河南卢氏盆地古近纪气候环境及地层时代探讨——以卢氏县三角沟、大峪沟剖面孢粉资料为据

Paleocene Climate and Stratigraphic Era Based on the Sporopollen in Lushi Basin,Henan Province

河南省卢氏县三角沟、大峪沟剖面位于豫西卢氏盆地中南部,涉及地层为中始新世张家村组、晚始新世卢氏组和渐新世大峪组。孢粉总体以被子植物为主,可划分为5个孢粉组合。第一组合位于张家村组上部,蒿粉、栎粉含量高;第二组合位于卢氏组下部,菌孢类含量高。前者属亚热带干热气候下的洪泛盆地沉积,后者属还原环境湿润气候下的湖泊沉积,其孢粉特征更接近于邻区中晚始新世沙河街组三段上部和二段下部孢粉特征。第三组合到第五组合分别位于大峪组二段下部、中部和上部,其中第三组合蒿粉含量高,与邻区沙河街组二段上部和一段下部孢粉特征较为相似,属于干热气候下的泛滥平原沉积。第四组合和第五组合中栎粉含量低,草本植物含量高,其特征更接近北半球渐新世晚期孢粉特征。前者菌孢类含量比第二组合低,但比其它组合高,属于静水环境下半湿润半干旱气候下的洪泛盆地沉积;后者蒿粉含量高,属于干旱气候下的河流沉积。通过孢粉分析和区域对比,进一步确定了张家村组形成于中始新世,卢氏组形成于晚始新世,大峪组形成时代为渐新世。古近纪卢氏地区的气候经历了干热—湿润—干热—半湿润半干旱—干旱的变化过程。

In order to study their climate environment and stratigraphical era, Sporopollen has been analyzed for the samples from Zhangcun, Lushi and Dayu Formations in Sanjiaogou and Dayugou sections in the middle-southern part of Lushi Basin, Henan Province. The sporopollen is mainly from angiosperms which can be divided into 5 groups. The upper part of Zhangjiacun Fro. with high Sporopollen content of Artemisia and Quercus formed in the flood-basin in the subtropical zone under the lithothermal climate. The Lushi Fro. with high Sporopollen content of fungal spore belongs to the lake sediment in the reduced environment under the humid climate. The second part of Dayu Ft. with high Sporopollen content of Artemisia deposited in the flood-plain under the lithothermal climate. The middle part of Dayu Ft with lower Sporopollen content of fungal spore than Lushi Ft. but higher than other stratahorizons is the flood-basin sediment under the semidry-subhumid climate. And the up part with high Sporopollen content of Artemisia belongs to the river sediment in the grassland under the dry climate. With the contrast of the Sporopollen in the region, it is suggested that Zhangcun Fro. formed in the middle Eocene epoch, Lushi Fro. formed in late Eocene epoch, and Dayu Fro. formed in Oligocene epoch. The climate of Lushi basin in Paleocene experienced the change from the lithothermal-humid-lithothermal-semidry-subhumid-dry climate.