The Paleocene Hangu formation: A key to unlocking the mysteries of Paleo-Tethys tectonism
The Paleocene Hangu formation: A key to unlocking the mysteries of Paleo-Tethys tectonism
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DOI：
10.1016/j.marpetgeo.2023.106508
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发表时间：
2023-09-22
影响因子：
4.2
通讯作者：
Luan，Xiwu
中科院分区：
文献类型：
--
作者：
Bilal，Ahmer;Yang，Renchao;Luan，Xiwu
巴基斯坦北方上印度河盆地Yadgaar剖面古新统汉沽组沉积岩是综合野外、岩相学和沉积学研究的对象。本研究的目的是提高我们的沉积环境，相变的理解，以及构造作用对所调查的沉积相成因的影响。更好地理解上述因素之间的复杂关系将澄清区域构造驱动是否部分控制或完全控制沉积过程。研究结果表明，汉沽组由铝土矿相、砂岩相、煤相和灰岩相组成。铝土矿形成于潮湿-极潮湿气候条件下的岩溶环境，化学风化作用强烈。薄煤层表明泥炭地环境形成于潮湿的热带气候。亚长石砂岩相、砂屑岩相和长石砂岩相分别标志着三角洲（亚湿润）、海岸-近海岸（湿润-湿热）和高能河流（干旱-半干旱）沉积环境。最后，泥灰质石灰岩的出现表明沉积作用发生在沿海半咸水环境中的浅海碳酸盐台地上。沉积物的相变提供了证据，从大陆逐渐过渡到海洋条件下的研究领域，再加上情节海进和海退周期，以及不断变化的气候和地貌条件。因此，所有这些变化都是由古特提斯洋内俯冲作用的影响控制和塑造的。通过目前的工作，这一进展有助于理解构造沉积力学，即，区域构造-沉积过程如何影响沉积层序的形成。
The sedimentary rocks of the Paleocene Hangu Formation in the Yadgaar Section of the Upper Indus Basin in northern Pakistan, have been the subject of an integrated field, petrographical, and sedimentological investigation. The goals of this study are to improve our understanding of the sedimentary environment, facies shifts, and the impact of tectonism on the genesis of the investigated sedimentary facies. A better understanding of the intricate relationships between the aforementioned factors will clarify whether the regional tectonic drive has partial control over or complete command of the sedimentation processes. The results of this study shows that the Hangu Formation consists of four facies: bauxite, sandstone, coal, and limestone. The bauxite deposits formed in a karst environment with severe chemical weathering in a humid to extremely humid climatic setting. Thin coal laminae indicate a peatland environment that formed within a humid tropical climate. Sub-arkose, arenite, and arkose sandstone facies mark deltaic (sub-humid), coastal–near shore (humid to hot-humid), and high-energy fluvial (arid to semi-arid) sedimentary environments, respectively. Finally, the occurrence of marly limestone points towards deposition on a shallow marine carbonate platform within a coastal-brackish environment. The facies shift of the sediments provides evidence for a gradual transition from continental to marine conditions within the study area, together with episodic transgressive and regressive cycles as well as changing climatic and geomorphological conditions. In consequence, all these changes are controlled and shaped by the effects of Paleo-Tethys tectonism during the Indo-Eurasian intra-oceanic subduction. This advancement through the current work helps in understanding tectonic-sedimentary mechanics, i.e., how regional tectono-sedimentological processes influence the formation of sedimentary sequences.