科研之友
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摘要
Granodiorite intrusions (from south to north, namely, Lunong, Linong, Jiangbian, and Beiwu pluton) and diabase dyke are spatially and temporally associated with the copper mineralization in Yangla copper deposit, Deqin County, Yunnan, Southwest China. They commonly distributed in Yangla copper deposit. To constrain the age of a number of major granodioritic plutons and diabase dyke related to Cu mineralization, U-Pb analysis of zircon was conducted. Hafnium isotope data was also acquired through laser-ablation multicollector ICPMS analysis of zircon, with the aim of gaining insight into the age and nature of the source region of the plutons. Four age groups have been identified from five igneous samples: Middle Triassic (238 similar to 239Ma, Linong pluton, Lunong pluton), Middle-Late Triassic (228Ma, Jiangbian pluton), Late Triassic (222Ma, diabase dyke) and Late Triassic (214Ma, Beiwu pluton). While the Re-Os isochron age for molybdenite from Linong Cu ore body was 228Ma to 230Ma. These data suggest that the formation of different granodiorite plutons by multi-stages of gushing emplacement of the magmas. The ore-forming of Yangla copper is developed in Middle Triassic. Hafnium analysis shows the Triassic granodiorites having negative and positive and variable epsilon(Hf)(t) values (-4.3 similar to +2.4) and Mesoproterozoic (1.1 similar to 1.5Ga) depleted-mantle model ages, which is interpreted to reflect the derivation from an isotopically heterogeneous, mixing source of mantle with crust source. The source region for these magmas may be tentatively correlated with the Mesoproterozoic material of Yangtze Craton, which has been suggested to underlie the Yangla; however, further work is necessary to demonstrate this suggestion.
- 出版日期2010-6
- 单位云南省地质调查局; 中国地质科学院矿产资源研究所
