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Fenitisation associated with alkaline-silicate complexes. Implications for HFSE mobility in late-stage fluids, Gardar Rift, SW Greenland

Citation

Sokol, K and Finch, AA and Cloutier, J and Humphreys, MCS, Fenitisation associated with alkaline-silicate complexes. Implications for HFSE mobility in late-stage fluids, Gardar Rift, SW Greenland, Proceedings of the 15th SGA Biennial Meeting: Life with Ore Deposits on Earth, volume 4, 27-30 August 2019, Glasgow, Scotland, pp. 1840-1841. ISBN 9780852619643 (2019) [Conference Extract]


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Official URL: https://www.sga2019glasgow.com/abstract

Abstract

Alkali metasomatism associated with carbonatitic-alkaline magmatism (or fenitisation) is of interest for our understanding of chemical behaviour of economically important high-field-strength (HFSE) and rare-earth (REE) elements during late-stage magmatic-hydrothermal activity.

In this project, we explore the expression of alteration and the physic0-chemical factors controlling fenitisation across the Proterozoic Gardar Province of Southern Greenland. We present our findings of bulk-rock (XRF/ICP-AES) and microbeam (BSE-SEM-EDAX/ EPMA) analyses.

Our main case study, the lllerfissalik centre, comprises a series of nested syenitic intrusions. Fenites are exposed at its western margin, where a feldspar-poor Eriksfjord Formation quartz arenite protolith experienced intense metasomatism and deformation.

Detailed petrography demonstrates interstitial K-feldspar (commonly perthitic), mafic minerals including pyroxene or Na-amphibole, and titanite (often LREE-bearing) in the proximal high-grade fenite zone. The absence of feldspar in unaltered arenite (<5% mode further than 1.5 km distance from the contact zone) suggests that K-feldspar was introduced by early-stage fenitisation, along with the relatively Na-poor pyroxene. The presence of HFSE-rich phases i.e. Sr-chevkinite also attests to variable mobility of numerous alkali, alkali-earth metals and HFSE in fenitising fluids. Bulk-rock geochemical trends away from the contact are also presented. Further work including isotope systematics will constrain the geochemistry of fenitising fluids.

Item Details

Item Type:Conference Extract
Research Division:Earth Sciences
Research Group:Geochemistry
Research Field:Exploration geochemistry
Objective Division:Mineral Resources (Excl. Energy Resources)
Objective Group:Other mineral resources (excl. energy resources)
Objective Field:Other mineral resources (excl. energy resources) not elsewhere classified
UTAS Author:Cloutier, J (Mr Jonathan Cloutier)
ID Code:138806
Year Published:2019
Deposited By:CODES ARC
Deposited On:2020-04-30
Last Modified:2020-04-30
Downloads:0

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