【作者】 吕大炜；

【导师】 李增学；

【作者基本信息】 山东科技大学 ， 矿产普查与勘探， 2009， 博士

【摘要】 本文采用沉积学、古生物地层学、层序地层学、岩石学、构造地质学等多学科的方法,结合测井、地球物理、地球化学等多种手段,研究了华北地区晚古生代陆表海盆地沉积相及层序地层学特征,分析出华北晚古生代海平面变化规律,研究了海侵事件沉积类型和特点,发现华北地区有3次重要的海侵事件,并绘出海侵事件沉积期的古地理图。论文主要成果如下:对华北晚古生代陆表海盆地沉积进行了分析,发现研究区存在着六大沉积体系:碳酸盐台地沉积体系、障壁—泻湖沉积体系、潮坪沉积体系、河控浅水三角洲沉积体系、冲积扇沉积体系、河流湖泊复合沉积体系;在此基础上,运用层序地层学的方法,将研究区晚古生代沉积地层划分两个构造层序(Ⅰ和Ⅱ)和7个三级层序,建立了南北向和东西向层序地层格架,重点研究了陆表海充填层序的三级层序分布;在层序地层学基础上,对晚古生代海平面变化进行研究,将其划分成两个长周期,即构造—海平面变化周期:构造层序Ⅰ的短期大规模海侵及长时间的海退阶段、构造层序Ⅱ的海退阶段。绘制出不同级别的海平面变化曲线,总结出影响海平面变化的主要因素是构造沉降和冰川溶解,基于此,分析不同级别的海平面变化旋回与不同级别层序的对应关系;分析出渐侵型海侵与突发型海侵两种不同类型海侵的三点区别:第一,二者发生背景不同;第二,海侵沉积序列有所差别;第三,泥炭化、煤化原理不同。总结得出存在四种海侵事件沉积组合:海相灰岩—煤层—暴露沉积组合、海相灰岩—深水泥岩—煤层—暴露沉积组合、深水泥岩—煤层—暴露沉积组合及深水泥岩(海相灰岩)—铝质泥岩或根土岩组合。分析海侵事件沉积序列的地化特征,发现了海相层与煤层在环境上的巨大差异;总结出华北地区晚古生代风暴沉积的特征和类型,建立了陆表海波状盆地风暴沉积模型;研究了晚古生代突发性海侵的规律,指出存在三次较大的海侵事件沉积组合:层序1(晚石炭世)海侵体系域的吴家峪灰岩与11号煤层组合;层序2(早二叠世紫松期)海侵体系域的庙沟—毛儿沟灰岩与8号煤层组合和高水位体系域的斜道灰岩与7号煤层组合;其中,层序2海侵体系域为全区规模最大的海侵事件沉积组合;完善了海侵事件成煤模式,进行海侵事件沉积的广泛对比,总结出海侵事件成煤的四个特点:第一,煤层发育在海侵体系域;第二,煤层具高的硫含量和低的硫同位素比;第三,煤层的煤岩组分富集程度不同;第四,煤层中高荧光强度和低反射强度在煤层剖面中是不均匀分布的。按照海侵持续的时间和规模以及聚煤作用的强弱分析出海侵事件成煤的四种组合,即:①厚层海相灰岩与薄层煤层组合;②薄层海相灰岩与薄层煤层组合;③中厚层灰岩与薄层煤层的组合;④厚层灰岩与较厚层煤的组合。分析了研究区典型海侵事件成煤组合特征,综合海侵事件成煤思想和风暴异地煤成煤规律,构建了海侵事件成煤模式图;重点分析了层序1、层序2海侵事件沉积古地理,发现层序1突发型海侵沉积期海水由东北向西南侵入,煤层分布与海相层分布呈现一致性。事件沉积组合主要集中在华北中北部地区,可进行区域对比。层序2海侵体系域庙沟-毛儿沟灰岩与8号煤层沉积组合是重要的海侵事件组合,分布于华北大部地区,可进行全区对比,其聚煤中心位于华北中部的山西等地,灰岩与煤层呈负相关关系,层序2高水位体系域中的斜道灰岩与7号煤层沉积也具有局部的事件沉积组合,聚煤中心位于华北中部和南部的两淮地区,分析其原因是由于南华北构造运动引起两淮地区海侵表现为渐侵型,北方地区表现为突发型,该事件组合在中部或北部地区具有局部对比意义。更多还原

【Abstract】 In this paper, depositional systems and the characteristic of sequence stratigraphy are studied. Then the sea level characteristics of the Neopaleozoic of North China are analyzed. According to the above, the depositional types and characteristics of transgressive event are studied in detail. Three transgressive events are found, and the paleogeographic maps are drawn. The trangressive event is studied by many subjects, such as sedimentary, paleontology, sequence stratigraphy, lithology, tectonics, and so on. And many methods are applied to the subjects, including logging, physical geography, geochemistry. Main conclusions are in below:Six depositional systems are found by studying the epicontinental basin of the Neopaleozoic in North China, which are carbonate platform depositional systems, tidal flat depositonal system, the barrier-lagoon depositional system, fluvial-controlled shoal water deltaic depositional system, alluvial fan depositional system and river-lake depositional system. On the basis, two tectonic sequences （I and II） and seven third-order sequences are divided by the way of sequence stratigraphy. Then the sequence strata frame of South-North and East-West is constructed. And the distribution of third-order sequences is specially studied.The sea-level was studied based on the sequence stratigraphy. It was divided two long cycles, that is the ones of the tectonic-sea-level change: one is the stage of short larges scale transgression and long time regression in the cycle of tectonic sequence 1^th, the other is regression stage of tectonic sequence 2^th . Different curves of sea-level change were drawn. And the main causes of influencing the change of the sea-level are conclude, which are tectonic subsidence and glacier dissolver. Then the different levels of sea-level change cycles response to the sequences are analyzed.Three differences are concluded between process transgression and spasmodic transgression, which are the background, deposition sequence and the principle of paludification and coalification. Four assembled deposits are founded: the combination of marine limestone-coal bed-exposure deposition; the combination of marine limestone-deeper water mudstone-coal bed-exposure deposition; deeper water mudstone-coal bed-exposure deposition; and the combination of marine limestone or deeper water mudstone-exposure deposition （pelite）. The geochemistry characteristics of the transgressive event deposition are analyzed. Many differences are founded in depositional environment between marine sedimentation and coal. The storm deposit model of the epicontinental undulant basin is constructed by studying the characteristics and types of its sedimentation.There are three larger combinations of transgression event deposition, which are Wujiayu Limestone and 11^th coal seam in the transgressive system stand of sequence 1^th, Miaogou-Maoergou Limestone and 8^th coal seam in the transgressive system stand of sequence 2^th, Xiedao Limestone and 7^th coal seam. The transgressive event combination of the trangressive system stand in sequence 2^th is the largest one.By perfecting the coal accumulation theory of transgressive event, four special characteristics can be found. Firstly, coal seam develops in the transgressive system stand; secondly, sulfur content is higher and sulfur isotope ratio is lower in coal seam; Thirdly, coal petrology enrichments are different in the same coal seam. Finally, higher fluorescence intensity and lower reflected intensity become maldistribution in the same coal seam. Four combination of transgressive event coal accumulation between limestone and coal is concluded by the time of transgressive duration and strength of coal accumulation. That is, thicker limestone and thin coal seam, thin limestone and thin coal seam, medium bed limestone and thin coal seam, thicker limestone and thicker coal seam. Each combination characteristic of lime and coal seam is studied. And coal accumulation model figure is drawn by the consideration of the theory of transgressive event and the law of the the storm allochthonous coal accumulation.Transgressive event paleogeography distributions of sequence 1^th and 2^th are studied in detail. The transgression happened from North-East to South-West. The distributions of coal are the same to the marine deposition. So the combination of event deposition lies in the middle-north of China. And it can be traced to the North of North China, Shanxi and Huaibei, etal. The combination of Miaogou-maoergou Limsstone and 8^th coal seam is the most important one, which distributed most of the North China. So it can be founded in the most of North China. Its coal accumulation centre lies in Shanxi and so on, which has negative correlation to the distribution of limestone. The combination of Xiedao Limestion and 7^th coal seam in high system stand of sequence 2^th is event depositon in some areas, such as Shanxi, Henan, etal. Because different sedimentation causes the process transgression in Lianghuai, and event transgression in the north of North China, coal accumulation centre lies in the middle of North China and Lianghuai. And its combination can be founded in limited areas, especially in the middle or north of North China.更多还原