Sedimentray Petrography and Origin of Phosphate Peloids of the Mazıdağ-Derik Area (Mardin, Southeast Turkey)

 The Mazıdağ phosphate beds of the Upper Cretaceous carbonate sequence were deposited in an area of upwelling water which supplied phosphorous was deposited on the sea bottom as biogenic detritus of zoo— and phytoplankton, fish bones and scales. The biogenic accumulation with high content of organic matter and phosphorous was a prime source of the phosphate which formed the phosphate deposits of the Mazıdağ—Derik area. Commonly, currents transported the phosphatic sediments laterally, forming parallel and low angle cross laminations. In some cases, the sea floor was uplifted after upwelling periods. Consequently, some phosphate beds underwent karstification, giving rise to phoscretes and silcretes. Ground water percoalating into the karstic realm caused phosphate replacement of many carbonate grains of the shallow water limestone facies. These complex events resulted in the formation of three basic phosphate peloid types in the Mazıdağ-Derik phosphate sequence, which are classified to the following origin of peloids : (1) in situ precipitation; (2) abrasion of phosphatized intraclast and bioclast and (3) phosphate micritization of fish bones. The phosphate peloids show the following different microstructures under the electron microscopy : (1) amorphous; (2) microglobular; (3) semi-crystallized; (4) microcrystallized and (5) cementing. 
Keywords:

-,

___

  • Ames, L.L., 1959, The genesis of carbonate apatites: Econ. Geol., 54,829-841.
  • Arthur, M.A. and Jenkyns, H., 1981, Phosphorites paleo- cography: Oceanologica Acta, 4, 83—96.
  • Balson, P.S., 1980, The origine and evulation Tertiary phos- phorites from eastern England: Jour. Geol. Soc. London, 137,723-729.
  • Bathurst, R.B.C., 1976, Carbonate sediments and their diagene- sis (2nd ed.): Developments in Sedimentology, 12, Elsevier, 658 p, Amsterdam.
  • Baturin, G.N., 1971, Stages of phosphorite formation on the ocean floor: Nature, 232, 61-62.
  • —, 1982, Phosphorites on the sea floor, origin, composition and distrubition: Developments in Sedimentology, 33, Elsevier, 343 p, Amsterdam.
  • — and Bezrukov, P.L., 1979, Phosphorites on the sea floor and their origin: Mar. Geol., 31, 317-332.
  • Bromley, R.G., 1967, Marine phosphorites as depth indicators: Marine Geol., 3, 503-509.
  • Cook, P.J., 1972, Petrology and geochemistry of the phosphate deposits of Northwest Queensland, Australia: Econ. Geol., 67, 1193-1213.
  • Friedman, G.M.; Gebelin, C. and Sanders, J.E., 1971, Micritic envelopes of carbonate grains are not exclusively of photsynthetic algal origin: Sedimentology, 16, 89—96. Kazakov, A.V., 1939, The phosphate facies: Origin of the phosphorites and geologic factors of formation of the deposits: Proc. Sci. Ins. Per., 145, 1—106.
  • Köksoy, M., 1977, Mazıdağ bölgesindeki fosforun ikincil dağı- lımı ve jeokimyasal anomalileri: III) Yerbilimleri Mecm., 3/1-2,24-41.
  • Longman, M.W., 1980, Carbonate diagenetic textures from Nearsurface diagenetic environments: AAPG Bull., 64,461-488.
  • Lucas, J.; Prevot, L.; Ataman, G. and Gündoğdu, N., 1979, Etude mineralogique et geochimique de la serie phos- phate au Sud—Est de la Turquie (Mazıdağ—Mardin): Sci. Geol. Bull., 32 (1-2), 59-63.
  • Marshall, J. F. and Cook, P.J., 1980, Petrology of iron-and phosphorous—rich nodulus from the E Australian conti- nental shelf: Jour. Geol. Soc., 137, 765, 771, London.
  • McKee, E.D. and Gutschick, R.C., 1969, History of Redwall limestone Arizona: Mem. Geol. Soc. America, 114, 711-726.
  • Price, N.B. and Calvert, S.E., 1978, The geochemistry of phos- phorites from the Namibian shelf: Chem. Geol., 23, 151-170.
  • Seyhan, L; Sündal, Ü.; Yılmaz. S. and Özoğul, İ, 1973, Mardin- Mazıdağ-Kasrık bölgesi fosfat yataklarının fizibilite araştırması: MTA Rep., vol. 2, Rezerv ve Kalite, 154 p. Sheldon, R.P., 1964, Exploration for phosphorite in Turkey, A case history: Economic Geology, 59, 1159—1175.
  • Sholkowitz, E., 1973, Interstitial water chemistry of the Santa Basin sediments: Geochim. Cosmochim Acta, 37, 2043-2073.
  • Slansky, M., 1986, Geology of sedimentary phosphates: North Oxford Academic, 210 p.
  • Soudry, D., 1979, Intervention de schzophytes dans la phos- phomicritization des debrits osseux : C.R. Seances Acad. Sci., 288, 1186-1214, Paris.
  • — and Nathan, Y., 1980, Phosphorite peloids from the Negev phosphorites: Jour. Geol. Soc., 137, 749—755, London.