The onset of the Tan–Lu fault movement in eastern China: constraints from zircon (SHRIMP) and 40Ar/39Ar dating
The onset of the Tan–Lu fault movement in eastern China: constraints from zircon (SHRIMP) and 40Ar/39Ar dating
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DOI：
10.1111/j.1365-3121.2006.00708.x
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发表时间：
2006-12
期刊：
影响因子：
2.4
通讯作者：
Yu Wang
中科院分区：
文献类型：
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作者：
Yu Wang
在中国东部，大别山—苏鲁造山带被郯庐左旋走滑断裂分隔开。糜棱岩沿南段走滑断裂体系和大别山造山带东缘出露。糜棱岩的围岩为逆行超高压榴辉岩、片麻岩花岗岩、白云母花岗岩和片麻岩。韧性走滑剪切带走向30-40°N （NE30-40°走向），并表现出伸展的线理和几乎垂直的、东南倾斜的层理。从糜棱岩中分离出的大部分锆石颗粒的加权平均辐射年龄为233±6 ~ 225±6 Myr。这些资料约束了郯庐左旋走滑运动的开始，暗示郯庐左旋走滑运动是在超高压逆变质后发展起来的。郯庐断裂带西侧榴辉岩中相关的辉长岩，其40Ar/39Ar高原年龄为约182 ~ 190myr，也呈变形排列，与近NE向的伸展线序平行。非变质花岗岩表现出左旋走滑剪切作用，表明郯庐断裂最初发育于182 - 190myr之后。从糜伦岩中收集的白云母产40Ar/39Ar，高原年龄为162±1-156±2 Myr。锆石SHRIMP年龄、白云母40Ar/39Ar高原年龄以及构造和岩石学资料均支持郯庐走滑断裂与华北-长江板块碰撞无关的解释，而与中国东部约165-160 Ma开始的NE向构造格架的形成相对应。
In eastern China, the Dabie Shan–Su–Lu orogenic belt has been separated by the Tan–Lu sinistral strike–slip fault. Mylonites are exposed along the strike–slip fault system in the southern segment, and along the eastern margin of the Dabie Shan orogenic belt. The country rocks of the mylonites are retrograde UHP eclogites, gneissic granites, muscovite granites and gneisses. The ductile strike–slip shear zone trends 30–40°N (NE30–40°‐trending) and exhibits stretching lineations and nearly vertical, SE‐dipping foliations. Most of the zircon grains separated from mylonites have a weighted average radiometric age of 233 ± 6–225 ± 6 Myr. These data constrain the onset of the Tan–Lu sinistral strike–slip movement and imply that the Tan–Lu sinistral strike–slip motion developed after retrograde UHP metamorphism. The related phengite within the eclogite rocks on the western side of the Tan–Lu fault, with 40Ar/39Ar plateau ages of c. 182–190 Myr, is also deformed and aligned parallel to the almost NE trending stretching lineations. Non‐metamorphosed granites exhibit sinistral strike–slip shearing and indicate that the Tan–Lu fault initially developed after 182–190 Myr. Muscovite collected from the mylonite yields 40Ar/39Ar plateau ages of 162 ± 1–156 ± 2 Myr. The zircon SHRIMP age data, the muscovite 40Ar/39Ar plateau ages, together with structural and petrological field information support the interpretation that the Tan–Lu strike–slip fault was not related to the Yangtze–north China plates collision, but corresponded to the formation of a NE‐trending tectonic framework in eastern China starting c. 165–160 Ma.