摘要
西藏冈底斯成矿带拉抗俄斑岩铜钼矿床位于西藏特提斯构造域拉萨地块东段中南部,是近年来青藏高原地质大调查项目评价的重点矿床之一。本文在钻孔地质编录的基础上,采用辉钼矿Re-Os同位素测年技术,对拉抗俄铜钼矿床中8件产于花岗闪长斑岩中的辉钼矿进行定年,获得了拉抗俄矿床辉钼矿成矿年龄,辉钼矿Re-Os模式年龄为(13.20±0.20)Ma^(13.64±0.21)Ma,加权平均值为(13.38±0.15)Ma,等时线年龄为(13.12±0.44)Ma,代表了拉抗俄斑岩铜钼矿床的成矿时代,成矿作用发生于中新世。辉钼矿中Re的含量为343.6×10-6~835.7×10-6,平均557.8×10-6,指示其成矿物质中有幔源物质加入。拉抗俄斑岩铜钼矿床形成于印度—亚洲大陆碰撞造山带碰撞过程的伸展背景,其成矿年龄与冈底斯斑岩铜矿带东段中亚带众多斑岩-矽卡岩成矿系统年龄基本一致(17~12 Ma),相对于同一矿集区的驱龙、甲玛、邦铺斑岩-矽卡岩型铜多金属矿的成矿年龄小2~3 Ma,但其形成受控于相同的成矿地球动力学背景。
The Lakange porphyry Cu-Mo deposit in the Gangdise metallogenic belt of central and southern East Lhasa block within the Tethys tectonic domain is one of the key deposits in the Tibet Plateau geological survey project evaluation in recent years. ReOs isotopic dating technique was applied for determination of mineralization events, and eight molybdenite samples were analyzed for Re-Os isotopic compositions, with the model ages obtained ranging from（13.20±0.20） Ma to（13.64±0.21） Ma, and the isochron age being（13.12 ± 0.44）Ma which represents the metallogenic age of the Lakange porphyry Cu- Mo deposit, indicating Miocene.The Re content of the molybdenite is 343.6 × 10^-6-835.7×10^-6, with an average of 557.8 × 10^-6, suggesting that the metallogenic material originated from a source with mantle components. The Lakange porphyry Cu- Mo deposit was formed in a stretching background of India-Asia continental collision orogenic collision, the age（17-12 Ma） is identical with ages of numerous porphyryskarn mineralization systems in the eastern of Gangdise metallogenic belt, and is 2-3 Ma younger than ages of the porphyry-skarn copper polymetallic deposits in the same ore concentration area, such as Jiama, Qulong and Bangpu, with the formation controlled by the same metallogenic geodynamics setting.
出处
《中国地质》
CAS
CSCD
北大核心
2015年第2期570-584,共15页
Geology in China
基金
中国地质调查局地质大调查项目(12120114050501,12120113093700)
国家自然科学基金项目(41302060)
国家973项目(2011CB403103)共同资助
关键词
地球化学
RE-OS同位素测年
成矿时代
拉抗俄
冈底斯
西藏
geochemistry
Re-Os isotopic dating
metallogenic age
Lakange porphyry Cu-Mo deposit
Gangdise metallogenic belt
Tibet
