云南东川播卡—拖布卡地区含金石英脉的^(40)Ar/^(39)Ar年龄及其地质意义  

^(40)Ar/^(39)Ar Dating of Quartz from Auriferous Quartz Veins of Boka-Toubuka Area, Dongchuan, Yunnan and Its Geological Implication

作　　者：应汉龙[1] 刘和林 李志伟 

机构地区：[1]中国科学院地质与地球物理研究所,北京100029 [2]云南省地勘局第二地质大队,文山653000 [3]云南省储量评估中心,昆明610011

出　　处：《地质论评》2004年第2期196-202,共7页Geological Review

基　　金：国家重点基础研究项目(编号G1999043200)的成果

摘　　要：东川播卡—拖布卡地区金矿是云南中部“康滇地轴”中、新元古界昆阳群岩石中发现的第一个金矿,位于接近三江褶皱带的扬子地块西缘。原生金矿化为含金黄铁矿石英脉、细脉、网脉和浸染状石英黄铁矿。四个不同产状的典型含金石英脉的石英的阶段加热^(40)Ar/^(39)Ar 年龄谱为马鞍形,坪年龄值范围为 59.93±0.21～42.38±0.32 Ma,最小视年龄范围 59.30±4.30～41.90±1.8 Ma,与计算坪年龄加热阶段相应数据的^(40)Ar-^(39)Ar 等时线年龄范围 59.34±0.17～41.25±0.10 Ma,三者基本一致。等时线年龄计算的相关系数大于 0.998,^(40)Ar/^(36)Ar 初始值范围为 293.17±1.40～295.2±0.43,与尼尔值一致。石英形成后没有受到后期地质作用。石英样品的坪年龄没有受到过剩氛和氩丢失的影响,可以作为石英和金矿的年龄。金矿形成于新生代第三纪古新世和始新世初的陆内拉张地质构造环境中。Gold ores in the Boka-Tuobuka area, Dongchuan, Yunnan are the first gold discovery in Mesoproterozoic-Neoproterozoic Kunyang Group in 'Kang-dian' axis in the central Yunnan, tectonically in western margin of Yangtze block close to Sanjiang (means three rivers: Jinsha River, Nujiang River and Lancang River) folded belts. Range of stage-heating 40Ar/39Ar plateau ages of four quartz samples from typical gold-bearing quartz veins is 59. 93±0. 21 Ma to 42. 38 ± 0. 32 Ma, that of the lowest 40Ar/39Ar apparent ages is 59. 30 ± 4. 30-41. 90± 1. 8 Ma and that of 40Ar-39Ar isochron ages of corresponding heating stages for the plateau ages is 59. 34 ± 0. 17-41- 25 ± 0. 10 Ma. These values are almost identical. Correlation coefficients for isochron ages are >0. 998 and range of initial 40Ar/36Ar values is 293. 17 ± 1. 40-295. 2 ± 0. 43, which is very close to 295. 5. The quartz has not been affected by post-mineralization geological motion. Neither surplus argon nor argon loss influence the plateau ages of the quartz and therefore the plateau ages can represent ages of the quartz and gold mineralization. The gold mineralization in the Boka-Tuobuka area took place in Paleocene and early Eocene, intra-continental extensional geotectonic environment.

关 键 词：成矿时代 石英 金矿床 云南 ^40Ar/^39Ar年龄谱 

分 类 号：P597[天文地球—地球化学]