Petrography and Geochemistry of the Javaherdasht basalts (east of Guilan Province): The investigation of the role of crystal fractionation and crustal contamination in the magmatic evolution

Abstract

The Javaherdasht Basalts show compositional range from olivine basalts to quartz basaltic andesites. Petrographic studies indicate that the differentiation of clinopyroxene and olivine minerals has main role for lithologic variety of the basalts.The corosion golf, crenated margins and lack of the same colour in the clinopyroxene phenochrysts margins with matrix Pyroxene grains express a nonequilibrium and are petrographic features for crustal contamination of the basalts.The positive correlation CaO,CaO/Al2O3 and Cr with Mg# and CaO/Al2O3 with Sc and the negative correlation Al2O3 with Mg# are geochemical  characters for the differentiation of clinopyroxene and olivine in the magmatic evolution of the area.The high ratios of Ba/Zr and Pb/Nd and low ratio of Ce/Pb and positive correlation of SiO2 and Rb with 87Sr/86Sr and negative correlation of Nd-Sr isotopes display the contamination of these basalts with continental crust.

Keywords


1 Wilson M., "Igneous petrogenesis-A global tectonic approach", Unwin Hyman London, (1989)466s.

2 Jung C., "Geochemische und Isotopen-geochemische Untersuchungen an tertiaeren Vulkaniten der Hocheifel-ein beitrag zur identifizierung der mantelquellen von Rift-bezogenen Vulkaniten", Dissertation zur Erlangung des doktorgrades Naturwissenchaften, vorgelegt dem fachbreich Geowissenschaften der Philipps-Universitaet Marburg. (2003)

3 Duda A., Schmincke H.-U., "Polybaric differentiation of Alkali basaltic magmas: evidence

from green-core Clinopyroxenes (Eifel, FRG)", Contrib. Mineral. Petrol.91 (1985)340-353

4 Miyashiro A., "Nature of alkalic volcanic rock series'', Contrib.Mineral.Petrol.66 (1978)91-104

5 Winchester J.A., Floyd P.A., "Geochemical discrimination of different magma series and their differentiation product using immobile elements", Chemical Geology.20 (1977)325-343

6 Pearce J.A., "A users guide to basalt discrimination diagrams: in trace element geochemistry of volcanic Rocks: applications for massive sulfide exploration", (ed) D.A. Wyman Geological association of Canada.short course notes.12 (1996)79-113

7 Rickwood P.C., "Boundary lines within petrologic diagrams which use oxide of major and minor elements", Lithos.22 (1989)225-240

8 Middlemost E.A.K., "The Basalt Clan", Earth Sci.Rev.11 (1975)337-364

9 Kempton P.D., Downes H., Sharkov E.V., Vetrin V.R., Ionov D.A., Carswell

D.A., Beard A., "Petrology and Geochemistry of xenoliths from the Northern Baltic shield:evidence for Partial melting and metasomatism in the Lower Crust beneath and Archean terrane", Lithos.36 (1995)157-184

10 Kelemen P.B., Hanghoj K., Greene A.R., "One view of the geochemistry of subduction-related magmatic arcs.With an emphasis on primitive Andesite and lower crust", Treatise on Geochemistry. 3(2004)593-659

11 Raymond L.A., Petrology Mc, “Graw Hill.”, (2002)720P.

12 COX K.G., "A model for flood basalt volcanism", J.Petrol.21 (1980)629-650

13 COX K.G, Bell J.D., Pankhurst R.J., "The interpretation of igneous rocks", George Allen and unwin, London. (1979) 450P.

14 Rollinson H.R., "Using Geochemical Data: Evolution, Presentation, and Interpretation" Longman Scientific and Technical, England, (1993) 352p.

15 Hopper D.J., Smith I.M., "Petrology of the gabbro and sheeted basaltic intrusives at North Cape,New Zealand", New Zealand Journal of Geology and Geophysics.39(1996)389-402

16 Skates D.S., Shervais J.W., Hopson C.A.,"The volcanic-tectonic cycle of the FAMOUS and AMAR Valleys, Mid-Atlantic Ridge: Evidence from basalt glass and phenocryst compositional variations for a steady state magma chamber beneath the valley midsections". AMARS.J.Geophys.Res. 89 (1984) 6995-7028

17 Class C., Altherr R., Volker F., Eberz G., McCulloch M.T., "Geochemistry of Pliocene to Quarternary alkali basalts from the Huri Hills, Nothern Kenya", Chemical Geology113(1994)1-22

18 Perfit M.R., Gust D.A., Bence A.E., Arculus R.J., Taylor S.R., "Chemical characteristics of island-arc basalts: implications for mantle sources", Chem. Geol.30 (1980)227-256

19 Weaver B.L., "Trace element evidence for origin of ocean –island basalts", Geology. 19(1991)123-126

20 Hofmann A.W., Jochum K.P., Seufert M., White W.M., "Nb and Pb in Oceanic basalts, new contraints on mantle evolution", Earth planet .Sci.Lett. 90(1986)297-314

21 Rudnick R.L., Fountain D.M., "Nature and composition of the continental crust: A lower crustal perspective", Rev.Geophys.33 (1995) 267-309

22 Krienitz M.-S, Hasse K.M, Mezger K., Eckardt V., Sheikh–Mashail, M.A., "Magmagenesis and crustal contamination of continental intraplate lavas in northwestern Syria", Contrib .Mineral.Petrol.151(2006)698-716

23 Sun S.S., McDonough W.f., "Magmatism in the oceanic basalts", A.D. Saunders & M.J.Norry, Her ausgeber, Geol. Soc. Special Publ. 42 (1989) 313 - 345

24 Fitton-T.G., Hardarson B.S., Ellam K.M., Rogers G., "Sr-, Nd, and Pb-isotopic composition of volcanic rocks from the Southeast Greenland Margin at 63N: temporal variation in crustal contamination during continental breakup", In saunders, A.D., Larsen, .H.C., and Wise, s.H., (Eds) Proc.ODP.Sci.Results.152 (1998) 351-357

25 Larsen H.C, Saunders A.D., "Tectonism and volcanism at the Southeast Greenland rifted margin: a record of plume impact and later continental rupture", in: Saunders, A.D., Larsen, H.C., and Wise, S.H., (ed) Proc.ODP.Sci. Results. 152(1998)503-533

26 Bernstein S., Kelemen P.B., Tegner C., Kurz M.D., Blusztajn J., Kent Brooks C., "Post-breakup basaltic magmatism along the East Greenland Tertiary rifted margin", Earth and Planetary Science. Letters. 160(1998)845-862

27 Kaiser C., "Multi-component evolution, age and plat-tectonic setting of high-Mg Lamprophyric dikes and small gabbroic intrusions on Isla Margarita (Venezuela)", Dissertation Zur Erlangung des Grades eines Doktors der Naturwissenschaften der Fakultaet fur Geowissenschaften an der Ruhr-universitat Bochum.( 1997) 174pp.