(Table 2) Stable carbon and oxygen isotope record of benthic foraminifera of eastern Mediterranean Sea sediment cores

The paleoproductivity, paleo-oxygenation, and paleohydrographic configuration of the southeastern Mediterranean during the late Holocene was reconstructed on the basis of the isotopic composition of the epibenthic Heterolepa floridana, shallow-endobenthic Uvigerina mediterranea, and the deeper endobenthic Bulimina inflata from two high-resolution cores GA-112 (470 m) and GA-110 (670 m). The Delta d13C between H. floridana and U. mediterranea reveals four intervals of enhanced productivity, from 3.3-2.6, 2.3-1.9, 1.5-1.1, and 0.8-0.4 kyr BP, coinciding with increased nutrient supply by the Nile River. The entire basin was well aerated, with oxygen consumption varying between 1.0 and 3.5 mL O2/L. Oxygen consumption increases toward present day, probably because of higher accumulation of total organic carbon at 1.7 kyr BP, coinciding with the appearance of the mesotropic benthic species. The hydrographic configuration of the basin has changed during the course of the last 3.75 kyr. The Levantine Intermediate Water (LIW) deepens below 470 m between 3.3 and 2.0 kyr, and especially between 2.5 and 2.0 kyr. During the last 1.5 kyr, the LIW becomes shallower than 470 m, similar to the present day. The change in the hydrographic configuration reflects changes in evaporation/precipitation ratio and in temperature.

Stable oxygen isotope ratios of benthic and planktonic foraminifera from early Miocene sediments of DSDP Site 90-593 on the Challenger Plateau, Pacific Ocean (Table 1)

Oxygen isotope data are compared with relative abundances of selected planktic foraminifera through a ca. 15 m interval at DSDP Site 593 (Tasman Sea, southwest Pacific, 40°S) in which there are prominent changes in population sizes, as well as several evolutionary events. We focus on the relation between faunal and climatic histories. The base of early Miocene oxygen isotope Zone Mi1b (uppermost planktic foraminiferal Zone N.6) is identified from closesampled (c. 14 kyr) isotope records of Globigerina woodi and Cibicides kullenbergi. Chronostratigraphic interpolations, using the first occurrences of Globorotalia praescitula, G. mimea and Praeorbulina curva give an age estimate of ca. 18.4 Ma (cf. 18.1 -18.3 Ma for the base of the zone at DSDP Site 608 (type level, north Atlantic, 43°N) ). Another significant benthic delta18O enrichment event, informally designated as the base of zone "Mi1c", is identified 10 m higher in the sequence at ca. 17.8 Ma. Populations of Globoquadriau dehiscens and Globigerinoides trilobus (inferred to be near the southern margin of their distributions) either reduced considerably or withdrew, particularly in the vicinity of zone "Mi1c". A bioseries linking Globorotalia incognita with G. zealandica developed following the benthic delta18O enrichment spike at the base of Zone Mi1b; the latter species became extinct (at least regionally) just above the base of zone "Mi1c". In contrast, the apparently opportunistic Globorotlia praescitula increased dramatically in abundance at this time; there were also transformations in its architecture, leading to the evolutionary appearance of G. miozea. While planktic foraminifera abundances often do not closely covary with the detailed isotope records and tend to be more stable through time, the near coincidence of evolutionary and biogeographic events with isotopic events suggests at least indirect adaptive responses to climatic changes. Early Miocene middle-latitude planktic foraminiferal evolution, biogeography, and biostratigraphy, may be intimately connected with climatic history.

(Table 2) Oxygen isotopic of composition of Pliocene to late Pleistocene planktonic foraminifera of the Mediterranean Sea

Stable isotopic and micropaleontological studies were made of selected sapropels (organic-rich sediments) deposited in the Mediterranean Sea during the last 5.0 m.y. to determine the processes responsible for their formation. Distinct isotopic and faunal changes occur across sapropels of late Pleistocene, early Pleistocene and latest Pliocene age, while smaller isotopic changes and more stable faunal assemblages are associated with the early and mid-late Pliocene sapropels. The large d18O depletions and euryhaline fauna associated with latest Pliocene-Pleistocene sapropels supports a density stratification model with a low salinity surface layer. In contrast, early Pliocene and mid-late Pliocene sapropels appear to have been formed as the result of sluggish circulation and low oxygen contents in bottom waters of the eastern Mediterranean due to the stable, warm climatic conditions of that time period.