“Tactites” Formed by Ca-Al Metasomatism on Amphibolites in the Seridó Scheelite Province — NE Brazil

  • H. Beurlen
Conference paper

Abstract

Petrographic observations made in several scheelite occurrences of NE Brazil proved that “tactites” — the local designation for all calc-silicate rocks — were formed by replacement of amphibolites and, or, amphibole-biotite gneisses successively by: (1) diopside + plagioclase; (2) vesuvianitegarnet-(epidote?); (3) epidote-tremolite-chlorite-quartz-calcite. A previous investigation on trace elements in the Brejuí Mine indicated that part of the amphibole-biotite gneisses that enclose the scheelitiferous “tactites” are orthoderived. Also orthoderived cummingtonitites, phlogopite schists and mylonites are the host rocks of the scheelite in Carnaubinha Mine as indicated by petrochemical investigation. In the Malhada Limpa Prospect, diabasic textures are preserved in amphibolites that are partially replaced by banded amphibole gneisses and calc-silicate rocks. In all of the above-mentioned occurrences, at least two phases of scheelite were observed: the first one crystallized during the pre- or early metamorphic stage, while the second phase was formed by recrystallization and remobilization during later tectono-metamorphic events. The spatial coincidence of orthoderived rocks and scheelite mineralization observed in the three important scheelite deposits mentioned above, and the petrographical similarities in dozens of other occurrences in the Seridó Province, indicated that a premetamorphic volcanogenic tungsten contribution in the Seridó scheelite province as a potentially important metallogenetic event can no longer be discarded.

Keywords

Crystallization Quartz Silicate Tungsten Calcite 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Andritzky G, Busch K (1975) Erläuterungen zur geologischen Karte des Scheelit-Gebietes von Santa Luzia, NE Brasilien, 1:100. 000. Bundesanstalt für Geowissenschaften und Rohstoffe, Hannover, 34 pGoogle Scholar
  2. Beurlen H, Busch K (1982) Protominério de tungstênio ortoanfibolítico na Provincia Scheelitífera do Seridó, Rio Grande do Norte, Nordeste do Brasil. Actas V Congr Latinoamericano de Geol, Buenos Aires V, II, pp 69–81Google Scholar
  3. Beurlen H, Melo EB, Villaroel HS (1982) Remobilization of strata-bound scheelite indicated by tectonic, textural and crystallographic features in Brejuí Mine, NE Brazil. In: Amstutz GC, El Goresy A, Frenzel G, Kluth C, Moh G, Wauschkuhn A, Zimmermann RA (eds) Ore genesis. The state of the art. Springer, Berlin Heidelberg New York, pp 418–425Google Scholar
  4. Busch K (1979) Geochemische Untersuchungen zur Genesis der Wolfram-Lagerstätte in Taktit bei Currais Novos, NE-Brasilien. Bundesanstalt für Geowissenschaften und Rohstoffe, Hannover, 47 p (unpubl report)Google Scholar
  5. Lima ES (1982) Geologia e petrologia da Jazida scheelitífera de Bonfim. Diss MS, Univ Fed Pernambuco, Recife Brazil, 96 pGoogle Scholar
  6. Leake BE (1964) The chemical distinction between ortho-and para-amphibolites. J Petrol 5: 238–254Google Scholar
  7. Maranhäo R (1970) Geologia econômica da regiäo de Currais Novos (RN). Thesis, Univ Sao Paulo, SP, 135 p (manuscript)Google Scholar
  8. Maucher A, Höll R (1968) Die Bedeutung geochemisch-stratigraphischer Bezugshorizonte für die Altersstellung der Antimonitlagerstätte von Schlaining im Burgenland, Österreich. Mineral Deposita 3: 272–285CrossRefGoogle Scholar
  9. Moeri E, Schnack PJ (1979) Mineralizac5es scheelitíferas na regiäo de Santa Luzia, PB 9th. Simp de Geologie do Nordeste. Soc Bras Geol Resumos das Comunicaçôes, Natal, RN, p 73Google Scholar
  10. Walker K, Joplin GA, Lovering JF, Green R (1960) Metamorphic and metasomatic convergence of basic igneous rocks and lime-magnesia sediments of the Precambrian of northwestern Queensland. J Geol Soc Australia 6: 149CrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 1984

Authors and Affiliations

  • H. Beurlen
    • 1
  1. 1.Universidade Federal de PernambucoRecifeBrazil

Personalised recommendations