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渭北地区晚古生代含煤层系层序划分及聚煤规律

Stratigraphic sequence divided and coal accumulation law of late Paleozoic coal measures in Weibei Area

  • 摘要: 为了探究渭北地区晚古生代石炭—二叠纪含煤层系的聚煤规律,运用高分辨率层序地层学方法对渭北地区石炭—二叠纪含煤层系进行了高分辨率层序地层划分,将太原组、山西组地层划分为15个短期基准面旋回及4个中期基准面旋回,以中期基准面旋回为对比单元建立层序地层格架并讨论了3、5、11号煤层在基准面旋回中所处的位置与其厚度和连续性的关系。结果表明:有利的聚煤条件与基准面旋回过程中可容纳空间变化的方向无关,而是取决于可容纳空间变化率与泥炭产生率的比值。当该值大于1时,有利的聚煤条件发生在基准面上升早期和下降中、晚期;当该值小于1时,有利的聚煤条件则发生在基准面上升的晚期及下降的早、中期。

     

    Abstract: In order to explore the coal accumulation law of the late Paleozoic Carboniferous- Permian coal measures in Weibei Area, a high resolution sequence str atigraphy method was applied to the high resolution sequence stratigraphy divided on the Carboniferous- Permian coal measures in Weibei Area. Taiyuan Formation an d Shanxi Formation strata were divided into 15 short- term base- level cycles and 4 medium- term base- level cycles. Based on the medium- term base- level cycles as t he comparison unit, a sequence stratigraphic framework was established. The paper discussed the locations of No.3, No. 5 and No. 11 seams in the base- level cycles and the relationship to the thickness and continuity. The results showed that the favorable coal accumulation condition had no relation to the direction of the accommod ation space variation in the process of the base- level cycles and would respond to the specific ratio between the accommodation space variation rate and the slime yiel d rate. When the specific ratio was higher than 1, the favorable coal accumulation conditions would be occurred at the rising early stage, in dropping down process and late stage of the base level. When the specific ratio was lower than 1, the favorable coal accumulation conditions would be occurred at the rising late period or the down ing early period and medium period of the base level.

     

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