摘要
南泥湖钼(钨)矿化复式花岗岩体,从早期到晚期由班状花岗岩类组成,它位于东秦岭地区。它们的钾长石具高温结构态,黑云母全为富镁型,副矿物主要是磁铁矿、磷灰石、榍石、锆石,但到晚期磁铁矿、磷灰石含量大大降低,而硫化物和萤石明显增长。这类花岗质岩石具有高 SiO_2、富 K_2O、铝近于过饱和,而低 MgO、CaO 及全铁;微量元素分析显示 Mo、Rb、Be、Th、U 及 F 富集,而 Sr、Ba 及过渡金属减少;稀土配分模式是平滑地向右倾斜,Eu 轻度亏损,重稀土有增高趋势;^(87)Sr/^(86)Sr 初始比值为0.7074—0.7080,年龄191—142M·Y·;δ^(18)O 为+8.9～+11.08‰;钾长石和黄铁矿铅同位素组成表明它们应属含放射性成因铅不高的异常铅。所有这些特征表明南泥湖花岗质侵入体属同熔型,并遭受到壳源物质混染及强烈结晶分异作用。古俯冲断裂带的重新复活,即华北地台南缘深断深裂带的活动,高钼背景值的厚度达40—45km 的硅铝质地壳,对木区印支晚期—燕山期岩浆产生及钼矿化起了极为重要的作用。
Located in the Eastern Qinling Mountains,the Nannihu molybdenum(tung- sten)-bearing composite granite body consists of,from early to late,porphy- ritic granites.Their K-feldspars have high-tomperature structure states and biotites are all of Mg-rich types.The accessory minerals are mainly magnetite, apatite,sphene and zircon,which show a considerable decrease of magnetito and apatite in the late phases,accompanied by a Significant increase of sulfides and fluorite. The granitic reeks are metaaluminous to peraluminous,rich in SiO_2 and K_2O,and poor in MgO,CaO and total Fe.Minor element analyses show α moderate enrichment of Mo,Rb,Be,Th,U and F,and depletion of Sr,Ba and transition metals.The REE patterns are smoothly inclined to the right with a slight depletion of Eu and a sendency of HREE increasing.The initial ^(87)Sr/^(86)Sr ratios range from 0.7074 to 0.7080 with ages from 191 to 142 m.y.. The ^(δ18)O are+8.9 to+11.08 per mil.Lead isotopes from K-feldspars and pyrite suggest a less radiogenetic character of anomalous lead sources. All these characteristics indicate that the granitic intrusives belong to syn- texis-typo,arc subjected to intensive contamination by crustal materials and strong differentiation in its crystalization process.It is suggcsted that the reativation of ancient subduction zones,i.e.the deep faults on the southern margin of the North China Platform,and the increased thtckness of sialic crust(40—45km)with a high molybdenum background have played important roles in magma generation and molybdenum mineralization in the Late Indosi- nian to Yanshanian orogeny of this region
出处
《南京大学学报（自然科学版）》
CAS
CSCD
1989年第2期333-346,共14页
Journal of Nanjing University（Natural Science）
基金
国家自然科学基金
关键词
花岗岩
钼
钨
河南
矿床
成因
granite
molybdenum (tungsten) ore deposit
syntexis type
stable isotope
Henan
