Moganite in the Chalcedony Varieties of Continental Cherts (Miocene,Madrid Basin,Spain) |
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| Authors: | Ma Ángeles Bustillo José Luis Pérez-Jiménez Ana Ma Alonso-Zarza Marta Furio |
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| Institution: | 1. Dpto. de Geología. Museo Nacional de Ciencias Naturales , CSIC. c/José Gutiérrez Abascal , Madrid , Spain abustillo@mncn.csic.es;3. Dpto. de Geología. Museo Nacional de Ciencias Naturales , CSIC. c/José Gutiérrez Abascal , Madrid , Spain;4. Centro Tecnológico de Repsol , Móstoles , Spain;5. Dpto. de Petrología y Geoquímica , Facultad de Geológicas, Instituto de Geociencias (UCM-CSIC), Universidad Complutense de Madrid , Madrid , Spain;6. Dpto. de Geología. Museo Nacional de Ciencias Naturales , CSIC. c/José Gutiérrez Abascal , Madrid , Spain |
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| Abstract: | Varieties of chalcedony (calcedonite, quartzine, and lutecite) and other optical micro- and cryptocrystalline textures of quartz and opal from Miocene silcretes of the Madrid Basin were studied using a Thermo Fisher DXR Raman microscope. The microscope has a point-and-shoot Raman capability of 1 µm spatial resolution and was coupled with a standard optical microscope. Our results show that all the varieties of chalcedony can have a composite Raman spectrum of both quartz and moganite. The spectra are independent of the chalcedony origin by ageing, direct replacement, and cementation processes. Moganite was absent only in some calcedonite cements. The presence of moganite is independent of the surface sedimentary setting of the host rocks in which the silcretes are formed. |
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| Keywords: | chalcedony chert micro-Raman moganite silcretes |
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