Namurian miospores from China and their correlation with Europe and North America

Abstract

Late Carboniferous deposits in Jingyuan, northwest China, were palynologically subdivided into TA, VR, SB, KM, BP, AS and TG miospore Zones, ranging from Namurian A to Westphalian A, based on the associated faunal evidence (mainly ammonoids, conodonts and fusulinids). Some more important characters and/or peculiarities of some of the components in the palynoflora in the Namurian deposits of Jingyuan, China are documented. The miospores for example assigned to Monoletes (mainly Laevigatosporites), with their known occurrence in lower frequency in the Tsingyuan Formation, increase markedly from the base of the BP miospore Zone (equivalent to R2-G1) of the upper part of the Hongtuwa Formation. Disaccites, including representatives of Limitisporites, Gardenasporites, Klausipollenites, Alisporites, Platysaccus, Illinites, Jugasporites and Vestigisporites, have their earliest records in the VR miospore Zone (equivalent to E2) of the upper part of the Tsingyuan Formation, and develop rapidly in the BP Zone. The stratigraphical distribution of these two important taxa is significantly different from their known occurrence in western Europe and North America, where the first appearance of Disaccites (non striatiti) and the first quantitatively significant increase of Laevigatosporites in coal-bearing peat deposits take place in the Westphalian within the Euramerican flora.Comparisons of the Namurian miospore assemblages of North America and Europe with those of China suggest that the KM and AS + TG Zones in Jingyuan can be correlated with the KV and SS Zones of the British palynological zonation, respectively. Other correlations of miospore zones from Jingyuan and other areas of the Northern Hemisphere are also suggested and discussed. A number of species, including Simozonotriletes verrucus Zhu, S. sinensis Zhu, Stenozonotriletes rotundus Wang emend. Zhu, S. circularis Zhu, Reinschospora granifer (Gao) Zhu and Procoronaspora odontopetala Zhu, are regarded as endemic species for Jingyuan and characterise the differences of the Namurian palynoflora between Jingyuan and other areas. The palynological differences combined with the peculiarities of fossil plants associated with the miospores imply that the differentiation of the Cathaysian from the Euramerican floras came into existence no later than the early Namurian rather than the latest Carboniferous which previously was considered the most probable time for the origin of the Cathaysian flora by Chinese palynologists.