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TitleMafic, ultramafic and layered mafic-ultramafic sills, Meta Incognita Peninsula, southern Baffin Island, Nunavut
AuthorSt-Onge, M R; Rayner, N MORCID logo; Liikane, D; Chadwick, T
SourceCanada-Nunavut Geoscience Office, Summary of Activities 2014, 2015 p. 11-16 Open Access logo Open Access
LinksOnline - En ligne
Alt SeriesEarth Sciences Sector, Contribution Series 20140285
PublisherCanada-Nunavut Geoscience Office
File formatpdf
NTS25I; 25J; 25K; 25L; 25M; 25N; 25O; 25P
AreaIqaluit; Kimmirut; Meta Incognita
Lat/Long WENS -72.0000 -64.0000 64.0000 62.0000
Subjectsgeneral geology; geochemistry; igneous and metamorphic petrology; structural geology; tectonics; metasedimentary rocks; metavolcanic rocks; ultramafic metavolcanics; sills; deformation; tectonic environments; tectonic history; tectonic interpretations; mafic metavolcanic rocks; metamorphic environment; metamorphic rocks; gneisses; meta-semipelites; metapelites; metapsammites; psammites; pelites; petrography; magmatic deposits; magmatic rocks; pyroxenites; peridotites; whole rock geochemistry; geochronometry
Illustrationslocation maps; photographs
ProgramGEM2: Geo-mapping for Energy and Minerals Baffin Bedrock Mapping
Released2015 01 01
AbstractThis paper summarizes the 2014 field observations on a suite of mafic, ultramafic and layered mafic-ultramafic sills on Meta Incognita Peninsula, Baffin Island, Nunavut. The sills, several of which are up to hundreds ofmetres in thickness, are emplaced into the dominantly psammitic to pelitic sedimentary strata of themiddle Paleoproterozoic Lake Harbour Group. Layering in bothmafic and ultramafic bodies was observed on the centimetre tometre scale, withmany intrusions containing disseminated sulphide, some associated with ferricrete.Within individual sills, compositional differentiation can range from pyroxenite/peridotite layers at the intrusive base to gabbro and leucogabbro units at the top. Similar bodies have previously been documented elsewhere on southern Baffin Island (Foxe, Hall and western Meta Incognita peninsulas), and a mantle-derivedmagmatic province of this size potentially represents amajor large igneous province (LIP) eventwarranting further study. Forthcoming geochemical, petrological and geochronological analyses, part of anM.Sc. thesis on the petrology and geochemistry of the layered suite and associated mineralization, will be utilized to compare and improve on existing regional tectonic models of middle Paleoproterozoic extension in the eastern Trans-Hudson Orogen.
Summary(Plain Language Summary, not published)
In 2014, geological observations, measurements and sampling were completed on a swarm of sheet-like rock units (sills) that occur on the Meta Incognita Peninsula, Baffin Island, Nunavut. These rock bodies, several of which are up to hundreds of metres in thickness, were intruded into older rusty sedimentary rocks. Many of the intrusions contain small but observable quantities of metals (sulphides) and are associated with very rusty zones (gossans). Within individual intrusions, the type of rock can change from ultramafic (chocolate brown and dense rock) at the base to mafic (salt and pepper texture and lighter rock) at the top. Similar bodies have previously been documented elsewhere on southern Baffin Island, as well as on the Ungava Peninsula of northern Quebec where the sills are associated with nickel-copper-platinum group element mineral deposits (Kattiniq). The presence of these rocks on Baffin Island warrants further study and the samples collected in 2014 for geochemical analysis and dating will form part of a Masters in Science thesis at Carleton University (Ottawa).

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