青海省早三叠世的孢子花粉及其地层意义

SPORES-POLLEN FROM EARLY TRIASSIC DEPOSITS IN QINGHAI PROVINCE AND THEIR STRATIGRAPHIC SIGNIFICANCE

青海省三叠纪地层发育、分布很广,占全省总面积的二分之一以上。原认为三叠纪地层以中、上三叠统为主,根据孢粉研究资料显示的特征修正为以下三叠统(包括部分原订为二叠纪的地层)为主,中、上三叠统次之或断续分布。首次对青海省的早三叠世孢子花粉组合,按地层分区进行了全面的归纳整理,识别出了5个地层群或组的9个孢粉组合,并讨论了其地层意义及对比等问题。华北区以下环仓组及赛尔贡切组组合为代表,分别以Lundbladispora或Aratrisporites的高含量为特征,并与少量Micrhystridium共生;过渡区以洪水川组的组合为代表,以Taeniaeporites及/或Limatulasporites/Tubermonocolpites的高含量为特征,并与少量Micrhystridium,Baltisphaeridium共存;华南区以下巴颜喀拉山群及池塘群组合为代表,以Lundbladispora较高含量为特征,并与Veryhachium为主的疑源类共存。同时讨论了孢粉的地层意义及对比等问题,建议将原布青山群划入下巴颜喀拉山群。

Triassic strata are well developed and widely distributed in Qinghai,occupying more than one half of the area of the province.The present paper attempts for the first time to give a synthesized and comprehensive analysis of the palynology of the Early Triassic strata in Qinghai.The Triassic strata were considered to be dominated by Middle-Upper Triassic sediments.However,more recent palynological studies have demonstrated that those strata are actually mainly of Early Triassic in age,while the Mid-Upper Series of Triassic is subordinate or intermittent in distribution.The paper discusses problems related to the Early Triassic stratigraphic subdivision and correlation.Nine spore-pollen assemblages from 5 groups or formations are recognized.In short,the assemblages from the Lower Huancanggou and Sairgongqie formations in North China Area are characterized by the high content of Lundbladisporaand Aratrisporites,respectively,in association with a few Micrhystridium.The transitional Area（belt）is represented by the assemblage of the Hongshuichuan Formation,and characterized by high content of Taeniaesporites and/or Limatulasporites/Tubermonocolpites.And the assemblages from the lower Bayanharshan and Chitang groups in South China are characterized by the high content of Lundbladisporain association with some acritarchs such as Veryhachium.