摘要
西昆仑木吉西北地区产有一种特殊类型的碳酸盐质岩体。该岩体内发育围岩的捕虏体,并与围岩呈港湾状侵入式接触,其边部发育穿入围岩的岩枝和岩脉,这些地质特征表明这种碳酸盐质岩体实为火成碳酸岩岩体。该碳酸岩在地球化学上具有富CaO、CO2,贫SiO2、TiO2、K2O、Na2O、Al2O3、FeO、Fe2O3、MnO、P2O5的特征,各种稀土和微量元素的含量和稀土元素的总量均很低,轻重稀土元素比值较小,稳定同位素δ18O、δ13C高,显示壳源碳酸岩的成因特点,明显不同于幔源成因的碳酸岩。据上述特征判断,该碳酸岩为沉积碳酸盐岩在内侵幔源岩浆作用下发生熔融而形成的壳源成因的火成碳酸岩。
A special type of carbonate intrusion occurs in the northwest of the Muji Area, West Kunlun Mountains, Xinjiang. Xenoliths of country rocks occur in the intrusion and are in embayed intrusive contact with the country rocks, with their edges occurring as apophyses and dikes penetrating into the country rocks, suggesting that this type of carbonate rocks is actually igneous carbonatite. Geochemically, the carbonatite is characterized by enrichment in CaO and CO2 and depletion in SiO2, TiO2, K2O, Na2O, Al2O3, FeO, Fe2O3, MnO and P2O5, and have very low REE, trace element and total REE contents, low LREE/HREE ratios and higher δ^18O and δ^13C values, indicating a crustal origin; so it is notably different from the carbonatite of mantle-derived origin. According to the above-mentioned characteristics, the carbonatite is igneous carbonatite of crustal origin which formed by melting of marine sedimentary carbonate rocks due to the intrusion of mantle-derived magma.
出处
《地质通报》
CAS
CSCD
北大核心
2007年第12期1665-1670,共6页
Geological Bulletin of China
基金
中国地质调查局<1:25万英吉沙幅
库尔干幅区域地质调查>项目(编号:200313000002)资助
关键词
西昆仑山
火成碳酸岩
地质
地球化学特征
壳源成因
West Kunlun Mountains
igneous carbonatite
geological and geochemical characteristics
crustal origin
