Karamürsel çevresindeki volkanik tüflerin ve zeolitleşmenin jeolojik, mineralojik ve petrografik incelenmesi

Abstract

Karamürsel ilçe merkezinin batısında yer alan çalışma alanında Paleosen - Eosen yaşlı volkanosedimanter istif içinde yer yer zeolitleşme olayı saptanmıştır. Bölgede en yaşlı olan ve taban birimi konumundaki Triyas kumtaşı ve konglomerasının üzerine Paleosen - Eosen yaşındaki içinde yer yer tüt seviyeleri de içeren killi formasyon diskordan olarak gelmiştir. Bunun üzerinde yine Paleosen - Eosen yaşlı ve killi formasyon tabakaları ile uyumlu volkanik tüflü seviyeler bulunmaktadır. Bazen oldukça kalın seviyelere ulaşan bu tüfler içinde zeolitleşme meydana gelmiştir. Tüm bunların üzerine diskordan olarak oturan Pliyosen yaşındaki kum, kil ve çakıldan oluşan genç birim gelmiştir. En üstte ise Kuvaterner örtü bulunmaktadır. Sahada zeoliti tanıtıcı herhangi bir özellik yoktur. Zeolit mineralinin türünün saptanması için bir dizi analiz ve deneyler yapılmıştır. X-ışını difraksiyon değerleri zeolit mineralinin klinoptilolit-hoylandit olduğunu göstermiştir. Ayrıca üç örneğin ısıl dayanımlılık deneyleri sonucunda minerallerin ikisi 400°C-12 saat ve daha sonra 550°C-12 saat ısıtmada kararlı kalmışlardır. Bu da mineralin hoylanditten ziyade klinoptilolit olduğunu göstermiştir. Kimyasal analiz değerleri bu ayrım için kesin bir veri sağlamoffa'Ja beraber K* değerinin, Na+ değerlerinden fazla bulunması, klinoptilolit mineralinin bir özelliği olmasına dayanarak yine zeolit minerali klinoptilolit olarak tanımlanabilir. Ayrıca çalışma sahasında zeolitleşmenin yanısıra killeşmeye ve demir bileşimli bazı minerallerin oluşumuna rastlanmıştır.

The study area is located between Denizçalı - Havuzdere - Geyikdere Hamlets in Karamürsel and covers about 40 km2. The Triassic sandstones make up of the basement complex and they are disconformably overlain by Paleocene - Eocene tuffs. This study documented that zeolitization (clinoptilolite - heulandite) of tuff series are present throughout the vol canic succession. It was the first time, recently clinoptilolite and analcime have been observed in the volcanosedimantery Neogene series in the Western Anatolia region. A high concentration of analcime has been found at the west of region. The minerals such as flipsite and erionite were rarely observed. Diagenetic alteration of mineral paragenesis with zeolite is common in the young lithologies in Turkey and the world. The degree of alteration can vary from unaltered to highly altered rocks in the some unit. Formation of zeolite minerals or other outhigenic minerals are controlled by pH, temperature, pressure, climate, time, permeability and porosity of the parent rock as well as by various chemical parameters. In this study, the mineralogic - petrographic properties, the formation and the distribution of zeolite minerals of lacustrine units which is located in Karamürsel have been investigated. Volcanic tuff units have undergone diagenetic alteration and zeolites (clinoptilolite, heulandite), clay minerals (smectite, iliite, celadonite) mica minerals (glauconite, biotite), siliceus minerals (opal-CT, quartz), car bonate minerals (calcite) and feldspar minerals are authigenecally formed. Ryolithic, dacitic and ryodacitic tuffs are glassy dust and ash, crystal and lithic type in general (Figure 1). So it is shown zeolitic zoning in the volcanic tuffs at EK ii. In addition, it is shown some minerals iike plajioklas, quartz, am- phibolite and in matrix outhigenic occurences at one tuff sample in Figure 2. Aiso prismatic zeolite minerals at the side of the volcanic glass pieces are illustrated in Figure 3. VI Figure 1. Two different tuff samples from Karamürsel a. Lithic tuff b. Crystal tuff (Both of them double nicol). VII Figure 2. One tuff sample from Karamürsel a. P&ra\e\ nicol b. Cross nicol VIII Figure 3. Prismatic zeolite minerals (clinop-heulan) at the side of the glass piece. The heat experiments are done only three samples. One of them is identified as Ca-clinoptilolite, two of them are identified as clinoptilolite. Descriptions of the heat experiments are done by following ALIETTI (1972). Although polymorphism was observed in one heulandite-2 (Ca- clinoptilolite) sample. The other two samples are clinoptilolite, because these two samples do not show any polymorphism (they show only natural phase=A). Thermal stability experiments indicate that clinoptilolite is durable at 550°C at two of three samples. All seamples did not show polymorphism at the end of thermal tests at 400°C for 12 hours. At 550°C temperature for 12 hours heating only structures of one sample broke down and the rest of samples did not change. At 550°C, SİO2/AI2O3 and (Na20 + K20)/(CaO + MgO) ratios are approximately 5.65 and 0.39 for the disordered samples and 2.62 and 0.53 for the ordered samples, respec tively. X-ray diffraction studies and chemical compositions have identified some samples as glauconite (Al-glauconite). Glauconite - celadonite dis tinction based on X-ray diffraction indicate that Karamürsel samples are typically glauconite (Figure 4 and Table 1). d(060) spacing is higher than 1.51A° (1.514A0). On the other hand absence of both 131 and 130 reflec tion lines (there is only 131) and intensities of the other reflections are important exidences in description of glauconite in ceiadonit - glauconite distinction. The relationship of d(060) spacing to Fe+3 ions is shown Figure 5. IX ! Table 1. The data of X-ray diffraction of Karamürsel gfauconite sample -ai B J8 » » 7a» a 29. ' ? ? ' * L 1 ' * 1 CL - (-2 b * * > 1 1 ^__j i 1 1 Figure 4. X-ray diffraction of Karamürsel samples o sû o iSIQ' ISIS' 131* 1S68 U3 IA tfl ?3 Fe J Figure 5. The diagram of d(060) Fe for glauconite-celadonite distinction. Chemical analysis of Karamürsel sample (average values of two samples) and cationic values recalculated on the basis of the 72 oxygen atoms are given in Table 2. Samples have an axerage half-unit cell com position Of Ko.53(Fe*0.89. AI0.53)(Mgo.48,Feo.17)(Sİ3.65, AIo.35)Oio(OH)2 and are on the boundary of glauconite and Al-glauconite fields on Al+3 - Fe+3 diagram (Figure 6). total number of octahedral trivalent atoms per- half unit cell is 1.42. The ratios of R+3/R + 2 and Fe+3/Fe+2 are 2.18 and 5.24 respectively. Principles of oxygen-nitrogen separation of air by selective adsorp tion onto zeolites are reviewed to demonstrate the possible economical utilization of newly found Turkish natural zeolites in oxygen production reguired in iron and steel industry. XI Table 2. Chemical values of Karamürsel glauconite sample Î.61 12 ^ pûeogıte: 1.5 yS*" -t - U-gliuccBite AL as- ?f-3 X'^t-5^ jUncooite.A: \ w \ v \ celiiic&ite \ ' \ \ \ T s 1 - r* - t - \ - N 8 0.4 as U Fe *3 Figure 6. The diagram of Al + 3-Fe"3 for glauconiîe - celadonite distinction