当前位置: X-MOL 学术Geolog. J. › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Magmatic gap associated with stepwise arc‐continent collision during the subduction of Banggong‐Nujiang Tethys Ocean: Evidence from Late Jurassic bimodal magmas
Geological Journal ( IF 1.8 ) Pub Date : 2020-10-08 , DOI: 10.1002/gj.4016
Hua‐Sheng Shao 1, 2 , Guo‐Li Yuan 1, 2 , Zhi‐Bo Liu 3 , Yang Song 3 , Ran‐Xiao Huang 1
Affiliation  

The magmatic suites in the southern margin of South Qiangtang Terrane (SQT) provide important clues to the process of northward subduction of the Banggong‐Nujiang Tethys Ocean (BNTO) and its geodynamic evolution. Previous studies identified a magmatic gap from Late Jurassic to Early Cretaceous (ca. 150–130 Ma) in the southern margin of SQT. Although the gap is generally correlated with the process related to BNTO subduction, the previous models on this remain equivocal. In this study, we investigated a suite of bimodal magmatic rocks newly recognized in the Rigenco area of SQT, including gabbros and granodiorites which were dated at 151.7 ± 3.8 Ma and 150.0 ± 2.0 Ma respectively. Based on geochemical and isotopic analyses, it is inferred that the gabbroic magmas were derived from a sub‐arc mantle source enriched by metasomatism of voluminous slab‐derived and crustal compositions, and that the granodiorites were derived from sub‐arc juvenile lower crust. Combining the petrogenesis of gabbros and granodiorites, it is proposed that the bimodal magmas were produced under a tectonic setting of general compression with local extension. A detailed evaluation of the tectonic setting of the magmatic bimodal suite suggests crustal thickening at ca. 150 Ma and that the BNTO involved multiple arcs and sub‐basins. A new model of arc‐SQT collision is proposed to account for the magmatic gap which commenced at ca. 150 Ma. The model of arc–continent collision in this case can well explain the present distribution and occurrence of magmatic rocks of late Jurassic age in the southern margin of the SQT, especially the magmatic gap. Our discovery of Late Jurassic bimodal rocks provides a critical evidence for step‐wise arc–continent collision during BNTO subduction, and contributes to the understanding of the magmatic gap in SQT and the evolution of BNTO.

中文翻译:

邦公—怒江特提斯洋俯冲过程中与逐步弧—陆碰撞碰撞有关的岩浆间隙:晚侏罗世双峰岩浆的证据

南Qian塘地带(SQT)南缘的岩浆组为邦公—怒江特提斯海(BNTO)向北俯冲的过程及其地球动力学演化提供了重要线索。先前的研究确定了南北向侏罗纪晚期至白垩纪早期(约150-130 Ma)的岩浆间隙。尽管差距通常与BNTO俯冲过程有关,但以前关于此的模型仍然模棱两可。在这项研究中,我们研究了在SQT的里根科地区新发现的一套双峰岩浆岩,包括辉长岩和花岗闪长岩,其日期分别为151.7±3.8 Ma和150.0±2.0 Ma。根据地球化学和同位素分析,可以推断,辉长岩浆岩是由大量的板状和地壳成分的交代作用富集的一个亚弧幔源,而这些花岗闪长岩则是由亚弧的下地壳衍生而来的。结合辉长岩和花岗闪长岩的岩石成因,提出双峰岩浆是在一般压缩和局部伸展的构造环境下产生的。对岩浆双峰组构造环境的详细评估表明,大约在1990年,地壳增厚。150 Ma,而BNTO涉及多个弧和子流域。提出了一种新的arc-SQT碰撞模型,以解决始于ca的岩浆间隙。150毫安。在这种情况下,弧-大陆碰撞模型可以很好地解释SQT南缘侏罗纪晚期岩浆岩的分布和发生。我们晚侏罗世双峰岩石的发现为BNTO俯冲过程中逐步的弧-陆碰撞提供了重要证据,并有助于了解SQT的岩浆间隙和BNTO的演化。
更新日期:2020-10-08
down
wechat
bug