Background

Description

Noodleook Complex 1 (Anoo1): Amphibolite

Noodleook Complex 2 (Anoo2): Tonalite, Quartz Diorite and Granodiorite Gneiss

The unit outcrops near the southern and eastern contact of the Killinek Suite. It occurs as decametric to hectometric continuous bands. It is composed of light grey gneiss of mainly tonalitic composition, but which also contains granodioritic and granitic bands and layers, and minor proportions of intermediate to mafic bands. Banding is sharp and regular. Tonalitic layers are not magnetic; however, the magnetic susceptibility of granitic layers is high. Centimetric banding is associated with alternating laminae of 1-20% mafic minerals. Some millimetric to centimetric bands are hololeucocratic, medium grained, commonly discontinuous and have igneous texture. These bands are interpreted as mobilisate. Gneiss also contains millimetric and centimetric amphibolite bands. In addition, the unit is commonly intruded by transposed layers of coarse-grained leuocratic granite, whitish and deformed.

The dominant ferromagnesian phases are brown biotite and green hornblende. Hornblende is most abundant in the most mafic bands. Biotite is rich in zircon inclusions. The other phases are muscovite and, in places, clinopyroxene. Opaque minerals, sphene and apatite are observed as accessory phases. The quartzofeldspathic matrix is fine to medium grained and granoblastic. In the most deformed zones, grain edge migration patterns are recognized and plagioclase twins arecurved. Quartz has undulatory extinction. Granodioritic to granitic bands contain orthose and myrmekites.

Noodleook Complex 2a (Anoo2a): Hornblende-Biotite Dioritic Gneiss

This subunit is composed of non-magnetic mesocratic dioritic gneiss. The foliated rock is homogeneous and has a dark grey patina and fresh surface. It differs from the surrounding tonalitic gneiss beds due to the lack of banding, quartz poverty (<5%) and high homogeneity. In thin section, plagioclase is even grained, and hornblende and brown biotite are in equal proportions. Opaque minerals and apatite are observed as accessory phases. 

Noodleook Complex 2b (Anoo2b): Tonalitic, Granodioritic and Dioritc Granulitic Gneiss

This subunit consists of the same lithologies as the main Anoo2 unit, but is distinguished by the presence of orthopyroxene. It includes granulitic gneiss varying in composition between tonalitic, granodioritic and dioritic. Subunit Anoo2b outcrops on the edge of Killinek Suite hypersthene intrusions, close to the contact between the latter and Tasiuyak Complex metatexites. It is also mapped as hectometric to kilometric klippes in the far north portion of the Torngat Mountains. Rocks in this subunit bear the brown sugar and olive colours characteristic of orthopyroxene-rich lithologies. The ferromagnesian phases are orthopyroxene, variably altered to iddingsite, red biotite, hornblende and, more scarcely, garnet. Accesory phases are opaque minerals, apatite and zircon. Plagioclase is sericitized. 

Noodleook Complex 3 (Anoo3): Paragneiss

Bands and klippes of metasedimentary rocks outcrop as interstratifications in gneiss. These rusty, small (metric) layers are rarely mapped to the work scale. They are composed of paragneiss and metatexite of sedimentary origin. Lesser amounts (<10%) of biotite, garnet, muscovite, sulphides and graphite are present.

Noodleook Complex 4 (Anoo4): Banded Diorite and Gabbro, Amphibolitized with Numerous White Tonalite Intrusions

This unit consists of intermediate to mafic lithologies, amphibolitized and medium-grained. Green foliated rocks show banding of metric composition emphasized by many transposed intrusions (10-50%) of leucocratic tonalite. The partially recrystallized quartzofeldspathic matrix consists of medium grains with irregular edges, but also fine-grained granoblastic zones. It consists of 35-70% sericitized plagioclase and 5-15% quartz with undalory exticntion. Ferromagnesian phases account for up to 60% of the mode. The majority of them are green hornblende in granoblastic clusters or corroded poikiloblastic crystals containing numerous fine and rounded quartz inclusions. Clinopyroxene, orthopyroxene, brown biotite and garnet are also observed. Accessory minerals are apatite, epidote, scapolite, sphene, zircon and opaque minerals. Magnetic susceptibility is variable.

Thickness and distribution

The Noodleook Complex forms bands from a few kilometres to a few tens of kilometres long with decimetric to hectometric apparent thicknesses. These bands are located primarily between the main unit of the Tasiuyak Complex and intrusions of the Killinek Suite in the Point Le Droit area (sheet 24P). Klippes and enclaves are also reported in the northern portion of the Torngat Mountains in the Grenfeld Sound area (sheet 25A).

Dating

In Quebec, three Archean ages were obtained from tonalitic orthogneiss samples (Anoo2): 2797.6 ±5.8 Ma and 2823 Ma ±51 Ma (David, 2020), as well as 2757 ±12 Ma (Connelly, 2001). 

In Labrador, Scott (1995) and Connelly (2001) made several datings in rocks of the Torngat Mountains. Ages between 2802 Ma and 2751 Ma have been obtained in samples of tonalite or tonalitic orthogneiss. A mafic orthogneiss (Anoo4) was dated at 2784 ±6 Ma. Some Paleoproterozoic crystallization ages suggest that some gneiss dated in Labrador may have a different origin. These Paleoproterozoic ages could also be associated with a first episode of partial melting.

Stratigraphic Relationship(s)

Noodleook Complex gneiss is cut by intrusions of the Killinek Suite. Contacts between the two units are transposed. Klippes of metasedimentary rocks from the Tasiuyak Complex are also interbedded in the Noodleook Complex gneiss. Diabase dykes of the Falcoz and Avayalik swarms intrude into rocks of the complex and show straight and sharp contact.

Paleontology

Does not apply.

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