徐州地区新元古界中下部沉积环境演化及事件沉积

发布时间：2019-02-08 18:21

【摘要】：徐州地区新元古界中下部贾园组—倪园组在铜山区赵圩村寨山剖面出露完整连续,岩性组合极具代表性,沉积现象丰富,叠层石发育,具大量典型的事件沉积。依据岩性特征对三组间的岩石地层界限进行了讨论。在赵圩组鉴定出8个叠层石属,与淮南、吉辽地区具有相似的组合类型和演化规律。徐淮地区新元古界使用同一个地层柱状系统,最新的Sr、C同位素年龄和锆石U-Pb测年数据表明,其沉积时限应在1000-800Ma左右。叠层石和同位素年龄的对比印证了前人对吉辽徐淮地区属同一海盆沉积的认识。结合最新的同位素测年资料、叠层石衰减事件和新元古代冰期事件,将该套地层统一置于青白口系。依据岩性组合特征将贾园组分为4段,赵圩组分2段,倪园组分3段。结合岩石学特征及沉积相标志进行了沉积相的划分,贾园组—倪园经历了一个总体上由浅变深、再由深变浅的过程,其沉积环境演化顺序依次为:滨岸缓坡—台地边缘滩—浅缓坡—台地边缘生物礁—浅缓坡—中缓坡—深水斜坡—局限台地—蒸发台地—局限台地—蒸发台地。事件沉积包括地震沉积和风暴沉积两个方面。重点讨论了地震沉积中臼齿构造的形态、排列组合、赋存特征及板刺砾岩的形成过程。区分出4种类型的风暴沉积序列,其在垂向上的分布特征反映不同的水动力条件和古地理位置。讨论了臼齿构造与风暴沉积之间的关系,建立了事件综合沉积模式,在此基础上对臼齿构造的成因进行了分析。新元古代是超大陆聚合与裂解、低纬度冰川发育的特殊历史时期。Rodinia超级大陆复原图和古地磁数据表明,华北板块在1000-700Ma期间一直处于北半球的中低纬度地区。低纬度、Sturtian冰期前的湿热气候、特殊的海水条件是吉辽徐淮地区巨厚碳酸盐岩建造形成的原因。古地理位置决定了风暴沉积发育的特征,岩浆活动引起的全球构造运动诱发了频繁的地震沉积。地震引发的海洋风暴潮造成了臼齿构造和风暴沉积共生的现象。
[Abstract]:In Xuzhou area, the Jiayuan formation and Niyuan formation in the middle and lower part of the Neoproterozoic appear intact and continuous in Zhaowei village mountain section in Tongshan area, the lithologic assemblages are very representative, the sedimentary phenomena are abundant, stromatolites are developed, and there are a large number of typical event deposits. The lithostratigraphic boundary between the three groups is discussed according to the lithologic characteristics. Eight stromatolites have been identified in Zhaowei formation with similar assemblage types and evolution laws as those in Huainan and Jiliao regions. The Neoproterozoic in Xuhuai area uses the same stratigraphic columnar system. The latest Sr,C isotopic age and zircon U-Pb dating data indicate that the sedimentary time limit should be about 1000-800Ma. The comparison of stromatolites and isotopic ages confirms the previous understanding of the same basin deposits in the Jiliao Xuhuai area. Combined with the latest isotopic dating data, stromatolite attenuation events and Neoproterozoic glacial events, the strata were unified in Qingbaikou system. According to the characteristics of lithologic assemblage, the Jiayuan formation is divided into 4 sections, 2 sections of Zhao Wei component and 3 stages of Ni Yuan component. Combined with the petrological characteristics and sedimentary facies marks, the sedimentary facies were divided. Jiayuan formation-Ni Yuan experienced a process from shallow to deep and then from deep to shallow on the whole. The sequence of sedimentary environment evolution is as follows: shoreline gentle slope, platform edge beach, shallow gentle slope, platform edge biological reef, shallow gentle slope, medium gentle slope, deep water slope, limited platform and evaporation platform. Event deposition includes seismic deposition and storm deposition. The shape, arrangement and combination of molars, their occurrence characteristics and the formation process of bentonite are discussed in detail. Four types of storm deposition sequences are distinguished and their vertical distribution reflects different hydrodynamic conditions and paleogeographic locations. The relationship between molar structure and storm deposition is discussed, and the event integrated sedimentary model is established. On this basis, the origin of molar structure is analyzed. The Neoproterozoic is a special historical period of supercontinent aggregation and fragmentation and glacier development at low latitudes. The Rodinia supercontinent restoration map and paleomagnetic data indicate that the North China plate has been in the middle and low latitudes of the Northern Hemisphere during the 1000-700Ma period. The formation of super-thick carbonate rocks in the area of Jiliaoxuhuai area is due to the low latitude, the humid and thermal climate before the Sturtian ice age and the special sea water conditions. Paleogeographic location determines the characteristics of storm deposition, and the global tectonic movement induced by magmatic activity induces frequent seismic deposition. The ocean storm surge caused by the earthquake caused a symbiosis of molars and storm deposits.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P534.3

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