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Assessment of Mineralogical Influences on the Element Mobility in the W-Sn Enriched Granite of Regoufe and Its Derivatives (Portugal) by Means of XRF Analysis of Unpolished Rock Sections

  • P. F. M. Van Gaans
  • S. P. Vriend
  • R. P. E. Poorter
  • J. B. H. Jansen
Part of the Special Publication No. 6 of the Society for Geology Applied to Mineral Deposits book series (MINERAL DEPOS., volume 6)

Abstract

The relation of rock chemistry, mineralogy and geochemical processes was studied in the hydrothermally altered, W-Sn specialized granite of Regoufe, northern Portugal. To this end unpolished rock sections sawn from small drill cores were directly analyzed by X-ray fluorescence spectrometry, which is the basic aspect of an approach called Integral Rock Analysis (IRA). Chemical variation within the granite and its derivatives is mainly due to pervasive (auto)metasomatic activity. The effect of chemical weathering on the rock chemistry of this denuded granite is negligible. With the aid of factor analysis the imprints of albitization, muscovitization, apatitization and mineralization are traced throughout the granite and associated dyke system. Alteration generally increases from west to east. In the NE area the separate effect of disseminated wolframite mineralization, apart from the common W-Sn quartz-vein association, and late sericitization are recognized. The importance of mineralogy or major element chemistry in the response to the hydrothermal processes is typically evidenced by the element associations of Sr and of Ti and Zr. Sr preferentially substitutes for K in feldspar and mica in the western region, whereas it mainly substitutes for Ca in phosphates in the most altered eastern zone. As expected, Ti and Zr are closely related to biotite in the western part and appear to remain concentrated in the biotite alteration products. Depletion of Ti and Zr by leaching of refractory minerals is linked to Na2O, P and metal enrichment through albitization, apatitization and mineralization. The IRA approach offers a rapid method for the acquisition of large quantities of detailed rock geochemical data. An additional advantage is that data are indicative of mineralogy. Selected rock sections were investigated microscopically and by electron-probe microanalysis, resulting, among others, in the discovery of the trace minerals columbotantalite and scorodite in the granite.

Keywords

Element Mobility Trace Mineral Volcanogenic Massive Sulphide Elsevier Scientific Major Element Chemistry 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag Berlin Heidelberg 1988

Authors and Affiliations

  • P. F. M. Van Gaans
  • S. P. Vriend
  • R. P. E. Poorter
  • J. B. H. Jansen
    • 1
  1. 1.Department of Geochemistry and Experimental Petrology, Institute of Earth SciencesUniversity of UtrechtUtrechtThe Netherlands

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