山东玲珑岩体脉岩地球化学特征及其意义

Geochemical Characteristics and Significance of Inner Vein Rocks in Linglong Rock Mass, Shandong Province

在胶东地区广泛分布的中生代侵入岩中发育有玲珑–招风顶、巨山–龙门口和崂山–大珠山三条脉岩带,脉岩成分十分复杂,几乎包括了所有的岩浆岩类型,从超基性–基性到中酸性以及碱性脉岩皆有出露,主要有煌斑岩、闪斜云斑岩、辉绿玢岩、辉长岩脉、石英闪长玢岩、闪长玢岩、花岗闪长斑岩、石英二长斑岩、花岗斑岩、二长斑岩、正长斑岩、石英脉和碳酸盐岩脉等,它们是不同构造期和不同时代的综合产物。本文通过对招远石门郭家–谢家庄一带产于玲珑花岗岩中的脉岩进行岩石化学成分、微量元素、稀土元素地球化学研究表明,其化学成分与区内同类型的石英二长闪长岩相比,SiO2含量稍微偏高,而其它成分含量均偏低;脉岩微量元素以亲硫元素和富亲石元素为特征,亲铜元素Ag、W、Pb、Zn明显偏高,As、Mo、Cu偏低;亲铁元素Co、Ni偏高;在大离子亲石元素中,Li、Be、Rb、Sr、Ba、V大多呈富集状态,而其它元素均呈亏损状态。稀土总量ΣREE平均为168.50 ×10?6,ΣLREE平均157.57 ×10?6,ΣHREE平均10.93 ×10?6,ΣLREE/ΣHREE为15.79,轻重稀土间分馏较强,脉岩稀土曲线平缓右倾,轻、重稀土元素分馏程度均较低,从δEu值平均大于1.10说明区内脉岩是由地壳深部较基性的岩石经重熔作用或基性岩浆分异作用形成。根据区域玲珑花岗岩和脉岩资料综合分析,脉岩与玲珑花岗岩来源于不同的物质源区,脉岩是由地壳深部较基性的岩石经重熔作用或基性岩浆分异作用形成的,玲珑花岗岩是原地半原地交代型花岗岩,脉岩的形成是区域伸展作用结果的产物。胶东地区基性–中酸性脉岩形成的构造环境与金矿有着内在的成因联系,中基性脉岩中有一期与金矿形成关系密切。

Widely distributed in Jiaodong region development in Mesozoic intrusive rocks and Linglong- Zhaofengding, Jushan-Longmenkou and Laoshan-Dazhushan vein rock belt, vein rock composition is very complicated, including almost all the types of magmatic rocks from the ultrabasic, basic to acidic and alkaline vein rocks are exposed, lamprophyre, flash inclined cloud porphyry, fai green porphyrite, gabbro vein, quartz diorite porphyrite, diorite porphyrite diorite porphyry, granite, quartz monzonitic porphyry, granite porphyry, monzonitic porphyry, is long porphyry, quartz vein and carbonate vein, they should be a combination of different periods and different era. In this paper, the geochemical studies on the chemical composition, trace elements and rare earth elements of the vein rocks produced in linglong granite in the area of guojia-xiejiazhuang, shimen, zhaoyuan, show that compared with the quartz diorite of the same type in the area, the content of SiO2 is slightly higher, while the content of other components is lower. Trace elements in vein rock are characterized by sulfur-loving elements and lithophile elements, while Ag, W, Pb and Zn are obviously on the high side, while As, Mo and Cu are on the low side. Iron loving elements Co and Ni are relatively high;among the large ionic lithophile elements, Li, Be, Rb, Sr, Ba and V are mostly in the enriched state, while other elements are in the deficit state. Total rare earth ΣREE averaged 168.50 ×10?6, ΣLREE on average 157.57 ×10?6, ΣHREE average 10.93 ×10?6, ΣLREE/ΣHREE is 15.79, fractionation between light and heavy rare earth is stronger, vein rocks rare earth curves gently to the right, light and heavy rare earth elements fractionating degree is low. The fact that the average δEu value is greater than 1.10 indicates that the vein rocks in this area are formed by remelting or magmatic differentiation of relatively basic rocks deep in the crust. On the comprehensive analysis of the regional linglong granite and ground data, vein rocks and the linglong granite from different material source area, vein rocks are formed by remelting or magmatic differentiation of relatively basic rocks in the deep crust, exquisite is stuck half in-situ metasomatic type granites, the formation of vein rocks is the product of area extending action results. The tectonic environment of the basic-intermediate-acid vein rocks in Jiaodong area is closely related to the formation of gold deposits.