Petrochemical characterization of Neoproterozoic Colomine granitoids, SE Cameroon: Implications for gold mineralization

Ralain Bryan Ngatcha, Olugbenga Akindeji Okunlola, Cheo Emmanuel Suh, Kevin Ijunghi Ateh, Axel Hofmann

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)

Abstract

Biotite granites and K-feldspar granites are the dominant intrusive rock types of the Colomine gold district in the Neoproterozoic terrain of SE Cameroon. The silica contents of these granitoids range from 68.93–75.39 wt% and Au contents from 0.6 to 32 ppb. They are weakly peraluminous (ASI = 1.0–1.2) I-type granitoids with high-K calc-alkaline to shoshonitic character, emplaced within a syn-collisional arc setting. They have fractionated trace element patterns (LaN/YbN: ~ 11–331) with enrichment in LREE compared to HREE and weak to strong negative Ba, Nb, Sr, P, Ti, Lu, and Eu (Eu/Eu* = 0.12–0.52) anomalies. The geochemical characteristics suggest that the granitoids formed by partial melting of crustal source rocks with some input from greywackes. Differentiation of the hydrous parent magma was characterized by fractionation of muscovite, biotite, hornblende, plagioclase, and K-feldspar with minor zircon, apatite and Fe-Ti oxide. Mafic garnet-bearing inclusions represent an early crystallization phase that was incorporated in the later felsic melt. The granitoids became emplaced into Proterozoic schist belts. Along the contacts, they became brecciated, sheared, foliated and sericitized. These “contact granites” have higher gold contents (5–32 ppb) than the fresh granitoids (0.6–3 ppb). Remobilisation of gold from early magmatic sulfide minerals by post-magmatic hydrothermal fluids enriched the shear-related granitoids. Hydrothermal alteration results to enrichment in Cu, Ni, Cr, Mo, Ga, V, Tl, and Au and depletion in LREE (e.g., La, Ce, Pr). Micro-shear and fault zones in the vicinity of the granitoids constitute favourable sites for exploration.

Original languageEnglish
Pages (from-to)175-192
Number of pages18
JournalLithos
Volume344-345
DOIs
Publication statusPublished - 1 Nov 2019

Keywords

  • Fractional crystallization
  • Geochemistry
  • Granite-related Au mineralization
  • I-type granitoids
  • SE Cameroon

ASJC Scopus subject areas

  • Geology
  • Geochemistry and Petrology

Fingerprint

Dive into the research topics of 'Petrochemical characterization of Neoproterozoic Colomine granitoids, SE Cameroon: Implications for gold mineralization'. Together they form a unique fingerprint.

Cite this