【作者】 陈树旺；

【导师】 金成洙；

【作者基本信息】 东北大学 ， 矿产普查与勘探， 2005， 博士

【摘要】 四合屯地区是开展中生代火山活动与生物灾难事件耦合研究的典型地区。在区域地层划分和火山活动特征研究的基础上,本文以义县组化石及其围岩和相关的火山活动产物等为重点研究对象,开展了火山地质学、地球化学以及地层古生物学方面的系统研究,从时间、空间和物质组分特征等方面查明了生物灾难事件与火山活动的耦合关系。本文首次确定了化石层内火山物质的来源地并深入探讨了导致生物灾难事件的火山活动类型及其影响范围。提出了根据生物灾难特点、运用化石及其围岩地球化学异常探索古生态环境突变的新学术观点。这项研究将推动“热河生物群起源、辐射及灾难事件发生的地质背景”等重大理论问题的解决,有助于深入认识“火山活动”——这一重大地内事件的环境效应。主要研究进展有: 1. 根据火山活动特征和区域地层对比,将四合屯地区的义县组地层划分为三个岩性段,指出它们分别是早、中、晚三期火山活动的产物。2. 确认热河生物群化石的主要赋存层位是义县组一段凝灰岩类和二段的湖相沉积岩,具有粗、中、细3 个埋藏相。本文确定了“鹦鹉嘴龙”、“水生生物”以及“鸟类、爬行类等陆生脊椎动物”三种灾难事件类型。3. 本文分析了化石层内火山活动记录及其同位素年龄,查明了生物灾难事件与火山活动在时间、空间和物质组分特征等方面的耦合关系。首次确定化石层内火山物质的来源,指出后燕子沟火山机构和李八郎沟火山机构分别为义县组一段鹦鹉嘴龙化石层和义县组二段湖相化石层内火山物质的主要来源。4. 通过地球化学异常分析发现,热河生物群的古生态环境曾出现过氧化-还原环境的剧烈变化以及湖盆盐度和水位的动荡。进一步研究发现,火山活动导致了古生态环境中As、Hg 、S 等有毒、有害元素异常的增高。热河生物群灾难事件的发生层位(如SYP1 的39 层)多是古生态环境的突变层位。5. 运用元素生物地球化学异常对比,作者进一步确认义县组化石与其围岩在有毒、有害元素异常方面存在的一定的耦合关系:其有毒有害元素含量均呈现一定的高异常。化石自身的Ba、Sr 和ΣREE 含量甚至远远超过了围岩。本文讨论了导致生物灾难事件的火山灾害类型及其影响范围,初步建立了火山活动与生物灾难事件的时空演化模式。全文约十二万字,更多还原

【Abstract】 Sihetun is a typical area reprsenting the coupling relationship between volcanic activity and biological catastrophic events. Based on the strata classification and the characteristic study of volcanic activities, the fossils of Jehol Biota, the fossil beds of Yixian Formation and the related volcanic rocks are well studied in this paper with theoretic support of volcanology, geochemistry, petrology and palaeontology. The main object is to investigate the coupling relationship between volcanic activity and biological catastrophic events, including its occurring time, place and material characters. For the first time, the spot of volcanic material source of fossil-bearing beds is defined in this paper. On the basis of previous researches,the author put forward a new academic viewpoint of making good use of the character of biological catastrophic events, the geochemistry data of fossils and fossil-bearing beds to realize the mutation of paleo-environment.. The study will be helpful for the resolution of important problems about Jehol Biota, such as the geological background of the source, migration and disaster event. And what’s more, this paper may be a contribution to recognize the environmental effects of volcanic activities, the main inner planet events. The study in this paper covers five aspects. 1. Based on the stratum comparison and characteristic study, the Yixain Formation can be classified into three members that were formed by volcanic activities of three periods respectively. 2. The fossils of Jehol Biota occurred in tuffite or sedimentary beds of the first and second member of Yixian formation. The fossil buried phase of Jeho Biota can be divided into three types, that is, coarse fragment phase, middle fragment phase and fine fragment phase. And there are three types of important biological catastrophic events respectively, that is, psittacosaurus disaster event, the aquatic animal (e.g. bivalves) disaster event and vertebrate (bird and reptile etc.) disaster event. 3. According to the analysis of volcanic record in fossil beds and the isotopic data, the paper makes a systemic comparison between the fossil beds and the related volcanic rocks. The coupling relationship between volcanic activity and biological catastrophic events, including its occurring time, place and material characters, are well investigated. And for the first time, the spot of volcanic material source of fossil-bearing beds is defined: Houyanzigou edifice and Libalanggou edifice is the volcanic material source of the psittacosaurus beds of the first member and lake-phase fossil beds of the second member of Yixian Formation respectively. 4. The analysis of geo-chemical abnormal indicates that there were mutations of paleo-environment at the aspect of oxidation-reduction system, as well as the saltness and water level of the paleo-lake. A comprehensive research confirms that the volcanic activity resulted in the high level of toxic element abnormal, such as As, Hg and S. The disaster beds of Jehol Biota correspond to the beds with paleo-environmental mutation. 5. The special element comparison of biochemical abnormal indicates that the fossils of Yixian Formation couple with its fossil-bearing beds at the respect of the high level toxic element abnormal. On the other hand, the average content of Ba, Sr and ΣREE in fossils are higher than that in the fossil-bearing beds. The types and the range of volcanic hazard that resulted in the biological catastrophic event are discussed at the end of this paper. As another discussion, the author sets up a sketch model of the evolution of volcanic activity and biological event. The full text is about 120 thousand words.更多还原