云南中部富碱斑岩成岩成矿的大地构造控制作用

TECTONIC CONTROL FOR PETROGENESIS AND METALLOGENESIS OF THE ALKALI RICH PORPHYRIES IN CENTRAL YUNNAN

云南富碱斑岩是地洼阶段的产物，受大地构造位置和构造单元的控制。富碱斑岩形成于源岩的分离熔融过程，因此源岩的形成和演化又间接地控制斑岩的成岩成矿作用。构造历史－动力分析表明，源岩的形成是构造长期演化的结果。早在太古代初本区就形成雏陆壳，而后晚太古代原陆壳活动阶段超基性岩浆侵入构成了富碱斑岩的源岩，同时富集了部分成矿物质。地洼激烈期深部流体上侵引发源岩的重熔，使成矿物质进一步富集成为含矿岩浆。不同岩区构造背景的微小差异，造成源岩的组成、深度和重熔程度的差异，直接影响富碱斑岩的岩石类型、化学成分、微量元素丰度和成矿作用，形成与富碱花岗斑岩有关的铜钼矿和与富碱正长斑岩有关的铅银矿两个成矿亚系列。

The alkali rich porphyries in Yunnan were formed by differentiation melting of the source rock in the Diwa stage.Their petrogenesis and metallogenesic were controlled by tectonic location,tectonic unit,and indirectly,by the formation and evolution of the source rock.Tectonic historic dynamic analysis shows that the formation of the source rock derived from tectonic evolution over a long period of time.As early as the beginning of Archaen era,an embryonic continental crust was developed in this region,intruded by ultrabasic magmas during the active stage of late Archean protocontinental crust,resulting in the source rock of the alkali porphyries in which some metallogenic materials were enriched.During the most active period of the diwa stage,fluids from the depth of the earth intruded out to cause the source rock to be remelted,by which metallogellic materials were further enriched and ore bearing magma was formed.Small differences of the tectonic basements among different rock provinces resulted in the differences of composition,depth and remelting degree of the source rock, which directly influenced the rock type, chemical composition,trace elements abundance and metallogenesis of the alkali rich porphyries,and formed two metallogenetic subseries:i.e.,the Cu Mo minenalization related to alkali rich granite porphyry and the Pb Ag mineralization related to alkali rich syenite porphyry.