Sarıalan (Altıeylül, Balıkesir) civarındaki Tersiyer yaşlı Bağburun volkanitlerinin petrografik ve jeokimyasal özellikleri

Öz

Balıkesir, Altıeylül'de bulunan Bağburun volkanitleri, Batı Anadolu'daki Neojen volkanizmasının anlaşılmasını geliştirmek amacıyla petrografik ve jeokimyasal özellikleri açısından incelenmiştir. Bu kayaçlar ağırlıklı olarak plajiyoklaz, amfibol, biyotit, sanidin ve altere klinopiroksenden oluşmaktadır. Elek dokulu plajiyoklaz ve ksenolitlerin varlığı gibi dokusal özellikler, magma karışımı ve asimilasyon da dahil olmak üzere karmaşık kristalleşme süreçlerini göstermektedir. Ana element jeokimyası, MgO ve TiO2'de azalma ve K2O içeriğinde artış ile karakterize yüksek K'li kalk-alkali bir yapı ortaya koymaktadır. Na2O ve Sr içeriklerindeki değişimler muhtemelen alterasyonun göstergesidir. İz element örüntüleri, LILE zenginleşmesi, HFSE tükenmesi, negatif Eu anomalileri ve yüksek La/Yb (13,5-18,2) ve Th/Nb (13,5-18,2) oranları sergileyerek, manto eriyikleri, levha altı sıvıları ve kıtasal kabuk katkılarını içeren çok bileşenli bir magma kaynağına işaret etmektedir. Mekânsal dağılımları, magma yükselişinin yerel fay sistemleri tarafından kolaylaştırıldığını göstermektedir. Özetle, Bağburun volkanitleri, Batı Anadolu'daki Neojen magmatizmasının yerel ancak önemli bir tezahürünü temsil etmekte ve bölgenin tektonik evriminin daha kapsamlı bir şekilde anlaşılmasına katkıda bulunmaktadır.

Anahtar Kelimeler

• Bağburun volkaniti
• Balıkesir
• jeokimya
• petrografi
• Sarıalan

Petrographic and geochemical characteristics of the Tertiary Bağburun volcanites around Sarıalan (Altıeylül, Balıkesir)

Öz

The Bağburun volcanites, located in Altıeylül, Balıkesir, were examined for their petrographic and geochemical properties to enhance the understanding of Neogene volcanism in western Anatolia. These rocks predominantly comprise plagioclase, amphibole, biotite, sanidine, and altered clinopyroxene. Textural features, such as sieve-textured plagioclase and the presence of xenoliths, indicate complex crystallization processes, including magma mixing and assimilation. The major element geochemistry reveals a high-K calc-alkaline nature, characterized by decreasing MgO and TiO2 and increasing K2O content. Variations in Na2O and Sr contents are likely indicative of alteration. Trace element patterns exhibited LILE enrichment, HFSE depletion, negative Eu anomalies, and elevated La/Yb (13.5–18.2) and Th/Nb (13.5–18.2) ratios, suggesting a multicomponent magma source involving mantle melts, subplate fluids, and continental crustal contributions. Their spatial distribution implies that magma ascent was facilitated by local fault systems. In summary, the Bağburun volcanites represent a localized yet significant manifestation of Neogene magmatism in western Anatolia, contributing to a more comprehensive understanding of the tectonic evolution of the region.

Anahtar Kelimeler

• Bağburun volcanite
• Balıkesir
• geochemistry
• petrography
• Sarıalan

Kaynakça

1. Ercan, T., Interpretation of geochemical, radiometric and isotopic data on Kula volcanics (Manisa, Western Anatolia). Türkiye Jeoloji Bülteni, 36/1, 113–130, (1993).
2. Genç, S. C., Evolution of the Bayaramiç magmatic complex, northwestern Anatolia. J. Volcanol. Geotherm. Res., 85, 233–249, (1998).
3. Erkül, S. T., Petrogenetic evolution of the Early Miocene Alaçamdağ volcano-plutonic complex, northwestern Turkey: implications for the geodynamic framework of the Aegean region. Int. J. of Earth Sci., 101, 197–219, (2012).
4. Erkan, S., Şen, C., Yalçın, H. and Yıldız, A., Geochemical and petrological features of Upper Miocene ultrapotassic volcanic rocks from the Şuhut area (Afyon, SW Anatolia, Turkey). Journal of Asian Earth Sciences, 221, 104999, (2021).
5. Aldanmaz, E., Pearce, J. A., Thirlwall, M. F. and Mitchell, J. G., Petrogenetic evolution of late Cenozoic, post-collision volcanism in the western Anatolia, Turkey. Journal of Volcanology and Geothermal Research, 102, 67–95, (2000).
6. Gürer, F. Ö., A new look at the origin of N–S trending young basins of western Anatolia. Bulletin of the Mineral Research and Exploration, 170, 117–146, (2023).
7. Bozkurt, E., Neotectonics of Turkey - a synthesis. Geodinamica Acta, 14, 3–30, (2001).
8. Okay, A. I., Stratigraphic and metamorphic inversions in the central Menderes Massif: a new structural model. International Journal of Earth Sciences (Geologische Rundschau), 89, 709–727, (2001).

9. Okay, A. I. and Tüysüz, O., Tethyan sutures of northern Turkey. Geological Society of London, Special Publications, 156(1), 475–515, (1999).
10. Bozkurt, E. and Sözbilir, H., Evolution of the large-scale active Manisa Fault, southwest Turkey: implications on fault development and regional tectonics. Geodinamica Acta, 19(6), 427–453, (2006).
11. Seyitoğlu, G. and Scott, B. C., Age of Alaşehir graben (west Turkey) and its tectonic implications. Geological Journal, 31, 1–11, (1996a).
12. Pehlivan, Ş., Duru, M., Dönmez, M., Ilgar, A., Akçay, A. E., Erdoğan, K. and Özer, D., Türkiye Jeolojisi Haritaları No: 96, Balıkesir-İ 19 Paftası. Maden Tetkik Arama Genel Müdürlüğü, 40 s, Ankara, (2007).
13. Beard, J. S., Rushmer, T. and Ragland, P. C., Hydration crystallization reactions between anhydrous minerals and hydrous melt to yield amphibole and biotite in igneous rocks: Description and implications. The Journal of Geology, 112(5), 617–621, (2004).
14. Le Maitre, R. W., Bateman, P., Dudek, A. J. and Keller, M. J., A Classification of Igneous Rocks and Glossary of Terms. Blackwell, Oxford, 193, (1989).
15. Irvine, T. N. and Baragar, W. R. A., A guide to the chemical classification of the common volcanic rocks. Canadian Journal of Earth Sciencies, 8, 523–548, (1971).
16. Le Maitre, R. W., Streckeisen, A., Zanettin, B., Le Bas, M. J., Bonin, B., Bateman, P., Bellieni, G., Dudek, A., Efremova, S., Keller, J., Lameyre, J. A., Sabine, P. A., Schmid, R., Sorensen, H. and Wooley, A. R., Igneous Rocks: A Classification and Glossary of Terms: Recommendations of the International Union of Geological Sciences, Subcommission on the Systematics of Igneous Rocks. Cambridge University Press, Cambridge, (2002).
17. Sun, S. S. and McDonough, W. F., Chemical and isotopic systematics of oceanic basalts: Implications for mantle composition and processes. In A. D. Saunders and M. J. Norry (Eds.), Magmatism in the Ocean Basins (Vol. 42, pp. 313–345). Geological Society: London, (1989).
18. Jenner, F. E. and O’Neill, H. S. C., Analysis of 60 elements in 616 ocean floor basaltic glasses. Geochemistry, Geophysics, Geosystems, 13(2), Q02005, (2012).
19. Taylor, S. R. and Mc Lennan, S. M., The Continental Crust: Its Composition and Evolution. Blackwell Scientific, Oxford. Cambridge University Press, (1985).
20. Pearce, J. A., Role of the Sub-Continental Lithosphere in magma genesis at active continental margins. In: Hawkesworth, C. J. and Norry, M. J. (Eds.), Continental Basalts and Mantle Xenoliths. Shiva, Nantwich, 230–249, (1983).
21. Ersoy, E. Y. and Palmer, M. R., Eocene–Quaternary magmatic activity in the Aegean: Implications for mantle metasomatism and magma genesis in an evolving orogeny. Lithos, 180–181, 5–24, (2013).
22. Rollinson, H. and Pease, V., Using Geochemical Data. Cambridge University, (2021).