滇西北烂泥塘斑岩铜矿床原生晕异常结构研究

A study of primary halo anomaly structure of the Lannitang porphyry copper deposit in northwest Yunnan, China

关键词:  斑岩铜矿床  原生晕  异常结构  烂泥塘  滇西北

Key words:  porphyry copper deposit  primary halo  anomaly structure  Lannitang  northwestern Yunnan province

摘要:

烂泥塘矿床是云南香格里拉地区典型的斑岩型铜矿床，主矿体产于在地表以下300~500米，地表矿化带仅见脉状铜矿体和铜矿化体。为研究云南香格里拉烂泥塘斑岩铜矿床的原生晕异常结构，本文以异常结构模式理论和方法为基础，对矿床地表和坑道岩矿石样品开展了元素组合、异常特征和水平分带规律研究。结果表明，烂泥塘铜矿床地球化学系统的结构由成矿元素及其共伴生元素富集与亏损的原生晕组成，Cu和Mo的正异常占据了核心部位，Sc、Ti、V、Cr、W的负异常在空间上与Cu和Mo的正异常重合；S的正异常，Mn、Co、Zn、Cd的负异常出现在Cu、Mo正异常的边缘；Zn、Cd的正异常以及Ag、Pb、Hg、Sb的正异常在成矿带外围出现，Ag、Pb、Hg、Sb属于远矿指示元素；铜矿化带中CaO、K₂O、Na₂O的含量相对较低，为低背景或负异常，而其外围地区为中背景区或高背景区。研究结果显示，用Cu和Mo的几何平均值与Sc、Ti、V、Cr四个元素几何平均值的比值作为地球化学指标所圈定的衬值地球化学异常，能够更好地指示铜矿化体的空间位置。

Abstract:

The Lannitang deposit in Shangri-La county, Yunan Province, is a typical porphyry copper deposit. The main orebodies are distributed 300~500 meters below the surface and the vein-type orebodies develop in the surface. In order to decipher the primary halo anomaly structure, based on the theory and method of anomaly structure, the element association, anomaly characteristics and horizontal zonation of surface of tunnel rocks and ore samples of the deposit are conducted.Research results show that the structure of the geochemical system of the Lannitang copper deposit consists of a primary halo of enriched and depleted ore-forming elements and their associated elements. The positive anomalies of Cu and Mo occupy the ore primary haloes, and the negative anomalies of Sc, Ti, V, Cr and W coincide with the positive anomalies of Cu and Mo. Positive anomalies of S, and negative anomalies of Mn, Co, Zn and Cd appear at the edge of positive anomalies of Cu and Mo. The positive anomalies of Zn, Cd, Ag, Pb, Hg, and Sb appear in the periphery of the metallogenic belt. Ag, Pb, Hg, and Sb belong to distal indicator elements or supra ore halo elements. The contents of CaO, K₂O and Na₂O of the samples in the copper mineralization zone are relatively low, which belong to low background or negative anomaly, while the peripheral area belong to middle background area or high background area.It is suggest that the ratio of the geometric mean of Cu and Mo to the geometric mean of Sc, Ti, V and Cr can be used as a marker to delineate the contrast geochemical anomaly, which can better define the spatial location of copper mineralization bodies.