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TitleGiant circumferential dyke swarms: catalogue and characteristics
AuthorBuchan, K L; Ernst, R E
SourceDyke swarms of the world: a modern perspective; by Srivastava, R (ed.); Ernst, R E (ed.); Peng, P (ed.); 2019 p. 1-44, 1
Alt SeriesNatural Resources Canada, Contribution Series 20180022
PublisherSpringer Singapore
Mediapaper; on-line; digital
File formatpdf
ProvinceCanada; British Columbia; Alberta; Saskatchewan; Manitoba; Ontario; Quebec; New Brunswick; Nova Scotia; Prince Edward Island; Newfoundland and Labrador; Northwest Territories; Yukon; Nunavut; Canada
NTS1; 2; 3; 10; 11; 12; 13; 14; 15; 16; 20; 21; 22; 23; 24; 25; 26; 27; 28; 29; 30; 31; 32; 33; 34; 35; 36; 37; 38; 39; 40; 41; 42; 43; 44; 45; 46; 47; 48; 49; 52; 53; 54; 55; 56; 57; 58; 59; 62; 63; 64; 65; 66; 67; 68; 69; 72; 73; 74; 75; 76; 77; 78; 79; 82; 83; 84; 85; 86; 87; 88; 89; 92; 93; 94; 95; 96; 97; 98; 99; 102; 103; 104; 105; 106; 107; 114O; 114P; 115; 116; 117; 120; 340; 560
Lat/Long WENS-180.0000 180.0000 90.0000 -90.0000
Subjectstectonics; extraterrestrial geology; Science and Technology; Nature and Environment; tectonic setting; magmatism; intrusions; dykes, mafic; mantle; grabens; fissures; crustal uplift; volcanism
Illustrationstables; geoscientific sketch maps; 3-D models
ProgramDirector General's Office of GSC Central and Northern Canada Branch
Released2018 11 20
AbstractGiant circumferential dyke swarms have a primary geometry that is quasi-circular or quasi-elliptical. Examples and possible examples described previously or identified in this study have outer diameters that range from ~450 to ~2500 km. There has been little study of these features. Here, we present a global catalogue of giant circumferential dyke swarms and discuss their characteristics. All of the identified giant circumferential swarms are of mafic composition. Many, but not all, are associated with a roughly coeval giant radiating dyke swarm whose focus is at or near the centre of the circumferential system. As giant radiating swarms are usually interpreted to focus above mantle plume centres and form a key component of the plumbing system of large igneous provinces (LIPs), it is likely that giant circumferential swarms linked to radiating systems are also plume and LIP related. The largest giant circumferential swarms have diameters comparable to the diameters postulated for the flattened heads of plumes that have risen from the core-mantle boundary, suggesting that they may be associated with the outer edge of a flattening or flattened mantle plume head. Smaller giant circumferential swarms could be linked with small plumes from the mid-mantle or with the edge of a magmatic underplate above a plume head. Giant circumferential dyke swarms on Earth may be analogues of coronae on Venus and similar features on Mars. Coronae are large tectono-magmatic features that typically consist of a quasi-circular or quasi-elliptical graben-fissure system and associated topography (central uplift or depression, and circular rim or moat). In some instances, they are linked to a giant radiating graben-fissure system and LIP-scale volcanism. Both radiating and circumferential graben on Venus and Mars have been interpreted to be underlain by dykes.
Summary(Plain Language Summary, not published)
Giant circumferential dyke swarms have a quasi-circular geometry and outer diameters up to 2500 km. We provide the first global catalogue of these poorly studied feature, with many identified for the first time herein. Some are centred at the focus of a similar-aged giant radiating dyke swarm. As giant radiating swarms are interpreted to focus above mantle plumes that rise from the core-mantle boundary and to form part of the plumbing system of flood basalt provinces, it is likely that many giant circumferential swarms are also related to flood basalt provinces and plumes. They may be generated from the edge of plumes as they flatten at the base of the lithosphere. Giant circumferential dyke swarms on Earth may be analogues for tectonomagmatic features on Venus, termed coronae, which consist of a quasi-circular annulus of fractures (interpreted to be underlain by dykes) and topography such as a central uplift, raised rim and/or moat.

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