Hostname: page-component-cd9895bd7-gbm5v Total loading time: 0 Render date: 2024-12-24T01:53:41.809Z Has data issue: false hasContentIssue false
  • English
  • Français

A modern analogue for the Lower Ordovician Obolus conglomerate of Estonia

Published online by Cambridge University Press:  01 May 2009

Norton Hiller
Norton Hiller
Affiliation:
Department of Geology, Rhodes University, Grahamstown 6140, Republic of South Africa
Get access Rights & Permissions [Opens in a new window]

Abstract

Phosphate-bearing rocks of the lower Ordovician Kallavere Formation, northern Estonia, contain diverse fragments and, more rarely, complete shells of the phosphatic inarticulate brachiopods Schmidtites and Ungula. In places the concentration of brachiopod debris in sandstones is so dense that economically exploitable seams of phosphorite are formed. A directly analogous situation occurs along the coast of Namibia today. In places the extant phosphatic inarticulate brachiopod Discinisca is washed up on the beach in such large numbers that its shells dominate the littoral sediment. The distribution range of this species suggests that it is a product of the Benguela upwelling ecosystem, and the inference is drawn that the Estonian deposits are the products of a similar palaeo-upwelling system.

Type
Rapid Communication
Information
Geological Magazine , Volume 130 , Issue 2 , March 1993 , pp. 265 - 267
Copyright
Copyright © Cambridge University Press 1993

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Bremner, J. M. 1983. Biogenic sediments on the South West African (Namibian) continental margin. In Coastal Upwelling: Its Sediment Record, part B (eds J. Thiede and E. Suess), pp. 73–103. New York, London: Plenum Press.CrossRefGoogle Scholar
Bremner, J. M. & Rogers, J. 1990. Phosphorite deposits on the Namibian continental shelf. In Phosphate Deposits of the World, volume 3 (eds Burnett, W. C. and Riggs, S. R.), pp. 143–52. Cambridge, New York: Cambridge University Press.Google Scholar
Chapman, P. & Shannon, L. V. 1985. The Benguela ecosystem. Part II. Chemistry and related processes. In Oceanography Marine Biology Annual Review 23, 183–251.Google Scholar
Cook, P. J. & McElhinny, M. W. 1979. A re-evaluation of the spatial and temporal distribution of sedimentary phosphate deposits in the light of plate tectonics. Economic Geology 74, 315–30.CrossRefGoogle Scholar
Heinsalu, H. 1990. Tremadoc phosphate-bearing rocks of north Estonia and shelly phosphorite. In Field Meeting, Estonia, 1990 (eds D. Kaljo and H. Nestor), pp. 37–39. Tallinn: Estonian Academy of Sciences.Google Scholar
Kensley, B. & Penrith, M-L. 1973. The constitution of the intertidal fauna of rocky shores of Mocamedes, southern Angola. Cimbebasia (A) 2, 113–23.Google Scholar
Kensley, B. & Penrith, M-L. 1980. The constitution of the fauna of rocky shores of South West Africa. Part III. The north coast from False Cape Frio to the Kunene River. Cimbebasia (A) 5, 210–14.Google Scholar
Männil, R. 1990. The Ordovician of Estonia. In Field Meeting, Estonia, 1990 (eds Kaljo, D. and Nestor, H.), pp. 11–20. Tallinn: Estonian Academy of Sciences.Google Scholar
Parrish, J. T. 1982. Upwelling and petroleum source beds, with reference to the Paleozoic. American Association of Petroleum Geologists Bulletin 66, 750–74.Google Scholar
Parrish, J. T. & Humphreville, R. G. 1981. Upwelling and phosphorites in the Paleozoic (abstract). American Association of Petroleum Geologists Bulletin 65, 969.Google Scholar
Parrish, J. T., Ziegler, A. M., Scotese, C. R., Humphreville, R. G. & Kirschvink, J. L. 1986. Proterozoic and Cambrian phosphorites - specialist studies: Early Cambrian palaeogeography, palaeoceanography and phosphorites. In Phosphate Deposits of the World, Volume 1: Proterozoic and Cambrian Phosphorites (eds Cook, P. J. and Shergold, J. H.), pp. 280–94. Cambridge, London: Cambridge University Press.Google Scholar
Shannon, L. V. 1989. The physical environment. In Oceans of Life off Southern Africa (eds Payne, A. I. L. and Crawford, R. J. H.), pp. 12–27. Cape Town: Vlaeberg Publishers.Google Scholar
Sheldon, R. P. 1980. Episodicity of phosphate deposition and deep ocean circulation - an hypothesis. In Marine Phosphorites - Geochemistry, Occurrence, Genesis (ed. Bentor, Y. K.), pp. 239–47. Society of Economic Paleontologists and Mineralogists, Special Publication 29, Tulsa.CrossRefGoogle Scholar