Petrogenesis of the Mesoproterozoic (1.23 Ga) Sudbury dyke swarm and its questionable relationship to plate separation

J. G. Shellnutt, N. D. MacRae

研究成果: 雜誌貢獻期刊論文同行評審

19 引文 斯高帕斯(Scopus)


The Mesoproterozoic (~1. 23 Ga) Sudbury dyke swarm was emplaced at equatorial latitudes and cross-cuts the Grenville, Southern and Superior Provinces of the Canadian Shield. The dyke swarm has been linked to the break-up of the Mesoproterozoic supercontinent Columbia (1. 8 to 1. 3 Ga). The Sudbury dykes are alkaline olivine diabases that extend ~300 km to the W and NW from the Grenville Front. Major element trends and MELTS modeling indicate fractional crystallization of olivine and plagioclase. Detailed mineral chemical analyses across a 90-m-wide dyke shows a symmetric M-shaped pattern indicating vertical flow differentiation. The highest measured Fo value of olivine from the chilled margin of one dyke is 70, suggesting the parental magmas of the dykes were evolved. Unlike other dykes of the Canadian Shield, the Sudbury dykes do not show significant chemical variation across the length of the swarm. The Sudbury dykes have high Sr/Y (>10), La/Yb N (>5) and Sm/Yb PM (>2. 4) values indicating they originated from a garnet-bearing source. The low Th/Nb (<1. 5) values contrast with the low Nb/La (<0. 6) and La/Ba (~0. 4) values, suggesting a possible lithospheric mantle or subduction-modified mantle source. In the context of Grenvillian tectonics, the Sudbury dykes intruded the Laurentian craton and parautochthonous rocks. The dykes occupy pre-existing west to northwest trending faults, suggesting that they exploited regional structural heterogeneities during the closure of the Elzevir basin (i. e., 1,250 to 1,190 Ma). The alkaline composition, limited spatial-chemical variation, volume, geometry and regional geological context suggest that the dykes are not likely related to a mantle plume or the break-up of a supercontinent.

頁(從 - 到)3-23
期刊International Journal of Earth Sciences
出版狀態已發佈 - 2012 1月

ASJC Scopus subject areas

  • 地球與行星科學(全部)


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