| Title | Geochronology and geochemistry of the Bashikaogong S-type granitic rocks: a record of Early Paleozoic subduction and collision in North Altun, Northwestern China |
| Authors | Wu, Di Zheng, Kun Wu, Cailai Chen, Hongjie Gao, Dong Zou, Fenghui |
| Affiliation | Chinese Acad Geol Sci, Inst Geomech, Beijing 100081, Peoples R China Chinese Acad Geol Sci, Inst Geol, Beijing 100037, Peoples R China Peking Univ, Sch Earth & Space Sci, Beijing 100871, Peoples R China Zhengzhou Univ, Zhengzhou 450001, Peoples R China |
| Keywords | ZIRCON U-PB HF ISOTOPIC COMPOSITIONS A-TYPE GRANITES ALTYN-TAGH NW CHINA PERALUMINOUS GRANITES I-TYPE LU-HF TECTONIC SIGNIFICANCE DUNHUANG BLOCK |
| Issue Date | Jul-2021 |
| Publisher | ARABIAN JOURNAL OF GEOSCIENCES |
| Abstract | The Altun orogenic belt (AOB) was the site of complex subduction of oceanic crust and continental collision during the Paleozoic. The North Altun ophiolitic melange belt (NAB) is a one of the key tectonic units of the AOB and contains abundant subduction- and collision-related rocks. In this paper, we report the petrography, zircon U-Pb ages, geochemistry, and zircon Hf isotopes of the Bashikaogong S-type granitic rocks from the North Altun ophiolitic melange belt (NAB) to constrain their petrogenesis and tectonic setting. The granitic rocks consist of three types of granites, i.e., (1) gray, medium- to coarse-grained porphyritic granite; (2) gray, medium-grained granite; and (3) pink, medium- to coarse-grained granite. Zircon U-Pb dating yielded ages of 483-477, 458-453, and 447-445 Ma for type 1, type 2, and type s3 granites, respectively. All the three types of granites share similar strongly peraluminous (A/CNK > 1.1), contain muscovite mineral, have K2O/ Na2O ratios of > 1, and display negative zircon epsilon (Hf)(t) values, which are similar to typical S-type granites. On the basis of our data and results of previous studies, we infer that type 1 granites (483-477 Ma) are related to subduction of North Altun oceanic lithosphere, type 2 granites (458-453 Ma) are syn-collision granites related to continental collision between the Central Altun and Dunhuang Blocks, and type 3 granites (447-445 Ma) are from the late-collision stage. The Bashikaogong S-type granitic rocks recorded early Paleozoic subduction and collision in the North Altun region and were generated by the partial melting of the protolith of the metasedimentary Paleoproterozoic-Mesoproterozoic basement in the CAB due to the collapse of the overthickened subduction orogen. |
| URI | http://hdl.handle.net/20.500.11897/619561 |
| ISSN | 1866-7511 |
| DOI | 10.1007/s12517-021-07658-3 |
| Indexed | SCI(E) |
| Appears in Collections: | 地球与空间科学学院 |
