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Age and origin of gem corundum and zircon megacrysts from the Mercaderes-Rio Mayo area, South-west Colombia, South America

Citation

Sutherland, FL and Duroc-Danner, JM and Meffre, SJM, Age and origin of gem corundum and zircon megacrysts from the Mercaderes-Rio Mayo area, South-west Colombia, South America, Ore Geology Reviews, 34, (1-2) pp. 155-168. ISSN 0169-1368 (2008) [Refereed Article]

DOI: doi:10.1016/j.oregeorev.2008.01.004

Abstract

Potential sources for alluvial gem corundum and zircon from the Rio Mayo area, near Mercaderes, Colombia are reviewed, based on U-Pb dating of syngenetic and protogenetic mineral inclusions in corundum samples and on a zircon megacryst. Corundum recovered from the region (approx. 99% sapphire, 1% ruby) commonly shows growth banding, includes colour change stones and exhibits overlaps in colour ranges and inclusion characteristics. This suggests a contiguous genetic suite. The U-Pb dating used laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) techniques. Because of the young ages and low-U contents of the dated zircons, the acquired data required a special statistical treatment. The results from zircon, fluorapatite and allanite-(Ce) inclusions provide a corundum crystallization age of 8 to 11Ma, in relation to northern Andean Miocene uplift and magmatism. The zircon megacryst gave a younger crystallization age of c. 0.6Ma, unrelated to the corundum genesis. Geochemical parameters (trace element and O isotope ranges) for corundum samples suggest a metamorphic/metasomatic origin. The age data rules out corundum genesis during the Late Cretaceous ophiolitic generation, but leave open possible later metasomatic interactions with this substrate. The Cr/Ga and Ga/Mg ratios and O isotope range for the corundum fall within the known limits for metasomatic, desilicated felsic/ultramafic 'plumasitic' associations, suggesting a possible parental source. Allanite, extremely rare as an inclusion in corundum elsewhere, may prove a characteristic inclusion for Rio Mayo corundum. © 2008 Elsevier B.V.

Item Details

Item Type:Refereed Article
Research Division:Earth Sciences
Research Group:Geology
Research Field:Ore Deposit Petrology
Objective Division:Mineral Resources (excl. Energy Resources)
Objective Group:Mineral Exploration
Objective Field:Titanium Minerals, Zircon, and Rare Earth Metal Ore (e.g. Monazite) Exploration
Author:Meffre, SJM (Dr Sebastien Meffre)
ID Code:56644
Year Published:2008
Web of Science® Times Cited:19
Deposited By:Centre for Ore Deposit Research - CODES CoE
Deposited On:2009-05-19
Last Modified:2014-11-07
Downloads:0

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