【作者】 曾萍；

【导师】 马永生； 梅冥相；

【作者基本信息】 中国地质大学（北京） ， 矿物学、岩石学、矿床学， 2005， 博士

【摘要】 下扬子区是我国东部具有油气远景的地区之一。充分结合野外观察,系统了分析本区构造演化史,以镜质体反射率、粘土矿物、裂变径迹、包裹体测温等为主要研究方法,对下扬子区的构造-热演化进行了系统的研究,取得了如下几个方面的认识:　通过对下扬子区镜质体反射率数据分析,取得几点以下主要认识和结论:(1)Ro 值与样品所在深度、地层时代具明显的相关性;(2)与下古生界相比,上古生界和三叠系烃源岩Ro 值主体上明显低一台阶;(3)Ro 剖面特征具分区性,皖南无为地区Ro 值随深度增加快,苏南、苏北相对较慢;(4)从区块西南到东北,Ro—深度剖面由上到下依次叠置,反映Ro 变化规律与变化特征具明显的地区性;(5)推覆体的存在,可导致Ro 值出现倒置现象。　磷灰石裂变径迹研究的结果表明:(1)晚印支-早燕山时期下扬子地区存在大幅度隆升剥蚀事件;(2)来自浦口组及其以前样品的磷灰石裂变径迹都不同程度的发生了退火,表明浦口组在整个苏皖下扬子区具有相当厚度的沉积和古埋深;(3)下扬子区发生了普遍的快速埋深,此后发生了快速的抬升,造成了苏南地区大面积缺乏第三系沉积;(4)苏北与苏南、皖南最后一次较大幅度的抬升剥蚀事件在时间上不同,苏北抬升时间晚,为38Ma 左右,与三垛事件相吻合。苏南升早,65～90Ma,与仪征运动相吻合;(5)磷灰石裂变径迹年龄数据反映晚中生代—新生代沉积物来自多个不同时代的物源区,物源区的隆升冷却开始的时间有68-94Ma、139-177Ma 和118—234Ma 之间三组不同的时间段,分别对应K2和J2-3及T2末隆起区抬升通过完全退火带等温线的时间。　包裹体研究方面成果说明:在普遍演化程度较高的下扬子中古生界地区,可以找到局部演化程度相对较低、具有油气勘探前景的层位是可能的。　粘土矿物研究的结果表明:汤山地区的S-P地层曾经发生倒转,由于构造推覆,然后在其上叠置了一套岩席,这套岩席在晚白垩以后遭受抬升剥蚀。　综上诸端,可以对烃源岩演化得出以下结论:(1)皖南无为地区四套海相烃源岩热演化程度都异常高,与该区印支-燕山期异常高基底热流相关;(2)苏南地区下古生界烃源岩热演化程度高,中、上古生界烃源岩热演化程度低。(3)苏北各凹陷区四套烃源岩热演化程度均很高,从凹陷区到斜坡区到隆起区,热演化程度依次递减;(4)时间上,苏北地区海相烃源岩成熟度演化在早第三纪末才终止,而苏、皖南地区烃源岩成熟度早白垩世末已不再明显增高;(5)特别是圣科1 井揭示的地层和Ro 倒转现象,得出与前人不同的认识:K-E 广布的苏北盆地应具有普遍的“二次”生烃,晚期成藏的主要时期应为晚白垩世—第三纪。更多还原

【Abstract】 The Lower-Yangtze region is one of the important regions with exploration prospect of oil-gas. Combine with the out-crop research, several methods are applied to the study of thermal evolution in the Lower-Yangtze region and several aspects of cognitions are obtained as introduced as follow. These methods include the reflectivity of the glass plastid, the study of clay, the fission track and the temperature-measure of inclusion and so on. Through the analysis of reflectivity data it is could concluded as follows: Firstly, there is relativity among the R0 values, the depth and the stratigraphic horizon of sample. Secondly, the R0 values of the source rock from the upper–Palaeozoic to the Triassic are clearly lower one step than those of the Lower-Palaeozoic. Thirdly, there is provincialism for the R0 values, it is increased swiftly with the increasing of the depth in the Wuwei area in south part of Anhui province but it is increased slowly both in south and in north of Jiangsu province. Fourthly, from the southwest to the northeast in the study area the devolutionary stacking pattern in the R0-depth section shows that there is provincialism for both the changing law and the feature of the R0 values. Fifthly, the existence of the nappe can result in inversion phenomenon of R0 values. The research results of the apatite fission-track demonstrate several geological features. Firstly, there is large-scale rising-denuding event from the late Indochina Period to the early Yanshan Period. Secondly, the different-degree anneal of the apatite fission-track for the samples from the strata before the Pukou Fm. indicates that there is large depositional thickness and the buried depth for the Pukou Fm.. Thirdly, the rapid buried process and the hereafter rapid rising lead to the absent of the Tertiary deposits in the south part of Jiangsu. Fourthly, the time is different for the last of the large-scale rising-denuding event both in the south and the north of Jiangsu, in north of Jiangsu it is very late (38Ma)　and corresponded to the Sanduo Event but in south of Jiangsu it is very early (65～90Ma) and corresponded to the Yizheng Event. Fifthly, the source region of sediments from the Mesozoic to the Cenozoic is different in times and in space, there are three sets of time-span (68-94Ma、139-177Ma and 118—234Ma)for the start rising-cooling time of the source region and these three sets of time-span respectively correspond to the time (K2,J2-3 and the end of T2) that the rising region transits the isotherm of the complete anneal zone. The study on the inclusion shows that it can be discovered the local regions with low-evolutionary extent and the exploration foreground of oil and gas in the Lower-Yangtze region that is marked a widespread high-evolutionary extent. The study on clay minerals shows that the strata from the Silurian to the Permian in the Tangshan area are turnover. Because of the tectonic thrusting, a set of rock sheet superimposes the strata from the Silurian to the Permian. This set of rock sheet is raised and denuded after the late of the Cretaceous. According to above materials it can be made some conclusions for the evolution of source rocks in the study area. Firstly, the high evolutionary extent of the lower-Palaeozoic source rocks in the Wuwei area of the south Anhui province is genetically relative to the abnormal base-thermal flux. Secondly, in the south Jiangsu the thermal-evolutionary extent for lower-Palaeozoic source rocks is very high but the thermal-evolutionary extent for upper-Palaeozoic to the Mesozoic source rocks is very low. Thirdly, the thermal-evolutionary extent for the four sets of source rocks in each depress of the north Jiangsu is very high and become descending from the depressed to the uplift region. Fourthly, the thermal evolution for the marine source rocks in north Jiangsu is end in the end of the Tertiary hut those in south Jiangsu and in south Anhui is end in the end of the Cretaceous. Fifthly, different cognition for the invert phenomenon of the R0 values and the strata that are opened out at the Shenke well, i.e. there is twin hydrocarbon-formation in the North-Jiangsu Basin that the strata from the Cretaceous to the tertiary, the late formation of the oil-gas is occurred from the late Cratacerous to the tertiary.更多还原