Palynological analysis of the lower member of the Hongguleleng Formation and discussion of the Frasnian/Famennian boundary in Western Junggar, NW China

Abstract

Palynological investigations have been carried out on samples from the Upper Devonian Hongguleleng Formation of Western Junggar, Xinjiang, NW China. In total, 26 miospore species belonging to 19 genera and 28 acritarch species assigned to 19 genera have been recognized from the lower member of the Hongguleleng Fm. in the Bulongguoer section. The palynofloral assemblages, in particular the miospore taxa, are similar to those from the eastern European early Famennian Corbulispora vimineus–Geminospora vasjamica (VV) and Cyrtospora cristifer–Diaphanospora zadonica (CZ) miospore biozones, albeit quantitatively and qualitatively depauperate. The miospore assemblage zone is also consistent with the previous zonal schemes in light of brachiopod and conodont fauna assemblages, as well as carbon isotope geochemistry, that indicates a correspondence to the Palmatolepis crepida conodont Biozone. Part of the earliest Famennian Corbulispora vimineus–Geminospora vasjamica (VV) (more or less equivalent to the Palmatolepis triangularis conodont Biozone) miospore Biozone is most likely to be missing in the Hongguleleng Fm. of the Bulongguoer section. The palynostratigraphy and sedimentary sequence in Western Junggar are very similar to those from some other regions of western and eastern Europe, which increases the knowledge of the evolution of the paleoclimate, paleogeography and regional sedimentary environment of the Central Asian Orogenic Belt (CAOB), Eastern European Platform, and Laurussia.