The East Side Story – The Transylvanian latest Cretaceous continental vertebrate record and its implications for understanding Cretaceous–Paleogene boundary events

The latest Cretaceous continental vertebrate faunas of the wider Transylvanian area figured prominently in discussions concerning the Cretaceous–Paleogene Boundary (K-Pg) events when they were first described by Nopcsa between 1897 and 1929, because they were assumed to be late Maastrichtian in age. Subsequently their age was reconsidered as early Maastrichtian, and were thus regarded of lesser importance in understanding the K-Pg boundary events in Europe and worldwide. Moreover, Transylvanian continental vertebrate assemblages (the so-called ‘Haţeg Island’ faunas) were often lumped together as a temporally restricted assemblage with a homogenous taxonomic composition. Recent fossil discoveries and more precise dating techniques have considerably expanded knowledge of the Transylvanian vertebrate assemblages, their ages, and their evolution. A synthesis of the available stratigraphic data allows development of the first comprehensive chronostratigraphic framework of the latest Cretaceous Transylvanian vertebrates. According to these new data, expansion of continental habitats and emergence of their vertebrate faunas started locally during the latter part of the late Campanian, and these faunas continued up to the second half of the Maastrichtian. During this time, long-term faunal stasis appears to have characterized the Transylvanian vertebrate assemblages, which is different from the striking turnovers recorded in western Europe during the same time interval. This suggests that there was no single ‘Europe-wide’ pattern of latest Cretaceous continental vertebrate evolution. Together, the available data shows that dinosaurs and other vertebrates were relatively abundant and diverse until at least ca. 1 million years before the K-Pg boundary, and is therefore consistent with the hypothesis of a sudden extinction, although this must be tested with future discoveries and better age constraints and correlations.     

Petroleum source rock potential of the Silurian Dadaş shales in the Hazro and Korudağ regions of Southeast Anatolia,Turkey

Shales of the Silurian Dadaş Formation exposed in the southeast Anatolia were investigated by organic geochemical methods. The TOC contents range from 0.24 to 1.48 wt% for the Hazro samples and 0.19 to 3.58 wt% for the Korudağ samples. Tmax values between 438 and 440 °C in the Hazro samples indicate thermal maturity; Tmax values ranging from 456 to 541 °C in the Korudağ samples indicate late to over-maturity. Based on the calculated vitrinite reflectance and measured vitrinite equivalent reflectance values, the Korudağ samples have a maximum of 1.91%R_(g-v), in the gas generation window, while a maximum value of 0.79%R_(amor-v) of one sample from the Hazro section is in the oil generation window. Illite crystallinity (IC) values of all samples are consistent with maturity results.Pr/Ph ratios ranging from 1.32 to 2.28 and C₂₉/C₃₀ hopane ratios > 1.0 indicate an anoxic to sub-oxic marine-carbonate depositional environment.The Hazro shales do not have any shale oil or shale gas potential because of their low oil saturation index values and early to moderate thermal maturation. At first glance, the Korudağ shales can be considered a shale gas formation because of their organic richness, thickness and thermal over-maturity. However, the low silica content and brittle index values of these shales are preventing their suitability as shale gas resource systems.