Occurrence of sepiolite in the Hirsizdere sedimentary magnesite deposit, bozkurt-denizli, SW Turkey

Abstract

The Hirsizderemagnesitedepositis foundin the upperMiocene-Pliocene lacustrinesedimentsofthe Cameli formation in the western Aegeandepression zone, whichwas upliftedto form a broad anticlineand in which consecutivefaults and fractures developeddue to the neotectonic activities. Thick alternation of carbonatecementedand weaklycementedconglomerate, sandstone,mudstoneintercalated with a fewthindolomiteand magnesitelayersis exposedat the lowerpartof the sequence. Theseunitsareoverlainby magnesiteanddolomite in associationwiththin claystoneand sandstone layersandlenses. Greenandclaretred-brownsmectiteis observedin detritalmaterialsas well as in sandycarbonateunits,and isaccompaniedbyserpentine,amphibole, illite,feldsparand quartz,whereassepioliteis developedinthe form of3-5 em thick,yellowandgreenishbrowncoloredveins,or asthin filmsliningparallelto theveinaxiswithinthe magnesiteunit. SEMstudies showthat sepiolitefibersare grown in theformof meshworks and bridgesbetweenrelictcarbonatemineralgrains. Thepresenceofplantstem imprints, and the abundance of gastropod and ostracode shells in carbonate units indicate shallow and alkaline lake conditions. Field observations and detailed mineralogical, chemicaland micromorphological determinations indicate that sepiolite is formed by diagenetical transformation of magnesiteduring the movementof silica-richmeteoricwater through the fractures of carbonate units under near-surface alkalineconditions.

ORIGIN OF SEPIOLITE AND LOUGHLINITE IN A NEOGENE VOLCANO-SEDIMENTARY LACUSTRINE ENVIRONMENT, MIHALlCClK ESKISEHIR, TURKEY

“…6C). On the other hand, sepiolite is observed either as bridges of fibers between partly abraded dolomite aggregates, or growing out of dolomite crystallites either as individual fibers or masses of fibers, such as described by Aqrawi (1993), Karakaş & Kadir (1998) and Kadir & Akbulut (2001) (Fig. 6D).…”

Transformation of Magnesite to Sepiolite and Stevensite: Characteristics and Genesis (Çayirbaği, Konya, Turkey)

“…Sepiolite and stevensite are authigenic Mg-rich clay minerals having different structural organizations. According to numerous published papers, these minerals form in a variety of geological environments: in Si-and Mg-rich alkaline lakes and shallow seas via direct precipitation from alkaline or saline water (Papke 1972;Tettenhorst and Moore 1978;Khoury et al 1982;Eberl et al 1982;Galan and Castillo 1984;Ece and Çoban 1994;Karakaş and Kadir 1998;Singer et al 1998;Pozo and Casas 1999;Buey et al 2000;Mayayo et al 2000;Kadir and Akbulut 2001;Kadir et al 2002;Akbulut and Kadir 2003;Karakaya et al 2004;Furquim et al 2008;Galan and Pozo 2011;Yeniyol 1992Yeniyol , 2007Yeniyol , 2012Yeniyol , 2014Kadir et al 2016Kadir et al , 2017; and many others), transformation from precursor Mg-bearing silicate phases (Stoessell and Hay 1978;Chahi et al 1997;Pozo and Casas 1999;Cuevas et al 2003;Hover and Ashley 2003;Yeniyol 1997Yeniyol , 2012Yeniyol , 2014, hydrothermal alteration of magmatic rocks (Faust and Murata 1953;Randal 1959;Imai et al 1970;Post 1984;April and Keller 1992;İrkeç and Ünlü 1993), and weathering of mafic and ultramafic rocks…”