摘要
位于上扬子地块东南缘的黔东南石阡地区,下古生界地层连续发育,地质现象丰富,是研究扬子台地演化最有利的地区之一。根据野外勘查、实测剖面以及镜下薄片观察资料,识别出陆棚相、台地边缘相、台地相、潮坪相4种沉积相类型,并对扬子碳酸盐岩台地的演化过程进行精细刻画,建立其台地演化模式,研究台地由出现至成熟至衰亡的发展过程。结果表明,黔东南地区下古生界碳酸盐岩台地演化经历过建设期、发展期、逆演化期3个明显阶段。第二世早期(清虚洞组沉积期)黔南地区开始出现碳酸盐岩沉积,晚期完整的台、坡、盆格局形成;特马豆克期,碳酸盐岩沉积累计厚度达千余米,为发展期的顶峰;早奥陶世大坪期,受郁南运动影响,黔东地区由局限台地向开阔台地转变,受郁南运动的持续影响,台地逐渐向缓坡相过渡,沉积了大套的碎屑岩以及碎屑岩与碳酸盐岩混积的缓坡相岩石组合,拉开了碳酸盐岩台地逆向的序幕。晚奥陶世末,黔中隆起、雪峰隆起相继形成,毕节—遵义—石阡—铜仁一线以南抬升遭受剥蚀,五峰组、龙马溪组地层缺失,中上扬子碳酸盐岩台地的演化迎来终结。
The Shiqian area situates in the southeastern Guizhou, geologically in the southeastern margin of the Upper Yangtze Block, and is ideal for studying the evolution of the Yangtze Platform because of the continuous development of the Lower Paleozoic strata and abundant geological phenomena. Based on field survey, mapping, and indoor microscopic thin section observation data, four types of sedimentary facies were identified, including shelf facies, platform marginal facies, platform facies, and tidal flat facies. The evolution process of the Yangtze Platform was described in detail. The results show as fouows. The evolution process is subdivided into initiation, development, and reversed development periods. In the early stage of the development period, the Qingxudong Formation of the early Cambrian is formed with carbonate deposits in the south of Guizhou Province, and in the late stage, a complete platform-slope-basin pattern is shaped. In the Tremadocian Stage of the earliest Ordovician, the cumulative thickness of carbonate deposits reach more than 1 000 m, which is the peak of the development period. In the early Ordovician Daping Stage, affected by the Yunan Movement, the east of Guizhou Province change from a restricted platform to an open platform, which is continuously affected by the Yunan Movement. The platform facies gradually shift to gentle slope facies, forming a large set of clastic rocks and gentle slope facies in combination of clastic and carbonate rocks, which announce the beginning of the reversed development of carbonate platform. At the end of the Late Ordovician, the central Guizhou Uplift and Xuefeng Uplift are formed one after another, the south of Bijie-Zunyi-Shiqian-Tongren line is uplifted and eroded as the strata of Wufeng Group and Longmaxi Group are missing, and the evolution of carbonate platform in the middle and upper Yangtze terminate.
作者
徐博
杜秋定
伊海生
夏国清
杜春阳
XU Bo;DU Qiu-ding;YI Hai-sheng;XIA Guo-qing;DU Chun-yang(Institute of Sedimentary Geology,Chengdu University of Technology,Chengdu 610059,China;Chengdu Institute of Geology and Mineral Resources,Chengdu 610081,China)
出处
《科学技术与工程》
北大核心
2020年第20期8019-8027,共9页
Science Technology and Engineering
基金
国家自然科学基金(41672108,41302091)。
关键词
黔东南地区
下古生界
碳酸盐岩
台地演化
southeast Guizhou
lower Paleozoic
carbonate rocks
platform evolution
