摘要
青藏高原龙木错地区发现了完整的志留纪地层,新建了早中志留世龙木错组、中晚志留世单面山组和晚顶志留世心形湖组。志留纪经历了开阔海台地—闭塞海湾—三角洲—潮坪的环境演变过程。其中单面山组下段发育大型古三角洲沉积,由前三角洲、三角洲前缘和三角洲平原构成。其中三角洲平原的分流河道、天然堤、决口扇、分流河道间湾、湖泊、沼泽等微相发育,沉积厚度巨大。晚志留世大型三角洲沉积的发现,海陆变化频繁的沉积环境,龙木错以东的五指山等地中上泥盆统不整合于奥陶系—志留系之上,证明龙木错-双湖缝合带北侧受到晚加里东运动的影响,与羌塘南部地区的沉积建造存在截然的差异。因此,这一现象的发现有助于了解羌南、羌北的构造演化,为探讨南、北古大陆的板块边界提供基础资料。
A complete set of Silurian stratum has been found in Longmu Co area, Qinghai-Tibet Plateau, also authors have established Longmu Co Formation of Lower Silurian, Danmianshan Formation of Middle-Upper Silurian, Xinxinghu Formation of Upper Silurian. During Silurian Period, the environment of study area has experienced four evolution stages: open sea platform, blocking gulf,delta and tidal flat. There is a large ancient delta deposition in the Lower Part of the Danmianshan Formation, and it is made up of the former and delta, the delta front and the delta plain. The triage river of delta plain, natural levee, river burst fan and segregation between the bay and lakes, swamps and other micro-phases of the ancient delta are developed and the sediment thickness is very big. The discovery of the large delta deposits, the frequent change between land and ocean, the unconformity between the Middle-Upper Devonian and Ordovician-Silurian around Wuzhishan, east of Longmu Co, these evidences have proven that the norther side of Longmu Co-Shuanghu suture zone was affected by the late Caledonian movement and it is distinctly different from the sediment structure in southern Qiangtang area. Therefore, the discovery helps to understand better the tectonic evolution of the southern and northern Qiangtang area, and to explore the north and south of the ancient continent plate boundaries.
出处
《地质通报》
CAS
CSCD
北大核心
2009年第9期1267-1275,共9页
Geological Bulletin of China
基金
国家自然科学基金项目(编号:40872146
40672147)
中国地质调查局项目(编号:200213000007
1212010818115)资助