海拉尔盆地查干诺尔凹陷伊敏组孢粉组合及其地质意义

为了建立查干诺尔凹陷伊敏组钻井地层等时对比标准和恢复沉积时期的古气候,对海参8井伊敏组开展了孢粉地层学和孢粉古气候学的系统研究。使用盐酸—氢氟酸冷处理法获取了岩石中十分丰富的孢粉化石,自下而上划分为2个孢粉组合,Lygodioisporites-Cyathidites-Triporoletes组合分布于伊敏组1段,Leiotriletes-PilosisporiteAsteropollis组合分布于伊敏组2+3段,是研究区钻井地层等时对比的有效标志。孢粉组合对比表明,伊敏组的地质时代为Barremian至Aptian期。依据孢粉谱恢复古气候的演变规律为:伊敏组1段植被演替是针叶-灌木林→灌草丛→常绿阔叶林、灌草丛→针叶-灌木林,气候由湿润的热带向热带、北亚热带气候转变;伊敏组2+3段植被演替是灌草丛→针阔叶混交林、灌草丛→针叶林、灌草丛→针阔叶混交林,气候属于湿润的热带气候。

SPOROPOLLEN ASSEMBLAGES AND THEIR GEOLOGICAL SIGNIFICANCES FOR YIMIN FORMATION IN CHAGANNUOER SAG OF HAILER BASIN

In order to establish the isochronic comparing standard of the drilled formations in Yimin Formation and restore the paleo-climate in the sedimentary periods for Chagannuoer Sag,the systematical studies on the palynostratigraphy and sporopollen palaeoclimatology of Yimin Formation in Well Haican-8 were conducted.With the help of the cold treating method by hydrochloric acid and HF acid,the pretty abundant palynologic fossils were obtained in the rocks and classified into two sporopollen assemblages from top to bottom,Lygodioisporites-Cyathidites-Triporoletes Assemblage distributes in Member 1 of Yimin Formation,while Leiotriletes-Pilosisporite-Asteropollis Assemblage in Member 2+3 of Yimin Formation,these assemblages can be recognized the effective markers for the isochronic comparison of the drilled strata in the study area.The assemblage contrast shows that the geological age of Yimin Formation is from Barremian to Aptian period.According to the evolution laws of the restored paleo-climate by the pollens,the vegetations of Member 1 in Yimin Formation develop from the coniferous shrub wood to shrub-tussock,evergreen broad-leaf forest mixed with the shrub-tussock to coniferous shrub wood.The climate during Member 1 changes from the humid tropical to sub-tropical one;while the vegetation of Member 2+3 evolves from the shrubtussock to conifer-broadleaf forest mixed with the shrub-tussock to coniferous forest and shrub-tussock to coniferbroadleaf forest,the climate during this time belongs to the humid tropics.