滇西北羊拉铜矿床里农—路农接合段构造地球化学与找矿预测

Tectono-Geochemical Features and Orientation Prognosis of Concealed Ores of Yangla Cu Deposit, Yunnan Province, SW China

羊拉铜矿床是金沙江构造带内的代表性铜矿床,其矿体产出明显受到断裂及层间破碎带控制。本文重点对羊拉矿床里农—路农接合段的3450 m中段进行了构造地球化学研究,R型聚类分析和因子分析表明:该中段断裂构造岩微量元素主要表现为地层岩石微量元素组合(Nb、Hf、Ta、Zr、Rb、V、Sc、Th、Cs、Be、Ga、Li、REE、Ba、Cr、U、Co、Tl、Ge、(Ag、In、Sn、Cu)),中-高温成矿元素组合(Cd、Pb、Bi、Ag、As、Sn、In、Sb、Cu、Zn、Ge、Tl、Mo、U、(Co、Ga))和地质意义不明元素组合(Ni、Sr),揭示羊拉矿床的形成可能经历了成矿前期成矿元素的初步富集和成矿期退夕卡岩化过程中成矿元素的沉淀成矿。构造地球化学异常的分布则指示了找矿预测靶区。

Yangla Cu deposit is the most representative deposit in Jinshajiang tectonic belt. Its orebodies are obviously controlled by fault and interformational fracture zones. This study focuses on the tectono-geochemistry of the junction area between Linong and Lunong ore sections, and shows three element associations, i.e., the strata rock elements （Nb, Hf, Ta, Zr, Rb, V, Sc, Th, Cs, Be, Ga, Li, REE, Ba, Cr, U, Co, T1, Ge and （Ag, In, Sn, Cu））, medium-high temperature ore-forming elements （Cd, Pb, Bi, Ag, As, Sn, In, Sb, Cu, Zn, Ge, Tl, Mo, U and （Co, Ga）） and elements with unclear geological implication （Ni and Sr）, based on cluster and factor analyses. This result indicates that Yangla orebodies formed mainly by retrograde skam alteration in the ore stage, and the ore-forming elements probably enriched in the pre-ore stage. Besides, the distribution of tectonic geochemical anomalies provides a target for further exploration engineering.