Geochronology and Geochemistry of Late Devonian I-and A-Type Granites from the Xing'an Block, NE China:Implications for Slab Break-off during Subduction of the Hegenshan-Heihe Ocean

• 作者: Zheng Ji Wenchun Ge Hao Yang Yanlong Zhang Yu Dong Junhui Bi Xiwen Liu
• 来源期刊: 地球科学学刊（英文版）
• 年，卷（期）: 2022,（1）
• 所属期刊栏目: Special Issue on Isotope Geochronology and Isotope Geochemistry
• 页码范围: 150-160
• 页数: 11页
• 语种: 英文

摘要

We present detailed geochronological, geochemical, and zircon Hf isotopic data for Late Paleozoic granitic rocks from Handagai and Zhonghe plutons in the Xing'an Block, NE China, aiming to provide constraints on their origin and tectonic implications. New zircon U-Pb ages indicate they were formed in the Late Devonian (ca. 379 Ma) immediately after a striking 50 Ma magmatic lull (ca. 430-380 Ma) in the Xing ' an Block. Petrological and geochemical features suggest that the Handagai monzogranites and Zhonghe alkali-feldspar granites are I-and A-type granites, respectively, although both of them have high-K calc-alkaline features and positive zirconεHf(t) values (+3.47 to+10.77). We infer that the Handagai monzogranites were produced by partial melting of juvenile basaltic crustal ma-terials under a pressure of<8-10 kbar, whereas the Zhonghe alkali-feldspar granites were generated by partial melting of juvenile felsic crustal materials at shallower depths (P≤4 kbar). Our results, together with published regional data, indicate their generation involves a subduction-related extensional set-ting. Slab break-off of the Hegenshan-Heihe oceanic plate may account for the subduction-related exten-sional setting, as well as the transformation of arc magmatism from the Early-Middle Devonian lull to the Late Devonian-Early Carboniferous flare-up in the Xing'an Block.