua-Mishan ductile shear zone near Zhiyi Town, Mishan County, among which the biotite ~(40)Ar/~(36)Ar- ~(39)Ar/~(36)Ar isochron age is 161±3Ma. The isochron age is the product of Tancheng-Lujiang fault zone used and of the second left-lateral strike-slip happening and stretching from the Northeast, China to Far East, Russia. The negative flower faults of Yehe Town, Siping City in the Jiamusi-Yitong fault zone were formed in the early mid period of K_1 , which is the typical representative of the northern segment of Tancheng-Lujiang fault zone suffering from left-lateral strike-slip and extension in K_1. Large-scale strike-slip and thrust fault-fold zone in Jiamusi-Yitong Fault of Shiling Town, Siping City, "obsequent graben " in Dunhna-Mishan fault of Huadian City and Shenyang-Harbin thrust fault were formed in the Nenjiang movement of later period of K_2-1ast stage of K_2,when the large-scale and influential extent of brittle fight-lateral strike-slip and thrust event caused the northern segment of Tancheng-Lujiang fault zone strongly transformed. Palaeogene basin in the Jiamusi-Yitong and Dunhua-Mishan fault zones took on an asymmetric graben on its transverse profile and the asymmetric graben changed the direction of fault depression and overlap to fight or left along the fault zone, which is the product of the northern segment of Tancheng-Lujiang fault zone controlled by fight-lateral strike-slip and extensional double machanism in Palaeogene. According to the deformation features of the different geologic periods in the northern segment of Tancheng-Lujiang fault zone of Mesozoic-Cenozoic, tectonic evolution sequence in the northern segment of Taacheng-Lujiang was established, namely, left-lateral strike-slip tenacity shear stage (the last stage of J_2), left-lateral tenso-shear stage (the earlier-mid period of K_1), fight-lateral compression shear stage (of later period of K_2-1ast stage of K_2), right-lateral strike-slip fault depression stage (E) and structural inversion (the end of E_3). The evolutionary history was mainly controlled by circum-Pacific tectonic domain.