两广云开大山地区开合旋回转换与金成矿作用的关系

Relationship between gold mineralization and opening-closing cycle transition in the Yunkaidashan area ,South China

开合构造是总结地壳或岩石圈水平扩张和压缩运动规律的一种大地构造观点,开合构造旋回代表了地壳或岩石圈的汇聚、离散和平移等宏观构造运动形式,以及由此引发的壳幔物质相互作用、沉积作用、变形与变质作用、熔融或重熔的岩浆活动、构造流体运移的过程。因此,开合构造运动促使地球表层成矿物质活化、迁移、聚集和成矿。对于多数内生金属矿床而言,特别是贵金属矿床,其主成矿期发生在开合构造由压缩向扩张快速过渡转变的时期,油气等非金属矿产则形成于扩张时期。成矿与容矿主断层多数都属于压性或压扭性向张性转换的复杂断层。云开地区自新元古代以来经历了多旋回的开合构造运动,产生了一系列不同期次、不同类型的金银矿床。

Opening-closing tectonics is a tectonic theory dealing with horizontal crustal or lithospheric movement,such as extension and constriction.The opening-closing cycle represents such forms of macro-scopic tectonic movements as crustal or lithospheric convergence,divergence and translation,and such pro-cesses as crust-mantle interaction,sedimentation,deformation,metamorphism,melting or re-melting of magmas and structural fluid migration.Consequently,opening-closing tectonic movement gives impetus to remobilization,concentration and mineralization of ore substances on the earth's surface.For most endo-genic ore deposits,especially precious metal deposits,their main metallogenetic epoch takes place in a pe-riod of rapid transition from constriction to extension of opening-closing tectonics,whereas nonmetallic de-posits such as oil/gas accumulations originate in an extension period.Most metallogenic and ore-hosting faults belong to complex faults that transform from compressive or compresso-shear fault to tensile faults.Polycyclic opening-closing tectonic movements had taken place in the Yunkai area since the Neoprotero-zoic,and as a result a series of gold-silver deposits with different types were formed in different periods.