东秦岭燕山期中酸性小岩体成矿规律

Metallogenic Regularity of Yanshanian Intermediate-acid Small Intrusions in East Qinling

总结了东秦岭钼矿带中与中酸性小岩体有关的斑岩矽卡岩型钼矿床地质特征；对其成矿时空分布、成矿特征以及成矿物质来源进行讨论，归纳其规律性；通过分析大岩基与中酸性小岩体的主量、微量元素数据及形成年龄，探讨二者的关系。结果表明：东秦岭与岩浆作用有关的钼矿床形成时间可分为141～156、110～138 Ma两个阶段；第一阶段形成的矿床主要集中在东秦岭南部，第二阶段主要集中在东秦岭北部；矿床成矿年龄由西至东、由南至北总体上具有逐渐变新的趋势；钼矿床具有成群成带、分段集中展布的特点，并且这些集中段之间的距离基本相等；成矿岩体的岩浆演化系列对矿化元素组合有一定的控制作用，具体表现为岩浆酸性越强，钼成矿越有利；微量元素及同位素资料显示成矿物质主要来源于地壳，地幔物质作用并不明显；大岩基与小岩体有成因联系，系同源岩浆演化的产物，大岩基为小岩体提供了充足热量与物质来源，从而出现小岩体成矿的现象。

Geological characteristics of porphyry-skarn Mo deposits, which were related to intermediate-acid small intrusions in Mo ore belt of East Qinling,were summarized;spatio-temporal distribution, metallogenic characteristics and ore-forming material sources were discussed,and then the metallogenic regularity was discovered;compositions of major element and trace element and ore-forming age for large batholith and intermediate-acid small intrusions were analyzed,and the relationships of them were discussed.The results show that the ore-forming ages of East Qinling Mo deposits related to magmatism can be divided into two stages, 141-156 Ma and 110-138 Ma;the deposits forming in the former stage are mainly distributed in the south of East Qinling,and those in the latter stage are mainly distributed in the north;the ore-forming ages become younger gradually from west to east and from south to north;Mo deposits distribute in groups or belts,and concentrate on sections with equal distance;the combination of mineralization elements is controlled by the magmatic evolution series,and the＆amp;nbsp;more acid magma is,the better Mo mineralization is;data of trace element and isotope indicate that the metallogenic materials are mainly from the crust,and the effect of mantle are not obvious;a close genetic relationship is present between large batholith and small intrusions from the comagmatic evolution,and large batholith provides heat and material substance for small intrusions,so that there are large orebodies hosted in small intrusions.