Revision of the Cretaceous–Paleogene stratigraphic framework, facies architecture and provenance of the Xigaze forearc basin along the Yarlung Zangbo suture zone
Revision of the Cretaceous–Paleogene stratigraphic framework, facies architecture and provenance of the Xigaze forearc basin along the Yarlung Zangbo suture zone
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DOI：
10.1016/j.gr.2011.09.014
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发表时间：
2012-09
影响因子：
6.1
通讯作者：
Chengshan Wang;Xianghui Li;Zhifei Liu;Yalin Li;L. Jansa;J. Dai;Yushuai Wei
中科院分区：
文献类型：
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作者：
Chengshan Wang;Xianghui Li;Zhifei Liu;Yalin Li;L. Jansa;J. Dai;Yushuai Wei
对藏南白垩纪-古近纪沉积地层的新野外调查、结构分析、生物地层学、地层格架、相结构、物源和流向的回顾导致了对日喀则弧前盆地（XFB）演化的重新解释。 XFB由以复理石为主的日喀则群（由恩甘林组、重堆组和桑祖岗组组成）和浅海相措江顶群（帕达纳组、曲北雅组、曲下组和嘉拉则组）组成，本文将它们的年龄分别修正为阿尔布阶-康尼亚阶和桑托阶-伊普勒阶。以 Ngamring 组为代表的深海复理石构成了 XFB 的早期沉积充填物。依次细分为5个巨型层序MS1~MS5：早期海底扇相阶段、河道海底扇阶段、成熟海底扇阶段、高位海底扇阶段、外扇-中上层阶段。盆地发育早、晚期古水流方向为东向和西向，中期为北向和南向，表现出典型的纵向供给侧向充填的弧前盆地沉积特征。物源研究表明安山岩碎片来自侏罗纪-下白垩统耶巴组和冈底斯南部火山岛弧链中形成的桑日群。 XFB发育的四个时期是：1）由日喀则蛇绿岩形成的XFB基底，完成于阿普第阶之前。陆架同期沉积物为桑祖岗组碳酸盐岩； 2）以Chongdoi组为代表的最早Aptian时代（约125/120Ma）的最早XFB矿床，与残弧有关； 3）复合弧前发育，分别以阿尔布阶晚期—塞诺曼阶晚期复理石巨型层序（MS1—MS2）和土伦阶—科尼亚期复理石巨型层序（MS3—MS5）为代表； 4)XFB发育的最后阶段开始于以晚白垩世晚期—早古近纪浅海措江顶群为代表的弧前末期,终止于中伊普勒世,此时嘉拉则组沉积。
New field investigation, structural analysis, review of biostratigraphy, stratigraphic framework, facies architecture, provenance, and flow direction of the Cretaceous–Paleogene sedimentary strata in southern Tibet resulted in reinterpretation of the evolution of the Xigaze forearc basin (XFB). The XFB is comprised by flysch-dominant Xigaze Group (consisting of Ngamring, Chongdoi, and Sangzugang Formations) and of the shallow marine Cuojiangding Group (Padana, Qubeiya, Quxia, and Gyalaze Formations), with their ages herein revised as the Albian–Coniacian and the Santonian–Ypresian respectively. The deep-sea flysch represented by the Ngamring Formation constitutes the early sedimentary fill of the XFB. It was subdivided into five megasequences MS1–MS5 in order: the early submarine fan facies stage, channel submarine fan stage, the mature submarine fan stage, the highstand submarine fan stage, and outer fan-pelagic stage. The paleocurrent flows were eastwards and westwards during the early and late stages of basin development and northwards and southwards during its middle stage, indicating typical forearc basin sedimentation with longitudinal supply and lateral filling. Provenance studies point to multiple sources, with andesitic debris sourced from the Jurassic–Lower Cretaceous Yeba Formation and Sangri Group formed in the volcanic island arc chains in the southern Gangdese. The four periods of the XFB development are: 1) the formation of the XFB basement by the Xigaze ophiolite, and completed before the Aptian. The coeval deposits on the shelf are the Sangzugang Formation carbonate; 2) the earliest XFB deposits of the earliest Aptian age (ca. 125/120Ma) represented by the Chongdoi Formation, related to the residual forearc; 3) composite forearc developed, represented by the late Albian–late Cenomanian flysch megasequences (MS1–MS2) and the Turonian–Coniacian flysch megasequences (MS3–MS5), respectively; and 4) the final stage of the XFB development started the terminal forearc stage represented by the late Late Cretaceous–Early Paleogene shallow marine Cuojiangding Group and terminated during middle Ypresian, when the Gyalaze Formation was deposited.