胶北日庄石墨结晶与寄主麻粒岩的变质演化关系  

Relationship between the crystallization of graphite and metamorphism of graphite-bearing granulite in Rizhuang,Jiaobei Terrane

作　　者：张保瑞 孔凡梅 李旭平 孙彤 玄金卉 高园明 申颖 ZHANG BaoRui;KONG FanMei;LI XuPing;SUN Tong;XUAN JinHui;GAO YuanMing;SHEN Ying(College of Earth Science and Engineering,Shandong University of Science and Technology,Qingdao 266590,China;Shandong Institute of Geological Sciences,Jinan 250013,China)

机构地区：[1]山东科技大学地球科学与工程学院,青岛266590 [2]山东省地质科学研究院,济南250013

出　　处：《岩石学报》2023年第9期2697-2722,共26页Acta Petrologica Sinica

基　　金：国家自然科学基金委山东联合基金重点项目(U1906207)资助.

摘　　要：日庄镇含石墨泥质麻粒岩出露于莱西石墨成矿带,详细的岩相学、地球化学、拉曼光谱、年代学等研究显示岩石经历了超高温变质作用。麻粒岩变质演化过程包括三个阶段,其中峰前M 1阶段矿物仅部分保留;峰期M 2阶段和峰后M 3阶段矿物组合分别为Grt+Qz+Pl+Kfs+Sil+Rt+Liq和Grt+Qz+Bt+Pl+Kfs+Sil+Rt+Liq;相平衡模拟结合二长石温度计和石英中Ti温度计研究结果显示峰期M 2阶段的温压条件为1025~1100℃、1.05~1.2GPa。研究样品中石墨结晶程度较高,石墨拉曼光谱特征与麻粒岩相变质条件下形成的石墨一致,岩相学特征指示高晶度石墨结晶于M 2向M 3转变过程中。麻粒岩中获得变质锆石年龄为~1.85Ga,该年龄是寄主岩石峰期变质作用后熔体冷却时间的记录。岩相学和年代学研究表明,优质高晶度石墨的形成和生长可能与胶-辽-吉活动带区域上碰撞折返过程中发生的深溶事件或混合岩化作用密切相关。The graphite-bearing pelitic granulite in the Rizhuang Town is located in the Laixi graphite metallogenic belt.Based on detailed studies of petrography,geochemistry,Raman spectroscopy and geochronology of the granulite,we considered it has undergone ultra-high temperature(UHT)metamorphism.The metamorphic evolution process of the granulite includes three stages although the mineral assemblage in the M 1 stage is not completely preserved.The mineral assemblages for the peak temperature stage M 2 and the post-peak stage M 3 are Grt+Qz+Pl+Kfs+Sil+Rt+Liq and Grt+Qz+Bt+Pl+Kfs+Sil+Rt+Liq,respectively.According to the phase equilibria modelling,combined with the two-feldspar geothermometers and the titanium-in-quartz geothermometers,we obtained the peak stage temperature and pressure conditions of the granulite variying at 1025~1100℃and 1.05~1.2GPa.The Raman spectrum characteristics of the graphites in the studied samples show that most of them are highly crystallinity,which are consistent with the graphites formed under the metamorphic condition of granulite facies.The petrographic characteristics indicate that the high crystallinity graphite should crystallize during the transition from M 2 stage to M 3 stage.Age of the metamorphic zircons from the graphite-bearing granulite is~1.85Ga,which is a record of the cooling time after UHT peak metamorphism.The petrological and geochronological studies show that the formation and growth of high crystallinity graphite might closely relate to the regional anatexis event or the regional migmatization which occurs during the regional collisional event of the Jiao-Liao-Ji mobile belt.

关 键 词：含石墨泥质麻粒岩 超高温变质 高晶度石墨 胶-辽-吉构造带 拉曼光谱 

分 类 号：P588.347[天文地球—岩石学] P597.3[天文地球—地质学] P619.252