洛南—豫西中酸性小岩体宏观特征及与钼矿床成矿的关系

THE RELATIONSHIP BETWEEN MACROSCOPIC CHARACTERISTICS OF THE MEDIUM ACIDIC ROCK MASS AND THE MOLYBDENUM DEPOSIT MINERALIZATION IN LUONAN-WEST OF HENAN PROVINCE

岩体出露面积一般较小,大于1 km^2的占24%,小于1 km^2的占76%,尤以出露面积为0.1~0.5 km^2者居多。小岩体一般具有上小下大的现象,平面上呈椭圆形、楔形、不规则的椭圆形等,多数为近等轴状、透镜状、岩脉状及岩墙状等;剖面上呈陡倾斜的岩株状、蘑菇状、岩筒、岩管等。东秦岭到大别山东西方向绵延800 km,大小中酸性侵入岩体176个,成矿岩体所形成的以7个超大型钼矿床为代表,自陕西华县金堆城(向东)→河南栾川南泥湖→河南汝阳东沟→河南信阳光山千鹅冲→安徽金寨沙坪沟,无论是钾-氩法、铀-铅法、铼-锇法所作出的同位素年龄测定结果,成岩时代是从222~112 Ma,绝大部分为燕山期成矿,极个别为印支期成矿。也就是从老到年轻,相应的成矿时代也是从老到新,两者本身相差就不大,可以视作同一时期产物。中酸性小岩体特别是酸性小岩体、强酸性小岩体是钼矿床的成矿母岩,虽然小岩体成岩及其出露面积非常小,但其形成的钼矿床则非常巨大,这就是斑岩型钼矿床地质工作者常说的"小岩体成大矿"的原因。

The surface area of rock mass is generally small,of which 24% is greater than 1 km2,and 76% is less than 1 km2,most of the exposed area is 0. 1 to 0. 5 km^2. The small rock mass has a phenomenon that bottom is bigger than top,the plane is elliptical,wedge-shaped,irregular ellipse,most of which are the near-equiaxial,lenticular,lithotype,and rocky wall,etc. The profile is of a steeply inclined rock plant shape,mushroom row,rock tube and so on. From the east Qinling mountains to the Dabie mountain range for 800 km,the number of acid intrusive rock is 176,the metallogenic rock formation is represented by 7 supermassive molybdenum deposits. From Jinduicheng in Huaxian county of Shaanxi province（ east）,to Nannihu in Luanchuan county of Henan province,to Donggou in Ruyang county of Henan province,to Qianechong in Guangshan county of Henan province,to Nannihu in Luanchuan county of Henan province,to Shapinggou in Jinzai county of Anhui province,the results of isotopic age determination of potassium-argon,uranium-lead and rhen-osmium were determined from 222 to 112 Ma in the age of diagenesis,and most of them were in Yanshan period. It is from the old to the younger,the corresponding mineralization age is also from the old to the new,the two themselves are not different,can be seen as the product of the same period. Medium acid small rock mass,especially acid and strongly acid rock mass of rock mass is molybdenum deposit ore-forming parent rock,although small rock diagenesis and its outcropped area is very small,but the formation of the molybdenum deposit is very huge,this is ＂small intrusions into mine＂that porphyry molybdenum deposit geological workers often say.