Geochemistry of halloysite-7å formation from plagioclase in trachyandesite rocks from limnos island, greece

D. Papoulis, Sridhar Komarneni, D. Panagiotaras

Research output: Contribution to journalArticle

2 Scopus citations

Abstract

Trachyandesite rocks, occurring over an area of about 1 km2 in the southwest part of Limnos Island, Greece, are altered mainly to halloysite. The samples were collected and analysed by polarizing microscopy, powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and chemical analysis. The alteration of plagioclase to halloysite follows seven discrete stages that are described in detail. The geochemical evaluation of the data shows enrichment of the light REE (LREE) over heavy REE (HREE) as expressed by the (La/Yb)n ratio. The SLREE range from 206.44 to 272.30, while the sum of HREE varies from 11.01 to 26.26. The (La/Yb)n ratio ranges from 9.72 to 27.64. Fractionation among LREE expressed as (La/Sm)n and between middle REE (MREE) and HREE is shown as (Tb/Yb)n ratios. The most altered rocks close to the fault zone have high (Tb/Yb)n ratios and low (La/Sm)n and Eu/Eu ratios. Although mineralogy and clay mineral textures indicate hydrothermal genesis of halloysite, the geochemical data are not conclusive due to a secondary weathering effect.

Original languageEnglish (US)
Pages (from-to)75-89
Number of pages15
JournalClay Minerals
Volume49
Issue number1
DOIs
StatePublished - Jan 1 2014

All Science Journal Classification (ASJC) codes

  • Geochemistry and Petrology

Fingerprint Dive into the research topics of 'Geochemistry of halloysite-7å formation from plagioclase in trachyandesite rocks from limnos island, greece'. Together they form a unique fingerprint.

  • Cite this