Oktay KILIÇ, Hüseyin KURT, Kürşad ASAN, Gürsel KANSUN

Pasinler (Erzurum) Kuzeyindeki Volkanik Kayaçların Mineral Kimyası ve Jeokimyası

Pasinler (Erzurum) kuzeyinde Üst Miyosen-Pliyosen yaşlı volkanik kayaçlar yüzeylemektedir. Bu volkanitler bazaltik andezit, andezit, dasit, riyolit türü lav ve riyolitik piroklastiklerden oluşmaktadır. Kayaçlarda porfirik, mikrolitik porfirik, hyalo-mikrolitik porfirik, vitrofirik, glomeroporfirik, pilotaksitik ve hyalopilitik dokular gözlenmektedir. Kayaçlar plajiyoklas (An29-80), olivin (Fo65-82), klinopiroksen (ojit), ortopiroksen (enstatit), amfibol (Mg#: 0.57-0.71), biyotit (filogopit: 0.44-0.47, annit: 0.33-0.37), sanidin, kuvars ve opak mineral (titanomanyetit ve ilmenit) içermektedir. Kayaçlar kalkalkali karakterli olup, orta-yüksek potasyum içeriğine sahiptirler. Ana oksit ve iz element değişimleri kayaçların gelişimindeki açık sistem mağmatik diferensiyasyona işaret etmektedir. Jeokimyasal veriler kayaçlardaki fenokristal fazların fraksiyonlaşmasının diferansiyasyon sürecinde etkili olduğunu göstermektedir. Fakat buna asimilasyon±mağma karışımının da eşlik etmiş olabileceği düşünülmektedir. Kayaçların yüksek büyük iyon yarıçaplı element (K, Rb, Ba, Th) ve göreceli olarak düşük yüksek alan enerjili element (Nb, Ta, Hf, Zr) içerikleri kayaçların yitim izleri taşıyan bir ana mağmadan oluştuklarına işaret etmektedir.

Anahtar Kelimeler:

Pasinler, Mineral kimyası, Jeokimya, Kalkalkali volkanitler.

Mineral Chemistry and Geochemistry of Volcanic Rocks in The North of Pasinler (Erzurum)

In the north of Pasinler (Erzurum), Upper Miocene-Pliocene volcanic rocks crop out. These volcanites are composed of basaltic andesite, andesite, dacite, rhyolite lavas and rhyolitic pyroclastics. The rocks show porphyritic, microlitic porphyritic, hyalo-microlitic porphyritic, vitrophyric, glomeroporphyritic, pilotaxitic and hyalopilitic textures. The investigated volcanites contain plagioclase (An29-80), olivine (Fo65-82), clinopyroxene (augite), orthopyroxene (enstatite), amphibole (Mg#: 0.57-0.71), biotite (phlogopite: 0.44-0.47, annite: 0.33-0.37), sanidine, quartz and opaque mineral (titano-magnetite and ilmenite). The volcanic rocks are calc-alkaline in character and have medium to high-K contents. Major oxide and trace element variations point out open-system magmatic differentiation in the evolution of rocks. Geochemical data indicate an important role of fractionation of phenocryst phases in the rocks during differentiation process. However, it is considered that assimilation±magma mixing might have accompanied to the process. High LILE (K, Rb, Ba, Th) and relatively low HFSE (Nb, Ta, Hf, Zr) contents of the rocks indicate that these rocks derived from parental magmas carrying subduction signature.

Keywords:

Pasinler, Mineral chemistry, Geochemistry, Calc-alkaline volcanites.,

PDF

___

hiomteric criteria. Mineral. Mag. (51), 431-435.
Dymek, R.F. 1983. Titanium, aluminum and interlayer cation distributions in biotite from high grade gneisses, West Greenland, Am. Min. (68), 880-899.
Edwards, C., Menzies, M. and Thirwall, M. 1991. Eviden- ce from muriah, ındonesia, for the ınterplay of supra-subduction zone and ıntraplate processes in the genesis of potassic alkaline magmas. J. Pet- rol. (32), 555-592.
Irvine, T. N. and Baragar, W.R.A. 1971. A guide to the chemical classification of common volcanic rocks. canadian journal of earth science. (8), 523-548.
Keskin, M. 1998. Erzurum-Kars platosunun çarpışma kö- kenli volkanizmasının volkano-stratigrafisi ve Yeni K/Ar yaş bulguları ışığında evrimi, Kuzey Anadolu. MTA Derg. (120), 135-157.
Keskin, M. 2003. Magma generation by slab steepening and breakoff beneath a subduction-accretion complex: An alternative model for collision- related volcanism in Eastern Anatolia, Turkey, Geophys. Res. Lett., 30 (24), 8046, doi:10.1029/ 2003GL018019.
Keskin, M. 2005. Domal uplift and volcanism in a collisi- on zone without a mantle plume: Evidence from Eastern Anatolia. http://www.mantleplumes. org/Anatolia.html.
Keskin, M., Pearce, J.A. and Mitchell, J.G. 1998. Volcano- stratigraphy and Geochemistry of Collision- related Volcanism on Erzurum-Kars Plateau, Nort- heastern Turkey, J. Volcanol. Geotherm. Res. (85), 405-422.
Kılıç, O. 2006. Pasinler (Erzurum) kuzeyindeki volkanik kayaçların petrografik ve jeokimyasal incelenme- si. Selçuk Üni. Fen Bil. Enst., Yüksek Lisans Tezi, 87 s.
Le Bas, M.J., Le Maitre, R.W., Streckeisen, A. and Zanet- tin, B. 1986. A Chemical classification of volcanic rocks based on total Alkali-Silica diagram. Journal of Petrology. (27), 745-750.
Leake, B.E., Woolley, A.R., Arps, C.E.S., Birch, W.D., Gil- bert, M.C., Grice, J.D., Hawthorne, F.C., Kato, A., Kisch, H.J., Krivovichev, V.G., Linthout, K., Laird, J., Mandaring, J.A., Maresch, W.V., Nickel, E.H., Rock, N.M.S., Schumacher, J.C., Smith, D.C., Stephenson, N.C.N., Ungaretti, L., Whittaker, E.J.W. and Youzhi, G. 1997. Nomenclature of amphiboles: Report of subcomittee on amphiboles of the ınternational mineralogical association, comission on new mi- nerals and mineral names. Canadian mineralogist. (35), 219-246.
Morimoto, N., Fabries, J., Ferguson, A.K., Ginzburg, I.V., Ross, M., Seifert, F.A., Zussman, J., Aoki, K. and Got- tardi, G. 1988. Nomenclature of pyroxenes. Ameri- can Mineralogist. (73), 1123-1133.
Pearce, J.A. and Cann, J.R. 1973. Tectonic setting of ba
sic volcanic rocks determined using trace element analysis. E.P.S.L. (19), 290-300.
Pearce, J.A. 1983. Role of the Sub-Continental lithosp- here in magma genesis at active continental mar- gins. In: Hawkesworth, C.J., Norry, M.J (Eds.), Con- tinental basalts and mantle xenoliths. Shiva, Nant- wich, pp. 230-249.
Pearce, J.A., Bender, J.F., De Long, S.E., Kidd, W.S.F., Low, P.J., Guner, Y., Saroglu, F., Yılmaz, Y., Moorbath, S. and Mitchell, J.G. 1990. Genesis of collision volca- nism in eastern anatolia, Turkey. J. Volcanol. Geot- herm. Res. (44), 189-229.
Sun, S. and McDonough, W.F. 1989. Chemical and ısoto- pic systematic of oceanic basalts: Implications for mantle compositions and processes. In: Saunders, A.D., Norry, M.J (Eds.), Magmatism in the Ocean Ba- sins. Geol. Soc. London Spec. Publ. (42), 313-345.
Şengör, A.M.C. and Yılmaz, Y. 1981. Tethyan evolution of Turkey: A plate tectonic approach. Tectonoph- ysics. (75), 181-241.
Şengör, A.M.C., Ozeren, S., Zor, E., and Genç, T. 2003. East Anatolian high plateau as a mantle-supported, N-S shortened domal structure, Geophys. Res. Lett., 30 (24), 8045, doi: 10.1029/2003GL017858.
Temel, A., Gündogdu, M.N. and Gourgaud, A. 1998. Pet- rological and geochemical characteristic of ceno- zoic High-K calcalkaline volcanism in Konya, Cent- ral Anatolia, Turkey. J. Volcanol. Geotherm. Res. (85), 327-354.
Wilson, M., Tankut, A. and Güleç¸ N. 1997. Tertiary volca- nism of the Galatia Province, North-West Central Anatolia, Türkiye. Lithos. (429), 105-121.
Wood, D.A. 1980. The Application of a Th-Hf-Ta diagram to problems of tectonomagmatic classification and to estabilishing the nature of crustal contami- nation of basaltic lavas of the british tertiary vol- canic province. Earth. Planet. Sci. Lett. (50), 11-30.
Yavuz, F. 2007. WinAmphcal: A Windows Prog- ram for the IMA-04 Amphibole Classificati- on. Geochem. Geophys. Geosyst. (8), 1-12, doi:10.1029/2006GC001391.
Yavuz, F. and Öztaş, T. 1997. BIOTERM-A Program For Evaluating and Plotting Microprobe Analyses of Biotite from Barren and Mineralized Magmatic Su- ites. Computers & Geosciences. (23), 897-907.