青海省南祁连地区维日克宁掌一带巴龙贡嘎尔组的重新厘定及其构造意义  

Redefinition and tectonic significance of the Balonggonggar Formation in the Weirikeningzhang area in southern Qilian,Qinghai Province

作　　者：孙中行[1] 李铁笔 王焱 李东[1] SUN Zhonghang;LI Tiebi;WANG Yan;LI Dong(Regional Geological and Mineral Resources Survey of Jilin Province,Changchun 130022,Jilin,China)

机构地区：[1]吉林省区域地质矿产调查所,吉林长春130000

出　　处：《吉林地质》2024年第4期8-15,共8页Jilin Geology

摘　　要：维日克宁掌地区位于青海省天峻县,出露最古老的地层为南祁连地块古生代巴龙贡嘎尔组,通过区域地层对比研究发现,维日克宁掌地区出露的巴龙贡嘎尔组,与原始含义不同,重新厘定命名为维日克宁掌片岩,其岩石组合为片岩、片麻岩、变粒岩组合,经历了多期变质变形的叠加改造,变质程度相当于低角闪岩相中低压相系变质,恢复原岩为海相中基性火山岩-碎屑岩,SiO_(2)质量分数为(50.43~62.71)×10^(-2),氧化物含量变化范围较大,从基性到中性,稀土元素配分模式曲线呈左高右低,轻稀土富集,贫重稀土,铕有轻微的负异常,几乎没有Ce异常,显示其物源区具有亲陆源性质,大离子亲石元素Ba的变化较大,说明Ba的含量变化除受原岩特征控制外,还与其变质过程中流体的活动相关,高场强元素Zr元素明显富集,显示陆源碎屑岩特征,具大陆裂谷盆地特点。该片岩的发现,填补了该区域元古代沉积序列的空白,与新元古代Rodinia超大陆的汇聚和裂解事件相吻合。The Weirikeningzhang area is located in Tianjun County,Qinghai Province.The oldest exposed stratum is the Paleozoic Balonggonggar Formation of the South Qilian Block.Through regional stratigraphic comparison research,it was found that the Balonggonggar Formation exposed in the Weirikeningzhang area is different from its original meaning and has been renamed as Weirikeningzhang schist.Its rock combination is schist,gneiss,and granulite combination,which has undergone multiple periods of metamorphic deformation and superimposed transformation.The degree of metamorphism is equivalent to the metamorphism of low amphibolite medium low pressure facies series,restoring the original rock to marine basic volcanic rock clastic rock,The SiO_(2)mass fraction is(50.43-62.71)×10^(-2),and the oxide content varies greatly from basic to neutral.The rare earth element distribution pattern curve shows a left high and right low trend,with light rare earth enrichment and heavy rare earth deficiency.Europium has slight negative anomaly and almost no Ce anomaly,indicating that its source area has terrigenous properties.The large ion lithophile element Ba has a significant variation,indicating that the content change of Ba is not only controlled by the characteristics of the original rock,but also related to the fluid activity during its metamorphic process.The high field strength element Zr is significantly enriched,showing characteristics of terrigenous clastic rocks and continental rift basins.The discovery of this schist fills the gap in the Neoproterozoic sedimentary sequence in the region and is consistent with the convergence and fragmentation events of the Rodinia supercontinent in the Neoproterozoic.

关 键 词：南祁连地区 巴龙贡嘎尔组 维日克宁掌片岩 天峻县 青海省 

分 类 号：P588.3[天文地球—岩石学]