摘要
本文从稀土元素地球化学角度,对金堆城—黄龙铺地区花岗岩类形成机制及其与钼矿化关系进行研究。结果表明:花岗岩类地质体起源于地壳岩石的深熔作用,其中金堆城花岗斑岩是岩桨体系内部热重扩散效应的产物,而石家湾斑岩体只是老牛山岩基的分枝脉。成岩方式制约着斑岩型钼矿床的规模和品位。岩桨期后热液蚀变可造成原岩稀土总量和轻稀土元素含量降低,但重稀土元素保持相对稳定,因此,岩石稀土元素地球化学可成为评价含钼岩体的重要标志。
This paper presents the systematic analytic result of rare earth elements (REE) from the granitic rocks associated with two large molybdenum deposits, which may have provided some special information for the Origin and evolution of the granitic rocks in the area.1. The REE patterns of the Laoneushan granitic batholith and Shijiawan graniteporphyry exhibit a rightward declined curve with a faint negative Eu anomaly. The REE have content of 207. 11—268.52ppm, HREE/LREE=0.03-0.06, and δEu=0.45-0.55. The Laoneushan batholith and the Shijiawan graniteporphyry, showing a similar chondrited normalized REE curve, are produced at the same evolution stage by magma derived mainly from crustal remelting. The Shijiawan graniteporphyry is a branch of the Laoneushan batholith.2. The Jinduicheng graniteporphyry bordered with the ribbon rocks is petrochemically characterized by high content of F, K, Mo and HREE and depletion in Ba, Sr, Ca and LREE. The REE values of this rock range from 117.10 to 140.20ppm with HREE/LREE=0.13-0.15 and δEu=0.46-0.47. The REE pattern of the graniteporphyry is presented as a rightward declined curve with negative Eu anomaly. This unique REE pattern can only be interpreted by thermogravitation diffusion of magma, which may be used for evaluation of molybdenum-bearing granitoids.3. The variation of LREE and HREE in the altered granitoids in a great degree is a result of the multiphase hydrothermal alteration. With increase of F in ore-forming solution, the LREE content in the altered granitoids becomes depletion, while the HREE still maintains unchangeably.These suggestions mentioned above are consistent with the result of the petrographic and isotope studies.
出处
《岩石矿物学杂志》
CAS
CSCD
1989年第1期24-33,共10页
Acta Petrologica et Mineralogica
关键词
含钼花岗岩类
稀土元素
地球化学
jinduicheng
molybdenum—bearing granitoids
rare earth elements
geochemistry
thermogravitational diffusion
