The a B C's of Metasomatism in the North Atlantic Craton ; Characterized by Fluid Inclusions in Chidliak Diamonds’

2021 ◽  
Author(s):  
Oded Elazar ◽  
Herman Grutter ◽  
Yakov Weiss
Keyword(s):  
Fluid Inclusions ◽  
North Atlantic ◽  
The North ◽  
The North Atlantic ◽  
North Atlantic Craton

The Metasomatized Mantle beneath the North Atlantic Craton: Insights from Peridotite Xenoliths of the Chidliak Kimberlite Province (NE Canada)

2019 ◽  
Vol 60 (10) ◽  
pp. 1991-2024 ◽  
Author(s):  
M G Kopylova ◽  
E Tso ◽  
F Ma ◽  
J Liu ◽  
D G Pearson
Keyword(s):  
North Atlantic ◽  
Thermal State ◽  
Mineral Chemistry ◽  
Mantle Metasomatism ◽  
Labrador Sea ◽  
The North ◽  
Rock Types ◽  
History Of ◽  
The North Atlantic ◽  
North Atlantic Craton

Abstract We studied the petrography, mineralogy, thermobarometry and whole-rock chemistry of 120 peridotite and pyroxenite xenoliths collected from the 156–138 Ma Chidliak kimberlite province (Southern Baffin Island). Xenoliths from pipes CH-1, -6, -7 and -44 are divided into two garnet-bearing series, dunites–harzburgites–lherzolites and wehrlites–olivine pyroxenites. Both series show widely varying textures, from coarse to sheared, and textures of late formation of garnet and clinopyroxene. Some samples from the lherzolite series may contain spinel, whereas wehrlites may contain ilmenite. In CH-6, rare coarse samples of the lherzolite and wehrlite series were derived from P = 2·8 to 5·6 GPa, whereas predominant sheared and coarse samples of the lherzolite series coexist at P = 5·6–7·5 GPa. Kimberlites CH-1, -7, -44 sample mainly the deeper mantle, at P = 5·0–7·5 GPa, represented by coarse and sheared lherzolite and wehrlite series. The bulk of the pressure–temperature arrays defines a thermal state compatible with 35–39 mW m–2 surface heat flow, but a significant thermal disequilibrium was evident in the large isobaric thermal scatter, especially at depth, and in the low thermal gradients uncharacteristic of conduction. The whole-rock Si and Mg contents of the Chidliak xenoliths and their mineral chemistry reflect initial high levels of melt depletion typical of cratonic mantle and subsequent refertilization in Ca and Al. Unlike the more orthopyroxene-rich mantle of many other cratons, the Chidliak mantle is rich (∼83 vol%) in forsteritic olivine. We assign this to silicate–carbonate metasomatism, which triggered wehrlitization of the mantle. The Chidliak mantle resembles the Greenlandic part of the North Atlantic Craton, suggesting the former contiguous nature of their lithosphere before subsequent rifting into separate continental fragments. Another, more recent type of mantle metasomatism, which affected the Chidliak mantle, is characterized by elevated Ti in pyroxenes and garnet typical of all rock types from CH-1, -7 and -44. These metasomatic samples are largely absent from the CH-6 xenolith suite. The Ti imprint is most intense in xenoliths derived from depths equivalent to 5·5–6·5 GPa where it is associated with higher strain, the presence of sheared samples of the lherzolite series and higher temperatures varying isobarically by up to 200 °C. The horizontal scale of the thermal-metasomatic imprint is more ambiguous and could be as regional as tens of kilometers or as local as <1 km. The time-scale of this metasomatism relates to a conductive length-scale and could be as short as <1 Myr, shortly predating kimberlite formation. A complex protracted metasomatic history of the North Atlantic Craton reconstructed from Chidliak xenoliths matches emplacement patterns of deep CO2-rich and Ti-rich magmatism around the Labrador Sea prior to the craton rifting. The metasomatism may have played a pivotal role in thinning the North Atlantic Craton lithosphere adjacent to the Labrador Sea from ∼240 km in the Jurassic to ∼65 km in the Paleogene.

The Isua Supracrustal Belt of the North Atlantic Craton (Greenland)

2017 ◽  
pp. 563-592 ◽  
Author(s):  
A.P. Nutman ◽  
V.C. Bennett ◽  
C.R.L. Friend ◽  
A.R. Chivas
Keyword(s):  
North Atlantic ◽  
The North ◽  
Supracrustal Belt ◽  
The North Atlantic ◽  
North Atlantic Craton

Origin of cratonic lithospheric mantle roots: A geochemical study of peridotites from the North Atlantic Craton, West Greenland

2008 ◽  
Vol 274 (1-2) ◽  
pp. 24-33 ◽  
Author(s):  
N. Wittig ◽  
D.G. Pearson ◽  
M. Webb ◽  
C.J. Ottley ◽  
G.J. Irvine ◽  
...  
Keyword(s):  
North Atlantic ◽  
Lithospheric Mantle ◽  
West Greenland ◽  
The North ◽  
Geochemical Study ◽  
The North Atlantic ◽  
North Atlantic Craton

Very early Archean crustal-accretion complexes preserved in the North Atlantic craton

Geology ◽  
1991 ◽  
Vol 19 (8) ◽  
pp. 791 ◽  
Author(s):  
Allen P. Nutman ◽  
Kenneth D. Collerson
Keyword(s):  
North Atlantic ◽  
Crustal Accretion ◽  
The North ◽  
The North Atlantic ◽  
North Atlantic Craton

The Eoarchaean foundation of the North Atlantic Craton

2014 ◽  
Vol 389 (1) ◽  
pp. 261-279 ◽  
Author(s):  
Penelope J. Lancaster ◽  
Craig D. Storey ◽  
Chris J. Hawkesworth
Keyword(s):  
North Atlantic ◽  
The North ◽  
The North Atlantic ◽  
North Atlantic Craton

The Majorqaq Belt: A record of Neoarchaean orogenesis during final assembly of the North Atlantic Craton, southern West Greenland

Lithos ◽  
2015 ◽  
Vol 220-223 ◽  
pp. 253-271 ◽  
Author(s):  
Brendan Dyck ◽  
Barry L. Reno ◽  
Thomas F. Kokfelt
Keyword(s):  
North Atlantic ◽  
West Greenland ◽  
The North ◽  
Final Assembly ◽  
The North Atlantic ◽  
North Atlantic Craton

Metallogeny of the North Atlantic Craton in Greenland

2015 ◽  
Vol 79 (4) ◽  
pp. 815-855 ◽  
Author(s):  
Jochen Kolb ◽  
Leon Bagas ◽  
Marco L. Fiorentini
Keyword(s):  
North Atlantic ◽  
Gold Mineralization ◽  
Shear Zones ◽  
Orogenic Gold ◽  
Iron Formation ◽  
Iron Deposit ◽  
Lower Grade ◽  
The North ◽  
The North Atlantic ◽  
North Atlantic Craton

AbstractThe North Atlantic Craton (NAC) extends along the coasts of southern Greenland. At its northern and southern margins, Archaean rocks are overprinted by Palaeoproterozoic orogeny or overlain by younger rocks. Typical granite-greenstone and granite-gneiss complexes represent the entire Archaean, with a hiatus from ∼3.55–3.20 Ga. In the granulite- and amphibolite-facies terranes, the metallogeny comprises hypozonal orogenic gold and Ni-PGE-Cr-Ti-V in mafic-ultramafic magmatic systems. Gold occurrences are widespread around and south of the capital, Nuuk. Nickel mineralization in the Maniitsoq Ni project is hosted in the Norite belt; Cr and PGE in Qeqertarssuatsiaq, and Ti-V in Sinarsuk in the Fiskenæsset complex. The lower-grade metamorphic Isua greenstone belt hosts the >1000 Mt Isua iron deposit in an Eoarchaean banded iron formation. Major Neoarchaean shear zones host mesozonal orogenic gold mineralization over considerable strike length in South-West Greenland. The current metallogenic model of the NAC is based on low-resolution data and variable geological understanding, and prospecting has been the main exploration method. In order to generate a robust understanding of the metal endowment, it is necessary to apply an integrated and collective approach. The NAC is similar to other well-endowed Archaean terranes but is underexplored, and is therefore likely to host numerous targets for greenfields exploration.

Sign in / Sign up

Export Citation Format

Share Document