Gunbarrel mafic magmatic event: A key 780 Ma time marker for Rodinia plate reconstructions

Harlan, Stephen S.; Heaman, Larry M.; LeCheminant, A N; Premo, Wayne R.

doi:10.1130/g19944.1

Cited by 186 publications

(95 citation statements)

References 27 publications

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“…The Coates Lake Group of the Mackenzie Mountains forms the base of the Windermere Supergroup and consists of siliciclastic, carbonate, and evaporitic strata of the Thundercloud, Redstone River, and Coppercap formations. The Coates Lake Group unconformably overlies the Little Dal basalt, which has been correlated geochemically with the Tsezotene sills (10), a 777 +2.5/−1.8 Mya ( 206 Pb/ 238 U multigrain zircon thermal ionization MS date) quartz diorite plug near Coates Lake (11), and the ∼780-Mya Gunbarrel magmatic event (12).…”

Section: Stratigraphy Of the Neoproterozoic Windermere Supergroupmentioning

confidence: 99%

Re-Os geochronology and coupled Os-Sr isotope constraints on the Sturtian snowball Earth

Rooney

Macdonald

Strauss

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

228

158

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After nearly a billion years with no evidence for glaciation, ice advanced to equatorial latitudes at least twice between 717 and 635 Mya. Although the initiation mechanism of these Neoproterozoic Snowball Earth events has remained a mystery, the broad synchronicity of rifting of the supercontinent Rodinia, the emplacement of large igneous provinces at low latitude, and the onset of the Sturtian glaciation has suggested a tectonic forcing. We present unique Re-Os geochronology and high-resolution Os and Sr isotope profiles bracketing Sturtian-age glacial deposits of the Rapitan Group in northwest Canada. Coupled with existing U-Pb dates, the postglacial Re-Os date of 662.4 ± 3.9 Mya represents direct geochronological constraints for both the onset and demise of a Cryogenian glaciation from the same continental margin and suggests a 55-My duration of the Sturtian glacial epoch. The Os and Sr isotope data allow us to assess the relative weathering input of old radiogenic crust and more juvenile, mantle-derived substrate. The preglacial isotopic signals are consistent with an enhanced contribution of juvenile material to the oceans and glacial initiation through enhanced global weatherability. In contrast, postglacial strata feature radiogenic Os and Sr isotope compositions indicative of extensive glacial scouring of the continents and intense silicate weathering in a post-Snowball Earth hothouse.rhenium-osmium geochronology | strontium isotopes | osmium isotopes | Windermere Supergroup | Neoproterozoic glaciation T he Snowball Earth hypothesis predicts that Neoproterozoic glaciations were global and synchronous at low latitudes and that deglaciation occurred as a result of the buildup of pCO 2 to extreme levels resulting in a "greenhouse" aftermath (1, 2). The temporal framework of Cryogenian glaciations is built on chemostratigraphy and correlation of lithologically distinct units, such as glaciogenic deposits, iron formation, and cap carbonates (3), tied to the few successions that contain volcanic rocks dated using U-Pb zircon geochronology (4). In strata lacking horizons suitable for U-Pb geochronology, Re-Os geochronology can provide depositional ages on organic-rich sedimentary rocks bracketing glaciogenic strata (5, 6). Moreover, Os isotope stratigraphy can be used as a proxy to test for supergreenhouse weathering during deglaciation (7). In a Snowball Earth scenario, we can make specific predictions for Cryogenian weathering: CO 2 consumption via silicate weathering should increase before glaciation, stagnate during the glaciation, and increase again during deglaciation. However, the use of a single weathering proxy to provide evidence for such a scenario, such as Sr isotopes from marine carbonates, is limited both by lithological constraints and an inability to distinguish between the amount of weathering and the composition of what is being weathered (8). The short residence time of Os in the present-day oceans (<10 ky) (9) provides a complementary higher resolution archive to Sr isotopes, and thus, insi...

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Section: Stratigraphy Of the Neoproterozoic Windermere Supergroupmentioning

confidence: 99%

Re-Os geochronology and coupled Os-Sr isotope constraints on the Sturtian snowball Earth

Rooney

Macdonald

Strauss

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

228

158

View full text Add to dashboard Cite

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“…780 Ma magmatic event stretching from Utah to the Yukon (Jefferson and Parrish, 1989;Harlan et al, 2003;Dehler et al, 2010;Spencer et al, 2012;Mahon et al, 2014;Kingsbury-Stewart et al, 2013), whereas rifting and associated magmatism along the eastern Laurentian margin occurred between 760 and 700 Ma (Su et al, 1994;Aleinkoff et al, 1995;Tollo and Hutson, 1996). Thermal subsidence studies show that the eventual rift-to-drift transition occurred along both margins at ca.…”

Section: Introductionmentioning

confidence: 99%

Detrital zircon geochronology of the Grenville/Llano foreland and basal Sauk Sequence in west Texas, USA

Spencer

Prave

Cawood

et al. 2014

Geological Society of America Bulletin

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“…In the MSM area, Neoproterozoic successions were deposited in extensional regimes (Narbonne and Aitken 1995;Turner and Long 2008), possibly in the vicinity of what is now Australia, Siberia, South China, Antarctica, or West Africa (Hoffman 1991;Park et al 1995;Rainbird et al 1996;Harlan et al 2003;Sears and Price 2003;Li et al 2004;Li et al 2007;Nelson and Colpron 2007;Evans 2009). The Neoproterozoic strata can be divided into two groups; the older Mackenzie Mountains Supergroup Turner and Long 2012) and the younger Windermere Supergroup (Fig.…”

Section: Neoproterozoicmentioning

confidence: 99%

“…A 778 Ma gabbro plug south of Coates Lake (Jefferson and Parrish 1989) and the cross-cutting ca. 780 Ma Tsezotene sills (Harlan et al 2003) provide a minimum age for the Mackenzie Mountains Supergroup. The Tsezotene sills are associated with the "Little Dal basalts" and are part of the Gunbarrel event (Dudás and Lustwerk 1997;Harlan et al 2003).…”

Section: Neoproterozoicmentioning

confidence: 99%

“…780 Ma Tsezotene sills (Harlan et al 2003) provide a minimum age for the Mackenzie Mountains Supergroup. The Tsezotene sills are associated with the "Little Dal basalts" and are part of the Gunbarrel event (Dudás and Lustwerk 1997;Harlan et al 2003). Stratigraphy, sedimentology, and regional correlations indicate that the overall depositional setting for the Mackenzie Mountains Supergroup was likely an epicratonic basin (Narbonne and Aitken 1995;Long et al 2008;Turner and Long 2008).…”

Section: Neoproterozoicmentioning

confidence: 99%

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Metallogenic Evolution of the Mackenzie and Eastern Selwyn Mountains of Canada’s Northern Cordillera, Northwest Territories: A Compilation and Review

Ootes

Gleeson

Turner

et al. 2013

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The Mackenzie and eastern Selwyn Mountains, Northwest Territories, Canada, are the northeast expression of the Cordilleran orogen and have a geologic history that spans the last one billion years. The region has undergone a diverse tectonic evolution, which is reflected in an equally diverse collection of mineral deposits and prospects. More than 300 of these deposits and prospects have been documented in this area of the Northwest Territories and here they are categorized into mineral deposit types and their mode of formation evaluated and highlighted. Stratiform/stratabound Cu-Ag occurrences are hosted in the Neoproterozoic Coates Lake Group, generally preserved in the hanging wall of the Cretaceous Plateau fault, and define a belt through the central part of the Mackenzie Mountains. Low-grade phosphatic stratiform iron (47.5% Fe) occurs as iron formation in the Neoproterozoic Rapitan Group in the very northwest of the Mackenzie Mountains. Sedimentary exhalative Zn-Pb (± Ba) deposits are preserved in Cambrian through Devonian strata of the Selwyn Basin in the eastern Selwyn Mountains. Numerous carbonate-hosted Zn-Pb (± base-metals) occurrences are located in the Paleozoic strata of the Mackenzie Platform in the Mackenzie Mountains. Cretaceous felsic-intermediate plutons, which occur throughout the eastern Selwyn Mountains, are associated with tungsten skarn (proximal to intrusions), base-metal skarn (distal from intrusions), rare metals, semi-precious tourmaline related to pegmatites, and vein-hosted emeralds. Other resources of potential interest include coal deposits, placer gold, and possible Carlin-type gold deposits that have recently been identified farther west in the Yukon.SOMMAIRELes monts Mackenzie et ceux de la chaîne orientale de Selwyn, dans les Territoires du Nord-Ouest, au Canada, sont l'expression au nord-est de l'orogène de la Cordillère, et leur histoire géologique s’étale sur le dernier milliard d’années. La région a été l’hôte d’une évolution tectonique diversifiée, et cela se reflète par une suite tout aussi diversifiée de gisements minéraux et d’indices prometteurs. Plus de 300 de ces dépôts et indices prometteurs ont été documentées dans cette région des Territoires du Nord-Ouest, et le présent article ils sont classés en types de gîtes minéraux, et l’attention est portée sur leur mode de formation. Les gisements de Cu-Ag stratiformes ou stratoïdes sont encaissés dans le Groupe néoprotérozoïque de Coates Lake, et ils sont généralement préservés dans l'éponte supérieure de la faille du plateau crétacé, et ils forment une bande qui traverse la partie centrale des monts Mackenzie. Le fer se retrouve dans des gisements phosphatées stratiformes à faible teneur (47,5% Fe) qui provient de formations de fer dans le Groupe néoprotérozoïque de Rapitan situé dans la pointe nord-ouest des monts Mackenzie. Des gisements sédimentaires exhalatifs de Zn-Pb (± Ba) sont préservés dans des strates cambriennes à dévoniennes du bassin de Selwyn dans la portion est des monts Selwyn. De nombreux indices de Zn-Pb (± métaux communs) dans des roches carbonatées des strates paléozoïques de la plate-forme de Mackenzie, des monts Mackenzie. Des plutons felsiques intermédiaires crétacés, qui pointent tout au long de la chaîne est de Selwyn, sont associées à des skarns de tungstène (proximaux), à des skarns de métaux communs (distaux), à des concentrations de métaux rares, de tourmaline semi-précieuses liés aux pegmatites, et à des émeraudes filoniennes. Parmi d’autres ressources d'intérêt, on retrouve des gisements de charbon, d'or alluvionnaire, et d’éventuels gisements d'or de type Carlin qui ont été découverts récemment plus à l'ouest au Yukon.

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Gunbarrel mafic magmatic event: A key 780 Ma time marker for Rodinia plate reconstructions

Cited by 186 publications

References 27 publications

Re-Os geochronology and coupled Os-Sr isotope constraints on the Sturtian snowball Earth

Re-Os geochronology and coupled Os-Sr isotope constraints on the Sturtian snowball Earth

Detrital zircon geochronology of the Grenville/Llano foreland and basal Sauk Sequence in west Texas, USA

Metallogenic Evolution of the Mackenzie and Eastern Selwyn Mountains of Canada’s Northern Cordillera, Northwest Territories: A Compilation and Review

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