摘要:蛇绿岩是认识古洋盆演化的关键，为人们研究大洋岩石圈特征、古板块重建、地幔物质组成以及板块俯冲过程等提供了重要依据。本研究新发现的雀儿山蛇绿混杂岩，位于中—蒙边境附近，大地构造位置属于大南湖—雀儿山—圆包山岛弧带，其围岩为绿条山组上段板岩段和白山群上亚群的绿泥千枚岩组，区域上的绿条山组和白山群上亚群可能不是连续沉积的岩石地层单元，而是弧前增生杂岩。雀儿山蛇绿混杂岩的岩性组合包括：片理化蛇纹岩、蛇纹石化辉石橄榄岩、辉长岩、玄武岩、安山质熔岩/角砾岩、英安岩、凝灰质砂岩、硅泥质岩、灰岩及大理岩。结合区域地质资料，雀儿山蛇绿混杂岩的增生就位时代可能为中三叠世。
关键词: 雀儿山蛇绿混杂岩/
构造特征/
甘肃北山/
中亚造山带
Abstract:The ophiolite is a key to understanding the evolution of the ancient ocean basin, which provides an essential basis to study the ocean lithosphere's characteristics, reconstruction of ancient plates, mantle materials, and plate subduction process. The newly discovered Queershan ophiolitic mélange in this study is located near the China?Mongolia border, and its tectonic position belongs to the Dananhu-Queershan?Yuanbaoshan island arc belt. The rocks of the Queershan ophiolitic mélange are mainly slates of the Upper Lvtiaoshan Formation and chlorite schists of the Upper Baishan Formation. The Lvtiaoshan and Baishan formations in the region probably are not continuously sedimentary units but fore-arc accretionary complex. The Queershan ophiolitic mélange comprises serpentinites, serpentinized peridotites, gabbros, basalts, andesitic lavas/breccias, dacites, tuffaceous sandstones, cherts, limestones, and marbles. The timing of accretion and emplacement of the Queershan ophiolitic mélange might be earlier than the Middle Triassic.
Key words:Queershan ophiolitic mélange/
Structural features/
Beishan/
Altaids
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