甘肃大水金矿田埃达克岩特征及成矿物质来源

The Geochemical Characteristics of Adakite Rock and the Source of Metallogenetic Material in Dashui Goldfield of Gansu Province

对大水地区印支晚期忠格扎拉岩体、忠曲岩体、格尔括合岩体的岩石学、岩石地球化学特征研究得出,SiO2含量为58.40%-63.95%,大于56%;A12O3含量为15.18%-16.66%,大于15%;MgO含量为1.31%-2.91%,小于3%;Sr含量为1 410×10-6-576×10-6,大于400×10-6;Y含量为12.2×10-6-15.3×10-6,小于18×10-6;Sr/Y比值42.57-85.52,大于40;（La/Yb）N比值为19.38-35.97,大于10,与典型埃达克岩特征基本一致。表明它们来自于基性下地壳部分熔融,埃达克岩的高温和高压萃取了大量Au元素,形成富金含矿热液,并沿构造通道上升沉积于三叠纪地层中,形成大水金矿田。

Study the petrology,geochemistry characteristics of the Zhonggezhala rock,Zhongqu rock and Geerkuohe rock which were become in the late indo-Chinese epoch. SiO2content is 58.40%~63.95%〉56%;A12O3content is 15.18%~16.66%〉15%;MgO content 1.31%~2.91%〈3%;Sr content 1410×10-6~576×10-6〉400×10-6;Y content is 12.2×10-6~15.3×10- 6〈18×10- 6;Sr/Y ratio is 42.57~85.52〉40;（La/Yb）Nratio is 19.38~35.97〉10.They have the same characteristics with the typical adakite ones that suggests they come from the situation of partial melting of under-crust.The adakite rock have high temperature and high pressure which can extracte a large amount of Au element and they form a abundence ore-bearing hydrothermal, rising along the tectonic channel deposition to the Triassic strata,formed the Dashui gold ore field.