高级检索

    扬子陆块西北缘新元古代早―中期地层与岩浆活动:进展、争议与认识

    Early–Middle Neoproterozoic strata and magmatism in the northwestern margin of the Yangtze Block: advances, controversies and insights

    • 摘要: 早―中新元古代是 Rodinia 超大陆聚合与裂解的关键时期。扬子陆块西北缘因保存了丰富的新元古代早―中期沉积地层与岩浆活动记录,成为揭示扬子陆块前寒武纪大地构造演化及其与超大陆聚散耦合关系的重要窗口。文章系统梳理了该区新元古代早―中期地层序列与岩浆活动特征,厘定了不同分区地层的时代归属、盆地性质及岩浆岩的构造背景。研究结果表明,扬子陆块西北缘碧口群、刘家坪组、铁船山组和西乡群为同期沉积地层,底界年龄为(825±5) Ma,以发育陆相火山岩、紫红色冲洪积相复成分砂砾岩为特征,形成于陆内裂谷盆地环境;其下伏的通木梁群、火地垭群、三花石群三湾组和白勉峡组,岩石组合和沉积序列在横向上变化较大,可能反映了不同块体各自的演化特征。岩浆活动可划分为 985~905 Ma、898~887 Ma、884~830 Ma和825~750 Ma 4个阶段,分别对应洋内弧初始俯冲、被动大陆边缘伸展、弧盆演化与块体拼合和陆内裂解的构造背景,整体响应了 Rodinia 超大陆从聚合到裂解的完整构造旋回。

       

      Abstract: The Early-Middle Neoproterozoic is a critical period for the assembly and breakup of the Rodinia Supercontinent. The northwestern margin of the Yangtze Block, preserving abundant information on stratigraphic records and magmatic activities during the Early to Mid-Neoproterozoic, serves as an important window to probe the Precambrian tectonic evolution of the Yangtze Block and its links to the supercontinent's assembly and breakup. This study systematically summarizes the Early-Middle Neoproterozoic stratigraphic sequences and magmatic characteristics to clarify the stratigraphic ages, basin properties, and tectonic settings of magmatic rocks in different subregions of the northwest Yangtze. Results prove that the Bikou Group, Liujiaping Formation, Tiechuanshan Formation, and Xixiang Group in the northwest Yangtze Block are coeval with the maximum depositional age of (825±5) Ma. They are characterized by continental volcanic rocks, pyroclastic rocks, and alluvial-pluvial purplish red polymictic conglomeratic sandstone, and formed in a continental rift basin. The Sanhuashi Group and Baimianxia Formation of the underlying Tongmuliang Group, Huodiya Group and Sanwan Formation exhibit significant lateral variations in rock associations and sedimentary sequences, which may reflect the distinct evolutionary characteristics of different masses. Magmatic activities can be divided into four stages: 985–905 Ma, 898–887 Ma, 884–830 Ma, and 825–750 Ma. These stages correspond to the tectonic settings of initial subduction of intra-oceanic arc, passive continental margin, evolution of arc-basin systems, and amalgamation of blocks, and intracontinental rifting and extension, respectively, responding to the entire assembly-breakup cycle of the Rodinia Supercontinent.

       

    /

    返回文章
    返回