地质论评2017，Vol.63Issue(1)：61-74,14.DOI:10.16509/j.georeview.2017.01.006
广西栗木花岗岩岩浆气—液分异作用与成矿作用
Liquid—Gas Fractionation and Mineralization in the Limu Granites, Guangxi
摘要
Abstract
The Limu granites in Guangxi Province,rich in tin—tungsten deposit and tantalum—niobium deposit,are typical rare-element granites in South China.There are some puzzling occurrences of silicate rocks that are intimately coexisted and show contrasting textures in the granites.On the basis of petrography study,we apply thermodynamic analysis to these abnormal phenomena to understand the evolution of magma.The resuhs constitute the chain of evidence of magmatic evolution,verify with each other and correspond to the results of tests from thermodynamic equation.The study result illustrated that the liquid—gas fractionation is the most important mechanism in the formation of silicate rocks and deposit.As water-rich magma moves up to emplace,large scale liquid—gas fractionation takes place,the liquid separates into a new liquid phase and bubbles.Rapid reduction of P(H2O) in the liquid system raises the solidus and liquidus temperatures abruptly,and causes the new liquid phase crystallizing quickly to form porphyritic texture rock.Some of the bubbles (vesiculation) rise to the top and upper parts of the magma chamber,and the others escape from the magma into the overlying rock,then they burst and separate into residual vapor and residual liquid phases.Later,the residual vapor can cause autometasomatism of granite,or crystallize to form pegmatite.The residual vapor is the main carrier transporting ore-forming metals too.The mineralization of altered granite-type tin—niobium—tantalum deposit is related to the autometasomatism of granite led by residual vapor,and the mineralization of veins-type tin—tungsten deposit is related to the crystallization of residual vapor in voids.关键词
稀有金属花岗岩/岩相学/热动力学/岩浆演化/气—液分异/成矿作用/栗木/华南Key words
rare-element granite/petrography/thermodynamics/magmatic evolution/liquid—gas fractionation/mineralization/Limu/South China引用本文复制引用
梁磊,张玲,颜自给,董业才..广西栗木花岗岩岩浆气—液分异作用与成矿作用[J].地质论评,2017,63(1):61-74,14.基金项目
This study was financially supported by Project of Superseding Resources Prospecting in Guangxi Limu Tin Deposit (No.200645091) (from Project of Superseding Resources Prospecting in Crisis Mine in China) and Geological Survey Project of Tin—Tantalum—Niobium Mine in Guangxi Limu (No.[2010] 604) (from Mineral Exploration Project in Guangxi Province).本文为全国危机矿山接替资源勘查项目“广西恭城县栗木锡矿接替资源勘查”(编号:200645091)、广西区大规模地质找矿项目“广西恭城县五福锡钽铌矿普查”(编号:[2010]604)的成果. （No.200645091）
