甘肃宝积山盆地中侏罗世植物群特征及古生态、古气候研究

本文对甘肃宝积山盆地窑街组植物大化石进行了系统研究,经鉴定共有19属50种,结合已有的宝积山盆地中侏罗世植物化石资料,发现甘肃宝积山盆地中侏罗世植物群由27属73种组成.其中,银杏类植物10属30种,真蕨类植物5属26种,松柏类植物5属6种,楔叶类植物3属5种,苏铁类植物2属4种,裸子植物球果和种子化石2属2种.基于当前植物群组成特征,对植物化石埋藏学特性进行分析,确定植物化石主要为原地埋藏或亚原地埋藏,少数属种为异地埋藏,并通过对化石类群古生态特征进行分析,结合现生植物的生存环境,初步重建了宝积山盆地中侏罗世植物群落,划分为四个植物群落:岸边湿地楔叶类植物群落、低地蕨类苏铁类植物群落、坡地银杏类植物群落和高地松柏类植物群落.通过对植物群组成特征和植物化石叶相特征的统计分析,并与其他气候带植物群特征进行对比,推断中侏罗世时期甘肃宝积山盆地为温暖潮湿的暖温带气候.

Characteristics of the Middle Jurassic flora in the Baojishan basin, Gansu Province, and its study on paleoecology and paleoclimate

This paper presents the results of a systematic study on plant macrofossils from the Middle Jurassic Yaojie Formation in the Baojishan basin, Gansu Province. A total of 73 species of 27 genera have been identified. Among them, there are Ginkgopsida of 30 species in 10 genera, Filicopsida of 26 species in 5 genera, Coniferopsida of 6 species in 5 genera, Sphenopsida of 5 species in 3 genera, Cycadopsida of 4 species in 2 genera, Gymnosperm flowers, cones are 2 species in 2 genera. Based on the characteristics of plant flora composition, the plant fossil burial and group ecology were analyzed. It was determined that the plant fossils are mainly autochthonous burial or subsoil burial, and a few are heterochthonous burial. Combined with the living environment of the existing plants, the Middle Jurassic plant community in the study area was preliminarily reconstructed and divided into four plant communities: the riparian wetland Sphenopsida plant community, the lowland Pteridophyte- Cycadopsida community, the slope broad- leaved plant community and the highland coniferous plant community. Based on the statistical analysis of the composition characteristics of the flora and the leaf facies characteristics of plant fossils, and the comparison with the flora of different climate zones, it is inferred that the Middle Jurassic palaeoclimate in the Baojishan basin of Gansu at that time was a warm, and humid warm temperate climate.