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Sedimentological, geochemical, and paleontological investigations of the coastline of northeastern Oman have provided the authors with an in-depth insight into Holocene sea levels and climate conditions. The spatial distribution and species assemblage of mangrove ecosystems are analyzed. These ecosystems are sensitive to changes in sea level and precipitation and thus reflect ecological conditions. The close proximity to archaeological sites allows us to draw conclusions regarding human interaction with the mangrove ecosystems. Our interdisciplinary inquiry reveals that the mangrove ecosystems along the east coast of Oman collapsed ~6000 cal yr BP on a decadal scale. There is no sedimentological evidence for a mid-Holocene sea-level highstand. The ecosystem collapse was not caused by sea-level variation or anthropogenic interferences; rather, it was the consequence of reduced precipitation values related to a southward shift of the Intertropical Convergence Zone. This resulted in a decrease of freshwater input and an increase in soil salinity. Further, the aridification of the area caused increased deflation and silting up of the lagoons.

The Marmara region is a key area to investigate the interconnection and environmental changes between the Black Sea and the Eastern Mediterranean related to climate patterns. Lake Iznik is an oligohaline lake located in the southeast of the Marmara Sea. To decipher the long-term signals recorded in the sediment column requires better understanding of the processes in the modern lake environs. Seasonal limnological investigations were paired with geochemical and sedimentological analyses. Lake Iznik is an alkaline, warm monomictic lake. During warm seasons, a thermocline is established between 15 m and 20 m water depth. Anaerobic bottom water is mixed during spring. Surface water currents became visible during a whiting event in the summer, corresponding with spatial accumulation patterns found in geochemical proxies of the surface sediment.

The identification of past connection routes between the Black Sea and the Sea of Marmara, other than the traditional one through to the Bosphorus Strait, would be of considerable interest to the international scientific community. Nazik et al. (Geo-Mar Lett 31:75–86 (2011) doi: 10.1007/s00367-010-0216-9 ) suggest the possibility of two alternative waterway connections via lakes Sapanca and Iznik. Their Black Sea to Sea of Marmara multi-connection hypothesis, which is based on undated marine fossils collected in both lakes from surficial grab samples, conflicts with many earlier studies. In this contribution, the hypothesis and the underlying data are discussed in the light of previous tectonic, sedimentological and limnological findings showing that it is impossible to have had marine connections through lakes Sapanca and Iznik during the last 11.5 ka. Global sea-level trends and tectonic uplift rates would accommodate a connection between the Sea of Marmara and Lake Iznik in the middle Pleistocene. Uplift rates for the northern block of the North Anatolian Fault, when compared with the global sea-level curve, clearly indicate that there cannot have been a connection through the Izmit Gulf–Lake Sapanca–Sakarya Valley for at least the past 500 ka. Moreover, borehole sediments along the western shores of Lake Sapanca, which reach down to the bedrock, do not contain any marine fossils.

ODP sites 1055–1062 recover a bathymetric transect from 1800 to 4800 water depth in the subtropical NW-Atlantic (Carolina Slope, Blake–Bahama Outer Ridge). This sediment drift region is known for high deposition rates (>40 cm/kyr) and offers the excellent opportunity to investigate the history of water mass circulation and chemistry as well as depositional changes during the Quaternary. A late Pleistocene time interval from 250 to 350 kyr (marine isotope stages 8–10) was investigated with centennial- to millennial-scale time resolution. Stable isotope records of benthic foraminifera provide new detailed insights on variations in climate and deep water ventilation. The δ13C records indicate well ventilated North Atlantic water masses between 2200 and 3000 m water depth during the time interval from stage 9 to interstadial 8.5. During the glacial stages 8.4 and 10.2, however, the decrease in δ13C reflects an extension of nutrient-rich Antarctic Bottom Water (AABW) up to 2200 m water depth. This is paralleled by a shoaling of the lysocline as indicated by the carbonate records. A comparison between carbonate dissolution proxies points out that the carbonate dissolution at the hemipelagic sites was not only influenced by the different carbonate ion concentration of the water masses (AABW contra North Atlantic Deep Water) but also by the organic carbon flux to the sea floor especially at the shallower sites, whereby the decay of organic matter enhanced carbonate dissolution in the sediments. Additionally the varying depth position and strength of the Deep Western Boundary Current (DWBC) plays an important role on the depositional system along the Blake–Bahama Outer Ridge. Comparisons between current intensities as inferred from grain size analyses, sand, and carbonate contents suggest that high intensities of the DWBC during cold stages caused an erosion of the fine carbonate and an enrichment of the sand fraction at shallower depth. During warm stages the main core of DWBC moved to greater depth and allowed the settling of finer material at shallower depth. Synchronously this led to an increased supply of carbonate and extremely high carbonate concentrations below 3500 m water depth.

ODP Sites 1055–1062 on the Blake-Bahama Outer Ridge (BBOR) are characterized by high sedimentation rates, which allow high-resolution analyses to reconstruct the behavior of the Deep Western Boundary Current (DWBC) as a function of depth along the BBOR. The ODP sites provide an intermediate and deep water transect from 1800 to 4760 m water depths. We focused on the time interval from 350 to 250 ka (marine isotope stages (MIS) 10.2–8.3). Grain size and magnetic properties were analyzed with centennial- to millennial-scale time resolution. Integrating the results of grain size analyses, lightness, and magnetic properties, the changes in the vertical position and the intensity of the DWBC core were inferred. During glacial periods (MIS 10.2 and 8.4–8.3) the DWBC core was located at around 2200 m water depth, whereas it deepened to 3000 m or more during warm periods (interglacial stage 9.3 and interstadial 8.5). Between these periods, the DWBC core moved to shallower depth (2500–3000 m) and its intensity increased, which generally provided coarser sediments to a broad depth range from 2100 to 4800 m. Furthermore, the magnetic properties imply that the DWBC supplied carbonate material other than terrigenous sediments to the deeper sites during MIS 9. The depositional processes at Site 1062 are characterized by sudden influxes of fine carbonate-rich sediments, which gradually decreased with time. Paleocurrent directions inferred from the direction of the great axis of the magnetic fabric are consistent with the modern topography at Sites 1055, 1056, 1058 and 1060 during the relatively warm period, from stages 9.3 to 8.5. At Site 1062, the deepest site, which exhibits a mud-wave field, the inferred flow direction is parallel to the bathymetric contours during warm periods, while the nearly cross-wave direction seemingly dominated during the other periods. It appears that topographic position may have affected the scattering of azimuth plots. Moreover, there is a possibility that the changes in flow direction correlate with climate changes.

Ten ODP sites drilled in a depth transect (2164–4775 m water depth) during Leg 172 recovered high-deposition rate (>20 cm/kyr) sedimentary sections from sediment drifts in the western North Atlantic. For each site an age model covering the past 0.8–0.9 Ma has been developed. The time scales have a resolution of 10–20 kyr and are derived by tuning variations of estimated carbonate content to the orbital parameters precession and obliquity. Based on the similarity in the signature of proxy records and the spectral character of the time series, the sites are divided into two groups: precession cycles are better developed in carbonate records from a group of shallow sites (2164–2975 m water depth, Sites 1055–1058) while the deeper sites (2995–4775 m water depth, Sites 1060–1063) are characterized by higher spectral density in the obliquity band. The resulting time scales show excellent coherence with other dated carbonate and isotope records from low latitudes. Besides the typical Milankovitch cyclicity significant variance of the resulting carbonate time series is concentrated at millennial-scale changes with periods of about 12, 6, 4, 2.5, and 1.5 kyr. Comparisons of carbonate records from the Blake Bahama Outer Ridge and the Bermuda Rise reveal a remarkable similarity in the time and frequency domain indicating a basin-wide uniform sedimentation pattern during the last 0.9 Ma.