喀什凹陷构造演化与砂岩型铀成矿关系

运用构造地质学与现代水成铀矿理论,分析喀什凹陷的构造特征与构造演化过程,并研究构造演化与铀成矿的关系,认为喀什凹陷作为一个相对独立的次级构造单元,经历了中新生代以来的多次扩张拗陷和被动挤压上隆的构造演化过程,为砂岩型铀成矿创造了条件,并决定砂岩型铀矿床的形成、改造与保存.晚三叠—中侏罗世扩张拗陷,沉积巨厚含煤碎屑岩建造,形成初始铀源;晚侏罗世挤压上隆,沿山前遭受风化剥蚀,形成古层间氧化带和铀矿化;早白垩—渐新世快速沉降,沉积巨厚层陆相与海相碎屑岩,使古层间氧化带和铀矿化得以保存;渐新世以来大规模上隆,沿山前快速剥蚀,破坏了早期的铀矿化,铀元素重新分配.表明以层间氧化带砂岩型铀矿化在中下侏罗统含煤碎屑岩建造中不甚发育,或者说不可能形成较大的层间氧化带或铀矿床,而下白垩统则形成了与油气次生还原作用有关的铀矿床,如巴什布拉克矿床.

RELATION OF TECTONIC EVOLVEMENT AND SANDSTONE TYPE URANIUM DEPOSITS FORMING IN KASHI SAG

The paper analyses tectonics character and process of it evolvement,and researches the relation of it tectonics evolvement and uranium depsosits forming. The paper thinks that Kashi sag is a secondary unit of southwestern depression of Tarim Basin,western China. It Experienced dilatation and compression uplift since Mesozoic and Cenozoic,created uranium mineralization conditions,and determined the fomation,alteration,and preservation of sandstone type uranium deposit. Late triassic-middle jurassic dilation sag,deposit huge-heavy layer elastic rocks.It come into being the initial uranium source . Late Jurassic,the sag compression uplift along yamasaki,and the stratums was airslake and denudation,forming paleo interlamination oxidized zone and uranium mineralization;Early Cretaceous-Oligocene fast sedimentation,deposit huge-heavy layer continental facies and marine facies clastic rock,made the paleo interlamination oxidized zone and uranium mineralization can be reserved. Since Oligocene large-scale uplift,along the yamasaki,the stratums was fast denudation,break down the early uranium mineralization,made the uranium element redistributed. So interlamination oxidized zone sandstone type uranium mineralling is developed in Middle and lower Jurassi,it means Middle and late Jurassic can not engender interlamination oxidized zone or uranium deposit;However there is an uranium deposits(BaShiBuLaKe unranium deposits)in lower Cretaceous and it forming is relation to oil and gas.The paper thinks that it likely to be most layer in the next working stage.