TRIASSIC CARBONATE AND EVAPORITE SEDIMENTATION IN THE IONIAN ZONE (WESTERN GREECE): PALAEOGEOGRAPHIC AND PALAEOCLIMATIC IMPLICATION


K. Getsos
F. Pomoni-Papaioannou
A. Zelilidis
Résumé

The Triassic is considered a crucial interval because during that time huge areas in our planet suffered an intense, long lasting, period of aridity, which favored the formation of worldwide evaporitic bodies. During the Triassic, great volumes of evaporites were formed in the Ionian basin (Western Greece). On the surface chaotically textured gypsum, surrounded by dolomitic breccias of solution-collapse origin, appears. Sedimentological and diagenetical data proposed that these salt bodies were formed in an intertidal to supratidal environment. Although halite suggests precipitation under long-term arid conditions, clay film intercalations reveal intervals of short term humid conditions. During arid periods sabkhas prevailed and brines were of marine origin. Instead, during humid intervals brines were modified by meteoric water and stormy episodes could be responsible for the transportation of clay-sized material, from the low relief surrounding terrains, into the evaporative basin. Death and burial of cyanobactehal population during storm events could be responsible for the enrichment of clayey layers in carbonaceous material. The co-existence of halite and clays in the Ionian evaporitic sequence imposes a complicated climate, possibly periodically and seasonally controlled. The impact of the precession of the equinoxes plus the palaeogeographical position dominates the local climate. The insolation over the Triassic Ionian basin and nearby sea and land areas is a crucial factor. Climate responses to gradual insolation forcing with an ocean land atmosphere feedback mechanism. The desert / monsoonal dominated climatic model seems to be most proper for the explanation of the existing lithologigal record.

Article Details
  • Rubrique
  • Palaeontology, Stratigraphy and Sedimentology
Téléchargements
Les données relatives au téléchargement ne sont pas encore disponibles.
Références
BP-British Petroleum Company Limited 1971. The geological results of petroleum exploration in Western Greece. Institute Geology and Subsurface Research, 80, 73p.
Berger A. 1977. Support for astronomical theory of climatic change. Nature, 269, 44-45.
Berger A. 1981. The astronomical theory of paleoclimates. In: Berger A. (ed), Climatic variations and variability: facts and theories. Reidel, Dordrecht, The Netherlands, 501-525.
Berger A. 1984. Accuracy and frequency stability of the earth's orbital elements during the Quaternary. In: Berger Α., Imbrie J., Hays J., Kukla G., Saltzman B. (eds) Milankovitch and climate. Reidal, Dordrecht, The Netherlands, 3-39.
Berger A. 1987. Long-term variations of caloric insolation resulting from the earth's orbital elements. Quat. Res. 9, 139-167.
Catalano R., Doglioni C, Merlini S., 2001. On the Mesozoic Ionian Basin. Geophys. J. Int., 144, 49-64.
DeMenocal P., Ortiz J., Guilderson T., Adkins J., Samthein M., Baker L., Yarusinsky M., 2000. Abrupt onset and termination of the African Humid Period: rapid climate responses to gradual insolation forcing. Quat. Sci. Rev. 19,347-361.
Flügel E. (1972). Mikrofazielle Untersuchungen in der Alpinen Trias. Methoden and Probleme. Mitt. Ges. Geol. Bergbaustud, 21, 9-64.
Griffin D. L. 2002. Aridity and humidity: two aspects of the late Miocene climate of North Africa and the Mediterranean. Palaeog. Palaeocl. Palaeoec, 182, 65-91.
Haq B., Hardenbol J., Vail P. 1987. Chronology of Fluctuating Sea Levels Since the Triassic. Sci. 235, 1156-1167.
Hay W.W., DeConto R.M., Wold C.N., 1997. Climate: Is the past the key to the future? Geol. Rundsch. 86, 471-491.
IGCP Project No. 369. Comparative evolution of Peritethyan Rift Basins. Internet site: http://wwwsst.unil.ch/iqcp 369/igcp369 plates.htm.
IGRS-IFP, 1966. Etude gélogique de l'Epire (Grece nordoccidentale). Ed. Technip, Paris, 306p.
Imbrie J & Imbrie J.Z. 1980. Modelling the climatic response to orbital variations. Sci. 107, 943-953.
Karakitsios V. & Pomoni-Papaioannou F. 1998. Sedimentological study of the triassic solution-collapse breccias of the Ionian zone (NW Greece). Carbonates and Evaporites, 13, 207-218.
Kutzbach J. E. & Liu Z. 1997. Response of the African Monsoon to Orbital Forcing and Ocean Feedbacks in the Middle Holocene. Sci., 278, 440-443.
Pomoni-Papaioannou F. 1980. Genesis-Diagenesis of Triassic Breccia and nodular gypsum of Epirus, IGME, Mineralogical and Petrografical Research, 2.
Pomoni-Papaioannou, F., 1985. The sedimentology and depositional environment of the Triassic dolomitegypsum fades of western Greece. 6* Eur. Reg. Meet. Int. Ass. Sed., 367-368.
Trichet J., Defarge C, Tribble J., Tribble G., Sansone F. 2001. Christmas Island lagoonal lakes, models for the deposition of carbonate-evaporite-organic laminated sediments. Sed. Geol., 140, 177-189.
Velaj T., Davison I., Serjan1 Λ., Alsop I. 1999. Thrust tectonics and the Role of Evaporites in the Ionian Zone of the Albanides, AAPG Bulletin, 83, 1408-1425.
Wilson J.L. (1975). Carbonate Facies in Geologic History. Berlin-Heidelberg-New York (Springer), 471 p.
Articles les plus lus par le même auteur ou la même autrice