摘要
新疆西天山吐拉苏地区发育的与中酸性火山-次火山岩有关的浅成低温热液-斑岩型金多金属成矿系统,是在晚古生代北天山洋向南部伊犁-中天山板块之下俯冲消减的活动大陆边缘背景下形成的。赋矿的大哈拉军山组火山岩及相关的次火山岩形成于晚泥盆世-早石炭世,岩石总体显示钾质-高钾质、准铝质-过铝质的钙碱性-高钾钙碱性特征,其轻稀土富集、Eu负异常显著、大离子亲石元素富集和高场强元素亏损等,均显示出俯冲带岛弧岩浆作用的特点。阿希(低硫型)和京希-伊尔曼得(高硫型)浅成低温热液金矿床以及塔北、吐拉苏铅锌矿床,受大哈拉军山组火山岩中的断裂破碎带以及具高孔隙度和渗透率的岩性控制;塔吾尔别克斑岩型金矿化主要受斑岩体及火山岩中的断裂和裂隙系统控制,并很可能存在浅成低温热液型金矿化的套合或叠加。硫、铅、碳、氧同位素特征显示,成矿物质主要来自岩浆所分泌的热液和/或赋矿的火山-次火山岩。根据成矿系统形成后的保存和变化情况,认为在吐拉苏盆地内剥蚀程度较低的地区,浅成低温热液型金铅锌矿床具备良好的保存条件,同时在其深部还应注意寻找斑岩型或矽卡岩型铜金矿床。
The epithermal and porphyry Au-polymetallic mineralization system associated with intermediate to acidic volcanicsubvolcanic rocks in the Tulasu area of the West Tianshan,Xinjiang formed during the southward subduction of the North Tianshan Ocean under the Yili-Middle Tianshan plate in the Late Paleozoic. The ore-hosting intermediate to acidic volcanic and related subvolcanic rocks of the Dahalajunshan Formation are of Late Devonian to Early Carboniferous. They typically have high contents of K_2O,are metaluminous to peraluminous,and belong to calc-alkaline to high-K calc-alkaline series. With significant negative Eu anomalies,the rocks are enriched in LREE and large-ion lithophile elements and depleted in high field strength elements,indicating subduction-related arc magmatism. The epithermal Au deposits, including Axi（ low-sulfidation） and Jinxi-Yiermande（ highsulfidation）,and Pb-Zn deposits（ e. g.,Tabei and Tulasu） are controlled by fracture zones and the stratigraphic horizons with high porosity and permeability in the Dahalajunshan volcanic rocks. The porphyry-type Au mineralization at Tawuerbieke is controlled by faults and fractures in porphyries and associated volcanic rocks and was probably overprinted or telescoped by epithermal Aumineralization. Isotopic geochemistry of S,Pb,C and O indicates that the ore-forming materials were derived from magmatic hydrothermal fluids and / or the host volcanic-subvolcanic rocks. Based on the analysis of preservation conditions of the mineralization system,it is suggested that epithermal Au,Pb and Zn deposits are well preserved in the areas with a low denudation and that porphyryand skarn-type Cu-Au mineralization should have a good potential for prospecting at the deep sites of these areas.
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
2016年第5期1283-1300,共18页
Acta Petrologica Sinica
基金
国家自然科学基金项目(41572062
U1303292)
中央返还两权价款资金综合研究项目(Y15-1-LQ04)
国家科技支撑计划项目(2011BAB06B02-02)联合资助
