Formation Ages, Petrogenesis and Geological Implications of the Archean Granitoid Rocks in the Xinbin-weiziyu Area, Northern Liaoning Province

WANG Kang1, LIU Shuwen1,†, WANG Maojiang1, WANG Wei2, YAN Ming3

1. The Key Laboratory of Orogenic Belts and Crustal Evolution (MOE), School of Earth and Space Sciences, Peking University, Beijing 100871; 2. State Key Laboratory of Geological Processes and Mineral Resources, School of Earth Sciences and Resources, China University of Geosciences (Beijing), Beijing 100083; 3. Research Institute of Petroleum Exploration & Development, Liaohe Oilfield Company, Petrochina, Panjin 124000; † Corresponding author, E-mail: swliu@pku.edu.cn

Abstract The granitoid rocks in the Xinbin-weiziyu area, northern Liaoning Province, comprise tonalitictrondhjemitic gneisses and monzogranite-syenogranite plutons. To determine their formation ages and petrogenesis, zircon U-PB-HF isotopic analyses and whole-rock geochemical analyses are conducted on these granitoid rocks. LAICP-MS zircon U-PB isotopic dating data reveal that the tonalitic and trondhjemitic gneisses emplaced at 2588±4 Ma (MSWD=1.3) and 2587±6 Ma (MSWD=1.8), respectively, and the monzogranite-syenogranite intrusions formed at 2555±4 Ma (MSWD=0.51). Whole-rock geochemistry and zircon Lu-hf isotopes suggest that magmatic precursors of the tonalitic-trondhjemitic gneisses were derived from partial melting of subducted slabs and the magmas were contaminated by the mantle wedge materials during their ascent. Some of the monzogranitesyenogranite plutons were produced by partial melting of metagreywackes, whereas the others were generated by partial melting of a mixed source composed of metabasalts and metasedimentary rocks. Integrated with recent studies, the Neoarchean granitoid rocks in the Xinbin-weiziyu area may have been generated under an active continental margin.