青海昆仑河晚志留世—早泥盆世S型花岗岩成因与原特提斯洋构造演化OA
Genesis of Late Silurian to Early Devonian S-type granites in the Kunlun River area,Qinghai Province,and the tectonic evolution of the Proto-Tethys Ocean
位于东昆仑造山带中段昆仑河地区的二道沟、五路沟西和加组它士沟西岩体的岩性为二长花岗岩,其成因与侵位时代不明,制约了对区域构造演化的认识.锆石U-Pb年代学数据表明,二道沟、五路沟西和加组它士沟西岩体的侵位时代分别为 423.6 Ma、427.9 Ma和 413.8 Ma.3个岩体含白云母,无角闪石,具有高硅(w=68.92%～73.69%)、富铝(w=13.86%～15.72%)、总碱含量高(w=5.50%～7.70%)的特点,铝饱和指数(A/CNK)为 1.06～1.37,CIPW标准矿物计算出现刚玉分子(w=1.04%～4.66%),未出现透辉石,指示这 3个岩体属于强过铝质S型花岗岩;较高的CaO/Na2O比值、较低的K2O/Na2O和Rb/Sr比值表明3个岩体的形成与变质杂砂岩的水致熔融有关.锆石Ti温度计显示,3个花岗岩中锆石的结晶温度分别为 723～834℃、733～858℃和 586～870℃.锆石氧逸度计算结果指示岩浆处于较低的氧逸度水平.综合东昆仑造山带古生代岩浆岩记录以及高压-超高压榴辉岩等变质岩研究,本文认为昆仑河地区晚志留世—早泥盆世S型花岗岩形成于原特提斯洋闭合后的伸展环境.
The Erdaogou,Wulugouxi,and Jiazutashigouxi granites,located in the Kunlun River area of the middle part of the east Kunlun orogenic belt(EKOB),are composed of monzogranite.However,their origin and emplacement time frames remainunknown,posing a challenge to understanding the region's tectonic evolution.Results from LA-ICP-MS zircon U-Pb dating revealed crystallization ages of 423.6 Ma,427.9 Ma,and 413.8 Ma for the Erdaogou,Wulugouxi,and Jiazutashigouxi granites,respectively.These intrusions are characterized by minor muscovite,the absence of hornblende,high silica content(68.92%to 73.69%),an aluminum-rich composition(13.86%to 15.72%),and elevated total alkali content(5.50%to 7.70%).The aluminum saturation index(A/CNK)varies from 1.06 to 1.37,with corundum molecules(1.04%to 4.66%)identified in the CIPW standard mineral calculations,while the absence of clinopyroxene suggests a classification as strongly peraluminous S-type granites.High CaO/Na2O ratios along with low K2O/Na2O and Rb/Sr ratios indicate a connection to H2O-fluxed melting of metasandstones during their formation.The Zircon Ti thermometry data indicate zircon crystallization temperatures within the three granites ranging from 723 ℃ to 834 ℃,733 ℃ to 858 ℃,and 586 ℃ to 870℃,respectively.Oxygen fugacity values of zircons suggest a relatively low oxygen fugacity level during magma formation.Considering the Paleozoic magmatic rock record and our investigation of these metamorphic rocks,including high-pressure to ultra-high-pressure eclogite in the EKOB,this study proposes that the Late Silurian to Early Devonian S-type granites in the Kunlun River area originated in an extensional environment following closure of the Proto-Tethys Ocean.
冯李强;沈睿文;彭艳雯;顾雪祥;章永梅;杜治利;王大伟
中国地质调查局 自然资源综合调查指挥中心,北京 100055中国地质调查局 自然资源综合调查指挥中心,北京 100055||中国地质调查局 哈尔滨自然资源综合调查中心,哈尔滨 150081北京建工集团有限责任公司总承包部,北京 100055中国地质大学(北京) 地球科学与资源学院,北京 100083||中国地质大学(北京) 地质过程与矿产资源国家重点实验室,北京 100083中国地质大学(北京) 地球科学与资源学院,北京 100083||中国地质大学(北京) 地质过程与矿产资源国家重点实验室,北京 100083中国地质调查局 自然资源综合调查指挥中心,北京 100055中国地质调查局 自然资源综合调查指挥中心,北京 100055
天文与地球科学
U-Pb年代学S型花岗岩昆仑河地区东昆仑青海
U-Pb geochronologyS-type graniteKunlun River areaeast KunlunQinghai
《成都理工大学学报（自然科学版）》 2026 (2)
403-421,19
新疆维吾尔自治区重点研发计划项目(2023B03016)中国地质调查局地质调查专项(DD20230374).
评论