库车坳陷东部晚白垩世古隆起及构造应力场恢复

库车坳陷东部具有丰富的油气资源,其构造变形机制与南天山造山带密切相关。综合采用露头共轭节理及白垩系残余厚度分布,分析了库车坳陷东部晚白垩世古隆起特征及构造应力场属性。吐格尔明、克孜勒努尔沟、库车河、卡普沙良河、吉迪克以及库车河西6条剖面的共轭节理分析表明,库车坳陷东部新生代构造挤压应力为NNW-SSE向,而中生代的构造挤压应力为NE-SW向。原型盆地恢复显示,库车坳陷白垩纪的沉积中心大致位于大北1井―吐北2井―克拉2井一线,且发育秋里塔格―新和―牙哈―提尔根古隆起带,白垩系原始沉积厚度总体上北厚南薄。在晚白垩世区域抬升剥蚀的构造背景下,坳陷东部受压隆升遭受剥蚀,白垩系残余厚度减薄,呈西厚东薄的趋势。位于坳陷东部的吐格尔明背斜在石炭纪―三叠纪为一个长期存在的继承性沉积古隆起,晚白垩世进一步隆升形成构造古隆起,背斜周缘的白垩系残余厚度进一步减薄。吐格尔明背斜和背斜周缘白垩系残余厚度等值线以及库北1井和库车河剖面周缘白垩系残余厚度等值线的长轴方向均为NW-SE向,进一步证实了库车坳陷东部晚白垩世的构造应力为NE-SW向。库车坳陷东部晚白垩世古隆起与构造应力场属性主要与特提斯造山带中地体增生和拼贴作用导致的特提斯北缘盆地群中发生的区域性抬升有关。

The palaeo uplift of Late Cretaceous and tectonic stress field reconstruction of the eastern Kuqa Depression

The eastern Kuqa depression is rich in oil and gas resources, and its structural deformation mechanism is closely related to the Southern Tianshan orogenic belt. Based on conjugate joints in outcrops and distribution of residual Cretaceous, the characteristics of the palaeo uplift and palaeo stress field property in the eastern Kuqa depression at late Cretaceous were analyzed. Conjugate joints analysis in the Tugerming, Kezilenuer, Kuqa river, Kapushaliang river, Jidike and western Kuqa river outcrops indicates that the compressive stress direction of eastern Kuqa depression was NNW-SSE at Cenozoic while NE-SW at Mesozoic. The recovery of prototype basin demonstrates that the sedimentary center of Kuqa depression was roughly along well Dabei 1 -Tubei 2-Kela 2, and developed Qiulitage-Xinhe-Yaha-Tiergen palaeo uplift belt at Cretaceous, which leads to thick residual Cretaceous in the north and thin residual Cretaceous in the south. Under the background of regional uplift and denudation at late Cretaceous, the east of Kuqa depression lift and been denudated due to tectonic compression, which results in the thinning of residual Cretaceous, and therefore the residual Cretaceous is thick east and thin west. The Tugerming anticline in the eastern Kuqa depression was a long standing inherited sedimentary palaeo uplift at Carboniferous-Triassic, and became a tectonic palaeo uplift by further uplift at late Cretaceous, which leads to further thinning of residual Cretaceous around the anticline. The long axis strikes of the Tugerming anticline and residual Cretaceous isolines around the anticline and Well Kubei 1 and Kuqa river outcrop are all NW-SE, which further confirms that the palaeo tectonic stress direction was NE-SW at late Cretaceous in the eastern Kuqa depression. The late Cretaceous uplift and tectonic stress field in the eastern Kuqa depression is primarily related to the regional uplift in the north margin of Tethys basin group caused by the hyperplasia and collision of geological terrain in the Tethys orogenic belt.