西昆仑山前东段新生代褶皱冲断带及其锥形楔机制

西昆仑山前东段的和田-柯克亚构造带与塔里木盆地内的麻扎塔格构造带相距为200 km,两者近似平行,遥相对应,麻扎塔格构造带是和田-柯克亚构造带的前沿,山前挤压变形量沿古近系阿尔塔什组膏泥岩向北传递约200 km到麻扎塔格,形成往北东逆冲的断层传播褶皱,在盆地腹部表现为一条显著的北西向地形隆起。因此,整个西昆仑山前东段新生代褶皱冲断带宽约为270 km,长约为220 km,由和田-柯克亚构造带、麦盖提斜坡和麻扎塔格构造带组成。中部近200 km的麦盖提斜坡内没有明显构造变形,且整个褶皱冲断带的锥形楔角度远小于活动造山带的临界锥形角,说明古近系底部阿尔塔什组膏泥岩以及新生代沉积体的形态是这个褶皱冲断带锥形楔形成的主控原因,膏泥岩控制了锥形楔的顶面坡度α基底构造形态及上覆沉积楔形体则控制了锥形楔的底部滑脱层倾角β。

Cenozoic fold and thrust belt in eastern section of the piedmount of west Kunlun and its taper wedge mechanics

Hetian-Kekeya structural belt is away from Mazartagh structural belt in Tarin Basin about 200 km,they are almost parallel.Mazartagh structural belt is leading edge of Hetian-Kekeya structural belt,the Cenozoic compressive deformation of Hetian-Kekeya along the gypsum-mudstone of Aertashi Formation slide to Mazartagh and transformed to Fault-propagation-folds,leaded obvious topographic rise in Tarim Basin.So,the Cenozoic fold and thrust belt in eastern section of the piedmount of west Kunlun is 270 km in width and 220 km in length,it consisted of Hetian-Kekeya structural belt,Maigaiti slope and Mazartagh structural belt.Maigaiti slope is almost 200 km in length,but it hasn't obvious deformation,and taper wedge angle of this fold and thrust belt is less than those active orogenies,it's means the gypsum-mudstone of Aertashi Formation and the shape of Cenozoic deposition are key factors,the gypsum-mudstone controls α of taper wedge,the shapes of basement and dispositive wedge control β of taper wedge.