This review paper provides a synopsis of ongoing research and our understanding of the fundamentals of sea-level change today and in the geologic record, specially as illustrated by conditions and processes during the Cretaceous greenhouse climate episode. We give an overview of the state of the art of our understanding on eustatic (global) versus relative (regional) sea level, as well as long-term versus short-term fluctuations and their drivers. In the context of the focus of UNESCO-IUGS/IGCP project 609 on Cretaceous eustatic, shortterm sea-level and climate changes we evaluate the possible evidence for glacio-eustasy versus alternative or additional mechanisms for continental water storage and release for the 3 Cretaceous greenhouse and hothouse phases during which the presence of larger continental ice shields is considered very unlikely. Increasing evidence in the literature suggests a correlation between long-period orbital cycles and depositional cycles that reflect sea-level fluctuations, implying a globally synchronized forcing of (eustatic) sea level. Fourth-order depositional sequences seem to be related to a ~405 ka periodicity, which most likely represents long-period orbital eccentricity control on sea level and depositional cycles. Thirdorder cyclicity, expressed as time-synchronous sea level falls of ~20 to 110 m on ~0.5 to 3.0 Ma timescales in the Cretaceous are increasingly recognized as connected to climate cycles triggered by long-term astronomical cycles that have periodicity ranging from ~1.0 to 2.4 Ma. Future perspectives of research on greenhouse sea-level changes comprise a high-precision timescale for sequence stratigraphy and eustatic sea-level changes and high-resolution marine to non-marine stratigraphic correlation.

Western Anatolia is a complex assemblage of terranes, including the Sakarya Terrane and the Tauride-Anatolide Platform that collided during the late Cretaceous and Palaeogene (80-25 Ma) after the closure of the Izmir-Ankara Ocean. Determining the precise timing at which this ocean closed is particularly important to test kinematic reconstructions and geodynamic models of the Mediterranean region, and the chronology of suturing and its mechanisms remain controversial. Here, we document the Cretaceous-Eocene sedimentary history of the Central Sakarya Basin, along the northern margin of the Neotethys Ocean, via various approaches including biostratigraphy, geochronology, and sedimentology. Two high-resolution sections from the Central Sakarya Basin show that pelagic carbonate sedimentation shifted to rapid siliciclastic deposition in the early Campanian (~79.6 Ma), interpreted to be a result of the build-up of the accretionary prism at the southern margin of the Sakarya Terrane. Rapid onset of deltaic progradation and an increase in accumulation rates in the late Danian (~61 Ma), as well as a local angular unconformity are attributed to the onset of collision between the Sakarya Terrane and the Tauride-Anatolide Platform. Thus, our results indicate that though deformation of the subduction margin in Western Anatolia started as early as the Campanian, the closure of the İzmir-Ankara Ocean was only achieved by the early Palaeocene.

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A Cretaceous-Paleogene (K-Pg) succession is studied in detail in the Mudurnu-Göynük basin in northwestern Turkey. To characterize the K-Pg transition in this basin, two stratigraphic sections were measured and sampled at high resolution: the Okçular and the Göynük North sections. These sections were analysed for siderophile trace elements, including Ir and other platinum group elements (PGE: Ru, Rh, Pd, Ir, Pt), bulk stable carbon isotopes, calcareous nannofossils, planktic foraminifera and organic-walled dinoflagellate cysts (dinocysts). In this basin, the upper Maastrichtian consists of monotonous grey mudstones, mostly intercalated with turbidites and the basal Danian is characterised by grey mudstones, that are overlain by a rhythmic alternation of limetones and mudstones. The K-Pg boundary is marked by a thin, reddish ejecta layer, characterized by an enrichment of PGE and an abrupt negative shift in bulk δ13C. This ejecta layer is followed by 15-17cm of thick darker, clayey mudstone, the so-called boundary clay. The upper Maastrichtian to lower Danian interval displays a succession of biostratigraphic events, such as the globally recognized spike of the dinocyst taxon Manumiella druggii in the Maastrichtian, followed by the extinction of Cretaceous planktic foraminifera at the K-Pg boundary, and a subsequent rapid succession of First Occurrences (FOs) of dinocysts, such as Senoniasphaera inornata, Membranilarnacia? tenella and Damassadinium californicum and planktic foraminifera, including Parvularugoglobigerina eugubina and Subbotina triloculinoides in the lower Danian. Overall the sedimentological and palaeontological data suggest that the studied sites in the Mudurnu-Göynük basin were deposited under normal marine conditions, likely in an outer neritic to upper bathyal environment. Our geochemical and biostratigraphic characterization of the K-Pg boundary transition in the Mudurnu-Göynük basin provides a new K-Pg boundary record in the Northern branch of the Neo-Tethys and allows a detailed comparison with K-Pg boundary sections worldwide

The sediment of Lake Çubuk in NW Anatolia, which is situated very close to the climate boundary between the dry Central Anatolia and the wet Marmara region, is regarded as a suitable climate archive to test inward and outward movements of this boundary in accordance with past climate variations. Herein, we study the stratigraphic record of the last 2800 years of this landslide-dammed lake at 1030 m elevation, using multi-proxy tools (sedimentology, major and trace element geochemistry, stable isotopes, pollen, diatoms and ostracods) and compare the results with other contemporaneous Anatolian climatic records. Our findings indicate that Lake Çubuk recorded seven distinct climatic periods in the last 2800 years that have been previously revealed elsewhere in Anatolia. The most arid period occurred at the end of the Near-East Aridification Phase at approximately 200 BC when the δ 18 O shifted to very negative values, and the planktonic diatom ratio considerably decreased. The Dark Ages and the late Byzantine periods between AD 670 and 1070 are characterized by more positive δ 18 O values, increasingly higher lake levels and the most extensive arboreal cover of the entire record. The 'Little Ice Age' appeared suddenly, within 40 years, at AD 1350 and is reflected in all of the proxies, including a positive shift in δ 18 O, a sharp decrease in pollen of shrub and herb to the benefit of pine trees and a rapid increase in benthic diatom abundance indicating a lake level shallowing. In many parts of the record, a close match between the stable isotopes and the pollen assemblage zones in the last 2800 years demonstrates that climate rather than human activity was the primary driver of vegetation cover in this mid-altitude mountain of NW Anatolia.

<p><strong>Abstract.</strong> It is by now unequivocally shown that the mass extinction associated with the Cretaceous-Paleogene (K-Pg) boundary (~ 66 Ma) is related to the environmental effects of a large extraterrestrial impact. The biological and oceanographic consequences of the mass extinction are, however, still poorly understood. According to the Living Ocean model of D’Hondt et al. (1998), the biological crisis at the K-Pg boundary resulted in a reduction of export productivity in the earliest Paleocene. Here, we combine organic-walled dinoflagellate cyst (dinocyst) and benthic foraminiferal analyses to provide crucial new insight into changes in the coupling of pelagic and benthic ecosystems. To this end, we perform dinocyst and benthic foraminiferal analyses on the recently discovered Tethyan K-Pg boundary section at Okçular, Northwestern Turkey, and compare the results with other K-Pg boundary sites in the Tethys. The post-impact dominance of epibenthic taxa and an increase of inferred heterotrophic dinocysts in the earliest Paleocene at Okçular are consistent with published records from other Tethyan sites. Together, these Tethyan records indicate that during the early Paleocene more nutrients were available for the Tethyan planktonic community, whereas benthic communities were deprived of food. Hence, the post-impact phase the reduction of export productivity likely resulted in enhanced recycling of nutrients in the upper part of the water column, all along the Tethyan shelves.</p>

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