Skip to main content
SpringerLink
Log in

Geochemical and petrological characteristics of Eppawala phosphate deposits, Sri Lanka

  • Article
  • Published:
Mineralium Deposita Aims and scope Submit manuscript

Abstract.

The apatite-bearing carbonate rocks at Eppawala, Sri Lanka occur as massive, discontinuous bodies in a Precambrian, high-grade metamorphic terrain, which weather to form economically important phosphate deposits. The ore bodies at Eppawala contain ≤42% P2O5, and citric acid solubility of different components varies from 4 to 6%. The parent rocks are mainly made up of calcite, dolomite and apatite, with lesser amounts of ilmenite, magnetite, pyrite, forsterite, phlogopite, enstatite, magnesite, diopside, tremolite and spinel. Most of minerals show an euhedral habit, with a wide range of crystal sizes (from a few millimetres to several decimetres). The Eppawala rocks are characterised by low silica (≤0.41%), high phosphorous (≤10.58%) and high strontium content (2,960–6,819 ppm). Concentrations of light rare-earth elements in these rocks are comparably higher than those of marbles. The REE fractionation of these rocks is pronounced, and La/Yb ratios vary between 14 and 43. Both apatite and calcite show markedly elevated strontium levels (≤0.6%). The δ 13CPDB and δ 18OSMOW values of the carbonates are in the range of –3.4 to –2.2 and 7.7 to 16.4‰ respectively. The euhedral habit, as well as the presence of major quantities of apatite and considerable amounts of iron-bearing minerals suggest that the ore host rock has genetic links to an igneous source rather than to an intensely metamorphosed limestone. The higher light REE contents of the rocks, compared to marbles, also argue against a metamorphic or sedimentary origin. The Sr/Mn and Ce/La ratios in the apatite are ~40 and ~2 respectively, suggesting that they were formed in a carbonatite magma. The markedly increased REE concentrations in the bulk chemistry of the rocks have been shown to be mainly controlled by the content of phosphate minerals. Compared to most carbonatites, the Eppawala rocks are generally depleted in selected trace elements, particularly Ba, Nb, Th, V, U and Zr. This depletion may be due to either a primary infertility of the parent magma with regard to such trace elements, or it is a result of fractional crystallisation during the rock formation. The stable isotope ratios do not plot within the defined "mantle carbonatite box", but still lie within the broader range of carbonatitic rocks. With these data at hand, it can be readily argued that the mode of occurrence, petrography and geochemistry of the Eppawala apatite-bearing carbonates provide conclusive evidence of their carbonatitic origin.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1.
Fig. 2.
Fig. 3.
Fig. 4.
Fig. 5.

Similar content being viewed by others

References

  • Bell K, Blenkinsop J (1989) Neodymium and strontium isotope geochemistry of carbonatites. In: Bell K (ed) Carbonatites: genesis and evolution. Unwin Hyman, London, pp 278–300

  • Brasseur H, Herman P, Hubaux A (1962) Apatites de 1'est du Congo et du Ruanda. Ann Soc Géol Belgique 85(2):61–85

    Google Scholar 

  • Cooray PG (1994) The Precambrian of Sri Lanka: A historical review. Precambrian Res 66:3–18

    Google Scholar 

  • Craig H (1953) The geochemistry of the stable carbon isotopes. Geochim Cosmochim Acta 3:53–92

    Google Scholar 

  • Dahanayake K, Subasinghe SMND(1989) Secondary phosphate mineralization in a karsric environment in central Sri Lanka. Miner Deposita 24:169–175

    Google Scholar 

  • Deines P (1989) Stable isotope variations in carbonatites. In: Bell K (ed) Carbonatites: genesis and evolution. Unwin Hyman, London, pp 301–359

  • Dinalankara DMSK (1995) Eppawala phosphate deposit of Sri Lanka-present status. In: Dahanayake K, Van Kauwenbergh SJ, Hellums DT (eds) Proc Int Worksh Direct Application of Phosphate Rock and Appropriate Technology Fertilizers in Asia – what hinders acceptance and growth. Institute of Fundamental Studies, Sri Lanka, pp 153–163

  • Droop GTR (1987) A general equation for estimating Fe3+ concentrations in ferromagnesian silicates and oxides from microprobe analyses, using stoichiometric criteria Mineral Mag 51:431–435

    Google Scholar 

  • Fleischer M, Altschuler ZS (1986) The lanthanides and yttrium in minerals of the apatite group – an analysis of the available data. N Jahrb Mineral Monatsh 10:467–480

    Google Scholar 

  • Gittins J (1989) The origin and evolution of carbonatite magmas. In: Bell K (ed) Carbonatites: genesis and evolution. Unwin Hyman, London, pp 580–600

  • Haggerty SE (1989) Mantle metasomes and the kinship between carbonatites and kimberlites. In: Bell K (ed) Carbonatites: genesis and evolution. Unwin Hyman, London, pp 546–560

  • Hamilton BL, Bedson P, Esson J (1989) The behaviour of trace elements in the evolution of carbonatites. In: Bell K (ed) Carbonatites: genesis and evolution. Unwin Hyman, London, pp 405–427

  • Hapuarachchi DJAC (1995) Some thoughts on the origin of the Eppawala apatite deposit. J Geol Soc Sri Lanka 6:77–79

    Google Scholar 

  • Hapuarachchi DJAC (1997) On the origin of the Eppawala apatite deposits, Sri Lanka. J S Am Earth Sci 10:3–4

    Google Scholar 

  • Hoefs J (1988) Stable isotope geochemistry, 3rd edn. Springer, Berlin Heidelberg New York

  • Hoernes S, Fiorentini E, Hoffbauer R (1991) Oxygen and carbon isotope rations in high-grade rocks from Sri Lanka as a monitor of fluid-rock interaction. Geol Surv Dept Sri Lanka Prof Pap 5:225–236

    Google Scholar 

  • Hogarth DD (1989) Pyrochlore, apatite and amphibole: distinctive minerals in carbonatite. In: Bell K (ed) Carbonatites: genesis and evolution. Unwin Hyman, London, pp 105–148

  • Jarvis JC, Wildeman TR, Banks NG (1975) Rare earths in the Leadville limestone and its marble derivatives. Chem Geol 16:27–37

    Google Scholar 

  • Jayawardena DE de S (1976) The Eppawala carbonatite complex in north-west Sri Lanka (Ceylon). Geol Surv Dept Sri Lanka Econ Bull 3

  • Jenner GA (1990) ICP-MS – A powerful tool for high-precision trace-element analysis in earth sciences: Evidence from analysis of selected U.S.G.S. reference samples. Chem Geol 83:133–148

  • Kawabe I, Toriumi T, Ohta A, Miura N (1998) Monoisotopic REE abundances in seawater and the origin of seawater tetrad effect. Geochem J 32:213–229

    Google Scholar 

  • Keller J, Hoefs J (1995) Stable isotope characteristics of recent natrocarbonatites from Oldoinyo Lengai. In: Bell K, Keller J (eds) Carbonatite volcanism: Oldoinyo Lengai and the pathogenesis of natrocarbonatites. IAVCEI Int Assoc Volcanol Chem Earth Interior Proc Volcanol 4:113–123

  • Kröner A, Cooray PG, Vitaage PW (1991) Lithotectonic subdivision of the Precambrian basement in Sri Lanka. Geol Surv Dept Sri Lanka Prof Pap 5:5–21

    Google Scholar 

  • Le Roex AP, Lanyon R (1998) Isotope and trace element geochemistry of Cretaceous Damaraland lamprophyres and carbonatites, northwestern Namibia: evidence for plume-lithosphere interactions. Geol Sci 39:1117–1146

    Google Scholar 

  • Marchenko YeYa, Chashka AI, Storchak PN, Timoshenko OD, Lapitskiy EM (1975) Typomorphism of apatite from carbonatite. Doklady Acad Sci Earth Sci Sect 224:138–140

  • McCrea JM (1950) On the isotopic chemistry of carbonates and a paleotemperature scale. J Chem Phys 18:849–857

    Google Scholar 

  • Moecher DA, Anderson ED, Cook CA, Mezger K (1997) The petrogenesis of metamorphosed carbonatites in the Grenville Province, Ontario. Can J Earth Sci 34:1185–1201

    Google Scholar 

  • Nelson DL, Chivas AR, Chappell BW, McCulloch MT (1988) Geochemical and isotopic systematics in carbonatites and implications for the evolution of ocean-island sources. Geochim Cosmochim Acta 52:1–17

    Google Scholar 

  • Parekh PP, Möller P, Dulski P (1977) Distribution of trace elements between carbonate and non-carbonate phases of limestone. Earth Planet Sci Lett 34:39–50

    Google Scholar 

  • Pohl J, Emmermann R (1991) Chemical composition of the Sri Lanka Precambrian basement. Geol Surv Dept Sri Lanka Prof Pap 5:94–123

    Google Scholar 

  • Schidlowski M, Eichmann R, Junge CE (1975) Precambrian sedimentary carbonates: carbon and oxygen isotope geochemistry and implications for the terrestrial oxygen budget. Precambrian Res 2:1–69

    Google Scholar 

  • Smithies RH, Marsh JS (1998) The Marinks Quellen carbonatite complex, southern Namibia; carbonatite magmatism with an uncontaminated depleted mantle signature in a continental setting. Chem Geol 148:201–212

    Google Scholar 

  • Srivastava RK (1998) Petrology of the Proterozoic alkaline carbonatite complex of Samalpatti, District Dharmapuri, Tamil Nadu. J Geol Soc India 51:234–243

    Google Scholar 

  • Stoppa F, Cundari A (1995) A new Italian carbonatite occurrence at Cupaell (Rieti) and its genetic significance. Contrib Mineral Petrol 122:275–288

    Google Scholar 

  • Stoppa F, Woolley AR (1997) The Italian carbonatites: field occurrence, petrology and regional significance. Mineral Petrol 59:43–67

    Google Scholar 

  • Subbarao KV, Le Bas MJ, Bhaskar Rao (1995) Are the Vinjamur rocks carbonatites or meta-limestones? J Geol Soc India 46:125–137

  • Taylor SR, McLennan SM (1985) The continental crust: its composition and evolution. Blackwell, Oxford

  • Tazaki K, Fyfe WS, Dissanayake CB (1987) Weathering of apatite under extreme conditions of leaching. Chem Geol 60:151–162

    Google Scholar 

  • Treloar PJ, Colley H (1996) Variation in F and Cl contents in apatites from magnetite-apatite ores in northern Chile, and their ore-genetic implications. Mineral Mag 60:285–301

    Google Scholar 

  • Veizer J, Holzer WT, Wilgus CK (1980) Correlation of 13C/12C and 34S/32S secular variations. Geochim Cosmochim Acta 44:579–587

    Google Scholar 

  • Viladkar SG, Subramanian V (1995) Mineralogy and geochemistry of the carbonatites of the Sevathur and Samalpatti complexes, Tamil Nadu. J Geol Soc India 45:505–517

    Google Scholar 

  • Viladkar SG, Wimmenauer W (1986) Mineralogy and geochemistry of the Newania carbonatite fenite Complex, Rajasthan, India. N Jahrb Mineral Abh 156:1–21

    Google Scholar 

  • Woolley AR, Kempe DRC (1989) Carbonatites: Nomenclature, average chemical compositions, and element distribution. In: Bell K (ed) Carbonatites: genesis and evolution. Unwin Hyman, London, pp 1–14

  • Woolley AR, Barr MWC, Din VK, Jones GC, Wall F, Williams CT (1991) Extrusive carbonatites from the Uyaynah area, United Arab Emirates. J Petrol 32:1143–1167

    Google Scholar 

Download references

Acknowledgements.

This study was supported by the Deutscher Akademischer Austausch Dienst (DAAD) and the Max-Plank Gesellschaft, Germany. We are grateful to Profs. J. Keller and J. Otto for help in analysing the samples by XRF spectrometry, and to Prof. G. Jenner for trace-element analysis on ICP-MS. Our acknowledgement also goes to Mrs. I. Bambach and Mrs. G. Feyerherd for the cartographic work, and to Mr. G. Josten for assisting in the stable isotope work carried out at the Max-Plank Institute for Chemistry, Mainz, Germany. We thank Dr. Richard J. Goldfarb and Dr. Francoise Chalot-Prat for constructive reviews which have led to a number of improvements in the manuscript.

Author information

Authors and Affiliations

  1. Department of Geology, University of Peradeniya, Peradeniya, Sri Lanka

    Amarasooriya Pitawala & Kapila Dahanayake

  2. Max-Planck Institut für Chemie, Abteilung Biogeochemie, Postfach 3060, 55020, Mainz, Germany

    Manfred Schidlowski

  3. Johannes Gutenberg-Universität, Mainz, Germany

    Wolfgang Hofmeister

Authors
  1. Amarasooriya Pitawala
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Manfred Schidlowski
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Kapila Dahanayake
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Wolfgang Hofmeister
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Amarasooriya Pitawala.

Additional information

Editorial handling: A. Cheilletz

Rights and permissions

Reprints and permissions

About this article

Cite this article

Pitawala, A., Schidlowski, M., Dahanayake, K. et al. Geochemical and petrological characteristics of Eppawala phosphate deposits, Sri Lanka. Miner Deposita 38, 505–515 (2003). https://doi.org/10.1007/s00126-002-0327-y

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s00126-002-0327-y

Keywords.

Search

Navigation