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  • 1
    Online Resource
    Online Resource
    Temperature and stable isotope variations in different water masses from the Alboran Sea (Western Mediterranean) between 250 and 150 ka (2008)
    Associated volumes
    Details Availability
    In: Geochemistry, geophysics, geosystems, Hoboken, NJ : Wiley, 2000, 9(2008), 10, 1525-2027
    In: volume:9
    In: year:2008
    In: number:10
    In: extent:14
    Description / Table of Contents: Mg/Ca, Sr/Ca, and stable isotope measurements have been performed on tests from the planktonic foraminifers Globigerinoides ruber (white), Globigerina bulloides, and Neogloboquadrina pachyderma (right coiling) in samples from Ocean Drilling Program site 977A in the Alboran Sea (Western Mediterranean). The evolution of different water masses between 250 and 150 ka is described. Warm substages were characterized by strong seasonality and thermal stratification of the water column. By contrast, less pronounced seasonality and basin stratification seem to prevail during cold substages. Several periods of stratification due to the low salinity of the upper water mass occurred during the formation of organic-rich layers and also during a possible Heinrich-like event at 220 ka. The three foraminifer species studied show a common and large shell Sr/Ca variability in short timescales, suggesting changes in the global ocean Sr/Ca ratio as one of the main causes of variations in shell composition.
    Type of Medium: Online Resource
    Pages: 14 , graph. Darst
    ISSN: 1525-2027
    DOI: 10.1029/2007GC001906
    Language: English
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  • 2
    Electronic Resource
    Electronic Resource
    Sequence stratigraphy of Holocene incised-valley fills and coastal evolution in the Gulf of Cádiz (southern Spain) (1998)
    Springer
    Netherlands journal of geosciences 77 (1998), S. 263-281 
    Details
    ISSN: 1573-9708
    Keywords: estuarine deposits ; Flandrian transgression ; Late Pleistocene ; radiocarbon data ; spit barriers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract This first sedimentary interpretation of two incised-valley fills in the Gulf of Cádiz (southern Spain), which accumulated during the last fourth-order eustatic cycle in response to fluvial incision, changes of sea level, and correlative deposition, relates the filling of the estuarine basins and their barriers with four regional progradation phases, H1 to H4. The cases studied are the wave-dominated Guadalete, and the mixed, tide and wave-dominated Odiel-Tinto estuaries. The sequence boundary is a type-1 surface produced during the lowstand of the Last Glacial period ca. 18 000 14C yr BP. No fluvial lowstand deposits were found in the area. Due to rapid transgression the valley fills consist of transgressive and highstand sediments. The maximum landward advance of the estuarine barriers occurred ca. 6500–6000 14C yr BP during the maximum of the Flandrian transgression, but there is no evidence of sea level rising appreciably above the present. A large part of the estuaries was filled during H1 (ca. 6500–4400 14C yr BP) but ravinement by shifting tidal inlets destroyed most of the coeval barriers. During the H2 phase (ca. 4200–2550 14C yr BP) sedimentation was favoured by arid conditions and concentrated in the axial estuarine zones and the barriers. Between H2 and H3 prevailing winds changed from W to WSW, increasing spit growth to the east and south-east. Progradation of bay-head deltas and flood-plains during H3 (ca. 2300–800 14C yr BP) and H4 (500 yr ago to the present) further reduced the accommodation space in the largely-filled valleys, and sediment by-passed the estuaries and accumulated in the estuarine barriers as fast-growing spits. Arid conditions and increasing human activity have caused rapid coastal modifications.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003643006015
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    Paper (German National Licenses)
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  • 3
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    Evolution of the Late Miocene Mediterranean–Atlantic gateways and their impact on regional and global environmental change (2015)
    Elsevier
    In:  Earth-Science Reviews, 150 . pp. 365-392.
    Details
    Publication Date: 2015-12-18
    Description: Marine gateways play a critical role in the exchange of water, heat, salt and nutrients between oceans and seas. As a result, changes in gateway geometry can significantly alter both the pattern of global ocean circulation and associated heat transport and climate, as well as having a profound impact on local environmental conditions. Mediterranean-Atlantic marine corridors that pre-date the modern Gibraltar Strait, closed during the Late Miocene and are now exposed on land in northern Morocco and southern Spain. The restriction and closure of these Miocene connections resulted in extreme salinity fluctuations in the Mediterranean, leading to the precipitation of thick evaporites. This event is known as the Messinian Salinity Crisis (MSC). The evolution and closure of the Mediterranean-Atlantic gateways are a critical control on the MSC, but at present the location, geometry and age of these gateways are still highly controversial, as is the impact of changing Mediterranean outflow on Northern Hemisphere circulation. Here, we present a comprehensive overview of the evolution of the Late Miocene gateways and the nature of Mediterranean-Atlantic exchange as deduced from published studies focussed both on the sediments preserved within the fossil corridors and inferences that can be derived from data in the adjacent basins. We also consider the possible impact of evolving exchange on both the Mediterranean and global climate and highlight the main enduring challenges for reconstructing past Mediterranean-Atlantic exchange.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
    DOI: 10.1016/j.earscirev.2015.08.007
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 4
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    Temperature and stable isotope variationsin different water masses from the Alboran Sea (western Mediterranean) between 250 150 ka (2008)
    AGU (American Geophysical Union)
    In:  Geochemistry, Geophysics, Geosystems, 9 (Q10016).
    Details
    Publication Date: 2018-03-08
    Description: Mg/Ca, Sr/Ca, and stable isotope measurements have been performed on tests from the planktonic foraminifers Globigerinoides ruber (white), Globigerina bulloides, and Neogloboquadrina pachyderma (right coiling) in samples from Ocean Drilling Program site 977A in the Alboran Sea (Western Mediterranean). The evolution of different water masses between 250 and 150 ka is described. Warm substages were characterized by strong seasonality and thermal stratification of the water column. By contrast, less pronounced seasonality and basin stratification seem to prevail during cold substages. Several periods of stratification due to the low salinity of the upper water mass occurred during the formation of organic-rich layers and also during a possible Heinrich-like event at 220 ka. The three foraminifer species studied show a common and large shell Sr/Ca variability in short timescales, suggesting changes in the global ocean Sr/Ca ratio as one of the main causes of variations in shell composition.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1029/2007GC001906
    Location Call Number Limitation Availability
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 5
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    XRF core-scanning signal interpretation in Miocene carbonate and siliciclastic contourite deposits (IODP sites U1387 and U1475) (2017)
    In:  EPIC3XRF Core Scanning 2017, National Taiwan University, Taiwan, 2017-03-20-2017-03-24
    Details
    Publication Date: 2017-03-31
    Description: Contourites are deposits formed by along-slope bottom currents and are therefore sensitive to changes in current velocity, sediments supply and paleoceanographic conditions. They are typically associated with high accumulation rates making these archives ideal for paleoenviromental reconstructions. Nevertheless, they are also occasionally affected by winnowing of fine particles and erosion/deposition of allochthonous material, which alters the grain-size and mineralogy. These processes can, as such, promote significant bias in proxy interpretation compared with other pelagic deposits. X-ray fluorescence (XRF) core-scanning is ideal to assess elemental variations in these high accumulation rate sequences. The comparison between lithological changes, Natural Gamma Ray and other parameters with XRF scanning data, along with statistical analysis can provide very useful information to support improved proxy interpretation. Using this approach at Site U1387, (detrital contourite system at Gulf of Cadiz), results indicate that the Zr/Al ratio represents a promising proxy for bottom current speed and show the transition from a hemipelagic to a contouritic system during the Miocene/Pliocene transition. Carbonate content and Ba/Al ratio appear to represent paleo-productivity variations and later to be completely overprinted by current activit y. At Site U1475 (carbonate contourite system at Agulhas Plateau) Zr content is just one artifact associated with high Sr content and the Ca/Sr ratio appears to be a more promising proxy for contourite reconstruction that is influenced by carbonate dissolution by deep corrosive waters. Comparing both locations we can conclude that proxies associated with the continuous background sediment settling over the seafloor (e.g. planktonic foraminifera) do not appear to be severely biased in countourite systems.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , notRev
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