辽东兰花岭地区古元古代Ⅰ型花岗岩类与辽吉A型花岗岩对比研究  

Comparative study of the Lanhualing Paleoproterozoic Ⅰ-type granitoids and the Liaoji A-type granitoids in eastern Liaoning

作　　者：顾玉超[1] 鞠楠[1] 陈仁义[2] 杨凤超[1] 胥嘉[1] 杨宏智[1] GU Yuchao;JU Nan;CHEN Renyi;YANG Fengchao;XU Jia;YANG Hongzhi(Shenyang Center,China Geological Survey,Shenyang 110034,Liaoning,China;Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037,China)

机构地区：[1]中国地质调查局沈阳地质调查中心,辽宁沈阳110034 [2]中国地质科学院矿产资源研究所,北京100037

出　　处：《地质通报》2024年第2期317-339,共23页Geological Bulletin of China

基　　金：中国地质调查局项目《吉黑东部成矿带战略性矿产调查》(编号:DD20240060);国家自然科学基金项目《碱性岩浆作用中铌钽元素富集机制研究:以辽东地区赛马铌钽矿床为例》(批准号:42102087)。

摘　　要：辽东半岛是华北克拉通胶-辽-吉古元古代活动带的重要组成部分,古元古代经历了复杂的构造演化过程,并记录了多期岩浆-变质作用,约2.2 Ga的辽吉A型花岗岩和1.89~1.85 Ga的巨斑状花岗岩、正长岩分别标志着辽东古元古代造山作用的开端和结束。最新研究显示,2.20~2.15 Ga的岩浆作用形成了2种不同类型的花岗岩,它们可能具有不同的岩石成因和构造意义。在青城子铅锌矿集区北部采集的兰花岭、白砬子花岗闪长岩和黄泊辉绿岩,锆石U-Pb年龄分别为2177±19 Ma、2129±36 Ma、1876±29 Ma。花岗闪长岩的岩石成因类型、地球化学特征与典型的约2.2 Ga的辽吉A型花岗岩明显不同,属于弱过铝质、低钾钙碱性—碱性岩石,Zr、Hf、Nb、Rb含量较低,K_(2)O/Na_(2)O值、稀土元素总量极低,为典型的Ⅰ型花岗岩类。根据锆石Lu-Hf同位素分析,ε_(Hf)(t)值为-5.1~9.0,二阶段Hf模式年龄t_(DM2)为2089~2817 Ma,岩浆源区为约2.5 Ga的太古宙地壳物质和少量软流圈地幔物质。兰花岭地区花岗闪长岩具备岛弧或活动大陆边缘的地球化学亲缘属性,可能形成于弧岩浆俯冲挤压环境;结合形成于伸展环境的A型条痕状花岗岩特征,认为约2.2 Ga辽东地区古元古代活动带呈现总体伸展、局部挤压的构造环境,为洋壳板块向龙岗地块俯冲碰撞过程中或碰撞后的弧后盆地。Liaodong Peninsula is a significant component of the Jiao-Liao-Ji belt.It experienced complex process of structural evolution with the recorded effects of magma metamorphism in multiple periods.The 2.2 Ga Liaoji A-type granite and 1.89~1.85 Ga porphyritic granite/syenite indicate the beginning and end of the effects of mountain formation in Paleoproterozoic respectively.The latest research shows that two unique types of granites have been formed under the effects of magmatism of 2.20~2.15 Ga.These two granites have different petrogenesis mechanisms and tectonic significance.In this paper,a detailed study of the Lanhualing granodiorite,Bailazi granodiorite and Huangpo diabase collected in the North of Qingchengzi lead-zinc concentrated area was conducted.The corresponding zircon U-Pb ages are 2177±19 Ma,2129±36 Ma and 1876±29 Ma,respectively.The rock type and geochemical characteristics of the granodiorite show obviously differences from the typical 2.2 Ga Liao-ji A-type granites.It is characterized by weak peraluminous,low potassium calc-alkaline to alkaline,low content of Zr,Hf,Nb,Rb,low K_(2)O/Na_(2)O value,and extremely low content of total rare earth element.Therefore,it is categorized as typical I-type granite.According to the analysis of zircon Lu-Hf isotope,the value of ε_(Hf)(t)is-5.1~9.0.The age of the two-stage model(t_(DM2))is in a range of 2089 Ma to 2817 Ma.The magma source consists of 2.5 Ga Archean crustal materials and a small amount of asthenospheric mantle materials.The granodiorite from Lanhualing area has the affinity geochemical property of island arcs or active continental margin.It may have been formed in the subduction and compression environment of arc magma;according to the A-type granite formed in extensional settings,we believe that the Paleoproterozoic belt of eastern Liaoning had experienced a tectonic environment of overall extension and local compression in the period of 2.2 Ga,which is the back-arc basin formed during or after the collision of the oceanic plate with the Longga

关 键 词：弧岩浆作用 Ⅰ型花岗岩类 古元古代 锆石U-PB测年 LU-HF同位素 地质调查工程 辽东半岛 

分 类 号：P534.3[天文地球—古生物学与地层学] P588.121[天文地球—地质学]