辽西喀左盆地九佛堂组的划分及相关问题

SUBDIVISION OF THE JIUFOTANG FORMATION AND RELATED ISSUES IN THE KAZUO BASIN

针对辽西九佛堂组存在多种内部划分方案及其他相关问题,通过实测累计达106km的十余条地质剖面,运用岩石地层学、沉积学的基本原理,从喀左盆地九佛堂组识别出5个由凝灰质岩石构成的标志层或层组,并以标志层或层组1、2、4、5的顶界将九佛堂组划分为4个段:一段主要以浅灰、灰白色富凝灰质岩石为特征,砂岩、砾岩比例大;二段以浅灰、深灰色粉砂岩、泥岩为主,部分地段夹油页岩、砂岩、砾岩;三段以褐灰色泥质粉砂岩、深灰及绿灰色粉砂质泥岩为主,根据由标志层或层组,此段又可分为2个亚段,其中上亚段含有工业意义较大的油页岩;四段主要由浅灰、灰白色粉砂岩、黄灰色砂岩、绿灰色泥岩构成。在此基础上,讨论了凝灰质沉积造成大量生物死亡这一与火山活动相关的事件,认为盆地不同地段同期沉积的碎屑岩和部分泥质岩受源区母岩类型控制致使颜色存在差异。沿用前人意见将九佛堂组与沙海组的界线放在标志层或层组5的顶界。

In view of these facts that there are many subdivision plans of the Jiufotang Formation of Western Liaoning and other related issues, the authors measured more than ten sections which was 106km in all. Using the basic principles of lithostratigraphy and sedimentology, five tuffaceous rocks marker beds or measures are distinguished from the Jiufotang Formation in the Kazuo Basin. The Jiufotang Formation is subdivided into four members bounded on the top of Marker Bed or Measure 1,2,4,5. Member 1 mainly consists of light-gray, off-white tuffaceous rocks, to which sandstone and conglomerate are high in proportion;Member 2 mainly consists of light-gray, dark-gray siltstone and mudstone with oil shale, sandstone and conglomerate in partial regions; Member 3 mainly consists of brown-gray pelitic siltstone and darkgray, glaucous silty mudstone and is subdivided into two sub-members by Marker Bed or Measure 3, and the upper sub-member contains oil shale with great industry significance; Member 4 mainly consists of light-gray, off-white siltstone, yellow-gray sandstone and glaucous mudstone. On this basis, these conclusions are elaborated that the deposition of tuffaceous material concerned with volcanic events in origin leads to the death of massive organisms and syndepositional elastic rocks and argillaceous rocks rooting in different types of mother rocks have differences in color in different parts of the basin. Finally, it is discussed that if there is the Shahai Formation above the Jiufotang Formation and the issue of its bottom boundary.