摘要:
四川会东县“马鞍山组”的发现,是近年来康滇地轴中段前震旦系地质研究的重要进展,对提高基础地质研究,进一步寻找会理拉拉式铜矿具有重要意义。“马鞍山组”的剖面特征和岩石学研究表明,该组相当于古元古界河口群,岩性组合主要为海相喷发的钠质火山岩-细碧岩组合,蚀变强烈;火山岩岩石化学特征表现为富钠、贫钾,高钙、低铁,岩性偏中酸性,火山岩属碱性玄武岩系列。微量元素以Cu-Au-U-Zn-As-Sb-Fe-Cr-Co组合为特征。岩石的稀土总量低,轻重稀土比值大,为轻稀土富集型;具中等铕亏损和微弱铈亏损;其配分模式图呈向右倾斜的“Ⅴ”字型。
Abstract:
The discovery of the Presinian Ma' anshan Formation in the Huidong region, Sichuan marks an important progress in the research on the Presinian strata in the central part of the Kang-Dian Axis, especially in the prospecting and exploration of the Lala-type copper deposits in Huili, Sichuan. The Ma' anshan Formation consists of a suite of metamorphic sodic volcanic rocks-spilite associations, and may be correlated with the Palaeoproterozoic Hekou Group in Huili, Sichuan and Xiaoliukou Formation in Dongchuan, Yunnan. The volcanic rocks in the Formation that are assigned to the alkaline basalt series are characterized by:(1) higher contents of sodium and calcium and lower contents of potassium and iron; (2)REE association Cu-Au-U-Zn-As-Sb-Fe-Cr-Co; (3) relatively low ΣREE and relatively high LREE/HREE ratios indicating a LREE-enriched type of the rocks; (4) Eu and Ce depletion and a slightly rightward-dipping V-type distribution pattern.
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