Geochemical and numerical constraints on Neoarchean plate tectonics

Halla, Jaana; Hunen, Jeroen van; Heilimo, Esa; Hölttä, Pentti

doi:10.1016/j.precamres.2009.07.008

Cited by 210 publications

(82 citation statements)

References 39 publications

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“…This could indicate that these melts evolved in equilibrium with an eclogitic residue (Halla et al 2009), although the data are too few for a firm conclusion.…”

Section: Ga-old Ttg Gneissesmentioning

confidence: 99%

Archaean crustal evolution in West Africa: A new synthesis of the Archaean geology in Sierra Leone, Liberia, Guinea and Ivory Coast

Rollinson

2016

Precambrian Research

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A new synthesis of the geology and geochronology of the little-known Archaean rocks in Sierra Leone, Liberia, Guinea and Ivory Coast is presented in order to better understand the processes of Archaean crustal evolution in this region, and to attempt to interpret these data in the light of our current understanding of Archaean crustal evolution. In addition, this study seeks to identify those aspects of Archaean crustal evolution which are currently not known in this area and which need to become the subject of future studies, given the economic importance of this region in terms of the mineral deposits hosted in the Archaean rocks. These include greenstone-belt hosted iron ore, lode gold, chromite and columbite-tantalite and younger diamondiferous kimberlites intrusive into Archaean felsic gneisses.The new results show that this cratonic nucleus comprises of four main geological units: 1. The oldest crust is made up of 3.5-3.6 Ga TTG (tonalite-trondjemite-granodiorite) gneisses. These only outcrop in the east of the craton in Guinea but their presence is indicated elsewhere in the central part of the craton though xenocrystic zircon cores in younger rocks. 2. The major rock type found throughout the craton is 3.26-2.85 Ga TTG gneiss. In detail these magmas are thought to have formed in two episodes one between 3.05-3.26 Ga and the other between 2.85-2.96 Ga. The presence of inherited zircons in the younger suite indicate that this event represents the partial reworking of the older gneisses. 3.4 Ga eclogite xenoliths in kimberlite derived from the sub-continental lithospheric mantle are thought to be the restite after the partial melting of a basaltic protolith in the production of the TTG magmas. 3. Supracrustal rocks form linear belts infolded into the TTG gneisses and metamorphosed to amphibolite and granulite grade. They are of different sizes, contain a variety of lithological sequences and may be of several different ages. The larger supracrustal belts in Sierra Leone contain a thick basalt-komatiite sequence derived by the partial melting of two different mantle sources, unconformably overlain by a sedimentary formation. They are seen as an important resource for gold, iron-ore, chromite and columbite-tantalite. 4. A suite of late Archaean granitoids formed by the partial melting of the TTG gneisses in a craton wide deformation-metamorphic-partial melting event at 2800 +/-20 Ma. This thermal event is thought to be responsible for the stabilisation of the craton.This new synthesis highlights major geological and geochronological similarities between the Archaean rocks of Sierra Leone, Liberia, Guinea and Ivory Coast and those in the Reguibat Shield in the northern part of the West African Craton suggesting that the two regions were once more closely related.

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“…This could indicate that these melts evolved in equilibrium with an eclogitic residue (Halla et al 2009), although the data are too few for a firm conclusion.…”

Section: Ga-old Ttg Gneissesmentioning

confidence: 99%

Archaean crustal evolution in West Africa: A new synthesis of the Archaean geology in Sierra Leone, Liberia, Guinea and Ivory Coast

Rollinson

2016

Precambrian Research

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“…Recently, Heilimo et al (2010) and Laurent et al (2014a) defined sanukitoid as a granitoid suite with high compatible (Mg, Cr and Ni) and incompatible (K, Ba, Sr, P and light rare earth elements -LREE) elements, for a given SiO 2 content, which often are arranged as late-to post-tectonic batholiths and stocks, spatially and temporally associated with shear zones (Halla et al 2009). …”

Section: Introductionmentioning

confidence: 99%

Rio Maria granodiorite and associated rocks of Ourilândia do Norte – Carajás province: Petrography, geochemistry and implications for sanukitoid petrogenesis

Santos

Oliveira

2016

Journal of South American Earth Sciences

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“…The Neoarchean is a discernible era in the formation, evolution and stabilization of large volumes of continental crust (Moyen et al 2001;Martin and Moyen 2002;Halla et al 2009;Hawkesworth et al 2010;Rapp et al 2010;Laurent et al 2011;Heilimo et al 2013). This time period represents a transition to the generation of moderate to high pressure tonalite-trondhjemite-granodiorite (TTG), sanukitoid rocks, and high-K granite (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…This time period represents a transition to the generation of moderate to high pressure tonalite-trondhjemite-granodiorite (TTG), sanukitoid rocks, and high-K granite (e.g. Shirey and Hanson 1984;Smithies and Champion 2000;Martin et al 2005;Halla et al 2009;Rapp et al 2010;Laurent et al 2014) and the final stability of Archean cratons that had previously undergone rapid recycling (Hawkesworth et al 2010). The sanukitoid suite is composed of Neoarchean granitoid lithologies that contain both an 'arc-like' and 'mantlelike' signatures that reflect their generation from a mantle peridotite source, rich in incompatible elements (Stern et al 1989;Laurent et al 2014 and references therein).…”

Section: Introductionmentioning

confidence: 99%

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Neoarchean Mantle-derived Magmatism within the Repulse Bay Block, Melville Peninsula, Nunavut: Implications for Archean Crustal Extraction and Cratonization

LaFlamme

McFarlane

Corrigan

2015

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SUMMARYThe Repulse Bay block (RBb) of the southern Melville Peninsula, Nunavut, lies within the Rae craton and exposes a large (50,000 km 2 ) area of middle to lower crust. The block is composed of ca. 2.86 Ga and 2.73-2.71 Ga tonalite-trondhjemitegranodiorite (TTG) and granitic gneiss that was derived from an older 3.25 and 3.10 Ga crustal substrate. This period of crustal generation was followed by the emplacement of ca. 2.69-2.66 Ga enderbite, charnockite, and granitoid intrusions with entrained websterite xenoliths. These voluminous batholith-scale bodies (dehydrated and hydrated intrusions), and the associated websterite xenoliths, have similar whole rock geochemical properties, including fractionated light rare earth element (LREE)-heavy (H)REE whole rock patterns and negative Nb, Ti, and Ta anomalies. Dehydrated intrusions and websterite xenoliths also contain similar mineralogy (two pyroxene, biotite, interstitial amphibole) and similar pyroxene trace element compositions. Based on geochemical and mineralogical properties, the two lithologies are interpreted to be related by fractional crystallization, and to be the product of a magmatic cumulate processes. Reworking of the crust in a ca. 2.72 Ga subduction zone setting was followed by ca. 2.69 Ga upwelling of the asthenospheric mantle and the intrusion of massif-type granitoid plutons. Based on a dramatic increase in FeO, Zr, Hf, and LREE content of the most evolved granitoid components from the 2.69-2.66 Ga cumulate intrusion, we propose that those granitoid plutons were in part derived from a metasomatized mantle source enriched by fluids from the subducting oceanic slab that underwent further hybridization (via assimilation) with the crust. Large-scale, mantle-derived Neoarchean sanukitoid-type magmatism played a role in the development of a depleted lower crust and residual sub-continental lithospheric mantle, a crucial element in the preservation of the RBb. RÉSUMÉ

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Geochemical and numerical constraints on Neoarchean plate tectonics

Cited by 210 publications

References 39 publications

Archaean crustal evolution in West Africa: A new synthesis of the Archaean geology in Sierra Leone, Liberia, Guinea and Ivory Coast

Archaean crustal evolution in West Africa: A new synthesis of the Archaean geology in Sierra Leone, Liberia, Guinea and Ivory Coast

Rio Maria granodiorite and associated rocks of Ourilândia do Norte – Carajás province: Petrography, geochemistry and implications for sanukitoid petrogenesis

Neoarchean Mantle-derived Magmatism within the Repulse Bay Block, Melville Peninsula, Nunavut: Implications for Archean Crustal Extraction and Cratonization

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