塔西南缘沉积岩层控型铅-锌矿带区域构造控矿作用

新疆喀什—叶城一带层控沉积岩型铅-锌矿床沿着塔西南缘分布,受区域性的克孜勒陶断裂带控制,成矿作用与区域构造的时空演化密切相关。早古生代末,原特提斯洋封闭使昆仑地体拼贴于塔里木地台南缘,并沉积了一套泥盆系陆相碎屑岩。石炭纪中昆仑以南的古特提斯洋的活动,使塔里木南西边缘形成了陆内裂陷沉积（形成火山块状硫化物矿床）和克拉通边缘拗陷盆地沉积,后者形成了台地边缘相沉积的碎屑岩-碳酸盐,覆于泥盆系之上,构成本区铅-锌矿层位。随着古特提斯在石炭纪末向北消减,二叠纪塔里木地台南缘遭受南北挤压,三叠纪时期处于隆起剥蚀状态,造成盆地构造向隆起造山之间的构造转化。侏罗纪在推覆体前缘下盘形成含煤盆地,后缘出现拉张性盆地。在这种张性和压性构造应力的反复作用下,形成开放环境的宏观破裂构造;在褶皱变动和断裂变动过程,大气降水渗入地层,萃取成矿元素并在构造作用过程中迁移,在发生温度下降、含矿热液稀释、pH增高、氧逸度降低等介质条件变化时,成矿元素沉淀,形成改造作用明显的铅-锌矿床。

Regional Metallotectonics of the Lead-Zinc Deposits Zone in Southwestern Margin of the Tarim Plate

From Kashi to Yecheng, Xinjiang Province, the lead-zinc strata-bound deposit zones are distributed along the southwestern margin of the Tarim Plate, where ore deposits are controlled by the regional fault zone (Keziletao faults) which is correlated with the mineralization of deposits. In the early Paleozoic, Kunlun land mass put together with the south margin of the Tarim Platform because the Proto-Tethys ocean was closed down and sedimentary formation of Devonian continental facies clastic rock was formed. Because of the Paleo-Tethys ocean movements, a continental rift basin and a depression basin were formed in the margin of the Tarim craton in Carboniferous, the former had some VMS in rifting sedimentary stratum, the latter comprised lead-zinc deposits in clastic rock-carbonate host stratum that cover up the Devonian. Along with the Paleo-Tethys ocean's subducting erosion toward North in last Carboniferous, Tarim platform was undergone extrusions from south and north directions in Permian, west Kunlun was formed by orogenisis in Triassic, napping occurred in Jurassic making the coal-contained basin and the tensil basin were located respectively on the nappe-front and the nappe-back. Because of the reiteration between the tensil structural stress and the compressive structural stress, tectogenesis was formed that resulted in opening structural environment, folding, faulting. In these structural positions, the meteoric water filtered downward to the source-stratum extracting metallogenic elements from the source bed and then was heated; lead and zinc leached from the source bed migrated in forms of complex ion. During transport, metallogenic elements were precipitated in the compounding structural position when environment condition changed, e.g. temperature descended, hydrothermal diluted and pH value increased.