Kuqaia孢型体在柴达木盆地的发现及对冷科1井地层时代再认识

THE DISCOVERY OF KUQAIAPALYNOMORPH AND THE RECOGNITION ON STRATIGRAPHIC AGE OF WELL LENGKE 1 IN QAIDAM BASIN

长期以来,柴达木盆地冷科1井井深4666m^5200m井段地层的时代归属存在侏罗纪、石炭纪和三叠纪之争。为了进一步明确该套地层的地质时代,消除混乱,对该套地层及其上覆部分地层(4395m^4666m井段)的岩屑进行了孢粉分析,结果在39块样品中分析出丰富的孢粉化石,孢粉组合面貌基本一致。孢粉组合中,裸子植物花粉居统治地位,占总含量的93.6%以上,以本体无肋纹的两气囊花粉含量为主,占总含量的58.4%~92%;蕨类植物孢子的含量只有0~6.4%,主要是Osmundacidites(0~5.4%);且普遍含库车孢型体(Kuqaia),这两井段地层的时代同属早侏罗世。

Over the years,there have been three viewpoints on the stratigraphic age of 4666～5200mdepth interval in well Lengke 1,Qaidam Basin：Jurassic,Carboniferous,and Triassic.In order to further clarify the depositional age of this stratigraphic interval,we analyzed palynomorphs collected from this interval and its overlying strata（4395～4666m）.Abundant spores and pollen grains were recovered from 39 samples.The sporopollens from 4395～5200mdepth interval represent the same assemblage,indicating a similar depositional age.In this assemblage,gymnospermous pollen grains are dominant,accounting for more than 93.6% of the total diversity,mainly including Disaccites（58.4%～92%）.Fern spores represent only0～6.4%,mainly including Osmundacidites（0～5.4%）.We also discovered the palynomorph Kuqaia which belongs to the Early Jurassic.Thus,we conclude that the studied interval at well Lengke 1is Early Jurassic in age.