Linking high-pressure mafic granulite, TTG-like (tonalitic-trondhjemitic) leucosome and pluton, and crustal growth during continental collision

Abstract

Research Article| November 09, 2018 Linking high-pressure mafic granulite, TTG-like (tonalitic-trondhjemitic) leucosome and pluton, and crustal growth during continental collision Shengyao Yu; Shengyao Yu † 1Key Laboratory of Submarine Geosciences and Prospecting Technique, MOE and College of Marine Geosciences, Ocean University of China, Qingdao 266100, China2Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266061, China †yushengyao@ouc.edu.cn Search for other works by this author on: GSW Google Scholar Sanzhong Li; Sanzhong Li 1Key Laboratory of Submarine Geosciences and Prospecting Technique, MOE and College of Marine Geosciences, Ocean University of China, Qingdao 266100, China2Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266061, China Search for other works by this author on: GSW Google Scholar Jianxin Zhang; Jianxin Zhang 3Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China Search for other works by this author on: GSW Google Scholar Deyou Sun; Deyou Sun 4College of Earth Sciences, Jilin University, Changchun 130061, China Search for other works by this author on: GSW Google Scholar Yinbiao Peng; Yinbiao Peng 1Key Laboratory of Submarine Geosciences and Prospecting Technique, MOE and College of Marine Geosciences, Ocean University of China, Qingdao 266100, China Search for other works by this author on: GSW Google Scholar Yunshuai Li Yunshuai Li 5Institute of Surface-Earth System Science, Tianjin University, Tianjin 300072, China Search for other works by this author on: GSW Google Scholar GSA Bulletin (2019) 131 (3-4): 572–586. https://doi.org/10.1130/B31822.1 Article history received: 06 Apr 2017 rev-recd: 10 Jan 2018 accepted: 14 Aug 2018 first online: 10 Nov 2018 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Shengyao Yu, Sanzhong Li, Jianxin Zhang, Deyou Sun, Yinbiao Peng, Yunshuai Li; Linking high-pressure mafic granulite, TTG-like (tonalitic-trondhjemitic) leucosome and pluton, and crustal growth during continental collision. GSA Bulletin 2018;; 131 (3-4): 572–586. doi: https://doi.org/10.1130/B31822.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract The early continental crust is composed predominantly of Archean tonalite-trondhjemite-granodiorite (TTG); however, the tectonic regime and melting conditions for TTG magmas have been debated. In this study, we report field and microscopic evidence for the partial melting of arc-related metagabbro and its products, including TTG-like melt, volumetrically significant plutons evolved from melt, and the associated granulitic residua during continental collision in the North Qaidam Mountains, China. Migmatite shows successive stages of initial intragranular or droplet-like melt along grain boundaries, which grew into a three-dimensional interconnected intergranular network, segregated, and accumulated in pressure shadow areas, and merged to form melt channels and sheets that finally combined to form a TTG-like tonalite pluton. Pressure-temperature (P-T) calculations indicate high-pressure granulite-facies metamorphism and the crystallization of leucosome at P = 15.5–18.5 kbar and T = 850–950 °C. Based on zircon U-Pb dating and petrological analyses, partial melting and magmatic crystallization occurred 438–430 m.y. ago, which is slightly younger or temporally overlaps with ultrahigh-pressure metamorphism in the region. The metagabbros exhibit a subduction-related arc signature with slightly positive εNd(t) values of 2.1–4.2. The felsic leucosomes and tonalite plutons are characterized by high Na, Sr, Sr/Y, and La/Yb values and low heavy rare earth element values, with εNd(t) values of 0.1–4.3, similar to typical TTGs. The geological context, geochemistry, and timing of the TTG-like melt formation observed in this study differ from the prevailing models; however, our observations and documentations demonstrate that melting of arc-like metagabbro under high-pressure granulite-facies conditions during continental collision may make important contributions to crustal growth and differentiation. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.