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The Kivalliq Igneous Suite: Anorogenic bimodal magmatism at 1.75Ga in the western Churchill Province, Canada

Peterson, Tony D. ; Scott, Jeffrey M.J. ; LeCheminant, Anthony N. ; Jefferson, Charles W. ; Pehrsson, Sally J.

Precambrian research, 2015-06, Vol.262, p.101-119 [Periódico revisado por pares]

Elsevier B.V

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  • Título:
    The Kivalliq Igneous Suite: Anorogenic bimodal magmatism at 1.75Ga in the western Churchill Province, Canada
  • Autor: Peterson, Tony D. ; Scott, Jeffrey M.J. ; LeCheminant, Anthony N. ; Jefferson, Charles W. ; Pehrsson, Sally J.
  • Assuntos: Anorogenic granite ; Churchill Province ; Kivalliq ; Mafic dyke swarm ; Nuna ; Proterozoic
  • É parte de: Precambrian research, 2015-06, Vol.262, p.101-119
  • Descrição: •We define the 1.75Ga Kivalliq anorogenic suite of the western Churchill Province.•The bimodal suite (intrusive/extrusive) encompasses an area of 1700km×700km.•It is accompanied by an unusually extensive sedimentary record.•It is one of the oldest anorogenic suites of Nuna.•Economic prospects include epithermal Au, REE, U, and Pb–Cu systems. The Kivalliq Igneous Suite (1.77–1.73Ga) includes the Nueltin Granite intrusions; gabbro and anorthosite intrusions; three swarms of mafic dykes; and basalt, rhyolite and pyroclastic rocks of the Pitz Formation (Wharton Group, middle Dubawnt Supergroup). It was emplaced in the reworked Archaean hinterland of the trans-Hudson orogen, in the central western Churchill Province (WCP) of the Canadian Shield. The Nueltin granites have field relations, mineral assemblages, and compositions typical of metaluminous to peraluminous, Proterozoic to Recent rapakivi granites, and the suite comprises a classic bimodal anorogenic province. Kivalliq rhyolites/granites were erupted/emplaced in a N–S band (the “Nueltin corridor”) about 700km long and 300km wide, with volcanic rocks and dykes concentrated at the north end and coarse plutonic rocks to the south. The McRae Lake dyke swarm originates among three prominent gabbro/anorthosite intrusions inside the corridor, and forms a narrow array extending a minimum of 600km to the NE along the central axis of the WCP. Early mafic rocks (intrusions and some lavas, 1.77Ga) had an alkali basalt parent, with subalkaline basalts (sills, dykes, and mafic enclaves) present at the peak time of granite emplacement (1.75Ga). Average initial ɛNd of basaltic rocks at 1.75Ga is −4.0, indicating a significant crustal component. Sm–Nd depleted mantle model ages of granites and rhyolites (average initial ɛNd=−8.7) range from 2.2 to 3Ga, consistent with melted Archaean crust variably mixed with juvenile basalt. Metallogenic prospects of the Kivalliq Suite include U–Th–Zr–Y–REE enriched granite and syenite, epithermal Ag/Au at silicic centres (including mafic/felsic ring complexes), and Pb–Cu sulphides associated with mafic intrusions. Topaz rhyolites are present, but Sn-enriched rocks have not been observed. The Kivalliq Suite is one of about 15 prominent anorogenic provinces and dyke swarms which erupted within the Nuna supercontinent at ca. 1.75Ga, and the thermal effects of the Kivalliq event are recorded in U–Pb and K–Ar data throughout most of the western Churchill Province.
  • Editor: Elsevier B.V
  • Idioma: Inglês
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  • Realização: ABCD-USP USP   Logos de Redes Sociais: Freepik

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