古地理学报 ›› 2025, Vol. 27 ›› Issue (3): 541-559. doi: 10.7605/gdlxb.2025.063

• 岩相古地理学及沉积学 •    下一篇

准噶尔盆地南缘晚侏罗世风成—冲积沉积特征及古环境恢复*

关旭同1(), 王国荣2, 孙潇2, 张亚楠1, 初亚男1, 任楚梵1, 吴朝东1()   

  1. 1 北京大学造山带与地壳演化教育部重点实验室,地球与空间科学学院,北京 100871
    2 核工业二一六大队,新疆乌鲁木齐 830011
  • 收稿日期:2025-01-21 修回日期:2025-02-13 出版日期:2025-06-01 发布日期:2025-05-29
  • 通讯作者: 吴朝东,男,1965 年生,教授,博士生导师,主要从事沉积学和储层地质学研究。E-mail: cdwu@pku.edu.cn。
  • 作者简介:

    关旭同,男,1996年生,博士后,主要从事沉积学研究。E-mail:

  • 基金资助:
    *新疆维吾尔自治区重大科技专项(2024A03003)

Sedimentary characteristics of the Late Jurassic eolian and alluvial deposits in southern margin of Junggar Basin and palaeoenvironment reconstruction

GUAN Xutong1(), WANG Guorong2, SUN Xiao2, ZHANG Ya'nan1, CHU Ya'nan1, REN Chufan1, WU Chaodong1()   

  1. 1 Key Laboratory of Orogenic Belts and Crustal Evolution,Ministry of Education,School of Earth and Space Sciences, Peking University,Beijing 100871,China
    2 Geologic Party No.216,China National Nuclear Corporation,Urümqi 830011,China
  • Received:2025-01-21 Revised:2025-02-13 Online:2025-06-01 Published:2025-05-29
  • Contact: WU Chaodong,born in 1965,is a professor and Ph.D. supervisor of Peking University. He is mainly engaged in sedimentology and reservoir geology. E-mail: cdwu@pku.edu.cn.
  • About author:

    GUAN Xutong,born in 1996,postdoctoral position,is mainly engaged in sedimentary geology. E-mail: .

  • Supported by:
    Major Science and Technology Project of the Xinjiang Uygur Autonomous Region(2024A03003)

摘要:

中亚内陆地区晚侏罗世气候干旱化,准噶尔盆地发育风成沉积,该风成沉积的分布范围和共存的沉积体系还有待研究。为探究该问题,作者对准噶尔盆地南缘上侏罗统进行了详细的沉积学考察,发现喀拉扎组风成沉积位于侏罗系—白垩系不整合面之下,沉积记录范围东西向可达100 km,最厚处约250 m,其中建功煤矿剖面的风成沉积砂体厚度十余米,受到多期砾质辫状河的冲刷。风成沙具有较好的成分成熟度和结构成熟度,以跳跃组分为主。风成沙丘具有大型高角度交错层理和反粒序层理,风成沙席发育平行层理和低角度交错层理,侧向延续性好。河流沙和同期的风成沙具有相似的粒度组成和沉积物源,古风向与河流古流向正交,这说明了风成物源来自于附近河流沙,河流沙来自于风成沙地。晚侏罗世风成—冲积沉积体系受到气候干旱化和天山构造活动的控制,气候干旱导致沉积物供给减少,基准面上升,辫状河转换为季节性曲流河; 天山的构造活化导致基准面下降,在准噶尔盆地南缘风成沉积扩大,且形成广泛分布的冲积扇砾岩。准噶尔盆地南缘侏罗纪至早白垩世沉积环境发生了从沼泽遍布的河流—三角洲体系演化到风成—冲积沉积体系、再到湖泊—三角洲沉积体系的2次重要变化,记录了中亚地区晚侏罗世气候变干和早白垩世气候转为半湿润的气候变化,可能与侏罗纪真极移事件和古天山水汽阻隔有关。

关键词: 喀拉扎砾岩, 侏罗系—白垩系不整合面, 盆缘沉积, 干旱环境, 无人机建模, 准噶尔盆地

Abstract:

The Late Jurassic climate in Central Asia was arid. The existence of the eolian deposits of the Junggar Basin in the southern Central Asia is contentious. In order for a better understanding of these eolian deposits,here we conducted detailed sedimentary investigations on the Upper Jurassic strata of the southern Junggar Basin. The eolian deposits of the Kalazha Formation underlie the Jurassic-Cretaceous unconformity. The sedimentary records extend ~100 km from east to west. The thickest eolian deposits are ~250 m in thickness. The Jiangong mine section exhibits approximately 10-meter-thick eolian deposits and several stages of gravely braided river deposits. The eolian sands show high compositional and textural maturity and are mainly composed of saltation grains. The eolian dune deposits show large-scale,high-angle cross-bedding and inverse-grading. The eolian sheet deposits develop low-angle oblique and parallel laminations with good lateral continuity. The river sands and coeval eolian sands have similar grain-size distribution and sediment sources. The paleo-wind direction is orthogonal to the river flow direction. These suggest that the eolian sands were sourced from river sands and the river sands were partly from the eolian dune field. The eolian-fluvial system was controlled by the Late Jurassic aridification and tectonic activities of the Tianshan orogen. The aridity caused the decrease of sediment supply and the rise of the base level,which caused the expansion of the eolian deposits. The tectonic reactivation of the Tianshan led to dropping of the base level,the formation of Kalazha alluvial conglomerates. The Jurassic to the Early Cretaceous sedimentary environments of the southern Junggar Basin witnessed two important changes: the marshy fluvial-lacustrine sedimentary system changed to eolian-alluvial system,and subsequently evolved to lacustrine-delta system. These climatic changes may be related to the Jurassic true polar wander and block of the moisture by the paleo-Tianshan.

Key words: Kalazha conglomerate, Jurassic-Cretaceous unconformity, basin margin sedimentation, arid environment, unmanned aerial vehicle modeling, Junggar Basin

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