The Archaean greenstone belt of Hidrolina (Centrai Goiás, Brazil) is a severely tectonized and metamorphosed volcano-sedimentary sequence. It consists of a lower sequence (LS) with ultramafic and mafic flows (compositionally corresponding to komatiites) and an upper scquence (US) with intercalated mafic and felsic flows (compositionally corresponding to tholeiites, dacites, and rhyolites). Practically no primary structure or texture is preserved. Geochemical major and trace element modelling allows distinction between liquid compositions and cumulates. Crustal contamination does not seem to have been effective in controlling the geochemical variations. Batch partial melting models and CMAS plot indicate that: (a) the komatiites probably resulted from moderate (28-30%) melting of a spinel peridotite rather than a garnet one; (b) the komatiites were formed by the mixing of a liquid of basaltic composition with peridotite source material; (c) the mantle source was heterogeneous, the flows higher in the stratigraphy coming from a more depleted source than the lower ones; and (d) US tholeiites resulted from lower degree melting of the same depleted source that produced the upper LS flows.

Geochemical Models for the Petrogenesis of Komatiites from the Hidrolina Greenstone Belt, CentraI Goias, Brazil / Rivalenti, Giorgio; Girardi, V. A. V.; Coltorti, M.; Correia, C. T.; Mazzucchelli, Maurizio. - In: JOURNAL OF PETROLOGY. - ISSN 0022-3530. - STAMPA. - 30:(1989), pp. 175-197.

Geochemical Models for the Petrogenesis of Komatiites from the Hidrolina Greenstone Belt, CentraI Goias, Brazil

RIVALENTI, Giorgio;MAZZUCCHELLI, Maurizio
1989

Abstract

The Archaean greenstone belt of Hidrolina (Centrai Goiás, Brazil) is a severely tectonized and metamorphosed volcano-sedimentary sequence. It consists of a lower sequence (LS) with ultramafic and mafic flows (compositionally corresponding to komatiites) and an upper scquence (US) with intercalated mafic and felsic flows (compositionally corresponding to tholeiites, dacites, and rhyolites). Practically no primary structure or texture is preserved. Geochemical major and trace element modelling allows distinction between liquid compositions and cumulates. Crustal contamination does not seem to have been effective in controlling the geochemical variations. Batch partial melting models and CMAS plot indicate that: (a) the komatiites probably resulted from moderate (28-30%) melting of a spinel peridotite rather than a garnet one; (b) the komatiites were formed by the mixing of a liquid of basaltic composition with peridotite source material; (c) the mantle source was heterogeneous, the flows higher in the stratigraphy coming from a more depleted source than the lower ones; and (d) US tholeiites resulted from lower degree melting of the same depleted source that produced the upper LS flows.
1989
30
175
197
Geochemical Models for the Petrogenesis of Komatiites from the Hidrolina Greenstone Belt, CentraI Goias, Brazil / Rivalenti, Giorgio; Girardi, V. A. V.; Coltorti, M.; Correia, C. T.; Mazzucchelli, Maurizio. - In: JOURNAL OF PETROLOGY. - ISSN 0022-3530. - STAMPA. - 30:(1989), pp. 175-197.
Rivalenti, Giorgio; Girardi, V. A. V.; Coltorti, M.; Correia, C. T.; Mazzucchelli, Maurizio
File in questo prodotto:
File Dimensione Formato  
1989RivalentiEtAl_reduced_OCR.pdf

Accesso riservato

Tipologia: Versione dell'autore revisionata e accettata per la pubblicazione
Dimensione 2.2 MB
Formato Adobe PDF
2.2 MB Adobe PDF   Visualizza/Apri   Richiedi una copia
Pubblicazioni consigliate

Licenza Creative Commons
I metadati presenti in IRIS UNIMORE sono rilasciati con licenza Creative Commons CC0 1.0 Universal, mentre i file delle pubblicazioni sono rilasciati con licenza Attribuzione 4.0 Internazionale (CC BY 4.0), salvo diversa indicazione.
In caso di violazione di copyright, contattare Supporto Iris

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11380/736906
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 2
  • ???jsp.display-item.citation.isi??? ND
social impact