Sedimentary characteristics and geological significance of Upper Triassic Huangshanjie Formation in Kuqa Depression
Objectives:The Upper Triassic Huangshanjie Formation in the Kuqa depression,Tarim Basin,is a set of strata with source,reservoir and cap coexistence,which is a potential target of oil and gas exploration in the future.However,at present there is a lack of detailed research on its sedimentary characteristics,which is not conducive to understanding the evolution of paleogeography.Methods:Based on careful observation of the sedimentary phenomena on the multiple outcrop sections,the sedimentary characteristics were analyzed in detail and the revealed geological significance were studied.Results:①In Huangshanjie Formation,the deep-up lower cycle is formed with the First and Second Members,the incomplete deep-up middle cycle is formed with the Third Member,and the upper cycle changing from shallow→ deep → shallow is formed with the Fourth Member;② the First and Third Members of the Huangshanjie Formation,formed with pebbly coarse clasts,are the sedimentary responses to two episodes of intense uplift in the provenance area during the Indosinian Movement;③ event deposits caused by floods,earthquakes,etc.are developed in the Huangshanjie Formation;④ in the 4th Member,the dark mudstone is the rapid deposition of sufficient provenance under high accommodation;⑤ after the deposition of the Third Member of the Huangshanjie Formation,regional tectonic uplift and tectonic—sedimentary transformation occurred,and the provenance also became quasi-plain;⑥ there is a certain hiatus between the 4th Member and the underlying 3rd Member of Huangshanjie Formation and the overlying Taliqik Formation.Conclusions:The sedimentary characteristics of the Huangshanjie Formation in the Kuaq Depression are controlled by the tectonic evolution,forming three sedimentary cycles with different characteristics,and event sedimentary responses have occurred.There are hiatus both inside and at the top of the Huangshanjie Formation.
sedimentary characteristicssedimentary evolutionbraided-river deltameandering river deltaHuangshanjie FormationTriassicKuqa DepressionTarim Basin
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