The last reconnection of the Marmara Sea (Turkey) to the World Ocean : A paleoceanographic and paleoclimatic perspective

Author Posting. © Elsevier B.V., 2008. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Marine Geology 255 (2008): 64-82, doi:10.1016/j.margeo.2008.07.005.During the late glacial, marine isotope Stage 2, the Marmara Sea transformed into a brackish lake as global sea level fell below the sill in the Dardanelles Strait. A record of the basin’s reconnection to the global ocean is preserved in its sediments permitting the extraction of the paleoceanographic and paleoclimatic history of the region. The goal of this study is to develop a high-resolution record of the lacustrine to marine transition of Marmara Sea in order to reconstruct regional and global climatic events at 24 a millennial scale. For this purpose, we mapped the paleoshorelines of Marmara Sea along the northern, eastern, and southern shelves at Çekmece, Prince Islands, and Imrali, using data from multibeam bathymetry, high-resolution subbottom profiling (chirp) and ten sediment cores. Detailed sedimentologic, biostratigraphic (foraminifers, mollusk, diatoms), X-ray fluorescence geochemical scanning, and oxygen and carbon stable isotope analyses correlated to a calibrated radiocarbon chronology provided evidence for cold and dry conditions prior to 15 ka BP, warm conditions of the Bolling-Allerod from ~15 to 13 ka BP, a rapid marine incursion at 12 ka BP, still stand of Marmara Sea and sediment reworking of the paleoshorelines during the Younger Dryas at ~11.5 to 10.5 ka BP, and development of strong stratification and influx of nutrients as Black Sea waters spilled into Marmara Sea at 9.2 ka BP. Stable environmental conditions developed in Marmara Sea after 6.0 ka BP as sea-level reached its present shoreline and the basin floors filled with sediments achieving their present configuration.Support for the analyses was from NSF-OCE-0222139; OCE-9807266 and PSC-CUNY 69138-00 38

Site 398: Evolution of the West Iberian Passive Continental Margin in the Framework of the Early Evolution of the North Atlantic Ocean

DSDP Site 398 is located on the West Iberian passive continental margin, south of Galicia Bank, 20 km to the south of Vigo Seamount (Figure 1).The kinematic evolution of the Iberian plate is closely controlled by the relative motions of the African, European, and North American plates. A study based on magnetic data and land data was undertaken to better define the relative motion of Iberia with respect to these main plates (Sibuet et al; in preparation).Trapped between these plates, microcontinents such as Galicia Bank and Flemish Cap (located between Iberia and North America) assumed their own relative motions with respect to Iberia and North America during the early evolution of the North Atlantic.Consequently, the initial oceanic circulation between small basins corresponding to the Bay of Biscay and the North Atlantic West of Iberia and Europe is closely controlled by relative positions and movements of these microcontinents. Site 398 paleoenvironment data, therefore, are of crucial interest in understanding the early evolution of the North Atlantic and the vertical evolution of continental margins. [NOT CONTROLLED OCR

Geophysical Data Collected Underway on Glomar Challenger, Leg 47B

The scientific party aboard Glomar Challenger collected geophysical data during DSDP Leg 47B, which commenced from Vigo, Spain, and terminated at Brest, France (Figure 1). Site 398 (40°57.6'N, 10°43.1'W), located just south of Vigo Seamount and about 95 miles West of Porto, Portugal, was drilled from 13 April 1976 to 9 May 1976. Table 1 gives satellite positions, distance (in nautical miles along the track) and the speed and course between successive navigation points. The positioning error along the trackline is approximately 1 nautical mile. Distances are shown (Figure 1) along the trackline every 50 nautical miles and annotated every 100 nautical miles. Time is marked by crosses every 2 hours and annotated every 4 hours. [NOT CONTROLLED OCR

Physiography and deposition on a distal deep-sea system: The Valencia Fan (Northwestern Mediterranean)

8 pages, 6 figuresThe Valencia Fan developed as the distal fill of a deep-sea valley, detached from the continental slope and the main sedimentary source. A survey of side-scan sonar, Sea Beam and reflection seismics shows that the sediment is largely fed through the Valencia Valley. The upper fan comprises large channels with low-relief levees, and the middle fan has sinuous distributary channels. Depositional bedforms predominate on the valley floor and levees, and erosional bedforms are common in the valley walls. A change to slope on the fan apex and the presence of volcanoes on the upper fan are the main factors influencing fan-growth pattern. © 1985 Springer-Verlag New York Inc

Factors controlling Ebro deep-sea fan growth, Mediterranean Sea

Peer reviewe

Morphology and downslope sediment displacement in a deep-sea valley, the Valencia Valley (Northwestern Mediterranean)

8 pages, 6 figuresThe Valencia Valley is a Quaternary, 200 km long deep-sea valley in the Valencia Trough, Western Mediterranean Sea. A swathmapping survey approximately mid-way along the valley length, where the floor has an average gradient of 1:250 (0.2°), shows valley walls that rise 200 to 350 m above the valley floor, with slopes of 2 to 18°. Sediment forming the walls is undergoing retrogressive, upslope-directed slumping with increasing bedding disruption along steeper walls. The valley exhibits a winding course with steep outer and gentler inner walls around bends, and bedforms on the valley floor. Lateral migration around bends is less than 5 km and the valley is deeply entrenched into Quaternary-bedded sediments. © 1985 Springer-Verlag New York Inc

Morphology of the Ebro fan valleys from SeaMARC and sea beam profiles

8 pages, 5 figuresThe northern continental slope off the Ebro Delta has a badland topography indicating major slope erosion and mass movement of material that deposits sediment into a ponded lobe. The southern slope has a low degree of mass movement activity and slope valleys feed channel levee-complexes on a steep continental rise. The last active fan valley is V-shaped with little meandering and its thalweg merges downstream with the Valencia Valley. The older and larger inactive channel-levee complex is smoother, U-shaped, and meanders more than the active fan valley. © 1985 Springer-Verlag New York Inc