Geology of the northern Nain Plutonic Suite and its envelope rocks, Labrador

The northern part of the Nain Plutonic Suite (NPS) is dominated largely by anorthositic rocks but includes major layered intrusions such as Kiglapait and Hettasch, local smaller intrusions of gabbronorite and troctolitic rocks, and granitoid rocks of the Umiakovik Lake batholith. Several intrusions of monzonite, quartz monzonite and granite and minor intrusions of ferrodioritic rocks also form part of the Nain Plutonic Suite. The eastern margin of the anorthositic complex includes a wide zone of variably recrystallized, foliated, and hydrated rocks intruded by altered and fresh diabase dykes. Archean and Paleoproterozoic supracrustal and plutonic rocks of Nain and Churchill provinces form the host rocks to the Nain Plutonic Suite. These include the Paleoproterozoic Tasiuyak gneiss and Ramah Group of the Torngat orogen and foreland, respectively, as well as Snyder Group, and Archean metasedimentary rocks of the Nain craton. Accessory sulphide minerals in rocks of these units represented a potential sulphur source accessible to intruding basic magmas of the Nain Plutonic Suite.