The mineralogy and geochemistry of zeolite-bearing volcanics from Acrotiri (Santorini island) and Polyegos (Milos group of islands), Greece. Implications for geochemical classification diagrams

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Published: Jan 1, 2001
DOI: https://doi.org/10.12681/bgsg.17100
Keywords:
volcanic tuffs ignimbrite pyroclastics parent rock precursor hydrothermal alteration zeolite minerals Santorini Polyegos Greece
K. P. KITSOPOULOS
Geology Department, Leicester University
P. W. SCOTT
Camborne School of Mines, University of Exeter
C. A. JEFFREY
Geology Department, Leicester University
N. G. MARSH
Abstract

Almost 100 samples of volcanic rocks from Akrotiri (Santorini Island) and Polyegos (Milos group of Islands) were studied. Clinoptilolite and mordenite dominate the mineralogy in Akrotiri and Polyegos respectively. In Akrotiri, an acidic mainly precursor, probably a rhyodacite-dacite type of rock, was the parent precursor, although some samples indicate a more basic one. In Polyegos, it seems that a trachyandesite/rhyodacite type of rock has acted as precursor. However, this could be due to the possible depletion of Y under hydrothermal alteration, the increase of the Nb/Y ratio, and the shift (in the (Nb/Y vs. Zr/Ti02 diagram) of the nature of the precursor towards a more alkaline character. Thus, the true nature of the unaltered fresh precursor could actually be closer to the rhyodacite-dacite type of rock field. Geochemical classification diagrams using Si02, Na20 and K20 are not suitable for use with such materials. Diagrams using less mobile elements, such as Zr, Ti, Nb and Y are much more reliable, but with hydrothermal alteration conditions, their usefulness is variably restricted, and they should also be used with caution.

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  • Mineralogy and Crystallography
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References
ALIETTI, A. 1972. Polymorphism and crystal-chemistry of heulandites and clinoptilolites. Amer. Mineral. 57, 1448-1462.
BOLES, J. R. 1972. Composition, optical properties, cell dimensions, and thermal stability of some Heulandite group zeolites. Amer. Mineral. 57, 1463-1493.
BOLES, J. R. & SURDAM, R. C. 1979. Diagenesis of volcanogenic sediments in a Tertiary saline lake; Wagon Bed Formation, Wyoming. Am. J. Sci. 279, 832-853.
FINLOW-BATES, T. & STUMPFL, E. F. 1981. The behaviour of so-called immobile elements in hydrothermally altered rocks associated with volcanogenic submarine-exhalative ore deposits. Mineral. Deposita 16, 319-328.
FYTICAS, M. & VOUGIOUKALAKIS, G. 1992. A report of the geological-volcanological-geothermal observations for Kimolos and Polyegos Islands. (Milos group of islands). Report by IGME (Institute of Geological and Mineralogical Research of Greece), Athens, 14 pp. (in Greek)
GOVINDARAJU, K. 1989. Geostandards Newsletters 13, Special Issue, July 1989.
HEMLEY, J. J. & JONES, W. R. 1964. Chemical aspects of hydrothermal alteration with emphasis on hydrogen metasomatism. Econ. Geol. 59, 538-569.
HOLE, M. J., ROGERS, G., SAUNDERS, A. D. & STOREY, M. 1991. Relation between alkalic volcanism and slab-window formation. Geology 19, 657-660.
HOLE, M. J., SAUNDERS, A. D., ROGERS, G. & SYKES, M. A. 1994. The relationship between alkalic magmatism, lithosphère extension and slab-window formation along continental destructive plate margins. In: J.S. Smellie (Editor), Volcanism Associated with extension at Consuming Plate Boundaries. Geological Society of London, Special Publications 81, 265-285.
IGME. 1980. Geological Sheet "Thera". 1:50,000. Institute of Geological and Mineralogical Research of Greece, Athens.
KANARIS, I. Τ 1989. Zeolites of the island of Polyegos. Report by IGME (Institute of Geological and Mineralogical Research of Greece), Athens, 21 pp. (in Greek)
KITSOPOULOS, K. P. 1995. The mineralogy, geochemistry, physical properties and possible industrial applications of volcanic zeolitic tuffs from Santorini and Polyegos islands, Greece. PhD Thesis, Leicester University, United Kingdom, 442 pp.
KITSOPOULOS, K. P. 1997. The genesis of a mordenite deposit by hydrothermal alteration of pyroclastics on Polyegos island, Greece. Clays and Clay Miner. 45, 632-648.
KITSOPOULOS, K. P. 1998. Compositional variations of mordenite from Polyegos island, Greece: Na-Ca and Krich mordenite. European Journal of Mineralogy 10, 569-577.
KITSOPOULOS, K. P. 2001. The relation between the thermal behavior of the clinoptilolite and its chemical composition. Clays and Clay Miner. 49, 236-243.
LE MAITRE, R. W., BATEMAN, P., DUDEK, Α., KELLER J., LAMEYRE LE BAS, M. J., SABINE, P. Α., SCHIMD, R., SORENSEN, H., STRCKEISEN, Α., WOOLLEY, A. R. & ZANETTIN, B. 1989. A classification of igneous rocks and glossary of terms. (Blackwell, Oxford).
PEARCE, J.A. & CANN J.R. 1973. Tectonic settings of basic volcanic rocks determined using trace elements analyses. Earth Planen. Sci. Lett. 19, 290-300.
PICHLER, H. & KUSSMAUL, S. 1972. The cale-alcaline volcanics rocks of the Santorini Group (Aegean Sea, Greece). Neues Jahrb. Mineral. Abh. 116, 268-307N.
RICKWOOD, P. C. 1989. Boundary lines within petrologie diagrams which use oxides of major and minor elements. Lithos 22, 247-263.
TSOLIS-KATAGAS, P. & KATAGAS, C. 1989. Zeolites in pre-caldera pyroclastic rocks of the Santorini Volcano, Aegean Sea, Greece. Clays and Clay Miner. 37, 497-510.
WINCHESTER, J. A. & FLOYD, P. A. 1977. Geochemical discrimination of different magma series and their differentiation products using immobile elements. Chem. Geol. 20, 325-343.
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