摘要
对栗木水溪庙矿区泥盆系上统融县组灰岩的碳氧同位素进行了研究,该地区灰岩的碳氧同位素组成可提供隐伏花岗岩隆起及其相关流体的重要信息。受隐伏花岗岩侵入驱动的流体与上覆融县组灰岩发生反应的温度在110℃左右,流体的初始同位素组成为δ18OSMOW=-3‰,δ13CPDB≤-7‰,反应的水岩比值(w/r)可能小于5。这种岩浆水与大气降水的混合流体与围岩之间的水岩反应使得地表灰岩的δ18O和δ13C值降低,产生负异常。研究表明,围岩的δ18O值降低受反应的水岩比值和温度控制;δ13C值降低主要与反应的水岩比值有关。反应的温度越高,w/r值越大,灰岩的碳氧同位素负异常越明显。因此,水溪庙矿区地表出露的碳酸盐地层中的碳氧同位素变化可在地球化学勘查中用于指示下伏花岗岩岩脊的隐伏位置。
Studies on the carbon and oxygen isotopic compositions of the Upper Devonian Rongxian Formation limestone in Shuiximiao mine district,Limu area show that the carbon and oxygen isotope composition characteristics can provide important information about hidden granite upwarps and the fluids involved.The temperature of the interaction between the fluid driven by granite intrusion and the overlying Rongxian Formation limestone was about 110℃.The carbon and oxygen isotopic compositions of the fluids wereδ 18 OSMOW=-3‰,δ 13 CPDB≤-7‰,and the water-rock ratios（w/r）were less than 5.This water-rock interaction between mixed fluids of magmatic water and meteoric water and wall-rock limestone decreased the carbon and oxygen isotopic composition values of surface limestone,forming negative anomalies.The higher the temperatures and water-rock ratios（w/r）of the interaction,the more obvious the negative anomalies of the carbon and oxygen isotopes.Research shows that for the oxygen isotopes,the decrease of limestoneδ 18 O values was controlled by the water-rock ratios（w/r）and temperatures,and the decrease of limestoneδ 13 C values was mainly related to the water-rock ratios（w/r）.Therefore,the carbon and oxygen isotopic composition variation of outcropped carbonate rocks in Limu mining area can be used to indicate the position of underlying hidden granite upwarps for geochemical exploration.
出处
《高校地质学报》
CAS
CSCD
北大核心
2009年第3期417-428,共12页
Geological Journal of China Universities
基金
中国地质调查局调查项目"南岭重要金属矿床成矿机理研究和找矿潜力预测"(1212010632100)资助
