4.3 Article

Petrogenesis of the peralkaline Flowers River Igneous Suite and its significance to the development of the southern Nain Batholith

Journal

GEOLOGICAL MAGAZINE
Volume 158, Issue 11, Pages 1911-1936

Publisher

CAMBRIDGE UNIV PRESS
DOI: 10.1017/S0016756821000388

Keywords

Peralkaline granite; Nain Plutonic Suite; AMCG magmatism; U-Pb zircon geochronology; Proterozoic magmatism

Funding

  1. Geological Survey of Canada GEM-2 initiative

Ask authors/readers for more resources

The study of the Flowers River Igneous Suite in north-central Labrador clarified the timing and relationships among the igneous associations in the region using new U-Pb zircon geochronology. The research found that volcanism occurred in three discrete events, with each generation of volcanic rocks derived from its coeval intrusive suite. Shared geochemical affinities suggest a relationship between the volcanic rocks and their coeval intrusive suites in the region.
The Flowers River Igneous Suite of north-central Labrador comprises several discrete peralkaline granite ring intrusions and their coeval volcanic succession. The Flowers River Granite was emplaced into Mesoproterozoic-age anorthosite-mangerite-charnockite-granite (AMCG) -affinity rocks at the southernmost extent of the Nain Plutonic Suite coastal lineament batholith. New U-Pb zircon geochronology is presented to clarify the timing and relationships among the igneous associations exposed in the region. Fayalite-bearing AMCG granitoids in the region record ages of 1290 +/- 3 Ma, whereas the Flowers River Granite yields an age of 1281 +/- 3 Ma. Volcanism occurred in three discrete events, two of which coincided with emplacement of the AMCG and Flowers River suites, respectively. Shared geochemical affinities suggest that each generation of volcanic rocks was derived from its coeval intrusive suite. The third volcanic event occurred at 1271 +/- 3 Ma, and its products bear a broad geochemical resemblance to the second phase of volcanism. The surrounding AMCG-affinity ferrodiorites and fayalite-bearing granitoids display moderately enriched major- and trace-element signatures relative to equivalent lithologies found elsewhere in the Nain Plutonic Suite. Trace-element compositions also support a relationship between the Flowers River Granite and its AMCG-affinity host rocks, most likely via delayed partial melting of residual parental material in the lower crust. Enrichment manifested only in the southernmost part of the Nain Plutonic Suite as a result of its relative proximity to multiple Palaeoproterozoic tectonic boundaries. Repeated exposure to subduction-derived metasomatic fluids created a persistent region of enrichment in the underlying lithospheric mantle that was tapped during later melt generation, producing multiple successive moderately to strongly enriched magmatic episodes.

Authors

I am an author on this paper
Click your name to claim this paper and add it to your profile.

Reviews

Primary Rating

4.3
Not enough ratings

Secondary Ratings

Novelty
-
Significance
-
Scientific rigor
-
Rate this paper

Recommended

No Data Available
No Data Available