中国东部胶东半岛昆嵛山变质核杂岩结构特征及其构造意义  

Structural characteristics and tectonic significance of the Kunyushan metamorphic core complex in the eastern Jiaodong Peninsula of China

作　　者：罗博文 田忠华[1] 王伟[1] 李俊[2] 贾督 李晓东 Luo Bowen;Tian Zhonghua;Wang Wei;Li Jun;Jia Du;Li Xiaodong(Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037;School of Earth Resources,China University of Geosciences(Wuhan),Wuhan 430074)

机构地区：[1]中国地质科学院地质研究所,北京100037 [2]中国地质大学(武汉)资源学院,武汉430074

出　　处：《地质科学》2025年第1期1-18,共18页Chinese Journal of Geology(Scientia Geologica Sinica)

基　　金：国家重点研发计划项目(编号:2023YFC2906901);国家自然科学基金项目(编号:42172222);中国地质科学院基本业务费项目(编号:JB2304)资助。

摘　　要：变质核杂岩为华北克拉通岩石圈减薄作用提供了重要例证。本文对中国东部胶东半岛昆嵛山变质核杂岩进行了深入研究,得出结论:其上盘由早白垩世胶莱盆地及部分古元古代荆山群沉积物组成;下盘则由太古宙深变质杂岩、古元古代荆山群变质沉积岩、新元古代的花岗片麻岩及侵入其中的中生代岩浆岩组成;拆离断层由韧性至脆性的低角度剪切带组成,具有典型的科迪勒拉变质核杂岩构造的3层结构。东侧米山韧性剪切带大部分区域面理低角度倾向北东,矿物拉伸线理倾伏向东北,脆性断层擦痕、不对称旋转碎斑及S-C组构指示拆离带具有向东北方向拆离的特征。西南侧海阳所韧性拆离带具有向西南方向拆离的特征,拆离带上可见大量鞘褶皱,暗示大量前寒武纪基底以鞘褶皱的方式快速拆离至地表。西侧王格庄韧性剪切带整体走向为近南北向,糜棱岩面理低角度倾向西,面理上矿物拉伸线理倾伏向为近东西向,不对称旋转碎斑及S-C组构等指示该韧性剪切带具有向西拆离的特征。本研究认为昆嵛山变质核杂岩是古太平洋板块后撤的产物,其形成及剥露时代为145~113 Ma,受WNW-ESE区域应力所控制。The metamorphic core complexes provide crucial evidence for the lithospheric thinning of the North China Craton.This paper presents an in-depth study of the Kunyushan metamorphic core complex in the Jiaodong Peninsula,eastern China.The results indicate that the hanging wall consists of the Early Cretaceous Jiaolai Basin and parts of the Paleoproterozoic Jingshan Group sedimentary rocks.The footwall is composed of Archean high-grade metamorphic complexes,Paleoproterozoic metamorphosed sedimentary rocks of the Jingshan Group,Neoproterozoic granitic gneisses,and intruding Mesozoic igneous rocks.The detachment fault is characterized by a low-angle shear zone that transitions from ductile to brittle deformation,exhibiting the typical three-layer structure of Cordilleran metamorphic core complexes.On the eastern side,the Mishan ductile shear zone mostly dips at low angles to the northeast,with mineral stretching lineations plunging toward the northeast.Slickenlines on brittle faults,asymmetric rotated porphyroclasts,and S-C fabrics suggest that the detachment zone displays a northeastward extensional characteristic.In contrast,the Haiyangsuo ductile detachment zone on the southwestern side shows a southwestward extensional feature.A significant number of sheath folds in the detachment zone indicate that a large volume of Precambrian basement rocks rapidly exhumed to the surface in the form of sheath folds.The Wanggezhuang ductile shear zone on the western side trends nearly north-south,with mylonitic foliations dipping at low angles toward the west and mineral stretching lineations plunging nearly east-west.Asymmetric rotated porphyroclasts and S-C fabrics suggest that this ductile shear zone has a westward extensional feature.This study concludes that the Kunyushan metamorphic core complex resulted from the rollback of the Paleo-Pacific Plate.Its formation and exhumation occurred between 145 Ma and 113 Ma,under the control of WNW-ESE regional stress.

关 键 词：昆嵛山变质核杂岩 拆离断层 锆石U-PB定年 鞘褶皱 板片后撤 

分 类 号：P542[天文地球—构造地质学] P588.3[天文地球—地质学]