浙东括苍山-雁荡山破火山白垩纪多旋回火山-侵入杂岩成因研究  

Petrogenesis of episodic Cretaceous volcanic-intrusive rocks in the Kuocangshan-Yandangshan calderas in the eastern Zhejiang

作　　者：王学颖 徐夕生[1] 赵凯[1] WANG Xue-ying;XU Xi-sheng;ZHAO Kai(State Key Laboratory for Mineral Deposits Research,Nanjing University,Nanjing 210023,China)

机构地区：[1]南京大学内生金属矿床成矿机制研究国家重点实验室,南京210023

出　　处：《矿物岩石地球化学通报》2023年第5期1062-1077,I0005,共17页Bulletin of Mineralogy, Petrology and Geochemistry

基　　金：国家自然科学基金重点项目(41930214)。

摘　　要：浙东括苍山-雁荡山破火山由时空上关联的括苍山巨型环状破火山及其东南缘的雁荡山破火山构成。为重塑该地区白垩纪岩浆演化历史,本文在结合雁荡山火山-侵入杂岩地质资料的基础上,对括苍山早期流纹质熔结凝灰岩和石英二长闪长岩进行了锆石年代学、地球化学分析。结果表明,括苍山-雁荡山破火山岩浆活动时间为130~98 Ma,具有多个旋回的结晶年龄和同位素组成相仿的巨厚火山岩地层和未喷发的富晶体侵入岩。火山岩和侵入岩可由分离结晶作用联系起来,前者由晶粥内晶体间熔体抽提形成,后者由残余熔体和晶体形成。从括苍山-雁荡山破火山的火山岩地层厚度、规模及区域性火山岩分布特点可知,浙东岩浆活动高峰期为130~120 Ma及112~88 Ma,前者岩浆活动规模大于后者,它们分别对应于古太平洋板块快速后撤及缓慢后撤的两个阶段,而120~112 Ma为陆缘伸展作用停滞的岩浆活动沉寂期。The Kuocangshan-Yandangshan calderas in the eastern Zhejiang are combined by the Kuocangshan volcanic ring caldera and the spatially and temporally related Yandangshan caldera.In this study,we have conducted zircon geochronological and geochemical analyses of the early-stage rhyolitic ignimbrite and quartz monzodiorite from the Kuocangshan caldera,together with the published geological and geochemical data of volcanic-intrusive rocks from the Yandangshan caldera,in order to reconstruct the Cretaceous magmatic evolution history of the area.The results show that the magmatism of the Kuocangshan-Yandangshan calderas,which was lasted from 130 Ma to 98 Ma,had produced multi-stage extremely thick volcanic rock strata and equivalent unerupted crystal-rich intrusive rocks with similar crystallization ages and isotopic compositions.The volcanic and intrusive rocks were formed through different forms of magmatic crystallization differentiation,i.e.,the former one was formed through the interstial melt extraction from the subvolcanic reservoir,while the latter one was formed from residual melt and crystals.Syntheses of the thicknesses,scales and regional distribution characteristics of the volcanic strata suggest that magmatisms occurred in the Eastern Zhejiang at two main peak periods at 130~120 Ma and 112~88 Ma,with the magmatism scale of the former period larger than that of the later one.Magamatisms of these two peak periods could correspond to two stages of fast and slow rollbacks of the paleo-Pacific plate,respectively.The volcanic lull between 120 Ma and 112 Ma may denote to a pause of lithospheric extension.

关 键 词：浙东 括苍山-雁荡山破火山 火山-侵入杂岩 古太平洋板块后撤 

分 类 号：P588.12[天文地球—岩石学]