铜厂花岗闪长斑岩体的形成机制

Discussion on the formation mechanism of the tongchang granodiorite porphyry

江西德兴铜厂大型斑岩铜矿床的成矿岩体,是以花岗闪长斑岩为主体的杂岩体,是在燕山期由脉动岩浆作用形成的,岩性从早期偏酸性向晚期偏基性演化。区域地质、岩体地质及岩石学、岩石地球化学的研究表明,它是由原先侵入于地壳中的深源火成物质和部分沉积物质,在燕山运动的脉动断裂作用影响下,不断产生部分熔融作用和侵入作用形成的。岩浆形成部位是在上部地壳或康腊面附近;脉动断裂活动是形成岩浆以及诱发岩浆上侵的主要因素;岩浆是随分熔作用的加强而逐渐转向偏基性;铜、硫等成矿物质是由成浆原始岩石在部分熔融过程中释放分馏而富集的。

The ore-related igneous body of the Tongehang large porphyry copper deposit, Dexing County, Jiangxi province,is a complex composed largely of granodiorite porphyry,and was formed by impulsive magmatism in Yanshanian time. The rock evolved in composition from weakly acidic in the early stage to weakly basic in late stage. Studies on regional geology, igneous geology and petrology and petro-geochemistry reveal that the stock was formed by continuously partial melting of the deep-source igneous materials originally emplaced in the crust as well as part of the sediments at the same place, and by repeatedly intrusion of the magmas derived thereof under the influence of impulsive fracturing of the Yansha nian movement, The position where the magmas were formed is in the up per crust or in the vicinity of the Conrad discontinuity; impulsive fract uring is the main stress leading to the formation of magma and inducing the upward intrusion of magma; the magma gradually became weakly basic in composition with the strengthening of partial melting; Cu, S and other ore materials were liberated, fractionated and concentrated during partical melting of the magma-forming primary rooke,