Early Miocene flora of central Kazakhstan(Turgai Plateau) and its paleoenvironmental implications

The investigation of the fossil floras from the Turgai plateau (central Kazakhstan) contributes to a better understanding of the origin of the temperate Turgai type flora which spread to Kazakhstan and adjacent areas during the Oligocene-Miocene transition. In this paper, we present the results of a carpological and palynological study of the Kumyrtas flora collected from a flora-bearing horizon of the regional coalbearing Zhilanchik suite, dated to the Aquitanian period. Pollen analysis identified 33 taxa, with are dominated by angiosperms (about 73%) and reflect zonal vegetation. The high percentages of Betula (27%) and Pterocarya (7.5%) that were found in this flora allows comparisons with other Aquitanian floras of Kazakhstan. Based on descriptions of fossil fruits and seeds, we determined that 19 taxa were dominant;these taxa had meosphytic herbaceous components, suggesting mostly edaphic local conditions. The incongruence between the carpological and the pollen records suggests a significant taphonomical effect. Quantitative reconstruction of the palaeoclimate based on pollen records supports—and slightly extends—previous findings based on fossil leaf data, but contradicts findings deduced from the carpological record. Plant Functional Type (PFT) classification was used to characterize the vegetation patterns. Pollen records show that about 45% of diversity relates to the arboreal broadleaved deciduous components and ca. 35% to conifers. Fossil fruit and seed data indicate riverine vegetation with a high diversity of aquatic components and shrub stratum.

In Search of the Cretaceous-Tertiary Boundary in Heilongjiang River Area of China

A new geological section recognized in Baishantou of Jiayin,Heilongjiang Province,China,was studied preliminarily in searching for the K/T boundary.An early Paleocene florule characrerized by abundant Tiliaephyllum tsagajanicum leaves and its associated plants,was collected from the Baishantou Member(new member representing the lower part of the Paleocene Wuyun Formation)overlying the possible K/T boundary.A tuff bed was found from the upper part of the Furao Formation(uppermost Cretaceous)in this section.The new findings imply that the K/T boundary is probable lying in the interval between the base of the Baishantou Member and the tuff bed,based on the correlation of the present strata with the stratotype of the Tsagajan Group spanning the K/T boundary in"Belaya Gara"of the Bureya Basin,Russia.The early Paleocene florule from the Baishantou Member and the early-middle Maastrichtian dinosaurs found from the Yuliangzi Formation underlying the Furao Formation suggest that the Baishantou section is more promising for searching for the K/T boundary in this area.Further studies of the section is needed,integrating paleontological,biostratigraphic,geochemical,paleomagnetic,and sedimentary research would benefit our understanding the mass extinction event and biotic recovery in the Heilongjiang River area,China,and even all of northeast Asia during the K/T boundary interval.