古地理学报2025，Vol.27Issue(3)：541-559,19.DOI:10.7605/gdlxb.2025.063
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
Sedimentary characteristics of the Late Jurassic eolian and alluvial deposits in southern margin of Junggar Basin and palaeoenvironment reconstruction
摘要
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 un-conformity.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 ma-turity 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 lami-nations with good lateral continuity.The river sands and coeval eolian sands have similar grain-size distri-bution and sediment sources.The paleo-wind direction is orthogonal to the river flow direction.These sug-gest 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 flu-vial-lacustrine sedimentary system changed to eolian-alluvial system,and subsequently evolved to lacu-strine-delta system.These climatic changes may be related to the Jurassic true polar wander and block of the moisture by the paleo-Tianshan.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Key words
Kalazha conglomerate/Jurassic-Cretaceous unconformity/basin margin sedimentation/arid environment/unmanned aerial vehicle modeling/Junggar Basin分类
地质学引用本文复制引用
关旭同,王国荣,孙潇,张亚楠,初亚男,任楚梵,吴朝东..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[J].古地理学报,2025,27(3):541-559,19.基金项目
新疆维吾尔自治区重大科技专项(编号:2024A03003)资助.Financially supported by Major Science and Technology Project of the Xin-jiang Uygur Autonomous Region(No.2024A03003) （编号:2024A03003）
