帕米尔中部含刚玉变质杂岩

刚玉矿化位于穆兹科尔(Muzkol)变质杂岩体内.该杂岩体近纬向展布在帕米尔中部阿尔卑斯褶皱带的东部,属蓝晶石—夕线石型阿尔卑斯带变质杂岩.地质填图发现有4个变质岩区:低绿片岩相(白云母—绿泥石)区,高绿片岩相(黑云母—绿泥石)区,绿帘石—角闪岩相区,角闪岩相区,而刚玉矿化集中在绿帘石—角闪岩及周围角闪岩相变质体内的交代蚀变区.交代蚀变区内的刚玉矿化通常与层面或 大型同倾斜褶皱轴面平行.根据母岩成分可将含刚玉交代岩分为3类,分别位于方解石大理岩内、白云石大理岩内及片岩内.在大理岩内,刚玉成粉红色,与白云母、黑云母、方柱石、钙长石、正长石、金红石、电气石、磷灰石、黄铁矿及石墨共生,以Al含量变化大和Fe含量低为特点.在片岩内,刚玉成蓝色,与黑云母、绿泥石、电气石及磷灰石共生各种类型的含刚玉岩石均以K,Na,Mg的含量较高而Fe含量较低为特点.根据P—T—XCO2图估算含刚玉交代岩的稳定范围在610℃

CORUNDUM-BEARING METASOMATITES OF CENTRAL PAMIR

Corundum mineralization is localized in the Muzkol metamorphic complex, which stretches in sub-latitude direction in the eastern part of the Alpine fold zone of Central Pamir. Muzkol complex is the Alpine zonal metamorphic complex of the kyanite-sillimanite type. Corundum manifestations are concentrated in the zones of metasomatic alteration in the limits of the epidote-amphibolite and adjoining part of the amphibolite metamorphic facies. Depending on the composition of the host rocks three types of corundum-bearing metasomatites may be distinguished: in calcite marbles, in dolomite marbles, in schists. In marbles pink corundum is present in association with muscovite, biotite, scapolite, anorthite, albite, rutile, tourmaline, apatite, pyrite and graphite. Schists contain bluish corundum in association with biotite, chlorite, tourmaline, apatite. Conditions of stability for corundum-bearing metasomatites are estimated on the base of the P-T-XC02 diagram within the limits of 610C< T< 660C, 4.5 kPa< Ptot < 6 kPa, 0.16 < XCO2 < 0.46. Numerical modeling by the method of multiwave flowing step reactor shows that the main process of corundum-bearing metasomatites formation is the desilication of marbles containing silicate materials or seams of terrigenous rocks by deep-seated fluids undersaturated by Al and Si.