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黔西北地区已发现中-小型矿床(点)100余处,它们的分布严格受到区域性构造的控制,是研究大规模成矿流体运移途径的理想场所。本文在系统收集前人资料的基础上,对黔西北地区铅锌矿床成矿流体的起源与运移方向进行了深入的探讨。天桥硫化物的(87Sr/86Sr)200 Ma为0.7118~0.7130(均值0.7123,n=7),筲箕湾闪锌矿的(87Sr/86Sr)200 Ma为0.7113~0.7129(均值0.7120,n=5),青山闪锌矿及其包裹体的(87Sr/86Sr)200 Ma为0.7099~0.7126(均值0.7111,n=8),杉树林闪锌矿的(87Sr/86Sr)200 Ma为0.7107~0.7115(均值0.7113,n=7),银厂坡热液方解石和矿石全岩的(87Sr/86Sr)200 Ma为0.7108~0.7255(均值0.7152,n=8)。可见,受NE向构造控制的银厂坡矿床最富放射性成因Sr,而受NW向构造控制的矿床其Sr同位素组成从NW的天桥向SE的杉树林呈现逐渐降低的趋势。经与地幔、峨眉山玄武岩、赋矿地层沉积岩和基底岩石的Sr同位素组成特征对比,发现黔西北地区铅锌矿床的成矿流体来源或流经了富放射性成因Sr的基底岩石。综合以往地质、地球化学资料,本文认为黔西北地区铅锌矿床成矿流体的运移方向至少可分为3组,即起源或流经基底岩石的富金属成矿流体沿NE或近EW向构造运移,起源或流经赋矿地层沉积岩的富金属成矿流体沿NW向构造向SE向运移,而起源于赋矿地层沉积岩的富硫成矿流体则沿NW向构造向NW方向运移。多组流体大规模运移过程中在有利的构造空间发生流体混合,形成矿(化)体,应加强构造流体复(耦)合部位的成矿和找矿相关研究工作。
More than 100 medium- and small-sized deposits (spots) have been found in northwestern Guizhou. Their distribution is strictly controlled by the regional structure and is an ideal place for studying the migration pathways of large-scale ore-forming fluids. Based on the systematic collection of previous data, the paper explores the origin and migration of the ore-forming fluid in the lead-zinc deposits in northwestern Guizhou. The (87Sr / 86Sr) 200 Ma of the flyover was 0.7118-0.7130 (mean 0.7123, n = 7), and the 87Sr / 86Sr 200 Ma of Shaufen Wan was 0.7113-0.7129 (mean 0.7120, n = 5) (87Sr / 86Sr) 200 Ma of Qingshan sphalerite and its inclusions ranged from 0.7099 to 0.7126 (mean 0.7111, n = 8), and the 87Sr / 86Sr 200 Ma of the cedary forest ranged from 0.7107 to 0.7115 (mean 0.7113, n = 7). The (87Sr / 86Sr) 200 Ma of calcite and ore from the Yinchangpo hydrothermal solution is 0.7108 ~ 0.7255 (mean 0.7152, n = 8). It can be seen that the Sr isotopic composition of the Yinchangpo deposit controlled by the NE tectonism is the richest radiogenic element in the deposit controlled by the NW structure and the Sr isotope composition of the deposit controlled by the NW trending structure shows a decreasing trend from the flyover of the NW to the fir plantation of SE. Comparing with the Sr isotope composition of the mantle, the Emei basalt, the ore-bearing sedimentary rocks and the basement rocks, it is found that the ore-forming fluid in the lead-zinc deposits in the northwestern Guizhou Province originated or flowed through the basement rocks rich in radiogenic Sr. Based on the previous geologic and geochemical data, this paper argues that the migration direction of the ore-forming fluids in the lead-zinc deposits in the northwestern Guizhou Province can be divided into at least three groups, that is, the metallogenic fluids originating or flowing through the basement rocks are formed along the NE or near EW direction The metallogenic fluids that migrate, originate or flow through the sedimentary rocks of the ore-bearing formations migrate to the SE direction along the NW direction while the sulfur-rich ore-forming fluids that originate from the sedimentary rocks of the ore-bearing formations migrate NW-wise along NW structures . During the large-scale migration of multiple fluids, fluid mixing takes place in the favorable structural space to form ore bodies. Research work related to metallogenesis and ore prospecting at the complex (coupling) part of the fluid should be strengthened.