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U-Pb Zircon Age Constraining the Source and Provenance of Gem-Bearing Late Cenozoic Detrital Deposits, Mamfe Basin, SW Cameroon

journal contribution
posted on 2023-05-17, 14:55 authored by Kanouo, NS, Khin ZawKhin Zaw, Yongue, RF, Sutherland, FL, Sebastien MeffreSebastien Meffre, Njonfang, E, Ma, C, Tchouatcha, MS
Zircons and other heavy minerals (corundum, rutile, ilmenite, magnetite, sillimanite) are identified in the Nsanaragati gem corundum placer deposit, in the western part of the Mamfe sedimentary basin, SW Cameroon. These alluvial minerals have different morphological characteristics and zircons, in particular, vary mostly in colour and shape. They are reddish, brownish, yellowish, pink or colourless. These minerals form rounded and sub-rounded alluvial grains, prismatic, pyramidal or dipyramidal crystals. Reddish zircons retain their original crystallographic shape. Trace element and U-Pb isotopic geochemical analyses of these reddish zircons, using the LA-ICP-MS method give significant Hf (4576-6334ppm), Th (46-1565ppm) and U (66-687ppm) contents, with Th/U ratio ranging from 0.6 to 3.0. The 206Pb/ 238U corrected mean age gave 12.39 ± 0.55Ma, which characterizes an Upper Cenozoic (Serravallian) magmatic event. The zircons are probably sourced from a magmatic field in the South eastern boundary of the Cross River Formation. The Cameroon Volcanic Line of basaltic and alkaline lavas and intrusions which lie east of the Mamfe Basin mostly range in age from 37Ma to <1Ma. The zircons may also relate to the Mount Bambouto plateau lavas which lie northeast of the Mamfe sedimentary basin and have an eruptive age range of 21-14Ma. The oldest Nsanaragati reddish zircon ages overlap within error with the end stages of the Bambouto eruptions. This eruptive or a related episode provides a potential source for megacrystic reddish zircons within the Nsanagarati placer deposit. © 2012 The Authors. Resource Geology © 2012 The Society of Resource Geology.

Funding

Australian Research Council

AMIRA International Ltd

ARC C of E Industry Partner $ to be allocated

Anglo American Exploration Philippines Inc

AngloGold Ashanti Australia Limited

Australian National University

BHP Billiton Ltd

Barrick (Australia Pacific) PTY Limited

CSIRO Earth Science & Resource Engineering

Mineral Resources Tasmania

Minerals Council of Australia

Newcrest Mining Limited

Newmont Australia Ltd

Oz Minerals Australia Limited

Rio Tinto Exploration

St Barbara Limited

Teck Cominco Limited

University of Melbourne

University of Queensland

Zinifex Australia Ltd

History

Publication title

Resource Geology

Volume

62

Pagination

316-324

ISSN

1344-1698

Department/School

School of Natural Sciences

Publisher

Wiley-Blackwell Publishing Ltd.

Place of publication

Southern Gate, Chichester, West Sussex PO19 8SQ UK

Rights statement

Copyright 2012 The Authors

Repository Status

  • Restricted

Socio-economic Objectives

Titanium minerals, zircon, and rare earth metal ore (e.g. monazite) exploration

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