山东及两淮地区石炭、二叠系高分辨层序序列对比

研究了山东和两淮煤田石炭、二叠系层序地层学特征,以陆表海聚煤盆地充填沉积为重点,进行了高分辨层序地层划分.研究表明,陆表海盆地充填序列可划分出三级层序12个,四级层序24个,五级层序最多可识别出46个.通过山东地区与两淮煤田的对比分析认为,三级和四级层序可以对比和追踪,其精度和准确程度较高,而五级层序对比较为困难.层序对比的关键问题是各级层序界面的识别与追踪,特别是低级别层序界面的识别与对比.提出了山东及邻区高分辨层序地层划分方案,以作为指导资源勘探和地层对比的参考依据.     

On the analysis of the high-resolution sequence stratigraphy and coal accumulating law of jurassic in Ordos Basin

The strata of Jurassic was divided into three tectonic sequences and eight sequences of third rank, according to the developing feature of the tectonic inconformity and the transforming feature of the depositional system tracts. Also the identification and the division of the base-level cycle of different period were carried through. Therefore three cycles of super period, eight cycles of long period, twenty-four cycles of middle period and some cycles of short period were identified. From the overall character of the coal-accumulation in the Mesozoic, we can see that the Yan’an formation is of the best nature of coal bearing. When the coal bearing systems of Jurassic were depositing, the Ordos area is the coal accumulating basin of terrene of large scale and located in the same tectonic unit. But the local structure of different part and the paleolandform are different in the basin, which resulted in the difference of the depositional environment. So the layer number and the distribution of the thickness of the coal beds are different in the different part of the basin. The coal-accumulating action migrated regularly along with the development, evolvement and migration of the depositional systems. The layer numbers of the coal beds, which can be mined, are more in the north and west fringe of the basin, whose distributing area is extensive, and they are more steady in the landscape orientation, also the total thickness is great. Therefore the nature of coal bearing and the coal-accumulating action of different part changed obviously in the space in Ordos area. Supported by National Basis Research Program of China(2003CB214608)     

HIGH-RESOLUTION SEQUENCE DIVISION ANDTRANSGRESSIVE EVENTS COAL FORMATION IN SOUTHEASTERN NORTH CHINA EPICONTINENTAL BASIN

The sea level changes in the Paleozoic epicontinental basin were of high frequency and the transgressive events were episodic. This kind of sea level changes controlled both the basinfilling and the coal accumulation within the basin. Coal acoJmulation in the transgressive process is one of the typical features of the North China epicontinental basin. High-resolution sequence analysis to the Permo-carboniferous coal series based on the core observation indicates that the epicontintental coal-bearing succession can be divided into 1 tectonic sequence (the original type of basin filling), 3 supersequences, 12 third-order sequences and about 48 parasequences. The third-order sequences are of dual configuration-sequences that are composed of transgressive systems tract in the lower part and highstand systems tract in the upper part. The transgressive systems tracts are relatively thin in thickness and have fewer parasequences (commonly 1 to 2),while the highstand systems tracts are thick, generally consist of several parasequences.     

HIGH-RESOLUTION SEQUENCE STRATIGRAPHIC ANALYSIS OF THE PERMIAN IN THE WESTERN SHANDONG AND HUAINAN-HUAIBEI COALFIELDS

The sedimentary characteristics and their combination succession of the Permian in the Shandong and Huainan-Huaibei coalfields are analyzed. The mid- and short-term stratigraphic base-level cycles are identified. High-resolution sequences are divided based on the above results. The study shows that the stratigraphic base-level cyclic method is an efficient way in the determination of the high-resolution sequences, especially in the classification of the terrestrial and transitional depositional succession.