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安徽省定远东部—明光地区古近—新近系划分方案不一,通过地层剖面的测制和利用构造—岩性—岩相法进行1∶5万地质填图,系统采集了ESR测年样,并结合区域对比,自下而上划分古近纪定远组、明光组,新近纪下草湾组和桂五组。该区古近—新近纪沉积物以陆相红色磨拉石和陆相火山岩建造为主,陆相红色类磨拉石的建造分析表明其形成于冲积扇和扇前河湖环境,碎屑物质来源于沉积区东边扬子地层区的浅变质岩和沉积区西北侧华北地层区变质岩和未变质岩石。其陆相火山喷发岩形成于大陆边缘活动性环境,是区内火山活动最盛的时期。其盆地类型为箕状断陷型、迁徒型和坳陷型。根据盆地充填沉积序列划分出4个层序(2个二级和2个三级层序),层序Ⅰ和层序Ⅳ不完整,层序Ⅱ和层序Ⅲ皆由冲积沉积体系域、湖扩张体系域和湖萎缩体系域3个基本单位构成。层序界面主要有区域构造运动界面和盆地构造应力转换面—体系域转换界面两种类型。
The sub-plan of Paleogene-Neogene in the eastern part of Dingyuan, Mingguang area, Anhui Province is divided into different sub-schemes. According to the lithosphere-lithofacies-lithofacies mapping and stratal profiling, the ESR dating samples , And combined with the regional contrast, the Lower Paleogene Dingyuan, Mingguang, Neogene Xiacaowan and Guiwu groups are divided from bottom to top. The Paleogene-Neogene sediments in this area are mainly composed of terrazzo red molasse and continental volcanic rocks. The analysis of the formation of continental red molasse shows that they formed in alluvial fans and in front of rivers and lakes, and the source of detritus Metamorphic rocks and metamorphic rocks in the North China stratigraphic zone on the northwest side of the sedimentary region in the Yangtze strata area east of the sedimentary region. Its continental volcanic eruption rock formed in the active environment on the edge of the continental margin, is the peak period of volcanic activity in the area. Its basin type is a half-graben fault type, a migratorial type and a depression type. Four sequences (two second-level and two third-level sequences) are divided according to basin-filling sedimentary sequence, and sequence I and sequence IV are incomplete. Sequence II and sequence III are formed by alluvial sedimentary system domain, lake Dilatation system domain and lake atrophy system composed of three basic units. There are two types of sequence interfaces: regional tectonic movement interface and basin tectonic stress-transform interface and system-domain transfer interface.