长江中下游成矿侵入岩的特征研究

STUDY ON CHARACTERISTICS OF INTRUSIVE BODIES RELATED TO METALLOGENY IN THE MIDDLE-LOWER YANGTZE AREA

长江中下游的侵入岩体，尤其是燕山期的侵入岩体面广量大．它们与区内铜、铁、金等矿产关系密切。本文通过对侵入岩体地质特征、岩石化学成分等对比研究后，总结出如下几个特点：1、侵入体主要形成时代为135-95Ma，自西向东有逐渐变新的趋势；2、与成矿有关者多数是复式岩体，与铜矿化有关的主要是燕山早期侵入岩，与铁矿化有关的则主要是燕山晚期侵入岩；3、多数岩体受到过中、下三叠统蒸发岩层（膏盐层）的同化混染；4、岩体含碱质高，在Na2O－SiO2关系图上显示出二者没有相关性；5、侵入体中的铜有可能提供部分铜矿床的物源；6、岩石化学成分上某些组分的对比研究表明，成铜矿与成铁矿岩体之间、成矿岩体和无矿岩体之间有一定程度的差异。

There are numerous intrusive bodies closely related to the formation of Cu, Fe and Au oredeposits, distributing widely in the Middle-Lower Yangtze area. They are petrographicallymedium-acidic to acidic, with various sise from 0. 2km2 to 200km2 exposed on the surface. Theauthors make a fairly thorough inquiry on the characteristics of these intrusive bodies, includ-ing their geological condition, petrochemistry, radiometric age, abundance of ore-forming ele-ments, etc, and sum up some criterin about the intrusbe bodies favorable and unfavorable tothe ore-formation. The followings are main points summed-up by the authors: (1)The main ages of the in-trusive bodies lie between 135Ma to 95Ma,and from west to east, there exists a tendency thatthey gradually become younger. (2)Most of the intrusive bodies related to ore-formation arecomposite-ones; (3)Most of them are suffered from contamilation -assimilation of the Triassic e-vaporite(especially anhydrite-halite) beds; (4)They are highly alkaline, on the Na2O vs SiO2dingram no correlationship is shown; (5)The Cu-abundance of intrusives related to ore-forma-tion might be one source of the Cu-ore deposits; (6)Coorelation between some major chemicalcomponents of the intrusive rocks reveals certain degree of discernig features between the intru-sive bodies favorable to Cu and Fe-ore-forming, as well as the features to distinguish those re-lated to Cu, Fe and Au ore-forming from that of the barren-