与超大型锡矿床相关的花岗岩熔融实验结果及其成矿学意义

EXPERIMENTAL RESULTS OF MELTING OF GRANITE IN RELATION TO SUPERLARGE TIN DEPOSITS AND THEIR METALLOGENIC SIGNIFICANCE

在６００～８５０℃，７５～３００ＭＰａ条件下对与个旧超大型锡（多金属）矿床密切相关的个旧复式花岗岩体，和与大厂长坡－铜坑、龙头山２个超大型锡（多金属）矿床密切相关的龙箱盖复式花岗岩体进行系统的实验研究。其结果表明，不仅形成这２个著名复式花岗岩的岩浆性质及岩浆的演化规律有明显的差异，而且形成同一个复式岩体的岩浆的性质及其演化特点亦有明显的不同。个旧花岗岩浆中，形成老卡岩体的岩浆固相线位置低，具有共结岩浆性质，而形成马松、龙岔河岩体的岩浆固相线位置稍高，具有近共结花岗岩浆的特点；形成龙箱盖复式花岗岩的岩浆在性质上有所不同，其固相线位置较高。这些研究结果表明，２类超大型锡矿床的成矿花岗岩浆的性质、起源与演化规律存在明显的差异，这些差异可能是造成这２个复式花岗岩体在超大型锡矿床形成过程中所起的作用不同的重要原因之一。

Systematical experiments have been carried out for the Gejiu granite complex in relation to the Gejiu superlarge tin-polymetallic deposits and the Longxiangai granite complex relating to the Changpo-Tongkeng and the Longtoushan supper large tin-polymetallic deposits under conditions of 600￣850℃ and 75￣300 MPa.The experimental results indicate not only that the properties and evolution features of magmas forming the two granite complexes are different,but also that the magmas forming each intrusive in the same granite complex have some significant differences in properties and evolution characteristics.For the Gejiu granite complex,the position of solidus of the magma forming the Laoka granite body is low,and the magma possesses properties of a eutectic granitic magma;the positions of solidi of the magmas forming the Masong granite body and Longchahe granite body are higher,and the magmas have features of subeutectic granitic magma.For the Longxiangai granite complex,the properties of the granitic magmas are different from the ones of the Gejiu magmas,and the positions of their magmas,solidi are highest.The differences in the properties,geneses and evolution regularities of the oreforming granitic magmas resulting in formation of tin deposits might account for why the two granite complexes could play a apparently different role in the formation of the two superlarge tin deposits.