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Flat Point Gneiss
Stratigraphic label: [arch]flp
Map symbol: Aflp

 

ABANDONED UNIT

Publication: 27 May 2019

 

 

  DISCLAIMER: This English version is translated from the original French. In case of any discrepancy, the French version shall prevail. 

Author: James et al., 1996
Age: Archean
Stratotype: None
Type area: Potel Lake area (NTS sheets 23I14 and 23I11), Labrador
Geological province: Churchill Province
Geological subdivision: Baleine Lithotectonic Domain
Lithology: Gneiss
Category: Lithodemic
Rank: Lithodeme
Status: Formal
Use: Active
Replacement Unit(s)
Table of contents
 
 

 

 

 

Background

The term “Flat Point Gneiss” was introduced in Labrador by James et al. (1996) to define a package of amphibolite facies dioritic to tonalitic gneiss. The term was retained by Hammouche et al. (2011) in the Bonaventure Lake area due to the continuity of these rocks in this area. As part of a synthesis of the Southeastern Churchill Province (SECP), Lafrance et al. (2018) identified new lithotectonic domains within the SECP. In the Baleine Lithotectonic Domain, Lafrance et al. (in preparation) reassigned Flat Point Gneiss units to the Knox Complex.

 

Reasons for Abandonment

Field checks in the summers of 2015 and 2016, as well as new geochronological dating, have enabled Flat Point Gneiss units to be related to the Knox Complex. Both of these units include Archean felsic to intermediate gneiss, mafic rock layers and felsic intrusions; they are differentiated only by the presence or absence of orthopyroxene. However, altered orthopyroxene relics or cores in hornblende were locally observed in subunits considered to be orthopyroxene-free (formerly Flat Point Gneiss).

Previously grouped in an undifferentiated unit in the Flat Point Gneiss, different lithologies were associated with different units depending on their composition. For example, felsic to intermediate gneiss, amphibolized gabbro and diorite, and tonalite and granodiorite intrusions were assigned respectively to subunits ApPgkx1b, ApPgkx2b and ApPgkx3b of the Knox Complex.

 

References

Author(s) Title Year of Publication Hyperlink (EXAMINE or Other)
HAMMOUCHE, H. – LEGOUIX, C. – GOUTIER, J. – DION, C. – PETRELLA, L. Géologie de la région du lac Bonaventure. Ministère des Ressources naturelles, Québec; RG 2011-03, 35 pages, 1 plan. 2011 RG 2011-03
JAMES, D.T. – CONNELLY, J.N. – WASTENEYS, H.A. – KILFOIL, G.J. Paleoproterozoic lithotectonic divisions of the southeastern Churchill Province, western Labrador. Canadian Journal of Earth Sciences; volume 33, pages 216–230. 1996 Source
LAFRANCE, I. – VANIER, M.-A. – CHARETTE, B.  Domaine lithotectonique de Baleine, sud-est de la Province de Churchill, Nunavik, Québec, Canada : synthèse de la géologie. Ministère de l’Énergie et des Ressources naturelles, Québec. In preparation Bulletin géologiQUE
LAFRANCE, I. – CHARETTE B. – VANIER, M.-A. Sud-est de la Province de Churchill, Nunavik, Québec, Canada : synthèse de la géologie. Ministère de l’Énergie et des Ressources naturelles, Québec. 2018 Preliminary BG

 

 

 

 

5 février 2020