Sporopollen Assemblages from the Cretaceous Yimin Formation of the Hailar Basin,Inner Mongolia,China

Three sporopollen assemblages are recognized for the first time from the Cretaceous Yimin Formation in the Hailar Basin of eastern Inner Mongolia. They are （in ascending order）： the lmpardecispora-Aequitriradites- Clawttipollenites assemblage; the Triporoletes-Pilosisporites-Asteropollis assemblage; and the Appendicisporites- Asteropollis-Tricolpites assemblage, distributed in Members 1, 2 and 3 of the Yimin Formation respectively. Recognition of this biostratigraphic sequence is very important for the division and correlation of the Yimin Formation in the basin. Meanwhile, the age of the Yimin Formation is considered to be Barremian to Early Albian based on the palynological data.

Quaternary Sporopollen Records and Environmental Evolution in the Dalangtan of Qaidam Basin

Since the Quaternary,very thick lacustrine sediments have been deposited in Dalangtan of Qaidam Basin.Based on a study of high-resolution sporopollen analysis on the Dalangtan ZK06 drilling,and paleomagnetic dating

Palynology of Yanchang Formation of Middle and Late Triassic in Eastern Gansu Province and Its Paleoclimatic Significance

Xifeng （西峰） oilfield was recently found in the southwest of the Ordos basin. The oil source rocks are the Chang 7 Section of Yanchang （延长） Formation. In order to study the paleoclimate that controlled the formation of source rocks, a systemically palynological research on related beds in Yanchang Formation has been carried out. The core samples were analyzed with classical palynological techniques and the organic-walled sporomorphs from these samples were observed, identified and photographed under a light microscopy and a fluorescence microscopy. Abundant sporopollen were found in drilling cores from Chang 8 and Chang 7 sections, and two assemblages were distinguished： the Aratisporites-Punctatisporites assemblage and the Asseretospora-Walchiites assemblage. Their characteristics are similar to those of the assemblage of Tongchuan （铜川 ） Formation and the assemblage of Yanchang Formation in southeast Ordos basin, respectively. Their geological times are Ladinian of late Middle Triassic and Carnian of early Late Triassic, respectively. The correlation of palynoflora with their parent plants suggests the paleoclimate of eastern Gansu （甘肃） Province in the Middle and Late Triassic was warm and rainy with prosperous vegetation. The palynoflora indicated the area was in a temperate to subtropical zone then. Both the ecological types and differentiation degree curves of sporopollen indicated the period during Chang 8 and Chang 7 sections was warm and wet, and the phase accorded with large-scale lake transgression in Chang 8 Section and the largest lake area in Chang 7 Section. North China in Middle and Late Triassic was located in a warm and rainy, temperate and subtropi- cal zone. The palynofloras in Chang 8 and Chang 7 sections have the characteristics of North China flora, however they also indicate wetter and warmer climate due to their proximity to the large lakes. The period of Chang 8 to Chang 7 sections is the climax of the expansion of the lake, and the bloom of fresh algae during the period, which helped form the high-quality source rocks in Chang 7 Section.