豫西汝阳盆地中新生代蟒川组孢粉植物群及其古环境研究

发布时间：2018-06-19 19:17

本文选题：汝阳盆地 + 蟒川组　；参考：《成都理工大学》2017年硕士论文

【摘要】：豫西汝阳盆地位于华北板块南缘和秦岭造山带接壤地带,其在中三叠世到晚侏罗世处于隆升,接受剥蚀,早白垩世形成火山盆地,沉积大营组,晚白垩世—古新世形成断坳陷盆地,沉积了蟒川组。本文在研究区地质概况的背景下,对三条蟒川组地层剖面进行详细的分层描述,查明了各组的岩性特征,地层厚度以及接触关系。在对实测剖面古生物化石的鉴定分析的基础上根据其组合特征,划立了Polypodiaceae Castanea Betulaceae孢粉组合带,Quercus Graminae Chenopodiaceae孢粉组合带,Pinus Quercus-Castanea孢粉组合带,以及Castanea-Ulmus-Artemisia孢粉组合带四个孢粉组合带。并通过对孢粉资料的定量分析完成了古气候、古环境的重建。总体得出整体显示亚热带-温带气候条件下半干旱的生长环境,其气温先变冷后变暖,降水逐渐稀少,气候逐渐干旱,湖泊面积逐渐缩小的结论。通过对研究区蟒川组地层进行了沉积环境分析,认识到蟒川组主要为一套湖泊沉积,间有辫状河及曲流河沉积,并通过其沉积特征以恢复沉积相及沉积亚相,并对其沉积亚相进行了简单分析。总体沉积环境显示半干旱气候下的辫状河流-曲流河-湖泊三角洲-湖泊的沉积特点。对研究区晚白垩世—古新世盆地的沉积环境进行了分析研究,初步新建研究区的盆地演化模式。该地区前人多认为为坳陷盆地,本次研究发现为南西侧坳陷,北东侧断陷的箕形盆地,其沉积中心自南西向北东迁移,盆地演化不同地段不同,在北部高山区,坳陷边到断陷边,从洪积—洪冲积到湖积,边缘洪积;中山区从坡洪积—洪冲积—湖积;低山丘陵地带为洪冲积—洪积的沉积模式。从构造演化、物源供给、古气候特征方面分析影响盆地发展演化的因素,认为构造因素在沉积相的控制上起着决定性作用,但气候和沉积物供应量的多少也对凹陷的充填构成重要影响。本次研究在调查区获得北部莽川一带下部71.4±7.0Ma、上部54.8±5.0Ma、中南部大营西一带下部66.8±6.0Ma,上部54.2±5.0Ma和南缘石龙区东一带70.1±7.0Ma的ESR年龄,发现下部晚白垩世的年龄信息,为莽川组进行了进一步厘定,初步确定其地层时代并与发现恐龙化石刘店一带地层对比及中新生代盆地演化提供非常重要资料,这些成果为研究该区域新构造运动研究提供了新的资料。
[Abstract]:The Ruyang basin in western Henan is located in the southern margin of the North China plate and the contiguous zone of the Qinling orogenic belt. It was uplifted from the Middle Triassic to the late Jurassic, accepted denudation, formed a volcanic basin in the early Cretaceous, and formed a sedimentary Daying formation. The late Cretaceous-Paleocene formed a fault depression basin and deposited the pyengchuan formation. In this paper, the stratigraphic profile of three pyengchuan formation is described in detail under the background of geological survey in the study area, and the lithologic characteristics, formation thickness and contact relationship of each group are found out. Based on the identification and analysis of the paleontological fossils in the measured section, four sporopollen assemblages of the Polypodiaceae Castanea and Betulaceae sporopollen assemblages, Quercus and Graminae Chenopodiaceae sporopollen assemblages, and Castanea-Ulmus-Artemisia sporopollen assemblages have been established, on the basis of the identification and analysis of the paleontological fossils in the measured sections, and four sporopollen assemblages in the Castanea-Ulmus-Artemisia sporopollen assemblage belt. The paleoclimate and paleoenvironment were reconstructed by quantitative analysis of sporopollen data. It is concluded that the semi-arid growing environment in the subtropical temperate climate shows that the temperature first becomes cold and then warms, the precipitation becomes scarce, the climate gradually dries, and the lake area shrinks gradually. Based on the analysis of sedimentary environment of the strata of the Xianchuan formation in the study area, it is recognized that the formation is mainly composed of a set of lake deposits with braided rivers and meandering rivers, and the sedimentary facies and sedimentary subfacies can be restored by their sedimentary characteristics. The sedimentary subfacies were analyzed briefly. The overall sedimentary environment shows the sedimentary characteristics of braided rivers, meandering rivers, lake deltas and lakes in semiarid climate. The sedimentary environment of the late Cretaceous to Paleocene basins in the study area was analyzed and the evolution model of the basin was preliminarily established. Most of the former people in this area considered the basin as a depression basin. In this study, we found that the basin is a dustpan basin with the south west depression and the north east fault depression. The sedimentary center of the basin moves from south to west to north east, and the basin evolves in different areas, in the northern alpine region. From the margin of depression to the edge of fault depression, from alluvial to lacustrine, marginal alluvial; from slope to alluvial to lacustrine; from slope to alluvial to lacustrine in middle mountain area; from low hill to hilly area, to the sedimentary model of flood alluvial and alluvial. The factors affecting the evolution of the basin are analyzed in terms of tectonic evolution, provenance and paleoclimate characteristics. It is considered that tectonic factors play a decisive role in the control of sedimentary facies. However, the amount of climate and sediment supply also plays an important role in the filling of the sag. The ESR ages of 71.4 卤7.0 Ma, 54.8 卤5.0 Ma, 66.8 卤6.0 Ma, 54.2 卤5.0 Ma, 54.2 卤5.0 Ma and 70.1 卤7.0 Ma in the lower part of Mangchuan area, the upper part, the west part of the central and southern part of Daying, and the east part of the Shilong district in the southern margin, respectively, were obtained in this study. The age information of the lower part of the late Cretaceous was found. It provides very important data for the further determination of the Mengchuan formation, the preliminary determination of its stratigraphic age and the stratigraphic correlation and evolution of the Meso-Cenozoic basin in the area of the discovery of the dinosaur fossil Liudian. These results provide new data for the study of neotectonic movement in the region.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：Q914

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