IJG  Vol.2 No.3 , August 2011
Emplacement and Evolution History of Pegmatites and Hydrothermal Deposits, Matale District, Sri Lanka
ABSTRACT
Excellent outcrops in Matale Sri Lanka provide unique insight into the emplacement and evolution history of hydrothermal and pegmatitic rocks in the central highlands of Sri Lanka. Field, structural, petrological, thermo-barometric studies in the metamorphic basement rocks in the central highlands and related hydrothermal deposits are presented in this study. Detailed petrographic and mineralogical data reveal peak metamorphic conditions for the crustal unit in the study area as 854 ± 44oC at 10.83 ± 0.86 kbar. Hydrothermal veins consisting of quartz and mica are closely related to cross-cutting pegmatites, which significantly post-date the peak metamorphic conditions of the crustal unit. Field relations indicate that the veins originated as ductile-brittle fractures have subsequently sealed by pegmatites and hydrothermal crystallization. Geological, textural and mineralogical data suggest that most enriched hydrothermal veins have evolved from a fractionated granitic melt progressively enriched in H2O, F, etc. Quartz, K-feldspar, mica, tourmaline, fluorite and topaz bear evidence of multistage crystallization that alternated with episodes of resorption. It was suggested that the level of emplacement of pegmatites of the Matale District was middle crust, near the crustal scale brittle-ductile transition zone at a temperature of about 600oC. For this crustal level and temperature range, it is considered very unlikely that intruding pegmatitic melts followed pre-existing cracks. As such the emplacement temperatures of the pegmatites could be well below the peak metamorphic estimates in the mafic granulites. The metamorphic P-T strategy and position of formation of hydrothermal deposits and pegmatites is summarized in the modified P-T-t-D diagrams.

Cite this paper
nullG. Fernando, A. Pitawala and T. Amaraweera, "Emplacement and Evolution History of Pegmatites and Hydrothermal Deposits, Matale District, Sri Lanka," International Journal of Geosciences, Vol. 2 No. 3, 2011, pp. 348-362. doi: 10.4236/ijg.2011.23037.
References
[1]   W. C. Brisbin, “Mechanics of Pegmatite Intrusion,” American Mineralogist, Vol. 71, No. 3-4, 1986, pp. 644-651.

[2]   H. R. Shaw, “The Fracture Mechanism of Magma Transport from the Mantle to the Surface,” In: R. B. Hargraves, Ed., Physics of Magmatic processes, Princeton University Press, Princeton, 1980.

[3]   C. W. Burnham, “The Importance of Volatile Constituents,” In: H. S. Yoder, Ed., The Evolution of the Igneous Rocks, Princeton University Press, Princeton, 1979, pp. 439-482.

[4]   T. K. Kyser, “Fluids, Basin Analysis and Mineral Deposits,” Geofluids, Vol. 7, No. 2, 2007, pp. 238-257. doi:10.1111/j.1468-8123.2007.00178.x

[5]   B. Baatartsogt, G. Schwinn, T. Wagner, H. Taubald, T. Beitter, G. Markl, “Contrasting Paleo Fluid Systems in the Continental Basement: A Fluid Inclusion and Stable Isotope Study of Hydrothermal Vein Mineralization, Schwarzwald District, Germany,” Geofluids, Vol. 7, No. 2, 2007, pp. 123-147. doi:10.1111/j.1468-8123.2007.00169.x

[6]   S. A. Gleeson and B. W. D. Yardley, “Extensional Veins and Pb-Zn Mineralization in Basement Rocks: The Role of Penetration of Formation Brines,” In: I. Stober, K. Bucher, Eds., Water-Rock Interaction, Kluwer Academic Publishers, Norwell, 2002, pp. 189-205.

[7]   R. R. Large, S. W. Bull, P. J. McGoldrick, S. Walters, G. M. Derrick and G. R. Carr, “Stratiform and Strata-Bound Zn-Pb-Ag Deposits in Proterozoic Sedimentary Basins, Northern Australia,” Economic Geology, Vol. 100, 2005, pp. 931-963.

[8]   N. H. S. Oliver, J. G. McLellan, B. E. Hobbs, J. S. Cleverley, A. Ord and L. Feltrin, “Numerical Models of Extensional Deformation, Heat Transfer and Fluid Flow across Basement Cover Interfaces During Basin-Related Mineralization,” Economic Geology, Vol. 101, 2006, pp. 1-31. doi:10.2113/101.1.1

[9]   A. Pitawala, T. H. N. G. Amaraweera, G. W. A. R. Fernando and C. A. Hauzenberger, “Pegmatites Derived from Fractionation of a Melt: An Example from Pegmatites in the Owala-Kaikawala Area, Matale, Sri Lanka,” Journal of Geological Society of India, Vol. 72, No. 6, 2008, pp. 815-822.

[10]   S. L. Harley, “An Experimental Study of the Partitioning of Fe and Mg between Garnet and Orthopyroxene,” Contribution to Mineralogy Petrology, Vol. 86, No. 4, 1984, pp. 359-373. doi:10.1007/BF01187140

[11]   R. C. Newton and D. Perkins, III, “Thermodynamic Calibration of Geobarometers Based on the Assemblages Ganet-Plagioclase-Orthopyroxene-(Clinopyroxene)-Quartz”, American Mineral, Vol. 67, 1982, pp. 203-222.

[12]   R. Schumacher, V. Schenk, P. Raase and P. W. Vitanage, “Granulite Facies Metamorphism of Metabasic and Intermediate Rocks in the Highland Series of Sri Lanka,” In: J. R. Ashworth, M. Brown, Eds. High Temperature Metamorphism and Crustal Anatexis, Unwin Hyman, London, 1990, pp. 235-271.

[13]   G. Voll, C. Evangelakakis and H. Kroll, “Revised Two-feld-spar Geothermometry Applied to Sri Lankan Feldspars,” Precambrain Research, Vol. 66, No. 1-4, 1994, pp. 351-377. doi:10.1016/0301-9268(94)90058-2

[14]   P. Raase, “Feldspar thermometry: A Valuable Tool for Deciphering the Thermal History of Granulite-facies Rocks, as Illustrated with Metapelites from Sri Lanka,” Canadian Mineralogist, Vol. 36, 1998, pp. 67-86.

[15]   G. W. A. R. Fernando, C. A. Hauzenberger, L. P. Baumgartner and W. Hofmeister, “Retrograde Diffusion Zoning in Garnet: Implications for Cooling History of Mafic Granulites in Highland Complex of Sri Lanka,” Mineralogy and Petrology, Vol. 78, No. 1-2, 2003, pp. 53-71. doi:10.1007/s00710-002-0224-1

[16]   K. Sajeev and Y. Osanai, “Osumilite and Spinel - Quartz from Sri Lanka Implications for UHT Metamorphism and Retrograde P-T Path,” Journal of Mineralogical and Petrological Sciences, Vol. 99, No. 5, 2004, pp. 320-327. doi:10.2465/jmps.99.320

[17]   K. Sajeev and Y. Osanai, “Ultrahigh-Temperature Metamorphism (1150oC, 12 kbar) and Multistage Evolution of Mg-Al Rich Granulites from the Central Highland Complex, Sri Lanka,” Journal of Petrology, Vol. 45, No. 9, 2004, pp. 1821-1844. doi:10.1093/petrology/egh035

[18]   K. Sajeev, Y. Osanai, J. A. D. Connolly, S. Suzuki, J. Ish- ioka, H. Kagami and S. Rino, “Extreme Crustal Meta- morphism during a Neoproterozoic Event in Sri Lanka: A Study of Dry Mafic Granulites,” The Journal of Geology, Vol. 115, No. 5, 2007, pp. 563-582. doi:10.1086/519778

[19]   C. Powell, S. R. Mac, Roosts and J. J. Veevers, “Pre-breakup Continental Extension in East Gondwanaland and the Early Opening of Eastern Indian Ocean,” Tectonophysics, Vol. 155, 1988, pp. 261-283. doi:10.1016/0040-1951(88)90269-7

[20]   A. Kr?ner, “African Linkage of Precambrian Sri Lanka,” Geologische Rundschau, Vol. 80, No. 2, 1991, pp. 429-440. doi:10.1007/BF01829375

[21]   M. Yoshida, M. Funaki and P. W. Vitanage, “Proterozoic to Mesozoic East Gondwana: The Juxtaposition of India, Sri Lanka and Antatica,” Tectonics, Vol. 11, No. 2, 1992, pp. 381-391. doi:10.1029/91TC02386

[22]   J. Jacobs, C. M. Fanning, F. Henjes-Kunst, M. Olesch and H. J. Paech, “Continuation of Mozambique Belt into East Antarctica: Grenville Age Metamorphism and Polyphase Pan-African High-Grade Events in Central Dronning Maud Land,” The Journal of Geology, Vol. 106, No. 4, 1990, pp. 385-406. doi:10.1086/516031

[23]   A. Kr?ner, P. G. Cooray and P. W. Vitanage, “Lithotectonic Subdivision of the Precambrian Basement in Sri Lanka,” In: A. Kr?ner, Ed, Part 1. Summary of Research of the German-Sri Lankan Consortium, Geological Survey Department, Lefkosia, 1991, pp. 5-21.

[24]   P. G. Cooray, “The Precambrian of Sri Lanka: A Historic Review,” Precambrain Research, Vol. 66, No. 1-4, 1994, pp. 3-18. doi:10.1016/0301-9268(94)90041-8

[25]   C. C. Milisenda, T. C. Liew, A. W. Hoffman and A. Kr?ner, “Isotopic Mapping of the Age provinces in Precambrian High-Grade Terrains; Sri Lanka,” The Journal of Geology, Vol. 96, No. 5, 1988, pp. 608-615. doi:10.1086/629256

[26]   K. V. W. Kehelpannala, “Structural Evolution of the Middle to Lower Crust in Sri Lanka- a Review,” Journal of Geological Society of Sri Lanka, Vol. 11, 2003, pp. 45-85.

[27]   P. W. Vitanage, “Post-Precambrian Uplifts and Regional Neotectonic Movements in Ceylon,” Proceedings 24th IGC, Montreal, Vol. 3, 1972, pp. 642-654.

[28]   L. R. K. Perera, “The Origin of the Pink Granites of Sri Lanka,” Precambrain Research, Vol. 20, No. 1, 1983, pp.17-37. doi:10.1016/0301-9268(83)90027-X

[29]   A. Pitawala, M. Schidlowski, K. Dahanayake, W. Hof- meister, “Geochemical and Petrological Chracteristics of Eppawala Phosphate Deposits, Sri Lanka,” Mineraium Deposita, Vol. 38, No. 4, 2003, pp. 505-515. doi:10.1007/s00126-002-0327-y

[30]   M. Sandiford, R. Powell, S. F. Martin and L. R. K. Perera, “Thermal and Baric Evolution of Garnet Granulite from Sri Lanka,” Journal of Metamorphic Geology, Vol. 6, No. 3, 1988, pp. 351-364. doi:10.1111/j.1525-1314.1988.tb00425.x

[31]   V. Schenk, P. Raase and R. Schumacher, “Very High Temperatures and Isobaric Cooling before Tectonic Uplift in the Highland Series,” Terra Cognita, Vol. 8, 1988, pp. 265.

[32]   R. Schumacher and S. Faulhaber, “Summary and Discussion of P-T Estimates from Garnet- pyroxeneplagioclase-quartz-bearing Granulite Facies Rocks from Sri Lanka,” Precambrain Research, Vol. 66, No. 1-4, 1994, pp. 295-308. doi:10.1016/0301-9268(94)90055-8

[33]   G. W. A. R. Fernando, “Genesis of Metasomatic Sapphirine-corundum-spinel Bearing Granulites in Sri Lanka: An Integrated Field, Petrological and Geochemical Study,” Ph.D. Thesis, University of Mainz, Mainz, 2001, pp. 175.

[34]   S. Faulhaber and M. Raith, “Geothermometry and Geobarometry of High-Grade Rocks: A Case Study on Garnet-pyroxene Granulites in Southern Sri Lanka,” Mineralogical Magzine, Vol. 55, 1991, pp. 33-56.

[35]   Y. Hiroi, Y. Ogo and L. Namba, “Evidence for Prograde Metamorphic Evolution of Sri Lankan Politic Granulites, and Implications for the Development of Continental Crust,” Precambrain Research, Vol. 66, No. 1-4, 1994, pp. 245-263. doi:10.1016/0301-9268(94)90053-1

[36]   P. Raase and V. Schenk, “Petrology of Granulite Facies Metapelites of the Highland Complex Sri Lanka: Implication for the Metamorphic Zonation and the PT Path”, Precambrain Research, Vol. 66, No. 1-4, 1994, pp. 265-294. doi:10.1016/0301-9268(94)90054-X

[37]   L. M. Kriegsman and J. C. Schumacher, “Petrology of Sapphirine-Bearing and Associated Granulites from Central Sri Lanka,” Journal of Petrology, Vol. 40, No. 8, 1999, pp. 1211-1239. doi:10.1093/petrology/40.8.1211

[38]   Y. Osanai, K. Sajeev, M. Owada, K. V. W. Kehelpannala, W. K. B. N. Prame, N. Nakano and S. Jayatileke, “Metamorphic Evolution of High-Pressure and Ultrahigh Temperature Granulites from Highland Complex, Sri Lanka,” Journal of Asian Earth Sciences, Vol. 28, No. 1, 2006, pp. 20-37. doi:10.1016/j.jseaes.2004.09.013

[39]   S. Chakraborty and J. Ganguly, “Compositional Zoning and Cation Diffusion in Aluminosilicate Garnets,” In: J. Ganguly, Ed., Diffusion, Atomic Ordering and Mass Transport—Selected Problems in Geochemistry, Advances in Physical Geochemistry, Vol. 8, Springer-Verlag, New York, 1991, pp. 120-170.

[40]   A. R. Berger and N. R. Jayasinghe, “Precambrian Structure and Chronology in the Highland Series of Sri Lanka”, Precambrain Research, Vol. 3, No. 6, 1976, pp. 559-576. doi:10.1016/0301-9268(76)90019-X

[41]   K. K. M. W. Silva, “Tectonic Environment of the Vein-Type Mineral Deposits of Sri Lanka,” ITC Journal, Vol. 2, 1986, pp. 170-176.

[42]   D. M. S. K. Dinalankara, “Structurally Controlled Graphite Deposits of Sri Lanka,” Geological Society of Sri Lanka, Vol.3, 1990, pp. 26-32.

[43]   S. Kumarapeli, “Topaz at Polwaththa Colony, Matale District: It’s Probable Source,” In: K. Dahanayake Ed., Handbook on Geology and Mineral Resources of Sri Lanka, South Asia Geological Congress Souvenir Publication, Colombo, 1995, pp. 19-25.

[44]   D. R. M. Pattison, T. Chacko, J. Farquhar and C. R. M. McFarlane, “Temperatures of Granulite-Facies Metamorphism: Constraints from Experimental Phase Equilibria and Thermobarometry Corrected for Retrograde Exchange,” Journal of Petrology, Vol. 44, No. 5, 2003, pp. 867-900. doi:10.1093/petrology/44.5.867

[45]   L. M. Kriegsman, “Geodymamic Evolution of the Pan- African Lower Crust in Sri Lanka-Structural and Petrolo- gical Investigations into a High-Grade Gneiss Terrain,” Ph.D. thesis, University of Utrecht, Utrecht, 1993, p. 207.

[46]   R. G. Berman, “Thermobarometry Using Multiequilibrium Calculations: A New Technique, with Petrological Applications,” Canadian Mineralogist, Vol. 29, 1991, pp. 833-855.

[47]   J. Ganguly, W. Cheng and S. Chakraborty, “Cation Diffusion in Aluminosilicate Garnets: Experimental Determination in Pyrope-almandine Diffusion Couples,” Contributions to Mineralogy and Petrology, Vol. 131, No. 2-3, 1998, pp. 171-180. doi:10.1007/s004100050386

[48]   J. Ganguly and V. Tazzoli, “Fe2+–Mg Interdiffusion in Orthopyroxene: Retrieval from the Data on Intracrystalline Exchange Reaction,” American Mineralogist, Vol. 79, 1994, pp. 930-937.

[49]   I. Parson and M. R. Lee, “Alkali Feldspars as Microtextural Merkers of Fluid Flow,” In: I. Stober, K. Bucher, Eds., Hydrogeology of Crystalline rocks, Kluwer Academic Publishers, Norwell, 2000, pp. 27-50.

[50]   D. London, “Estimating Abundances of Volatile and Other Mobile Components in Evolved Silicic Melts through Mineralmelt Equilibria,” Journal of Petrology, Vol. 38, 1997, pp. 1691-1706. doi:10.1093/petrology/38.12.1691

 
 
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