TY - JOUR A1 - Albrich, Sergi A1 - Frijia, Gianluca A1 - Parente, Mariano A1 - Caus, Esmeralda T1 - The evolution of the earliest representatives of the genus Orbitoides: Implications for Upper Cretaceous biostratigraphy JF - Cretaceous research N2 - The biostratigraphy of Campanian-Maastrichtian carbonate platforms is largely based on the larger foraminiferal genus Orbitoides. However, while the taxonomy and the chronostratigraphic age of the younger species of this genus are well established, there are still many controversies on the earliest species. We have restudied their morphological characters using a large collection of samples from the type-localities and from continuous sections in the southern Pyrenees. Based on these new observations, the long forgotten species O. sanctae-pelagiae is reinstated, while O. dordoniensis is considered a junior synonym. Successive populations of O. hottingeri, O. sanctae-pelagiae and O. douvillei show gradual morphological changes in time marked by an increase in the size and complexity of the macrospheric embryonal apparatus, an increase of the size of the adult specimens of both generations and the progressive appearance and development of true lateral chamberlets. The Font de les Bagasses Unit in the southern Pyrenees preserves a high-resolution archive of the evolution of the earliest Orbitoides. Strontium isotope stratigraphy indicates that the oldest species, O. hottingeri, made its first appearance in the earliest Campanian, close to the Santonian-Campanian boundary, and was replaced by O. sanctae-pelagiae at a level closely corresponding to the boundary between the Placenticeras bidorsatum and Menabites delawarensis ammonite zones. (C) 2014 Elsevier Ltd. All rights reserved. KW - Larger foraminifera KW - Biostratigraphy KW - Strontium isotope stratigraphy KW - Late cretaceous KW - Orbitoides Y1 - 2014 U6 - https://doi.org/10.1016/j.cretres.2014.04.013 SN - 0195-6671 SN - 1095-998X VL - 51 SP - 22 EP - 34 PB - Elsevier CY - London ER - TY - JOUR A1 - Schildgen, Taylor F. A1 - Cosentino, D. A1 - Frijia, Gianluca A1 - Castorina, F. A1 - Dudas, F. Oe. A1 - Iadanza, A. A1 - Sampalmieri, G. A1 - Cipollari, Paola A1 - Caruso, A. A1 - Bowring, S. A. A1 - Strecker, Manfred T1 - Sea level and climate forcing of the Sr isotope composition of late Miocene Mediterranean marine basins JF - Geochemistry, geophysics, geosystems N2 - Sr isotope records from marginal marine basins track the mixing between seawater and local continental runoff, potentially recording the effects of sea level, tectonic, and climate forcing in marine fossils and sediments. Our 110 new Sr-87/Sr-86 analyses on oyster and foraminifera samples from six late Miocene stratigraphic sections in southern Turkey, Crete, and Sicily show that Sr-87/Sr-86 fell below global seawater values in the basins several million years before the Messinian Salinity Crisis, coinciding with tectonic uplift and basin shallowing. 87Sr/86Sr from more centrally located basins (away from the Mediterranean coast) drop below global seawater values only during the Messinian Salinity Crisis. In addition to this general trend, 55 new Sr-87/Sr-86 analyses from the astronomically tuned Lower Evaporites in the central Apennines (Italy) allow us to explore the effect of glacio-eustatic sea level and precipitation changes on Sr-87/Sr-86. Most variation in our data can be explained by changes in sea level, with greatest negative excursions from global seawater values occurring during relative sea level lowstands, which generally coincided with arid conditions in the Mediterranean realm. We suggest that this greater sensitivity to lowered sea level compared with higher runoff could relate to the inverse relationship between Sr concentration and river discharge. Variations in the residence time of groundwater within the karst terrain of the circum-Mediterranean region during arid and wet phases may help to explain the single (robust) occurrence of a negative excursion during a sea level highstand, but this explanation remains speculative without more detailed paleoclimatic data for the region. Y1 - 2014 U6 - https://doi.org/10.1002/2014GC005332 SN - 1525-2027 VL - 15 IS - 7 SP - 2964 EP - 2983 PB - American Geophysical Union CY - Washington ER -