沉积学报2000，Vol.18Issue(3)：362-368,7.
鲁西陆表海盆地高分辨率层序划分与海侵过程成煤特点
The Division of High- resolution Sequences and the Transgressive CoalFormation in the Epicontinental Basin of the Western Shandong Province
摘要
Abstract
The high - frequency sea level changes in the North China epicontinental basin from the Late Carboniferous toEarly Permian are the main factors controlling the basin - filling and coal accumulation. The coal - bearing succes-sion, therefore, has distinct cycles. The sea level changes in the North China epicontinental basin were compositesea level changes. The long - term sea level changes are superposed by shorter - term cycles, the mid - term andshort - term sea level changes. There were short - term retrogressive events in the process of long term transgres-sive period, and multiple short periodic transgressive events superposed on the long - term transgressive period.Study shows that the base- level cycles in the North China epicontinental basin may be substitute by the relativesea level cycles, because the high - frequency sea level changes in the basin are the integrative results of the sea lev-d changes, the tectonic subsidence, the climate changes and the sediment supply. The later three factors, the tec-tonics, the climate and the sediment supply were relatively stable. The sea level changes, thus, become the domi-nant factor. Using the thought and methodology of high - resolution sequence stratigraphy, the authors investigate thecharacteristics of the high- resolution sequence stratigraphy of the coal measures in the Western Shandong, identi-fy and divide the mid - long term and mid - short term base - level cycles. Three long - term base - level changeslead to the formation of three third order sequences. The mid- term base- level cycles are approximately corre-sponded to the systems tracts. Large - scale marine flooding events were caused by the mid - term base - level rise. Because of the hysteresis of the deposition, the thick- bedded limestones were deposited in the period of maximumbase - level rises, which occurred three times in the history of the epicontinental basin, representing the depositionsof three times of maximum base- level rises. The outstanding feature of the paralic succession is the alternative oc-currences of the marine and terrestrial depositions, forming multiple cycles. That the marine layers directly super-posed on the coalbeds is another feature of the deposition in the epicontinental basin. Eighteen short - term base-level cycles may be recognized in the epicontinental succession of the Western Shandong. Most of cycles are asym-metric, seperated by episodic transgressive event surfaces, peatification event surfaces and large scope of scouringsurfaces. The short - term base- level cycles are of high frequency. The identification and correlation of short - term base - level cycles help to the division of high - resolution se-quence. The study of the epicontinental paralic base - level cycles in the Western Shandong indicates that the eigh-teen short - term base - level cycles are corresponded to eighteen fifth - order sequences (corresponding to theparasequences). The episodic transgressive events have great effect on the coal accumulation in the epicontinentalbasin; coal formation in the transgressive process is the outstanding feature of the coal formation in the Western Shandong coalfields. The transgressive coalbeds in the long - term base - level cycles develop in the transgressivesystems tracts, while the transgressive coalbeds in the short - term base- level cycles occur in the high stand sys-tems tracts.关键词
高分辨率层序海侵过程成煤基准面旋回鲁西Key words
high - resolution sequence stratigraphy coal formation in the transgressive process base- level cycle分类
天文与地球科学引用本文复制引用
李增学,魏久传,韩美莲..鲁西陆表海盆地高分辨率层序划分与海侵过程成煤特点[J].沉积学报,2000,18(3):362-368,7.基金项目
国家自然科学基金项目(批准号49872057)资助 （批准号49872057）
