辽西寺儿堡-白塔盆地晚侏罗世火山岩地质特征及其对燕山运动的响应  

Geological Characteristics of Late Jurassic Volcanic Rocks in Sierbao-Baita Basin,West Liaoning Province and Its Response to Yanshan Movement

作　　者：宋志伟 郑常青[1,2] 林波[1] 徐学纯[1] 梁琛岳[1,2] 陈龙 赵英利[1,2] 温泉波[1] Song Zhiwei;Zheng Changqing;Lin Bo;Xu Xuechun;Liang Chenyue;Chen Long;Zhao Yingli;Wen Quanbo(College of Earth Sciences,Jilin University,Changchun 130061,China;Key Laboratory of Mineral Resources Evaluation in Northeast Asia,Ministry of Natural Resources,Jilin University,Changchun 130061,China)

机构地区：[1]吉林大学地球科学学院,吉林长春130061 [2]吉林大学东北亚矿产资源评价自然资源部重点实验室,吉林长春130061

出　　处：《地球科学》2023年第10期3689-3706,共18页Earth Science

基　　金：国家重点研发计划项目(No.2017YFC0601401);国家自然科学基金项目(No.41972215).

摘　　要：辽西地区位于燕山造山带东段,发育大规模的中生代火山-沉积盆地,是研究中生代燕山运动构造体制转换、岩石圈减薄和克拉通破坏的关键地区之一.报道了辽西寺儿堡-白塔盆地晚侏罗世火山岩岩相学、锆石U-Pb年代学、地球化学和锆石Hf同位素组成等资料,确定了其形成时代、岩石成因及构造背景,探讨了晚中生代期间古太平洋板块对华北克拉通东部俯冲后撤作用时间,为进一步认识燕山运动和燕山期岩浆活动的地球动力学机制提供可靠的地质依据.盆地内大范围出露的流纹岩形成时代为153.8~160.3 Ma,在空间上呈NE向展布,具有较高的SiO_(2)、Al2O3和全碱含量,显示准铝质-过铝质和高钾钙碱性特征.样品相对富集大离子亲石元素(LILEs:Rb、Ba、Pb、K等)和轻稀土元素(LREEs),亏损高场强元素(HFSEs:Nb、Ta、P、Ti等)和重稀土元素(HREEs),具明显的Eu负异常和较低的Cr、Co、Ni含量,结合岩浆成因锆石具有负ε_(Hf)(t)值(-17.8~-23.2)和相对古老的Hf同位素二阶段模式年龄(T_(DM2)=2334~2697 Ma),暗示初始岩浆可能来自于太古代或元古代的古老下地壳的部分熔融.综合研究表明,辽西地区晚侏罗世岩浆构造活动主要受控于古太平洋板块俯冲和后撤.寺儿堡-白塔盆地中流纹岩形成于古太平洋板块俯冲的NW向挤压构造背景,同时,在辽西地区存在大量与古太平洋板块后撤密切相关的变质核杂岩和伸展盆地,暗示区域上伸展体系的存在.因此,认为燕山-辽西地区构造体制于晚侏罗世发生转变,由挤压体系逐渐过渡为伸展体系,为燕山运动的响应.The West Liaoning Province is located in the eastern part of the Yanshan orogenic belt,with large-scale Mesozoic volcanic-sedimentary basins.It is critical to study the transformation of the Yanshan movement tectonic regime,lithosphere thinning and craton destruction during the Mesozoic.In this paper it conducts a comprehensive study of the Late Jurassic volcanic rocks exposed in the Sierbao-Baita basin in West Liaoning from the aspects of the perspectives of petrography,zircon U-Pb chronology,geochemistry and zircon Hf isotopic composition,so as to determine the age of their formation,petrogenesis and tectonic setting,discusses the time of the subduction and rollback of the Paleo-Pacific plate to the eastern North China craton during the Late Mesozoic,which provides a reliable geological basis for further understanding the geodynamic mechanism of the Yanshan movement and Yanshanian magmatism.The formation age of the rhyolite exposed in the basin is 153.8-160.3 Ma,spatially distributed in NE direction,with high SiO_(2),Al2O3 and total-alkali contents,showing the characteristics of metaluminousperaluminous and high-K calc-alkaline.The samples are relatively enriched in large ion lithophile elements(LILEs:Rb,Ba,Pb,K)and light rare earth elements(LREEs),depleted in high field strength elements(HFSEs:Nb,Ta,P,Ti)and heavy rare earth elements(HREEs),with obvious Eu negative anomaly and low Cr,Co,Ni contents.Combined with the magmatic origin zircons exhibit negativeε_(Hf)(t)value(-17.8 to-23.2)and old Hf isotopic two-stage model age(T_(DM2)=2334-2697 Ma),all suggest that the primary magma may have originated from the partial melting of the Archaean or Proterozoic ancient lower crust.The Late Jurassic magmatism and tectonic movement in the West Liaoning Province were controlled by the subduction and rollback of the paleo-Pacific plate.The rhyolite in the Sierbao-Baita basin was formed in the NW direction compression tectonic setting caused by the subduction of the paleo-Pacific plate.At the same time,there are also a la

关 键 词：燕山运动 锆石U-PB年龄 华北克拉通 辽西地区 古太平洋板块 岩石学 构造 

分 类 号：P581[天文地球—岩石学] P597[天文地球—地质学]