Nain province

In Labrador, Canada, the North Atlantic Craton is known as the Nain Province. The Nain geologic province was intruded by the Nain Plutonic Suite which divides the province into the northern Saglek block and the southern Hopedale block.

The North Atlantic Craton is exposed in parts of the coast of Labrador, parts of central Greenland, the Scourian Complex of northwestern Scotland and is unexposed in northern Norway. The North Atlantic Craton fragmented 2450 to 2000 million years ago. When North America and Europe rejoined, the North Atlantic Craton was triangular shaped with each side 600 km (370 mi); this unit was separated when the Labrador Sea formed 61 to 40 million years ago. The crust of the North Atlantic Craton varies between 28 to 38 km (17 to 24 mi) thick and its rocks are 85% granitoid gneisses. The Nain Province was intruded by the 1350- to 1290-million-year-old Nain Plutonic Suite; composite anorthosite-granitic intrusions which divide the Nain Province into the northern Saglek Block and the southern Hopedale Block.

In Labrador the North Atlantic Craton is known as the Nain Province or Nain Craton. The Nain Province is more than 600 kilometres (370 mi) long and 100 km (62 mi) wide. The gneisses of the Nain Province were last deformed and metamorphosed when two blocks docked together 2500 million years ago with a collisional boundary extending 200 km (120 mi) to the north and 150 km (93 mi) to the south of Nain, Labrador, Canada. These two blocks appear to represent two distinct Archean cratonic nuclei, each with its own mineral depositional history. Major granitic intrusions – the Wheeler Mountain, Halbach, Alliger, Sheet Hill, Loon Island, Red Island, and Satok Island intrusions – form a north-trending 150 km (93 mi) linear chain which have a southerly decrease in age – 2135-million-year-old Wheeler Mountain granite in the north to the 2025-million-year-old Satok Island monzonite in the south. The Nain Province was then intruded by the 1350- to 1290-million-year-old Nain Plutonic Suite; composite anorthosite-granitic intrusions which divide the Nain Province into the northern Saglek block and the southern Hopedale block. The Torngat orogen developed during the oblique convergence of the Superior and Nain Provinces 900 million years ago. The crystalline crust in the Nain Province is 38 km (24 mi) thick; it thins to 9 km (5.6 mi) thick in the shelf area of the Labrador margin, where it is covered with up to 8 km (5.0 mi) of sediments.

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