广东揭阳赤寮花岗岩体成因及其对燕山晚期钨成矿的约束OA

The eastern coastal region of eastern Guangdong,located along the southeastern margin of South China,rep-resents one of the most important Yanshanian tungsten-polymetallic metallogenic provinces,where mineralization is mainly controlled by the NE-trending Lianhuashan fault system and is temporally concentrated in 135～145 Ma.The Chiliao granite pluton,situated in the central segment of this fault zone,is flanked by several tungsten depos-its to its north and south;however,its genetic relationship with regional tungsten mineralization remains poorly constrained.This study investigates the emplacement age,magmatic characteristics,and tungsten enrichment fea-tures of the Chiliao pluton based on petrographic observations,whole-rock major and trace element geochemistry,and zircon trace-element and U-Pb geochronology.The results indicate that the Chiliao pluton is mainly com-posed of coarse-grained and fine-grained biotite granites,characterized by high SiO2(w(SiO2)=72.87％～75.68％),high total alkalis(w(K2O+Na2O)=7.53％～8.43％),peraluminous compositions(A/CNK=1.04～1.11),and a high degree of magmatic differentiation(Zr/Hf=27～31;Nb/Ta=6～7).Whole-rock W contents range from 300× 10-6 to 869× 10-6,with an average of 677×10-6,representing an enrichment of approximately 450 times relative to the av-erage crustal abundance and indicating pronounced tungsten enrichment.Zircon U-Pb dating yields crystalliza-tion ages of 131～137 Ma for the biotite granites;together with previously reported ages of 144 Ma and 157 Ma,these data demonstrate that the Chiliao pluton is a composite granite formed by multi-stage magmatic activity.Whole-rock geochemistry and zircon trace-element characteristics suggest that the 131～137 Ma magmas were mainly derived from partial melting of crustal materials and experienced intense magmatic differentiation.In com-bination with the regional tectonic framework,the Chiliao pluton is interpreted to have formed in a transitional tectonic setting related to back-arc extension or the transition from compression to extension induced by rollback and retreat of the Paleo-Pacific slab.The 131～137 Ma magmatic episode indicates that,following the regional main tungsten mineralization period,tungsten-fertile magmatic activity with mineralization potential may still have developed,highlighting favorable exploration significance and providing a new example for understanding the multi-stage nature of Yanshanian tungsten-fertile granitic magmatism in the eastern Guangdong coastal region.