Title: Sytematics, palaeoecology and trophical structure of bivalve associations within the OAE2 in the Bohemian Cretaceous Basin (Upper Cenomanian): Pecínov quarry Author: Bc. Lucie Kunstmüllerová Department: Institute of geology and palaeontology Supervisor: doc. RNDr. Martin Košťák, Ph.D. Abstract: This master thesis provides an updated taxonomic inventory of the bivalve fauna of the Pecínov locality, places the fauna in its palaeobiogeographic setting, and addresses its palaeoecological significance. In the literature research part of the thesis the basic geology of the locality and an overview of the Bohemian Cretaceous Basin are presented. Processes connected to the ocean anoxic events, specifically to the OAE 2 are also discussed. The research part of the thesis describes the systematics of the bivalve assemblage (with the exception of Inoceramidae) and its statistical evaluation with the emphasis on the environment interpretations of the locality. In total, over 350 specimens have been considered and assigned to 20 genera within 15 families and 9 orders. Bivalve functional morphology and guilds are described to interpret palaeoecology. Guilds are based on life habit and feeding category. Four main guilds are recognized: epifaunal suspension-feeders, semi-infaunal suspension-feeders, infaunal...

The Eagle Ford Shale and equivalent Boquillas Formation (Late Cretaceous) contain abundant volcanic ash beds of varying thickness. These ash beds represent a unique facies that displays a range of sedimentary structures, bed continuity, and diagenetic alteration. They are prominent not only in West Texas outcrops, but also in the subsurface of South Texas where hydrocarbon production is actively occurring. The ash beds have the potential to be used for stratigraphic correlation for understanding early diagenesis and — most importantly — for obtaining high-resolution geochronology, which can then be used for defining depositional rates and chronostratigraphy. Study of the ash beds was conducted at outcrops along U.S. 90, west of Comstock, Texas, the subsurface in Atascosa and Karnes County, and at a construction site in South Austin. Bed thicknesses range from 0.1–33 cm and were collected throughout the entirety of the Eagle Ford succession. Mineral separation yielded abundant non-detrital zircons for U-Pb dating. Dating was conducted using LA-ICP-MS at The University of Texas at Austin, to attain a base level understanding of the age range for the Eagle Ford. High-resolution ages for the base and top of the Eagle Ford were obtained, in addition to radioisotopically defining the Cenomanian-Turonian boundary within the section. U-Pb ages for the Eagle Ford Shale range from Early Cenomanian to Late-Coniacian near Comstock, Mid-Cenomanian to the Turonian-Coniacian boundary in the subsurface, and Early Cenomanian to Late Turonian in Austin area. These findings contrast with many of the regional biostratigraphic studies across the Eagle Ford and indicate a more prolonged period of Eagle Ford deposition than previously observed. / text