The First Petrographic Textural Data of Sferulitic Rhyolites Observed in the İdrisyayla Volcanites (Kırka-Eskişehir)

Year 2023, Volume: 66 Issue: 1, 59 - 74, 31.01.2023

Yeşim Yücel Öztürk , Cüneyt Akal

https://doi.org/10.25288/tjb.1084686

Abstract

Spherulitic structures are classically defined as concentrically zoned crystal clusters that form in igneous systems (especially in alkaline igneous rocks), and usually occur as different mineral layers or shells.

The volcano-sedimentary series observed in the Kırka region, south of Eskişehir, within the Kırka-Afyon-Isparta Volcanic Province, Western Anatolia, consists predominantly of Lower Miocene volcanic and pyroclastic sequences with rhyodacitic-rhyolitic composition, lacustrine limestones, borate-bearing claystones, tuff, stromatolitic limestones and rhyolites and basalts. The formation mechanisms of the spherulitic structures observed in the marginal zone of the sub-alkaline rhyolitic lava dome outcropping within the Neogene series west of İdrisyayla in Kırka (Eskişehir) region are described for the first time with this study. The rhyolites are grayish light brown in color, have hypocrystalline hyalopilitic-holohyaline texture and have spherical structures defined as spherulites. These rocks have a completely flowing structure and are composed of volcanic glass containing rare euhedral plagioclase, sanidine and quartz microcrystals, the spherical structures observed on the surface of the rhyolites are up to 10-15 cm in size. The spherulites, which are almost round in shape, appear as concentric rings within the lava flow bands. The flow band texture of the volcanic glass phase is continuous with the inner texture of the spherulitic structures.

This study suggests that the spherulitic structures in the İdrisyayla (Kırka-Eskişehir) region formed by the devitrification mechanism as a result of high temperature and rapid cooling. The petro-mineralogical features of the spherulitic rhyolites show that during the early magmatic stage, the oversaturated liquid crystallized in silica-rich fluid phases with relatively different densities, and radial quartz-feldspar crystal growths from a center caused the formation of the spherulitic structure. It is also suggested that the lithophysae-like structures formed by the crystal growths representing the solid phase in axial cavities due to the local folding of flow bands and the later radial mineral growths representing the liquid phase also changed the laminated texture in the marginal phase of the rhyolite.

Keywords

Devitrification, lithophysae, rhyolite, spherulite, Kırka, Eskişehir

İdrisyayla Volkanitlerinde (Kırka-Eskişehir) Gözlenen Sferulitik Riyolitlere ait İlk Petrografik Dokusal Veriler / The First Petrographic Textural Data of Sferulitic Rhyolites Observed in the İdrisyayla Volcanites (Kırka-Eskişehir)

Abstract

Sferulitik (küresel) yapılar özellikle alkali magmatik kayaçlarda gelişen, eşmerkezli olarak zonlu kristal kümeleri olarak tanımlanırlar ve genellikle farklı mineral katmanları veya kabukları şeklinde ortaya çıkarlar.

Batı Anadolu’da Kırka-Afyon-Isparta Volkanik provensi içinde Kırka (Eskişehir) bölgesinde gözlenen volkanosedimenter seri baskın olarak Erken Miyosen yaşlı dasitik-riyolitik bileşimli volkanikler, gölsel kireçtaşları, borat-içerikli kiltaşları, tüf, stromatolitik kireçtaşları ve riyolitler ile bazaltlardan oluşmaktadır. Bu çalışma İdrisyayla kuzeyindeki Neojen seri içerisinde yüzlek veren sub-alkali riyolitik lav domunun kenar zonunda gözlenen sferulitik yapıların iç oluşum mekanizmaları tanımlanmıştır. Riyolitler, grimsi açık kahve renkte, hipokristalen hiyalopilitik-holohiyalin ve sferulit özellikler sunmaktadır ve tamamen akma yapısı sunan, nadir olarak gelişmiş özşekilli plajiyoklas, sanidin ve kuvars mikrokristalleri içeren volkanik camdan oluşmaktadır. Riyolitlerin dış yüzeyinde gözlenen küresel yapılar yaklaşık 10-15 cm boyutlarına kadar ulaşmaktadır. Neredeyse tam yuvarlağa yakın şekil sunan sferolitler lav akma bantları içinde konsantrik halkalar şeklinde görünmektedir. Sferulitik yapıların iç dokusunda volkanik cam fazının akma bant dokusu devamlılık sunmaktadır.

Söz konusu sferulitik yapılar, etkilendiği yüksek sıcaklık ve hızlı soğuma sonucunda, devitrifikasyon mekanizmasıyla ortaya çıkmıştır. Sferulitik riyolitlere ait petromineralojik özellikler, erken magmatik süreçte, silise aşırı doygun sıvının, nispeten farklı yoğunluktaki silikat sıvı fazları içinde kristalleştiğini ve bir merkezden itibaren ışınsal kuvars-feldispat kristal büyümelerinin, bu riyolitlerde sferulitik yapının oluşumuna neden olduğunu göstermektedir. Bunun yanında, yerel olarak akma bantlarının kıvrımlanması ile oluşan eksen boşluklarındaki katı faz mineral büyümesi ve devamında sıvı fazdan ışınsal mineral büyümelerinin geliştiği litofiz benzeri yapıların da riyolitin kenar fazında laminar dokuyu değiştirdiği önerilmektedir.

Keywords

Devitrifikasyon, küresel yapılar, litofiz, riyolit, Kırka, Eskişehir

References

• Aguirre, L., Hervé, F. & Del Campo, M. (1976). An orbicular tonalite from caldera, Chile. Journal of the Faculty of Science, Hokkaido University,17(2), 231-259.
• Alexander, D.H. (1974). Petrography and origin of an orbicular lamprophyre dike, Fremont County, Colorado [Unpublished PhD Thesis]. University of Michigan.
• Applegarth, L. J., Tuffen, H., James, M. R. & Pinkerton, H. (2013). Degassing-driven crystallisation in basalts. Earth-Science Reviews, 116, 1-16.
• Ballhaus, C., Raúl O.C. Fonseca, R.O.C., Münker,C., Kirchenbaur, M. & Zirner, A. (2015). Spheroidal textures in igneous rocks - textural consequences of H2O saturation in basaltic melts. Geochimica et Cosmochimica Acta, 167, 241-252. https://doi.org/10.1016/j.gca.2015.07.029
• Barriere, M. (1972). Orbicular gabbro of les Alharisses (Neouvielle granodirite, French Pyrenees). Bulletin de la Societe Francaise Mineralogie et de Cristallographie, 95(4), 495-506.
• Breitkreuz, C. (2013). Spherulites and lithophysae -200 years of investigation on high-temperature crystallization domains in silica-rich volcanic rocks. Bull Volcanology, 75:705, 1-16. https://doi.org/10.1007/s00445-013-0705-6
• Burkhard, D. J. M. (2003). Thermal interaction between lava lobes. Bull Volcanology, 65, 136–143
• Carl, J. D. & Amsutz, G. C. (1958). Three-dimensional Liesegang rings by diffusion in a colloidal matrix, and their significance for the interpretation of geological phenomena. GSA Bulletin 69 (11), 1467–1468. https://doi.org/10.1130/0016-7606(1958)69[1467:TLRBDI]2.0.CO;2
• Chauris, L., Hallegouet, B. & Riva, N. (1989). 1st data on an orbicular facies in the Ploumanach red granite (Armorican Massif). Comptes Rendus de l Academie des Sciences Serie Ii, 309(1), 59-62.
• Couturié, J. P. (1973). Un nouveau gisement de granite orbiculaire dans le Massif Central français: le granite du Signal de Randon (Lozere). Contributions to Mineralogy and Petrology, 42(4), 305-312.
• Elliston, J. N. (1984). Orbicules: an indication of the crystallisation of hydrosilicates, I. Earth-Science Reviews 20, 265–344.
• Enz, R. D., Kudo, A. M. & Brookins, D. G. (1979). Igneous origin of the orbicular rocks of the Sandia Mountains, New Mexico. Geological Society of America Bulletin, 90(1), 138-140, 348-380.
• Enz, R. D., Kudo, A. M. & Brookins, D. G. (1980). Igneous origin of the orbicular rocks of the Sandia Mountains, New Mexico: Discussion and reply: Reply. Geological Society of America Bulletin, 91(4), 246-247.
• Erkül, F., Helvacı, C. & Sözbilir, H. (2005). Evidence for two episodes of volcanism in the Bigadic ̧ boratebasin and tectonic implications for western Turkey. Geological Journal, 40, 545–570.
• Ersoy, E. Y., Helvacı, C. & Palmer, M.R. (2011). Stratigraphic, structural and geochemical features of the NE–SW trending Neogene volcanosedimentary basins in western Anatolia: implications for associations of supradetachment and transtensional strike-slip basin formation in extensional tectonic setting. Journal of Asian Earth Science, 41, 159–183.
• Fisk, M. & McLoughlin, N. (2013). Atlas of alteration textures in volcanic glass from the ocean basins. Geosphere, 9(2), 317-341.
• Gimeno, D. (2003). Devitrification of natural rhyolitic obsidian glasses: petrographic and microstructural study (SEM+ EDS) of recent (Lipari island) and ancient (Sarrabus, SE Sardinia) samples. Journal of non-crystalline solids, 323(1-3), 84-90.
• Goodspeed, C. E. (1942). Orbicular rock from Buffalo Hump, Idaho. American Mineralogist, 27, 37-41.
• Gottfried, C. (1933) Über Lithophysen aus dem Porphyr von Baden-Baden. Geologische Rundschau, 23, 1–6
• Helvacı, C. (1995). Stratigraphy, mineralogy, and genesis of the Bigadiç borate deposits, western Turkey. Economic Geology, 90, 1237–1260.
• Helvacı, C., & Yağmurlu, F. (1995). Geological setting and economic potential of the lignite and evaporite-bearing Neogene basins of western Anatolia, Turkey. Israel Journal of Earth Sciences, 44(2), 91-105.
• Helvacı, C., & Orti, F. (1998). Sedimentology and diagenesis of Miocene colemanite-ulexite deposits (western Anatolia, Turkey). Journal of Sedimentary Research, 68, 1021–1033.
• Helvacı, C. & Alonso, R.N. (2000). Borate deposits of Turkey and Argentina: A summary and geological comparison. Turkish Journal of Earth Sciences, 9, 1–27.
• Helvacı, C. & Orti, F. (2004). Zoning in the Kırka borate deposit, western Turkey: Primary evaporitic fractionation or diagenetic modifications?. The Canadian Mineralogist, 42, 1179–1204.
• Helvacı, C., Yücel-Öztürk, Y., Seghedi, I. & Palmer, M. (2020). Post-volcanic activities in the Early Miocene Kırka-Phrigian caldera, western Anatolia – caldera basin filling and borate mineralization processes. International Geology Review, 62, 1719-1736. https://doi.org/10.1080/00206814.2020.1793422.
• Holgate, N. (1954). The Role of Liquid Immiscibility in Igneous Petrogenesis. The Journal of Geology 62 (5), 439-480. https://doi.org/10.1086/626191
• Horwell, C. J., Williamson, B. J., Llewellin, E. W., Damby, D. E. & Le Blond, J. S. (2013). The nature and formation of cristobalite at the Soufrière Hills volcano, Montserrat: implications for the petrology and stability of silicic lava domes. Bulletin of Volcanology, 75(3), 696.
• Hudyma, N. B., Burçin, A. & Karakouzian, M. (2004). Compressive strength and failure modes of lithophysae-rich Topopah Spring Tuff specimens and analog models containing cavities. Engineering Geology, 73, 179–190. https://doi.org/10.1016/j.enggeo.2004.01.003
• Iddings, J. P. (1909). Igneous rocks: Composition, texture and classification, description and occurrance. University of Michigan Library, 744p.
• Johnson, S. J., Bertolett, E., Gualda, G., Davidson, J. & Hampton, S.J. (2018). Investigating the origin of an orbicular granite: Karamea, New Zealand. GSA Annual Meeting; 4 Nov. 2018; Indianapolis, Indiana, U. S. A.
• Leveson, D. J. (1966). Orbicular rocks: a review. Geological Society of America Bulletin, 77, 409-426.
• Lindh, A. & Näsström, H. (2006). Crystallization of orbicular rocks exemplified by the Slättemossa occurrence, southeastern Sweden. Geological Magazine, 143(5), 713–722. https://doi.org/10.1017/S001675680600210X
• Lofgren, G. (1971). Spherulitic textures in glassy and crystalline rocks. Journal of Geophysical Research, 76(23) 5635–5648. https://doi.org/10.1029/JB076i023p05635
• McArthur, A. N., Cas, R. A. F. & Orton, G. J. (1998). Distribution and significance of crystalline, perlitic and vesicular textures in the Ordovician Garth Tuff (Wales). Bulletin of Volcanology, 60, 260–285. https://doi.org/10.1007/s004450050232
• McPhie, J., Doyle, M. & Allen, R. (1993). Volcanic textures—a guide to the interpretation of textures in volcanic rocks. Univ Tasman CODES 196 pp.
• Moore, J. G. & Lockwood, J. P. (1973). Origin of comb layering and orbicular structure, Sierra Nevada Batholith, California: Reply. Geological Society of America Bulletin, 84(12), 4007-4010.
• Newton, T. S. (2020). A Compositional and Textural Investigation of the Goldie Lamprophyre, Fremont County, Colorado. [Unpublished MSc Thesis]. The Graduate Faculty of Texas Tech University, 258p.
• Okay, A. I., Satır, M., Maluski, H., Siyako, M., Metzger, R., & Akyüz, S. (1996). Paleo- and Neo-Tethyan events in northwestern Turkey. In: Y. An, M. Harrison, (Eds.), Geological and Geochronological Constraints, Tectonics of Asia. Cambridge University Press, 420-441.
• Okay, A. I., & Satır, M. (2000). Coeval plutonism and metamorphism in a latest Oligocene metamorphic core complex in northwest Turkey. Geological Magazine, 137(5), 495-516. https://doi.org/10.1017/S0016756800004532
• Özcan, A., Göncüoğlu, M., Turan, N., Uysal, S.¸ Şentürk, K., Işık, V. (1988). Late Paleozoic Evolution of the Kütahya-Bolkardağ Belt. METU Journal of Pure and Applied Sciences, 21(1-3), 211–220.
• Palmer, M. R. & Helvacı, C. (1997). The boron isotope geochemistry of the Neogene borate deposits of western Turkey. Geochemica et Cosmochimica Acta, 61, 3161-3169.
• Péloquin, A. S., Verpaelst, P. & Ludden, J. N. (1996). Spherulitic rhyolites of the Archean Blake River Group, Canada: Implications for stratigraphic correlation and volcanogenic massive sulfide exploration. Economic Geology, 91, 343-354.
• Piboule, M., Soden, L., Amosse, J. & Briand, B. (1989). Role of diabatic undercooling in the genesis of orbicular gabbros from Corsica. Comptes Rendus de l Academie des Sciences Serie II, 309(7), 713-718.
• Pourteau, A., Oberhänsli, R., Candan, O., Barrier, E., & Vrielynck, B. (2016). Neotethyan closure history of western Anatolia: a geodynamic discussion. International Journal of Earth Sciences (Geologische Rundschau), 105, 203–224. https://doi.org/10.1007/s00531-015-1226-7
• Prakash, H. S. M. (1996). Orbicular structures from Lingsugur Area, Raichur District, Karnataka. Journal of Geological Society of India, 47(5), 525-534.
• Ross, C. S. & Smith, R. L. (1961). Ash-flow tuffs: Their origin, geological relation and identification. USGS Prof Pap 366, 81pp (reprint in New Mex Geol Soc Spec Publ 9, 1980).
• Sandstå, N. R., Robins, B., Furnes, H. & De Wit, M. (2011). The origin of large varioles in flow-banded pillow lava from the Hooggenoeg Complex, Barberton Greenstone Belt, South Africa. Contributions to Mineralogy and Petrology, 162(2), 365-377.
• Sauer, A. (1893). Porphyr studien. Mitt Großherz Bad Geol Landesanst, 2, 793–836.
• Salotti, C. & Fouts, J. (1964). Orbicule formation through ıntrusive brecciation and compositional reorganization. The Mountain Geologist, 203-212.
• Sederholm, J. J. (1928). On orbicular granites. Comm. Geol. Finlande, 83, 1-105.
• Seghedi, I. & Helvacı, C., (2016). Early Miocene Kırka-Phrigian Caldera, western Turkey (Eskişehir province), preliminary volcanology, age and geochemistry data. Journal of Volcanology and Geothermal Research, 327, 503–519.
• Shrivastava, S. K., Nambiar, K. V. & Gaur, V. P. (2004). Orbucular structures in Bundelkhand Granitoid Complex near Pichhore, Shivpuri district, Madhya Pradesh Journal of Geological Society of India, 64, 677-684.
• Spilliaert, N., Allard, P., Métrich, N. & Sobolev, A. V. (2006). Melt inclusion record of the conditions of ascent, degassing, and extrusion of volatile‐rich alkali basalt during the powerful 2002 flank eruption of Mount Etna (Italy). Journal of Geophysical Research: Solid Earth, 111(B4). https://doi.org/10.1029/2005JB003934
• Srinivasan, K. N. & Kumar, D. R. (1995). Orbicular structures from a diorite body within the Granitoid Complex of Nellore Schist Belt. Journal of Geological Society of India, 45(3), 277-283.
• Şengör, A.M.C., & Yılmaz, Y., 1981. Tethyan evolution of Turkey: a plate tectonic approach. Tectonophysics, 75, 181-241.
• Thompson, T. B. & Giles, D. L. (1974). Orbicular rocks of the Sandia Mountains, New Mexico. Geological Society of America Bulletin, 85(6), 911-916.
• Thompson, T. B. & Giles, D. L. (1980). Igneous origin of the orbicular rocks of the Sandia Mountains, New Mexico: Discussion and reply: Discussion. Geological Society of America Bulletin, 91(4), 245-246.
• Vernon, R. H. (1985). Possible role of superheated magma in the formation of orbicular granitoids. Geology, 13, 843–845. https://doi.org/10.1130/0091-7613(1985)13<843:PROSMI>2.0.CO;2