Triassic diorites and granitoids in the Foping area: Constraints on the conversion from subduction to collision in the Qinling orogen, China
Triassic diorites and granitoids in the Foping area: Constraints on the conversion from subduction to collision in the Qinling orogen, China
复制标题
佛坪地区三叠纪闪长岩和花岗岩：秦岭造山带俯冲向碰撞转化的制约因素
DOI：
10.1016/j.jseaes.2011.06.005
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发表时间：
2012-03-30
影响因子：
3
通讯作者：
Yang, Chen
中科院分区：
文献类型：
--
作者：
Dong, Yunpeng;Liu, Xiaoming;Yang, Chen
西部Qinling的特征是三叠纪花岗岩岩石，它是钥匙TC限制了俯冲和中国南部街区之间的俯冲时间和碰撞过程的时机。本文介绍了一组新的LA-ICPMS U-PB锆石地质学，主要和痕量元素地球化学，用于foping区域的几种代表性的diorite和花岗岩岩体。 Diorites的特征是高MGO，Al2O3，Y和YB含量，但SiO2，SR/Y和LA/YB比率较低，以及NB，TA，P和Ti的耗竭，表明源自与俯冲相关的环境。 LA-ICPMS锆石U-PB年龄为216.9 +/- 1.5 mA（MSWD = 0.69），限制了俯冲事件的时间。中等和细粒的蒙Zogranites以及生物岩花岗岩表现出相对高的SIO2。 MGO和RB，低Y和YB含量，低SR/Y和LA/YB比，以及NB，TA，P和TI的各种耗竭。这些特征表明来自下大陆壳的衍生作品，但在同步环境中受到平板释放的流体的影响。中粒的Monzogrite和Biotite花岗岩产生LA-ICPMS锆石U-PB年龄为207.3 +/- 2.1 Ma（MSWD = 1.8）和201.6 +/- 1.2 mA（MSWD = 1.04）。提议在CA期间提议合成。 207-201 MA。地球化学和地质证据表明，侵入综合的mongogogogranites中的花岗闪长岩与中国和南中国南部街区发生碰撞后的后孤子崩溃有关。 Granodiente的LA-ICPMS U-PB锆石年龄为189.3 +/- 2.9 Ma（MSWD = 5.6），限制了后源性崩溃的时间。我们的年代学和地球化学数据对从俯冲到碰撞的三叠纪演变进行了重要的限制，然后再到沿Qinling造山机的后崩溃后塌陷。 （c）2011 Elsevier Ltd.保留所有权利。
The western Qinling is characterized by Triassic granitic plutons, which are keys tc constrain the timing of subduction and collisional processes between the North China and South China Blocks. This paper presents a set of new LA-ICPMS U-Pb zircon geochronology, major and trace element geochemistry for several representative diorite and granitoid plutons in the Foping area. The diorites are characterized by high MgO, Al2O3, Y and Yb contents, but low SiO2, Sr/Y and La/Yb ratios, as well as depletion of Nb, Ta, P and Ti, suggesting derived from a subduction related setting. LA-ICPMS zircon U-Pb age of 216.9 +/- 1.5 Ma (MSWD = 0.69) from the diorite constrains the time of the subduction event. The medium- and fine-grained monzogranites as well as the biotite granites exhibit relative high SiO2. MgO and Rb, low Y and Yb contents, and low Sr/Y and La/Yb ratios, as well as various depletions of Nb, Ta, P and Ti. These features indicate a derivation from lower continental crust but had been influenced by slab released fluids in a syn-collisional setting. The medium-grained monzogranite and biotite granite yield LA-ICPMS zircon U-Pb ages of 207.3 +/- 2.1 Ma (MSWD = 1.8) and 201.6 +/- 1.2 Ma (MSWD = 1.04), respectively. proposing the syn-collision during ca. 207-201 Ma. Geochemical and geological evidences suggest that the granodiorites intruding in the syn-collisional monzogranites were related to the post-orogenic collapse after the collision between the North China and South China Blocks. The LA-ICPMS U-Pb zircon age of 189.3 +/- 2.9 Ma (MSWD = 5.6) for the granodiorite constrains the time of the post-orogenic collapse. Our geochronological and geochemical data provide important constraints on the Triassic evolution from subduction to collision then up to post-collisional collapse along the Qinling orogen. (C) 2011 Elsevier Ltd. All rights reserved.