Revised age models and foraminiferal records obtained for the Last Interglacial period in six marine sediment cores

The dataset contains the revised age models and foraminiferal records obtained for the Last Interglacial period in six marine sediment cores: - the Southern Ocean core MD02-2488 (age model, sea surface temperatures, benthic d18O and d13C for the period 136-108 ka), - the North Atlantic core MD95-2042 (age model, planktic d18O, benthic d18O and d13C for the period 135-110 ka), - the North Atlantic core ODP 980 (age model, planktic d18O, sea surface temperatures, seawater d18O, benthic d18O and d13C, ice-rafted detritus for the period 135-110 ka), - the North Atlantic core CH69-K09 (age model, planktic d18O, sea surface temperatures, seawater d18O, benthic d18O and d13C, ice-rafted detritus for the period 135-110 ka), - the Norwegian Sea core MD95-2010 (age model, percentage of Neogloboquadrina pachyderma sinistral, sea surface temperatures, benthic d18O, ice-rafted detritus for the period 134-110 ka), - the Labrador Sea core EW9302-JPC2 (age model, percentage of Neogloboquadrina pachyderma sinistral, sea surface temperatures, benthic d18O for the period 134-110 ka).

Late Eocene larger foraminifera and other fossils of ODP Leg 115 holes

Shallow-water larger foraminifers have been recovered at two drill sites on the eastern Maldive Ridge. Despite the poor recovery in Hole 715A, a rather diversified larger benthic foraminifer assemblage allowed us to date the initiation of a carbonate platform, resting on volcanic basement, as late early Eocene. Several age-diagnostic species belonging to the genera Alveolina, Nummulites, Orbitolites, and Discocyclina have been identified. The assemblages may be attributable to the upper part of the Nummulites burdigalensis cantabricus Zone and/or to the lower part of the Nummulites campesinus Zone and to the Alveolina dainellii (upper part) and/or to the A. violae (lower part) zones. The carbonate platform had a very short life (a few hundred thousand years) and rapidly sank below the euphotic zone, as testified by the occurrence of several species of planktonic foraminifers associated with redeposited reef-derived skeletal debris, especially discocyclinids, in the upper part of the sequence. Among the planktonic foraminifers, the presence of Planorotalites palmeri, which has a range confined to the lower portion of the late early Eocene Zone P9, implies that the platform was drowned before the end of the early Eocene. At Hole 714A, the occurrence of several shallow-water foraminifer genera, such as Nummulites (N. fabianii gr.), Discocyclina, Fabiania, Heterostegina, and Operculina (O. gomezi), in pebbles derived from turbidite beds interbedded within late Oligocene pelagic sediments, allows us to suggest that a carbonate platform, possibly reduced in size, was still growing in the Maldive Ridge area after the late early Eocene time. The erosional event, responsible for the redeposition of middle to late Eocene reef-derived skeletal debris, is apparently coeval with the global sea-level fall recorded in late Oligocene Zone P22.

Cenozoic planktonic foraminifera of the Falkland Plateau and Argentine Basin

Sites 511 and 512 (Falkland Plateau) and 513 (Argentine Basin) penetrated calcareous-siliceous oozes of the middle and upper Eocene and lower Oligocene with rather numerous planktonic foraminifers. Upper Oligocene, Miocene, Pliocene, and Quaternary sections are composed mostly of siliceous sediments (Sites 511-514) where planktonic foraminifers are rare or absent. High-latitude planktonic foraminifers of the Austral Province are characterized by impoverished assemblages - only representatives of Globigerina, Globigerinita, Globorotaloides, and Globorotalia with a rounded peripheral margin are found. In the Paleogene, these species are supplemented, in lesser amounts, by representatives of Globigerapsis, Acarinina, Pseudogloboquadrina, Pseudohastigerina, and Chiloguembelina. Assemblages of planktonic foraminifers have low stratigraphic resolution, especially in the upper Oligocene-Quaternary. This reflects the generally deteriorating Cenozoic climate, which evinced a sharp change in the upper Oligocene that is connected with initiation of the circum-Antarctic current near the Paleogene/Neogene boundary. Comparison of Paleogene and Neogene planktonic foraminifers of the South Atlantic (Falkland Plateau, Argentine Basin, 46-51°S) and the North Atlantic (Rockall Plateau, 55-56°N) indicates that the South Atlantic climate was much colder than that of the same latitudes of the North Atlantic. Paleogene oozes of the Falkland Plateau rest unconf ormably on Maestrichtian sediments and in their turn are overlain unconformably by Neogene-Quaternary oozes. Cenozoic sections are stratigraphically discontinuous: periods of intensive biogenic sedimentation resulting in a thick succession of sediments alternated with periods of nondeposition and strong erosion that resulted in hiatuses and unconformities. In the Argentine Basin, Oligocene calcareous-siliceous oozes rest on basalts of the oceanic basement; they are replaced upward in the section by Neogene-Quaternary siliceous oozes with some hiatuses. Planktonic foraminifers here clearly demonstrate the processes of oceanic subsidence and CCD fluctuations as well as Polar Front migrations during Cenozoic time. Fifty species of planktonic foraminifers are discussed and illustrated.

Sedimentological and paleoclimatological investigation of two sediment cores off Cape Barbas, North-West Africa

Two box cores taken off Cape Barbas (North-West Africa) have been studied using three methods. The analyses of the coarse fraction, of biogenic opal and of planktonic foraminifera revealed : 1. Core GIK12310-4 penetrates Z, Y, X and upper part of W zone, whereas core GIK12379-1 penetrates Z and upper part of Y zone. 2. Holocene sedimentation rates are 2.5 cm/1000 y for core GIK12310-4 and 6.0 cm/1000 y for core GIK12379-1. During the Y zone 5 cm/l000 y were sedimented incore GIK12310-4 and > 10-20 cm/1000 y in core GIK12379-1. 3. Paleoclimatohgical results are: arid climate and relatively warm water temperatures during the Holocene (Z zone) and during X zone; humid climate and relatively cool water temperatures within the Wuerm (Y zone) (with a non-dated more arid interval found in the middle part of the Y zone) and in the upper part of the W zone. 4. Increased contents of benthos and radiolaria in the Y zone indicate upwelling. Upwelling, characterized by high content of biogenic opal and low water temperatures, was found in core GIK12310-4 at 250 to 350 cm in the lower part of the Y zone. The plankton/benthos ratio of foraminifera, the benthos/radiolaria ratio and water temperatures derived from planktonic foraminifera, differ in both cores in the Holocene, and are nearly identical during the Wuerm.

Distribution of planktonic foraminifera in Pleistocene sediments of the New Jersey margin, NW Atlantic Ocean

Abundance records of planktonic foraminifera (>150 µm) from the upper 520 m of ODP Site 1073 (Hole 1073A, Leg 174A, 639 m water depth) have been integrated with SPECMAP-derived isotope stratigraphy, percentage of calcium carbonate, and coarse sediment fraction data in order to investigate the Pleistocene climatic history of the New Jersey margin. Six planktonic taxonomic groups dominate the foraminiferal assemblage at Site 1073: Neogloboquadrina pachyderma (d) (mean 33.8%), Turborotalita quinqueloba (18.5%), N. pachyderma (s) (18.4%), Globigerina bulloides group (11.4%), Globorotalia inflata group (9.4%), and Globigerinita glutinata (4.1%). Based on the distributions of these six foraminiferal groups, the Pleistocene section can be divided into three paleoclimatic intervals: Interval I (intermediate) corresponds to the Quaternary sediments from sequence boundary pp1 to the seafloor (79.5-0 mbsf; Emiliania huxleyi acme [85 ka] at 72 mbsf); Interval II (warm) occurs between sequence boundaries pp3 and pp1 (325-79.5 mbsf; last occurrence of Pseudoemiliania lacunosa [460 ka] at 330 mbsf); and Interval III (coldest) occurs between sequence boundaries pp4 and pp3 (520-325 mbsf; Calcareous nannofossils and dinocysts in proximity to pp4 indicate that the sedimentary record for 0.9-1.7 Ma is either missing altogether or highly condensed within the basal few meters of the section). Neogloboquadrina pachyderma (d) displays eight peaks of abundance which correlate, for the most part, with depleted delta18O values, increases in calcium carbonate percentages, low coarse fraction percentages, increased planktonic fragmentation (greater dissolution), and low N. pachyderma (s) abundances. These intervals are interpreted as representing warmer/interglacial conditions. Neogloboquadrina pachyderma (s) displays seven peaks of abundance which correlate, for the most part, with delta18O increases, decreases in calcium carbonate percentages, increases in coarse fraction percentages, and low N. pachyderma (d) abundances. These intervals are interpreted as representing cooler/glacial conditions. In Interval III, a faunal response to relative changes in sea-surface temperature is reflected by abundance peaks in Neogloboquadrina pachyderma (d), followed by Turborotalita quinqueloba and then N. pachyderma (s) (proceeding from warmest to coolest, respectively). This tripartite response is consistent with the oxygen isotope record and, although not as clear, also occurs in Intervals I and II. Six peaks/peak intervals of Globigerina bulloides abundance are closely matched by peaks in Globigerinita glutinata and occur within oxygen isotope stage (OIS) 2 (latter part) 3, 4, 5, 8, 9, 13(?), 14(?), and 15(?). We speculate that these intervals reflect increased upwelling and nutrient levels during both glacials and interglacials. Eight peak intervals of Globorotalia inflata show a general inverse correlation with G. bulloides and may reflect lowered nutrient and warmer surface waters.

Distribution of benthic and planktic foraminifera in surface sediments of the Indian and Pakistan continental margin, Arabian Sea

During the Indian Ocean Expedition of the German research vessel "Meteor" and the following cruise with the Pakistani fishing vessel "Machhera" in February and March 1965, sediments were sampled from the shelf, continental slope and the Arabian Basin off Pakistan and India. The biostratigraphic studies are based on sedimentary material from 24 sediment cores up to 480 cm long and 100 grab samples. The faunal residues of the > 160 µ fraction (chiefly foraminifera and pteropods) were determined and counted in order to get an idea of the climatic conditions during the Late Quaternary of this region. Biostratigraphic correlations of these Late Quaternary deposits are only possible if the thanatocoenosis of the surface sediments are well known. The analysis of the benthonic foraminiferal populations resulted in the definition of several foraminiferal facies. The following sequence of forarniniferal facies, named after their most characteristic members, can be distinguished from the shelf to the deep-sea: 1. Ammonia-Florilus facies ; 2. Ammonia-Cancris facies; 3. Cassidulina-Cibicides facies; 4. Uvigerina-Cassidulina facies ; 5. Buliminacea facies ; 6. deepwater facies, partly with Bulimina aculeata or with Nonionidae. On the upper continental slope there is a zone extremely poor in benthonic foraminifera. In this water depth the oxygen minimum layer (0.05-0.02 ml/l) of the water column reaches the slope. Almost no connection can be observed between the living and the dead foraminiferal population of the same sample. The regional distribution of the planktonic foraminifera from plankton tows as well as from the surface sediments shows marked differences in the species composition of faunas from different regions within the area of investigation. That depends on oceanographic conditions such as upwelling, dissolution of carbonate at great depths etc. Based on the results of faunal analysis of samples from the recent sea-floor, a biostratigraphic subdivision of the sediments in the cores was established. The following biostratigraphically defined sections could be distinguished from the top of the sediment cores downwards : 1. Relatively cool climatic conditions are reflected by the foraminifera of the uppermost core sections. 2. The next section is characterized by much warmer conditions (Holocene climatic optimum). The C-14 ages of this interval range from 4000 to 10 000 years B.P. according to different authors. C-14 dates on the material investigated do not give reliable clues. 3. Foraminiferal populations adapted to much colder conditions can be observed in the underlying core section. The boundary between the warm climate reflected by the foraminifera of section 2 and the cold climate (section 3) is relatively sharp. It can be correlated from core to core over the whole area investigated. The cold climate sediments of section 3 are underlain by different cool-, warm- and cold-climate sediments which can only be correlated over very short distances. Since it appears certain that the last really cold conditions ended earlier in the Arabian Sea and its vicinity than in Europe it is recommended not to use the European stratigraphic terms for the Quaternary. Because of the lack of reliable absolute sediment ages for the cores no exact sedimentation rates can be given. According to rough estimates, however, the rates are 1-2 cm/1000 years in the deep basin and up to 40 cm/1000 years on the upper continental slope. Sedimentation rates are always larger near the mouth of the Indus-River than off South India at stations of about the same water depth. Planktonic gastropods (mainly pteropods) cannot be used for biostratigraphic purposes in the region under consideration. All of them seem to be displaced from the shelf. Their distribution there is given in.

Turbiditic trench deposits at the South-Chilean active margin

The active plate margin of South America is characterized by a frequent occurrence of large and devastating subduction earthquakes. Here we focus on marine sedimentary records off Southern Chile that are archiving the regional paleoseismic history over the Holocene and Late Pleistocene. The investigated records - Ocean Drilling Program (ODP) Site 1232 and SONNE core 50SL - are located at ~40°S and ~38°S, within the Perú-Chile trench, and are characterized by frequent interbedded strata of turbiditic and hemipelagic origin. On the basis of the sedimentological characteristics and the association with the active margin of Southern Chile, we assume that the turbidites are mainly seismically triggered, and may be considered as paleo-megaearthquake indicators. However, the long-term changes in turbidite recurrence times appear to be strongly influenced by climate and sea level changes as well. During sea level highstands in the Holocene and Marine Isotope Stage (MIS) 5, recurrence times of turbiditic layers are substantially higher, primarily reflecting a climate-induced reduction of sediment availability and enhanced slope stability. In addition, segmented tectonic uplift changes and related drainage inversions likely influenced the postglacial decrease in turbidite frequencies. Glacial turbidite recurrence times (including MIS 2, MIS 3, cold substages of MIS 5, and MIS 6), on the other hand, are within the same order of magnitude as earthquake recurrence times derived from the historical record and other terrestrial paleoseismic archives of the region. Only during these cold stages sediment availability and slope instability were high enough to enable recording of the complete sequence of large earthquakes in Southern Chile. Our data thus suggest that earthquake recurrence times on the order of 100 to 200 years are a persistent feature at least during the last glacial period.

Surface sediment samples from several fore-arc basins west and southwest of the Indonesian Archipelago, analyzed by planktonic foraminifera, stable oxygen and carbon isotopic signals and opal and CaCO3 contents in bulk sediment

A total of 69 surface sediment samples from several fore-arc basins located west and southwest of the Indonesian Archipelago was analyzed with respect to the faunal composition of planktonic foraminifera, the stable oxygen and carbon isotopic signal of a surface-dwelling (Globigerinoides ruber) and a thermocline-dwelling (Neogloboquadrina dutertrei) species, and the opal and CaCO3 contents in bulk sediment. Our results show that the distribution pattern of opal in surface sediments corresponds well to the upwelling-induced chlorophyll concentration in the upper water column and thus, represents a reliable proxy for marine productivity in the coastal upwelling area off S and SW Indonesia. Present-day oceanography and marine productivity are also reflected in the tropical to subtropical and upwelling assemblages of planktonic foraminifera in the surface sediments, which in part differ from previous studies in this region probably due to different coring methods and dissolution effects. The average stable oxygen isotopic values (d18O) of G. ruber in surface sediments vary between 2.9 per mill and 3.2 per mill from basin to basin and correspond to the oceanographic settings during the SE monsoon (July-October) off west Sumatra, whereas off southern Indonesia, they reflect the NW monsoon (December-March) or annual average conditions. The d18O values of N. dutertrei show a stronger interbasinal variation between 1.6 per mill and 2.2 per mill and correspond to the upper thermocline hydrology in July-October. In addition, the difference between the shell carbon isotopic values (d13C) of G. ruber and N. dutertrei (Delta d13C) appears to be an appropriate productivity recorder only in the non-upwelling areas off west Sumatra. Consequently, joint interpretation of the isotopic values of these species is distinctive for different fore-arc basins W and SW of Indonesia and should be considered in paleoceanographic studies.