从孢粉组合试论西藏西部隆格尔山地早白垩世的古地理概况

从西藏西部隆格尔山地的白垩系含煤地层中的化石孢粉组合,证实该山地曾经生长着以裸子植物短叶杉属和蕨类植物海金砂科为主的陆生植物群。本区早白垩世古植物属印度-欧亚植物地理区,古气候热而偏干,属热带、亚热带气候带。

EARLY CRETACEOUS SPORO-POLLEN ASSEMBLAGE AND ITS PALEOGEOGRAPHICAL SIGNIFICANCE IN WESTERN XIZANG

A sporo-pollen assemblage with dominant Classopollis-Cicatricosisporites has been found from a section of Cretaceous deposits in Lunggar mountain in western Xizang.The assemblage is characterized by the dominance of gymnos-permous pollen which occupied 69.2% in the total sporopollen numbers of the assemblage.Secondarily, it is rich in pteridophytic spores (30.8%) and there is not any angiospermous pollen.Within gymnospermous pollens, some primitive coniferae are absolute dominant which include Classopollis (47.0%), Callialasporites, Psophosphaera, Exesipollenites, Abietineae-pollenites and Parvissaccites etc.Besides, there are some Epedrapites and Monosulcites pollens.Pteridophytic spores are mainly Cicatricosisporites (23.3%).Others are Cyathidites and Cingnlalispor ites.It shows that continental flora, mainly gymnospermae Brachyphyllum and pteridophytic Lygodiaceae (Anemia and Mohria) existed in Lunggar mountain during the early Cretaceous stage.Also it infers that this area might belong to Indo-European region on a palaeobotany-geographical classification.Palaeo-climatecally, it was rather hot and dry and a tropic-subtropic zone could be proposed.