Lacustrine and hypersaline deposits in the desiccated Mediterranean and their bearing on paleoenvironment and paleo-ecology

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doi: 10.1029/ME003p0402
Author(s): Cita, M. B.
Volume Title: Deep drilling results in the Atlantic Ocean; continental margins and paleoenvironment
Volume Author(s): Talwani, M., editor; Hay, W.; Ryan, W. B. F.
Source: Maurice Ewing Series, 3, p.402-419; Deep drilling results in the Atlantic Ocean; continental margins and paleoenvironment, Harriman, N.Y., March 19-25, 1978, edited by M. Talwani, W. Hay and W. B. F. Ryan. Publisher: American Geophysical Union, Washington, DC, United States. ISSN: 0197-6346. ISBN: 978-1-118-66583-1 CODEN: MEWSDN
Note: In English. 60 refs.; illus. incl. sects., strat. col., plates, geol. sketch maps
Summary: The isolation of the Mediterranean from the world oceans brought about by plate motions by the end of the Miocene resulted in evaporitic draw-down and eventual desiccation which had catastrophic effects on the marine faunas and floras which, populated the Mediterranean waters before the salinity crisis. The evaporites represent an essentially abiotic environment and are usually barren; being basin-wide in extent, they document a kind of sterilization underzone by the Mediterranean. Exceptions are represented by algal stromatolites, which are common in the Mediterranean record, as related to the extraordinary development of unusual "intertidal" conditions. Sediments associated with the evaporites are occasionally fossiliferous. When it can be proved that fossils are in situ (reworking is common) they generally indicate salinities different from normal marine. Of special interest in the eastern Mediterranean record is the late Messinian "lago-mare" faunal assemblage of caspi-brackish affinity. Capture of the high standing lakes of the Paratethys is postulated, possibly through subterraneous aquifers. This kind of fauna was not recorded in the deep western Mediterranean basins, whereas it is present in peripheral or satellite basins of the Mediterranean. Sills had to play a major role in the distribution of this fauna, but dissemination through land is not impossible. The repopulation of the Mediterranean resulting from the early Pliocene flooding was almost instantaneous, and essentially from the west (from the Atlantic). Shallow sills separating the western from the eastern Mediterranean resulted in (a) marked difference in bottom current activity, the eastern basins being less well ventilated than the western basins, and (b) slower repopulation of the former by bottom living animals, with species having a shallow upper bathymetric limit coming first. The response of the world ocean to the Mediterranean salinity crisis is seen as a disturbance in the pelagic realm, detectable in the carbonate content of deep-sea sediments, and also recorded by the isotopic signal. The subtraction of over 1×106 km3 of salts in a time span of less than 1×106 y indeed lowered the salinity of the world ocean by 6%. This disturbance could be studied carefully in the eastern North Atlantic (DSDP Site 397) where a continuously cored succession of hemipelagic sediments deposited at an unusually high sedimentation rate offered the opportunity to calibrate with accuracy by means of micropaleontology and of paleomagnetic stratigraphy the Messinian event, and to clarify its climatic implications. Abstract Copyright 1979 by the American Geophysical Union.
Year of Publication: 1979
Research Program: DSDP Deep Sea Drilling Project
Key Words: 06 Petrology, Sedimentary; Algae; Arthropoda; Assemblages; Cenozoic; Chemically precipitated rocks; Congeria; Crustacea; Cyprideis; Cytheracea; Cytherideidae; Cytherocopina; Deep Sea Drilling Project; Deposition; Environment; Evaporites; Foraminifera; Hydrochemistry; Invertebrata; Lakes; Mandibulata; Marine environment; Mediterranean Sea; Microfossils; Miocene; Mollusca; Nannofossils; Neogene; Oceanography; Ostracoda; Paleoclimatology; Paleoecology; Paleogeography; Paleontology; Paratethys; Plantae; Podocopida; Protista; Research; Salinity; Sedimentary petrology; Sedimentary rocks; Sedimentation; Tertiary; Tethys; Thallophytes
Coordinates: N300000 N450000 E0370000 W0060000
Record ID: 1980017770
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute.