腾冲地块晚白垩世小龙河花岗岩年龄及其成矿意义  

Geochronology and mineralization significance of the Late Cretaceous Xiaolonghe granite in the Tengchong Block

作　　者：刘金梁 陈永清[1] 尚志 LIU Jinliang;CHEN Yongqing;SHANG Zhi(School of Earth Science and Resources,China University of Geosciences(Beijing),Beijing 100083,China;College of Field Engineering,Army Engineering University of PLA,Nanjing 210007,Jiangsu,China;China Fire and Rescue Institute,Beijing 102202,China)

机构地区：[1]中国地质大学(北京)地球科学与资源学院,北京100083 [2]中国人民解放军陆军工程大学野战工程学院,江苏南京210007 [3]中国消防救援学院,北京102202

出　　处：《地质通报》2024年第5期839-858,共20页Geological Bulletin of China

基　　金：云南省重点研发计划项目《云南省西部重点矿产成矿规律与分布预测研究》(编号:202303AA080006);国家自然科学基金项目《成矿系统自组织临界性与矿床定位预测》(批准号:41972312);《深部致矿异常信息提取与高精度数字找矿模型建立》(批准号:41672329);《超大型矿床成矿复杂性特征与成矿动力学机制探索》(批准号:41272365);国家重点研发计划课题《“三联式”数字找矿模型与深部定量成矿预测》(编号:2016YFC0600509)。

摘　　要：为厘定腾冲地块晚白垩世构造岩浆活动和花岗岩成矿意义,对小龙河花岗岩开展全岩地球化学、年龄和锶-钕-铅同位素研究。小龙河花岗岩由细粒淡色二长花岗岩和似斑状黑云母二长花岗岩组成,锆石U-Pb年龄数据指示它们的岩浆结晶年龄分别为67.0±1.0 Ma和68.5±1.6 Ma,辉钼矿Re-Os模式年龄分别为67.15±0.99 Ma和69.02±1.22 Ma,同为晚白垩世构造岩浆活动产物。锶-钕-铅同位素与主量和微量元素特征表明,细粒淡色二长花岗岩为S型花岗岩((^(87)Sr/^(86)Sr)_(i)=0.757~0.763);ε_(Nd)(t)=-8.89~-8.99,岩浆起源于中元古代(TDM2=1.59~1.60 Ga)上地壳富粘土硬砂岩部分熔融,其与小龙河锡-钨多金属矿床形成密切相关;似斑状黑云母二长花岗岩为I型花岗岩((^(87)Sr/^(86)Sr)_(i)=0.711,ε_(Nd)(t)=-8.72~-9.16),岩浆起源于中元古代(TDM2=1.58~1.62 Ga)下地壳富粘土硬砂岩重熔。腾冲地块晚白垩世小龙河花岗岩及其锡-钨矿化是中特提斯班公-怒江洋闭合后腾冲地块与保山地块碰撞-后碰撞阶段引发的岩浆活动与热液作用的产物。In order to determine the Late Cretaceous tectonomagmatic activities and the significance of granite mineralization in the Tengchong Block,this study applied the comprehensive methods of geochronology,Sr-Nd-Pb isotopic and whole-rock geochemical analyses to probe Xiaolonghe granites.The results show that the Xiaolonghe pluton is composed of fine-grained leuco-monzogranite and porphyritic-like biotite monzogranite.Zircon U-Pb chronological data indicate that their magmatic crystallization ages are 67.0±1.0 Ma and 68.5±1.6 Ma respectively,and the Re-Os model ages of molybdenite are 67.15±0.99 Ma and 69.02±1.22 Ma respectively,both of which are the products of the Late Cretaceous tectonomagmatic activities.The characteristics of Sr-Nd-Pb isotopes and major and trace elements show that the fine-grained leuco-monzogranite is S-type granite((^(87)Sr/^(86)Sr)_(i)=0.757~0.763,ε_(Nd)(t)=-8.89~-8.99),and the magma originated from the partial melting of clay-rich hard sandstone in the upper crust of Mesoproterozoic(TDM2=1.59~1.60 Ga),which is closely-related to the formation of Xiaolonghe tin-tungsten polymetallic deposit.The porphyritic-like biotite monzogranite is I-type granite((^(87)Sr/^(86)Sr)_(i)=0.711,ε_(Nd)(t)=-8.72~-9.16),and the magma originated from the remelting of clay-rich hard sandstone in the lower crust of Mesoproterozoic(TDM2=1.58~1.62 Ga).The Late Cretaceous Xiaolonghe granites and its tin-tungsten mineralization in the Tengchong Block are the products of magmatic activity and hydrothermal process caused by the collision or post-collision between the Tengchong Block and the Baoshan Block after the closure of the Meso-Tethys Bangong-Nujiang ocean.

关 键 词：腾冲地块 晚白垩世 锆石SHRIMP U-Pb定年 辉钼矿RE-OS定年 锶-钕-铅同位素地球化学 

分 类 号：P534.53[天文地球—古生物学与地层学] P588.121[天文地球—地质学] P597.3