滇中扬子西南缘戛洒地区大红山岩群高压榴闪岩的发现及厘定  

Discovery and determination of high-pressure garnet-amphibolite in Dahongshan Group in Gasa area,southwest margin of central Yangtze,Yunnan Province

作　　者：黄亮 黄钊 孙载波 曾文涛 何云龙 吕卫 杨旭山 刘福来[5] 何兆荣 HUANG Liang;HUANG Zhao;SUN Zaibo;ZENG Wentao;HE Yunlong;LYU Wei;YANG Xushan;LIU Fulai;HE Zhaorong(Yunnan Institute of Geological Survey(Yunnan Academy of Geological Sciences),Kunming 650216,Yunnan,China;Key Laboratory of Sanjiang Metallogeny and Resources Exploration and Utilization,MNR,Kunming 650051,Yunnan,China;Yunnan Key Laboratory of Sanjiang Metallogeny and Resources Exploration and Utilization,Kunming 65005l,Yunnan,China;Kungang Group Yuxi Dahongshan Mining Co.,Ltd.,Yuxi 653400,Yunnan,China;Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China)

机构地区：[1]云南省地质调查院(云南省地质科学研究院),云南昆明650216 [2]自然资源部三江成矿作用及资源勘查利用重点实验室,云南昆明650051 [3]云南省三江成矿作用及资源勘查利用重点实验室,云南昆明650051 [4]昆钢集团玉溪大红山矿业有限公司,云南玉溪653400 [5]中国地质科学院地质研究所,北京100037

出　　处：《地质通报》2024年第10期1818-1829,共12页Geological Bulletin of China

基　　金：云南省科技厅科技计划项目《昌宁−孟连结合带北端大理漕涧地区流纹岩型铌矿的成矿时代及矿床成因》(编号:202401AT070157);国家自然科学基金项目《三江南段景洪大勐龙地区高压变质岩p-T-t轨迹及其对原−古特提斯构造演化的制约》(批准号:42062005);云南省新一轮找矿行动暨地勘基金项目《云南省1∶5万乐在等3幅区域地质调查》(编号:D202306)。

摘　　要：通过野外地质调查,在滇中新平县戛洒的浅部熔岩铁矿地区原划分的大红山岩群红山组内部,新发现了一套变质强烈的变质岩。岩相学研究表明,该变质岩为榴闪岩类,退变质作用强烈,仅保留有部分俯冲-折返的矿物学记录,未见岩石早期变质及峰期变质阶段的矿物组合,且矿物世代具顺时针变质轨迹特征。据电子探针测试结果,通过GBP(石榴子石-黑云母-斜长石)平均温压计法,其记录的最大变质压力达1.52 GPa;角闪石单矿物温压计法获得角闪石记录的最大变质压力为0.66 GPa,表明榴闪岩为高压变质级。结合大红山岩群的成岩时代、变质时代、岩石地球化学特征等,认为大红山岩群成岩于Columbia超大陆裂解期,是古元古代晚期洋盆的岩石组分;主期变质作用形成于Rodinia超大陆拼合-裂解过程的俯冲-折返作用;大红山岩群可能是一套不完整的蛇绿混杂岩,代表了古元古代晚期洋盆的残迹。In the course of field geological investigation,a new set of metamorphic rocks with strong metamorphism was discovered inthe Hongshan Formation of Dahongshan Group in the shallow lava iron ore area of Jiesa,Xinping County,central Yunnan Province.Petrographic studies show that the metamorphic rocks are eclogite amphibolites with strong retrometamorphism and only partialsubduction−reentrant mineralogical records.There is no mineral association in the early metamorphic and peak metamorphic stages ofthe rocks,and the mineral generations have the characteristics of clockwise metamorphic tracks.According to the results of electronprobe test,the maximum metamorphic pressure recorded by GBP(Garnet−Biotite−Plagioclase)average temperature manometer is 1.52GPa.The maximum metamorphic pressure of hornblende recorded by temperature manometer method is 0.66 GPa,which indicates thatthe eclogite in this study is of high pressure metamorphic grade.According to the diagenetic age,metamorphic age and geochemicalcharacteristics of Dahongshan Group,it is believed that Dahongshan Group was formed in the cracking period of the Columbiasupercontinent and is a rock component of the Late Paleoproterozoic ocean basin.The main−stage metamorphism was formed by thesubduction−reentrant process of the Rodinia supercontinent,and the Dahongshan Group may be an incomplete set of ophioliticmelanomics,representing the remnants of the Late Paleoproterozoic ocean basin.

关 键 词：大红山岩群 榴闪岩 高压 顺时针变质 戛洒地区 滇中 

分 类 号：P588.3[天文地球—岩石学]