东疆沙泉子铜和铜铁矿床岩(矿)石地球化学研究与地质找矿前景

Geological exploration potentials and geochemical study on rocks and ores in Shaquanzi copper and copper-iron deposits,east Xinjiang.

沙泉子铜铁矿床安山岩类和闪长岩属偏碱性的钙碱性系列。(玄武)安山岩中含SiO_2在49．2%～59．97%,多数样品含铝在16．66%以上,具有高铝玄武安山岩特点,含Na_2O为2．19%～5．1%,K_2O为0．61%～3．2%,(Na_2O+K_2O)为5．32%～7．03%,Na_2O/K_2O值在1．07～8．36。本区安山岩类和闪长斑岩具有明显的Rb、Th-U-K、La-Ce、Pb和P正异常,富集大离子亲石元素(LILE)和轻稀土元素(LREE),具有明显的Ta-Nb、Sr负异常、中等Eu和Ti负异常,地球化学特征表明它们可能形成在活动大陆边缘上的陆缘岛弧构造背景中。这对于形成大型-超大型斑岩-夕卡岩型铜和铜铁矿床十分有利,深部隐伏矿床的找矿勘查是今后主攻方向。

Rock associations of andesites and diorite in Shaquanzi copper-iron deposits in East Tianshan Mountain in Xinjiang, China, are attributed to cal-alkaline, at close range of alkaline, volcanic rock series. The concentrations of SiO2 in andesites are from 49.2% to 59. 97%. Ranges of Na2O contents in andesites are 2. 19% to 5. 1% while K2O from 0.61% to 3. 2%,with the concentrations of Na2O and K2O from 5.32% to 7.03% ,and ratios of Na2O/K2O from 1.07 to 8.36. However, contents of Al2O3more than 16% in most andesite samples are similar to those in high-Al basalt. Furthermore, results of their geochemical properties showing that andesites and diorites are characterized by obvious positive anomalies of Rb, Th-U-K, La-Ce, Pb and P, obvious enrichment of LREE and LILE, noticeable negative anomaly of Ta-Nb and Sr, and moderate negative anomaly of Eu and Ti. Therefore, it can be inferred that the andesites and diorites related to copper and iron mineralization in the study area would possibly yield in the background of continental margin arc based on their observed geochemical natures, which is the most favorable geological background for skarn and porphyry Cu-Fe deposits. Exploration orientation can be focused on blinded skarn and porphyry Cu-Fe deposits at the depth with the high potential in the Shaquanzi area.