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Mechanism of illitization of bentonites in the geothermal field of Milos islandGreece: evidence based on mineralogy, chemistry, particle thickness andmorphology

Christidis Georgios

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URIhttp://purl.tuc.gr/dl/dias/050ED3BE-8E2C-4C22-80E2-5B910AF76B01-
Αναγνωριστικόhttps://doi.org/10.1346/CCMN.1995.0430507-
Γλώσσαen-
Μέγεθος16 pagesen
ΤίτλοςMechanism of illitization of bentonites in the geothermal field of Milos island Greece: evidence based on mineralogy, chemistry, particle thickness and morphologyen
ΔημιουργόςChristidis Georgiosen
ΔημιουργόςΧρηστιδης Γεωργιοςel
ΕκδότηςClay Minerals Societyen
ΠερίληψηHydrothermal alteration has caused illitization along a 40m vertical profile in the Tsantilis bentonite deposit, Eastern Milos, Greece which consists principally of a Wyoming-type montmorillonite and authigenic K-feldspar. The product K-bentonite which contains illite/smectite, kaolinite, K-feldspar, quartz, sulphates and sulphides exhibits an unusual tendency for increase of expandability with depth. Mineralogy and I/S textures were determined with X-ray diffraction and SEM and TEM methods respectively and chemistry using X-ray fluorescence. Illitization is characterized by a 5- to 6-fold increase of K and release of Si, Fe, Mg Na, and Ca from the parent rock, indicating a K-influx (K-metasomatism) in the system. The I/S particle morphology is characterized by both flaky and lath-like particles, the former dominating in the range 100-50% expandable layers (R0 ordering) and the latter in the range 50-10% expandable layers (R1 and R > 1 ordering). Flaky particles are also abundant in samples with R1 ordering and abundant kaolinite, indicating that the latter might affect illitization. The I/S particles are classified in populations with thickness multiples of 10 A, their thickness being probably smaller than the coherent XRD domain. As the reaction proceeds, particles grow thicker and more equant. The distribution of I/S particle dimensions forms steady state profiles showing log-normal distribution; however, sensu stricto Ostwald ripening is unlikely. It seems that the reaction proceeds toward minimization of the surface free energy of I/S, being affected principally by temperature and K-availability. The spatial distribution of expandability implies that the heating source was probably a mineralized vein with T < 200~ directed away from the bentonite, suggesting that illitization might be used as an exploration guide for mineral deposits.en
ΤύποςPeer-Reviewed Journal Publicationen
ΤύποςΔημοσίευση σε Περιοδικό με Κριτέςel
Άδεια Χρήσηςhttp://creativecommons.org/licenses/by/4.0/en
Ημερομηνία2015-10-02-
Ημερομηνία Δημοσίευσης1995-
Θεματική ΚατηγορίαX-ray diffraction en
Θεματική ΚατηγορίαElectron microscopy en
Βιβλιογραφική ΑναφοράG.E. Christidis , "Mechanism of illitization of bentonites in the geothermal field of Milos island Greece: Evidence based on mineralogy, chemistry, particle thickness and morphology ", Cl. and Clay Min. ,vol. 43, no.5, pp.569-585 ,1995.doi :10.1346/CCMN.1995.0430507en

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