摘要
本区太原组和山西组为一套过渡环境的沉积.太原组为有障壁海岸沉积体系和三角洲沉积环境.区内主要煤层的聚煤特征为太原组中的15、9及8号煤层均为层位稳定.厚度较大的全区稳定可采煤层;山西组的6号煤层为层位较稳定.厚度有些变化的较稳定部分可系煤系.
The coal bed in Shouyang coal field was composed mainly of Taiyuan Group(C3t) and Shanxi Group(P1s) containing 9 to 14 seams. The abounded coal reserve of this region made itself one of the important bases of energy.
The Taiyuan Group in this district can be divided into five complete cycles of sequence, containing 6-8 coal seams, and was made up of light gray, dark gray and grayish black mudstone, siltpelite, carbonaceous mudstone, silt-stone, sandstone, limestone and coal seams. According to the sedimentograghy, the authors considered environment that Taiyuan group of this area belonged to the transitional environment deposite. The lower three cycles i.e.the 1st, 2nd, 3rd were built up of continental clastic debris tidal flat deposition under marine regression and lower intertidal carbonate under marine inundation, while the upper two cycles (the 4th and 5th) belonged to deltaic deposition.
The Shanxi Group in this district containing 3-6 coal seams, consisted of gray and black mudstone, sandy mudstone, carbonaceous mudstone, siltstone, sandstone and coal seams.
On studying its sedimentation mechanism in detail, the authors proposed that the formation of Shanxi Group is not 'purely continental'as been known before, but as deltaic deposition. It can also be divided into five cycles (the 6th, 7th, 8th, 9th and 10th) most of them represent developing deltaic deposition except the cycle 6 which showed complete sequence of delta deposition.
The relationship between the depositional environment and the property of coal seams are as follows:
The 15th, 13th, 12th and 11th coal seams, located at the lower three cycles of the Taiyuan Group, were deposited under tidal flat environment. The characteristics of this sequence can be described in following words; the formations below each coal seam belonged to sea ebb sequence its continental clastic debris represent tidal flat while those above each coal seam belonged to lower tidal dcpositional carbonate rocks, the coal seams were usually located at the climax of marine regression, its vertical gradation displaied normal sequence.
All of the above coal seams mentioned, represented their features as wide distribution, stable sequence of deposition and high sulfur content, with the trend of thick coal belt parallel to the palaeo-coastal line. when the ancient swamp lasted for a longer period, the coal seam pertained to be of greater thickness, wide distribution and available to be minable seam. It is the case of the 15th coal seam. But in the reverse, the 13th, 12th, and 11th coal seams obviously got thinner and partly workable owing to a short period of swamping.
The 9th seam was formed on the abandoned delta flower in the fourth cycle, possessed the feature of greater thickness, medium ash, much lower sulfur content and wide distribution due to a stable period of swamping.
The deposition of the 8th seam was formed in swamps of river branches on the delta plain, therefore it had belter thickness but the wash-out by the branch river in succession caused the coal seam to be partly thinner.
The 6th seam located in Shanxi Group was also formed in swamp of branch river, and developed in the same history and same result as that mentioned above so it can be expected to be partly minable seam.
出处
《沉积学报》
CAS
CSCD
北大核心
1989年第1期91-99,共9页
Acta Sedimentologica Sinica
