与角岩有关的矿床主要类型及其对深部找矿的意义

Major Type of Hornfels-related Deposits and Application for Deep Prospecting

作为热接触变质的产物,角岩在石墨、硅灰石、红柱石等变质成因非金属矿床和各种金属矿床以及油气矿藏均可见,但对其调查研究成果并不多。在文献综述的基础上,结合在南岭、冈底斯等重要成矿带地质找矿的实践,通过对与矿产资源有关的角岩广义概念的界定,概述了与角岩有关的各主要类型矿床的地质特征,如石墨、硅灰石、红柱石等变质成因非金属矿床,钨、钼、铁、铜、铀、金、铅锌、锡、银和稀有金属矿床以及油气矿藏;举例阐述了近年来角岩发育矿区深部找矿中的新突破,如江西淘锡坑钨矿,广西大厂铜坑至拉么一带的锡多金属矿床,西藏甲玛铜多金属矿,云南老厂银铅锌矿、羊拉铜矿、雪鸡坪铜矿等矿区;讨论了角岩型矿床成矿预测的准则。结果表明:矿区和矿田大比例尺深部预测时应注意岩石组合、干湿关系、封闭与开放体系、岩石物性和分带性、原岩岩性及其空间配置关系;区域性中、小比例尺成矿评价时应注意角岩的空间分布、岩石学特征与矿产资源的专属性关系等;利用角岩预测隐伏岩体的应用前景广泛,在深部找矿中具有现实意义。建议加强角岩与成矿关系的理论研究,对以往地质填图工作中发现的"角岩化带"可重新评价其与成矿的关系。

Hornfels,as one product of heat contact metamorphism with fine granular metacryst texture and massive structure,exists widely in the metamorphic nonmetallic deposits of graphite,wollastonite and andalusite,and various metal deposits and oil-gas reservoir.However,the research and investigation on hornfels are insufficient.Based on the literature review,combined with the geological prospecting practice in Nanling and Gangdese metallogenic belts,the general concept of hornfels related to mineralization was defined;the geological features of major types of hornfels-related deposits were summarized,i.e.W,Mo,Fe,Cu,U,Au,Pb-Zn,Sn,Ag and rare metal deposits,the metamorphic nonmetallic deposits of graphite,wollastonite and andalusite,and oil-gas reservoir;new advances of deep prospecting in mining districts with hornfels in recent years were presented,i.e.Taoxikeng W mine in Jiangxi,tin-polymetallic deposits in Dachang of Guangxi,Jiama Cu polymentallic mine in Tibet,and Laochang Ag-Pb-Zn mine,Yangla Cu mine and Xuejiping Cu mine in Yunnan;standards for metallogenic prediction of hornfels-related deposits were discussed.The results showed that the rock assemblage,humidity content,seal-open system,hornfels physicality and zonation,lithology of original rock and its spacial distribution should be considered during the deep prediction for blind rock body at the large scale of district and ore field;the space distribution and the specificity relationship between petrologic feature and ore minerals should be considered in the metallogenic assessment at the regional medium and small scales;the application of hornfels for blind rock body is promising and significant for deep prospecting.Study on the relationship between hornfels and mineralization should be strengthened,and the relationship between the hornfelization zone found in previous geological mapping and mineralization should be revaluated.