西藏改则县多不杂斑岩型铜金矿床勘查模型

西藏改则县多不杂斑岩型铜金矿床是近年来由西藏地质五队在班公湖-怒江成矿带发现的一个具超大型规模的铜金矿床,系继玉龙、驱龙、雄村、甲玛等超大型铜矿床之后的又一重大找矿突破,也是班公湖-怒江成矿带的第一个超大型斑岩铜金矿。多不杂斑岩型铜金矿产于早白垩世花岗闪长斑岩及其与早侏罗世曲色组变长石石英砂岩的接触带,区域成矿地质背景得天独厚,岩浆活动频繁,为斑岩型铜金矿的成矿提供了有利的条件。该矿床具有典型的斑岩型铜矿的蚀变分带,在斑岩体及其围岩由内向外形成钾硅化带、粘土化带、青磐岩化带、角岩化带。地球物理勘查表明,含矿斑岩区为低视电阻率、高视极化率异常区;1:1万土壤测量显示,斑岩铜矿产于高背景区,并与强度高、浓集中心明显的Cu、Au、Ag、Mo元素的化探综合异常相对应,在空间上尤其与Cu、Au异常分布高度吻合。1:5万水系沉积物测量表明,Au、Ag、As、Sb、Cu、Pb、Zn元素高异常常与激电探测异常吻合。本文通过综合研究初步总结建立了适合本区地质-地球物理-地球化学综合勘查模型。通过勘查和初步评价,在矿区外围新发现了波龙、拿顿、拿若、赛角、尕尔勤、铁格龙、地堡那木岗等斑岩矿(床)点,并最终形成多龙斑岩型铜金矿集区,对该区域找矿起到指导作用。

An Exploration Model of the Duobuza Porphyry Cu-Au Deposit in Gaize Country, Northern Tibet

The Duobuza porphyry Cu-Au deposit of Gaize country in Tibet,newly-discovered by the Geological Brigade No.5 of Tibet,is a giant copper-gold deposit in the Bangong Lake-Nujiang metallogenic belt.It is another significant prospecting breakthrough after the Yulong,Qulong,Xiongcun and Jiama deposits,and also the first super-large porphyry Cu-Au deposit located in the Bangong Lake-Nujiang metallogenic belt.The Duobuza porphyry Cu-Au deposit occurs in the contact zones between Early Cretaceous granodiorites and Upper Jurassic Quse Formation degenerative quartzose arkose.This deposit possesses favorable metallogenic background where active magnetic activity provided good conditions for porphyry copper-gold mineralization.It presents typical alteration zoning characteristics of porphyry copper,showing potassium silication,beresitization,muddy zones and hornfels from porphyries to wall rocks.Geophysical survey shows that the ore-bearing porphyry has a low polarization rate and high apparent resistivity.The 1:10000 soil survey data reveals porphyry copper deposits are commonly discovered at high Cu and Au equatorial anomaly areas,corresponding to high strength and distinct concentration centers of Cu,Au,Ag and Mo geochemistry comprehensive abnormal areas.Furthermore,it especially coincides with the Cu and Au abnormal position.The 1:50000 stream sediment geochemical anomalies reveal that high anomalies of Au,Ag,As,Sb,Cu,Pb and Zn always coincide with the anomalies by induced electric detection.This paper establishes a geology-geophysics-geochemistry exploration model based on integrated studies.Through prospecting and initial evaluation,we discovered other porphyry deposits such as the Bolong,Nadun,Naruo,Saijiao,Ga’erqin,Tiegelong,Dibaonamugang porphyry deposits in the surrounding areas,forming the Duolong porphyry copper-gold concentration.This may provide guidance significance for regional prospecting in this region.