High-temperature geochronology constraints on the tectonic history and architecture of the ultrahigh-pressure Dabie-Sulu Orogen
High-temperature geochronology constraints on the tectonic history and architecture of the ultrahigh-pressure Dabie-Sulu Orogen
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DOI：
10.1029/2005tc001937
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发表时间：
2006-10-20
期刊：
影响因子：
4.2
通讯作者：
Gehrels, George
中科院分区：
文献类型：
--
作者：
Hacker, Bradley R.;Wallis, Simon R.;Gehrels, George
[ 1]在苏鲁超高压岩石中获得了新的锆石U/Pb和独居石Th/Pb年龄。结合Sm/Nd年龄、Rb/Sr年龄、包裹体关系和地质关系，确定了重结晶峰期、角闪岩相变质作用发生的时间以及中朝碰撞和扬子碰撞之间大别-苏鲁缝合带的构造。这些数据表明，类似于1500万年的超高压重结晶记录，第一个明确记录的一个巨大的超高压超高压岩石圈，这需要大陆俯冲在大别-苏鲁造山带涉及多个超高压构造或重结晶事件。一个244-236 Ma的“主超高压”事件（仅见于大别山）之后，紧接着又发生了一个类似于230-220 Ma的“主超高压”事件，其本身又被一个220-205 Ma的角闪岩相叠加所终止。秦岭造山带中的榴辉岩相事件提出了这些岩石经历过3 ~ 4次（U）HP变质作用的可能性，但目前在大别-苏鲁地区还没有年代学证据支持这一观点。扬子板块的俯冲并不是以简单的方式进行的：继承的锆石核的年龄表明，扬子亲缘关系的带状大陆逃脱了俯冲，并与中朝板块的上盘楔入。
[ 1] New U/Pb zircon and Th/Pb monazite ages are presented from the giant Sulu ultrahigh-pressure ( UHP) terrane. Combined with Sm/Nd ages, Rb/Sr ages, inclusion relationships, and geologic relationships, they help define the timing of peak recrystallization, the timing of subsequent amphibolite-facies metamorphism, and the architecture of the Dabie-Sulu suture zone between the collided Sino-Korean and Yangtze cratons. The data indicate a similar to 15 Myr record of UHP recrystallization, the first clearly documented for a giant UHP terrane; this requires that continental subduction in the Dabie-Sulu orogen involved multiple UHP tectonic or recrystallization events. A 244-236 Ma "precursor'' UHP event, seen only in the Dabie Shan, was followed by a second, similar to 230-220 Ma "main'' UHP event, which was itself terminated by a 220-205 Ma amphibolite-facies overprint. Older eclogite-facies events seen in the Qinling segment of this orogenic belt raise the possibility that these rocks have undergone ( U) HP metamorphism three or four times, but at present, there is no geochronological evidence in the Dabie-Sulu area to support this. The subduction of the lower, Yangtze plate did not proceed in a simple fashion: The ages of inherited zircon cores demonstrate that a ribbon continent of Yangtze affinity escaped subduction and became wedged against the Sino-Korean plate hanging wall.