Palynostratigraphy and palaeoenvironments around the Albian-Cenomanian boundary interval (OAEld), North Bulgaria  

作　　者：Polina PAVLISHINA 

机构地区：[1]Department of Geology, Palaeontology and Fossil Fuels, Sofia University, 15 Tzar Osvoboditel Bd. 1000, Sofia, Bulgaria

出　　处：《Science China Earth Sciences》2017年第1期71-79,共9页中国科学（地球科学英文版）

基　　金：carried out in the frame of the IGCP Project 609 "Climate-environmental deteriorations during greenhouse phases:Causes and consequences of short-term Cretaceous sea-level changes "

摘　　要：The palynological assemblages from two Albian-Cenomanian boundary sections in North Bulgaria are described. The samples analyzed yielded a diverse palynological content including dinoflagellate cysts and miospores. Based on dinocyst nutrient and productivity indices a phase of enhanced nutrient availability and high primary productivity is inferred for the latest Albian interval. The pronounced predominance of peridinioid dinocysts in this interval, namely O. verrucosum, O. scabrosum and especially P. infusorioides is considered to reflect eutrophic conditions. It coincides with the increased phosphorus mass accumulation occurring at the top part of the Upper Albian Dekov Formation. OAE ld is indicated in the Tolovitsa karst spring section, based on palynofacies dominated by high amounts of granular amorphous organic matter （AOM） related to anoxic environmental conditions. These sections serve as evidence suggesting a relationship between Cretaceous peridinioid cysts （including Palaeohystichphora infusorioides, Ovoidinium verrucosum, O. scabrosum） and anoxic/suboxic conditions and/or high primary productivity. The pollen spectrum inferred relatively stable vegetation patterns of surrounding continental areas during and after the AlbiardCenomanian boundary interval and the times of OAE ld formation. The hinterland vegetation integrated mainly pteridophyte spores and gymnosperms. The area was part of the Southern Laurasian floral province which was characterized by warm temperate to subtropical humid climate. Angiosperms were still minor part of this vegetation.The palynological assemblages from two Albian-Cenomanian boundary sections in North Bulgaria are described.The samples analyzed yielded a diverse palynological content including dinoflagellate cysts and miospores.Based on dinocyst nutrient and productivity indices a phase of enhanced nutrient availability and high primary productivity is inferred for the latest Albian interval.The pronounced predominance of peridinioid dinocysts in this interval,namely O.verrucosum,O.scabrosum and especially P.infusorioides is considered to reflect eutrophic conditions.It coincides with the increased phosphorus mass accumulation occurring at the top part of the Upper Albian Dekov Formation.OAE 1d is indicated in the Tolovitsa karst spring section,based on palynofacies dominated by high amounts of granular amorphous organic matter(AOM)related to anoxic environmental conditions.These sections serve as evidence suggesting a relationship between Cretaceous peridinioid cysts(including Palaeohystichphora infusorioides,Ovoidinium verrucosum,O.scabrosum)and anoxic/suboxic conditions and/or high primary productivity.The pollen spectrum inferred relatively stable vegetation patterns of surrounding continental areas during and after the Albian/Cenomanian boundary interval and the times of OAE 1d formation.The hinterland vegetation integrated mainly pteridophyte spores and gymnosperms.The area was part of the Southern Laurasian floral province which was characterized by warm temperate to subtropical humid climate.Angiosperms were still minor part of this vegetation.

关 键 词：ALBIAN CENOMANIAN Dinoflagellate cysts BIOSTRATIGRAPHY PALAEOENVIRONMENTS OAE1 d 

分 类 号：Q914[天文地球—古生物学与地层学]