Francesco Grossi

Orbitally forced paleoenvironmental and paleoclimate changes in the late postevaporitic Messinian of the central Mediterranean Basin

Paleoenvironmental and paleoclimate changes that occurred during the late postevaporitic stage of the Mediterranean Basin in the Messinian foreland domain of the Adriatic region offer a new perspective on the relationship between orbital forcing and climate response. The magnetic susceptibility record of the Fonte dei Pulcini A section (Maiella Mountains, Italy) allows us to orbitally tune the record between 5.394 and 5.336 Ma and to temporally constrain the paleoenvironmental and paleoclimate changes evidenced by quantitative paleontological (palynomorphs, ostracods, and calcareous nannofossils), stable isotope (δ 18 O and δ 13 C), and X-ray diffraction (XRD) analyses. The base of the Fonte dei Pulcini A section is characterized by Paratethyan ostracods and dinocysts, which point to the late Messinian Lago-Mare biofacies ( Loxocorniculina djafarovi zone) of the Mediterranean Messinian stratigraphy. From paleontological and geochemical (δ 18 O) analyses, there is no evidence of a marine incursion in the Fonte dei Pulcini A section. The major changes in terms of paleodepth, paleosalinity, evaporation versus precipitation, aridity versus humidity, and reworking processes occurred in the upper part of the Fonte dei Pulcini A section, during the last Messinian insolation cycle (i-cycle 511/512), which is characterized by high-amplitude oscillations. In contrast, the lower part of the Fonte dei Pulcini A section, which was deposited during relatively low-amplitude insolation cycles, is characterized by more stable environmental conditions. Comparing summer insolation with the paleoenvironmental changes at the Fonte dei Pulcini A section, we identify delays of several thousands of years between orbital forcing and climate response.

Easternmost Mediterranean evidence of the Zanclean flooding event and subsequent surface uplift: Adana Basin, southern Turkey

Abstract According to the literature, the Adana Basin, at the easternmost part of the Mediterranean Basin in southern Turkey, records the Pliocene stage with shallow-marine to fluvial deposits. Our micropalaeontological analysis of samples from the Adana Basin reveal Late Lago–Mare biofacies with Paratethyan ostracod assemblages pertaining to the Loxocorniculina djafarovi zone. Grey clays rich in planktonic foraminifera lie above the Lago–Mare deposits. Within the grey clays, the continuous occurrence of the calcareous nannofossil Reticulofenestra zancleana and the base of the Reticulofenestra pseudoumbilicus paracme points to an Early Zanclean age (5.332–5.199 Ma). Both ostracod and benthic foraminifera indicate epibathyal and bathyal environments. 87Sr/86Sr measurements on planktonic and benthic foraminifera fall below the mean global ocean value for the Early Zanclean, indicating potentially insufficient mixing of low 87Sr/86Sr Mediterranean brackish ‘Lago–Mare’ water with the global ocean in the earliest Pliocene. We utilize the ages and palaeodepths of the marine sediments together with their modern elevations to determine uplift rates of the Adana Basin of 0.06 to 0.13 mm a−1 since 5.2–5.3 Ma (total uplift of 350–650 m) from surface data, and 0.02–0.13 mm a−1 since c. 1.8 Ma (total uplift of 30–230 m) from subsurface data. Supplementary material: Microphotographs of foraminifers, ostracods, and calcareous nannofossils, plots of the calcareous nannofossil frequencies, occurrence of foraminifers and ostracods in the study sections, results of Sr isotopic analysis, and a complete list of fossils are available at www.geolsoc.org.uk/SUP18535.

Is the occurrence of a sigmoidal ventral border in Cyprideis torosa (Jones) valves linked to salinity? A morphometrical analysis approach

The living euryhaline species Cyprideis torosa (Jones) undergoes morphometric variations in size, noding and sieve-pore shape linked to environmental parameters. In particular it is known that salinity values around 8–9‰ represent the osmoregulation threshold and the turning point between smaller and greater valves and prevailingly noded as opposed to un-noded valves. Here, a character never studied before is analysed: the relationship between salinity and the C. torosa valve outlines, especially the morphology of the ventral border. Geometric–morphometric analysis was carried out on different populations of C. torosa collected in oligohaline (Massaciuccoli marsh, Tuscany, and Lake Trasimeno, Umbria) and hyperhaline waterbodies (Trapani–Paceco salt pans, Sicily). The results indicate that the species displays two morphotypes: a dominant one, characterized by a straight ventral border; and a morphotype with a sigmoidal profile ventral border. This latter morphotype seems to be related to higher salinity: the oligohaline waters are characterized only by C. torosa individuals with straight ventral outline, while the hyperhaline environments are marked by the occurrence of 17.6% of sigmoidal individuals. Furthermore, the sigmoidal ventral border is more emphasized in males than in females.