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Tajik Basin and Southwestern Tian Shan, Northwestern India‐Asia Collision Zone: 1. Structure, Kinematics, and Salt Tectonics in the Tajik Fold‐and‐Thrust Belt of the Western Foreland of the Pamir
Tectonics ( IF 3.3 ) Pub Date : 2020-05-11 , DOI: 10.1029/2019tc005871
Łukasz Gągała 1, 2 , Lothar Ratschbacher 1 , Jean‐Claude Ringenbach 3 , Sofia‐Katarina Kufner 4 , Bernd Schurr 4 , Ralf Dedow 1 , Sanaa Abdulhameed 1 , Edouard Le Garzic 3 , Mustafo Gadoev 5 , Ilhomjon Oimahmadov 5
Affiliation  

Surface, seismic, and borehole data characterize the Neogene‐Recent Tajik fold‐and‐thrust belt of the Tajik basin. The basin experienced little sub‐detachment basement deformation, acting as a rigid foreland plate during the Pamir orogeny. The Tajik fold‐and‐thrust belt contains variable thin‐skinned structural styles, changing along and across strike as a function of the thickness and facies of Upper Jurassic evaporites, which constitute the basal detachment, and the influence of the surrounding thick‐skinned belts. The southern Tajik fold‐and‐thrust belt shows regularly spaced, salt‐cored, thrusted detachment anticlines that transition northward into imbricated thrust sheets grouped in oppositely verging stacks facing each other across a common footwall syncline. The width of the fold‐and‐thrust belt decreases northeastward accommodated by the Ilyak fault, a lateral ramp developed over a seismically active dextral basement fault. The southeastern Tajik fold‐and‐thrust belt contains massive subaerial salt sheets, formed by squeezing of preexisting salt diapirs. The salt‐tectonic domain originates from a local depocenter within the Late Jurassic Amu Darya‐Tajik evaporitic basin. Serial cross sections, integrating the structural geometries, yielded minimum thin‐skinned shortening oriented at ~90° to the India‐Asia convergence direction, increasing from ~93 km in the south to ~148 km in the center, and dropping to ~22 km in the northeast; total shortening—including the foreland buttress—is ≥170 km. Most of the shortening in the central‐southern Tajik fold‐and‐thrust belt occurred by hinterland‐vergent, high‐displacement back thrusts. The Pamir played a dominant role in the transfer of shortening to the sedimentary infill of the Tajik basin with the Tian Shan acting as a semi‐passive buttress.

中文翻译:

塔吉克盆地和西南印度-亚洲碰撞带的天山西南部:1.帕米尔西部前陆的塔吉克褶皱冲断带的结构,运动学和盐构造

塔吉克盆地新近纪的塔吉克褶皱冲断带是地表,地震和钻孔数据的特征。在帕米尔造山运动中,该盆地几乎没有次分离基底变形,在前陆板中起着刚性作用。塔吉克褶皱冲断带包括多种变薄的构造样式,它们沿着上冲和横穿走向随上侏罗统蒸发岩的厚度和相的变化而变化,而上侏罗统蒸发岩构成了基底脱离,并受到了周围厚皮带的影响。塔吉克南部的褶皱-冲断带显示出规则间隔的盐芯逆冲冲断背斜,向北过渡成带褶皱的逆冲冲断片,成对并叠置,形成一个相对的,彼此相对的,跨过一个共同的底壁向斜线的叠层。褶皱冲断带的宽度向东北方向减小,由伊利亚克断层带提供,伊利亚克断层带是在地震活跃的右旋基底断裂上形成的侧向斜坡。塔吉克东南部的褶皱冲断带包含大量的海底盐薄板,是通过挤压先前存在的盐底壳而形成的。盐构造域起源于侏罗纪晚期Amu Darya-Tajik蒸发盆地内的一个局部沉积中心。系列截面结合了结构几何形状,产生了最小的薄皮起酥油,起伏方向与印度-亚洲收敛方向成90°,从南部的93 km增加到中心的148 km,然后下降到22 km在东北;包括前陆支撑在内的总起伏≥170km。塔吉克中南部褶皱冲断带的大部分缩短是由腹地到边缘的,高位移的反推力。帕米尔(Pamir)在起酥油向塔吉克盆地沉积填充物的转移过程中发挥了主导作用,而天山则是半被动的支撑。
更新日期:2020-05-11
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