Radiocarbon dating on cold-water corals, grain size, Corg, and benthic foraminfera assemblage of two sediment cores from the Ionian Sea

Continuous sedimentary records from an eastern Mediterranean cold-water coral ecosystem thriving in intermediate water depths (~600 m) reveal a temporary extinction of cold-water corals during the Early to Mid Holocene from 11.4-5.9 cal kyr BP. Benthic foraminiferal assemblage analysis shows low-oxygen conditions of 2 ml l**-1 during the same period, compared to bottom-water oxygen values of 4-5 ml l**-1 before and after the coral-free interval. The timing of the corals' demise coincides with the sapropel S1 event, during which the deep eastern Mediterranean basin turned anoxic. Our results show that during the sapropel S1 event low oxygen conditions extended to the rather shallow depths of our study site in the Ionian Sea and caused the cold-water corals temporary extinction. This first evidence for the sensitivity of cold-water corals to low oceanic oxygen contents suggests that the projected expansion of tropical oxygen minimum zones resulting from global change will threaten cold-water coral ecosystems in low latitudes in the same way that ocean acidification will do in the higher latitudes.

Benthic foraminifera in sapropels of the eastern Mediterranean Sea

High-resolution benthic foraminiferal and geochemical investigations were carried out across sapropels S5 and S6 from two sediment cores in the Levantine Sea to evaluate the impact of climatic and environmental changes on benthic ecosystems during times of sapropel formation. The faunal successions indicate that eutrophication and/or oxygen reduction started several thousand years prior to the onset of sapropel formation, suggesting an early response of the bathyal ecosystems to climatic changes. Severest oxygen depletions appear in the early phases of sapropel formation. The initial reduction of deep-water ventilation is caused by a warming and fresh water-induced stratification of Eastern Mediterranean surface waters. During the late phase of S5 formation improved oxygenation is restricted to middle bathyal ecosystems, indicating that at least some formation of subsurface water took place. During S6 formation oxygen depletions and eutrophication were less severe and more variable than during S5 formation. Estimated oxygen contents were low dysoxic at middle bathyal to anoxic at lower bathyal depths during the early phase of S6 formation but never dropped to anoxic values in its late phase. The high benthic ecosystem variability during S6 formation suggests that water column stratification at deep-water formation sites was in a very unstable mode and susceptible to minor temperature fluctuations at a millennial time-scale.

Neogene planktonic foraminifera of ODP Leg 101 holes

Leg 101 of the Ocean Drilling Program recovered a large volume of Neogene sediments from sites in the Straits of Florida, Little Bahama Bank, and Exuma Sound. In varying amounts, shallow-water, platform-derived carbonate debris is nearly ubiquitous. Reworked planktonic foraminifers are common, especially in the Pliocene-Pleistocene. At Site 626 in the Straits of Florida, a sequence of Holocene to upper Oligocene sediments was recovered. The greatest Neogene hiatus at this site spans the latest Miocene through Pliocene. Below this, several minor hiatuses are present in a generally conformable sequence. From the Little Bahama Bank transect (Sites 627, 628, and 630), a nearly complete composite Neogene section was sampled. At Site 627, a major unconformity separates lowermost Miocene sediments from middle to upper Eocene sediments. A second major unconformity occurs at Site 628. Here, middle Miocene sediments lie above uppermost Oligocene deposits. Sites 632, 633, and 631 in Exuma Sound all bottomed in a thick, lower Pliocene section. The mid-Pliocene is very thin at Sites 633 and 631, while it is better represented at Site 632. Major unconformities at Sites 627 and 628 appear to correlate with periods of elevated sea level, which suggests that carbonate platform shedding may be greatest during this part of the sea-level cycles. One of the salient features of the Bahamas is the lack of any systematic temporal distribution of hiatuses. Only a brief hiatus in the late Pliocene may be regional. It appears that local platform-shedding events were of equal or greater importance in developing the stratigraphy of the Bahamas than regional or eustatic events.

Geological, geochemical and biogeochemical data on boundary zones of the Atlantic Ocean

Results of studies in two biogeochemically active zones of the Atlantic Ocean (the Benguela upwelling waters and the region influenced by the Congo River run-off) are reported in the book. A multidisciplinary approach included studies of the major elements of the ocean ecosystem: sea water, plankton, suspended matter, bottom sediments, interstitial waters, aerosols, as well as a wide complex of oceanographic studies carried out under a common program. Such an approach, as well as a use of new methodical solutions led to obtaining principally new information on different aspects of oceanology.

Fossil record of Mollusca from Neogene sediments in Schleswig-Holstein, Germany

Über die Verbreitung, Gliederung und Ausbildung des Jungtertiärs im westlichen Schleswig-Holstein war bisher nicht viel bekannt. Am besten bearbeitet sind die glazial gestauchten Schollen von Morsum/Sylt. Eine Aufzählung erbohrter Miozänvorkommen mit nicht immer überzeugender Begründung lieferte H.-L. HECK 1935. S. THIELE (1941) hat die ihm bekannten Vorkommen hauptsächlich nach faziellen und petrographischen Gesichtspunkten bearbeitet. Er erkannte richtig die Stellung der Braunkohlensande. Die angekündigte palaeontologische Bearbeitung ist nicht erschienen. Eine allgemeine Übersicht über die Entwicklung des Jungtertiärs bringen W. WOLFE und H.-L. HECK 1949. W. HINSCH lieferte wertvolle Beiträge zur Molluskenfauna und zur Gliederung des Miozäns (1952, 1955). Über neue Vorkommen von Braunkohlen-Sanden berichtete E. DITTMER(1 956), eine erste Übersicht über neue Vorkommen der Hemmoorer Stufe gab derselbe Verfasser 1957.

Occurrence and estimated abundance of planktonic foraminifers at DSDP Leg 85 holes

Tropical planktonic foraminifers occur throughout the sequences at all sites of Leg 85, and the standard planktonic foraminiferal zonation of Blow (1969) is applicable to most of the recovered sequences. However, the abundance and state of preservation of foraminifers decline markedly in certain intervals because of the effects of dissolution. Although siliceous microfossils studied on this leg indicate recovery of nearly complete records for the Pleistocene to Oligocene interval, the planktonic foraminiferal biostratigraphy is interrupted by strongly dissolved sections at all sites. Particularly, faunas assignable to Zone N7 (early Miocene) and Zone N15-16 (early late Miocene) are almost totally unrecognizable throughout the eastern equatorial Pacific. Well-preserved and diverse planktonic foraminifers occur in the lower middle Miocene, where the evolutionary developments of Orbulina universa d'Orbigny and Globorotalia fohsi Cushman and Ellisor are well represented. The Orbulina first appearance datum is observed to be nearly coincident with the last occurrence level of the diatom Annellus californicus Tempère, thus .establishing an age of 15 Ma for this datum by using the paleomagnetic calibration of the diatom datum. Moderately well-preserved late Eocene planktonic foraminifers occur in the carbonate sediments immediately overlying the basalt basement at Sites 573 and 574. The Eocene-Oligocene faunal transition, however, is masked at both sites by an intercalation of metalliferous layers containing no planktonic foraminifers.

Planktonic foraminifers from Oligocene to Pleistocene sediments of DSDP Leg 92 sites

Leg 92 of the Deep Sea Drilling Project cored sediments containing calcareous microfossils at six sites along 19°S latitude in the South Pacific Ocean. Shipboard examination of these sediments revealed planktonic foraminifers of uppermost Oligocene through Pleistocene age that were identified and assigned to biostratigraphic zones according to the tropical zonation scheme of Blow (1969). Preservation of planktonic foraminifers in the sites from Leg 92 has been affected by the position of each site with respect to the lysocline and calcium carbonate compensation depth (CCD) at the time of deposition, depth of burial, and sediment accumulation rate (rate of burial). An additional factor may also be important, especially in the sediments deposited immediately above basement. Evidence of poor preservation in basal sediments of Holes 600C and 601, which have always been shallower than both the lysocline and the CCD, suggests that hydrothermal solutions circulating within young oceanic crust may penetrate the overlying sediments and affect the preservation of calcareous microfossils deposited there.