Opaline chert nodules in maar lake sediments from Camp dels Ninots (La Selva Basin, NE Spain)
Chert nodule samples from three different well cores (CC, CP1 & CA) from the lacustrine infill of the Camp dels Ninot maar-diatreme (La Selva Basin) have been studied by means of X-ray diffraction, and optical and electron microscope technique. The chert nodules replace diatomites and carbonates...
| Autores: | , , , , , , |
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| Formato: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2016 |
| País: | España |
| Recursos: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/147267 |
| Acesso em linha: | http://hdl.handle.net/10261/147267 |
| Access Level: | acceso abierto |
| Palavra-chave: | chert nodules maar lacustrine opal-A, opal-A/CT |
| Resumo: | Chert nodule samples from three different well cores (CC, CP1 & CA) from the lacustrine infill of the Camp dels Ninot maar-diatreme (La Selva Basin) have been studied by means of X-ray diffraction, and optical and electron microscope technique. The chert nodules replace diatomites and carbonates layers, and varies in mineralogy between opal-A to opal-A/CT. The microtexture of the opal-A rich nodules is characterized by smooth microspheres of ~2μm in diameter that forms aggregates of amalgamated microspheres. Commonly, the nodules contain diatoms and their moulds when replacing diatomites, and dolomite or ankerite crystals and their moulds when replacing carbonates. The opal-A/CT rich nodules exhibit a microtexture consisting of microspheres of ~8μm in diameter that form aggregates with botryoidal and finger-like morphologies. Results indicate that the early diagenetic transformation of opal-A to opal-CT is not complete in the studied sediments. |
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