SHRIMP U-Pb geochronology of Neoproterozoic Windermere Supergroup, central Idaho: Implications for rifting of western Laurentia and synchroneity of Sturtian glacial deposits

Lund, Karen; Aleinikoff, John N.; Evans, Karl V.; Fanning, Christopher

doi:10.1130/0016-7606(2003)115<0349:supgon>2.0.co;2

Cited by 179 publications

(139 citation statements)

References 62 publications

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“…770-735 Ma), and Marinoan (ca. 660-635 Ma) episodes, which repeat over time intervals of $30 million years (Frimmel et al, 1996;Allen et al, 2002;Lund et al, 2003;Zhou et al, 2004;Condon et al, 2005), as well as the Paleoproterozoic glacial events, suggest that the time interval was long enough, and that the weathering intensity was great enough to produce a deep regolith between glacial intervals.…”

Section: Syn-depositional Weatheringmentioning

confidence: 99%

Influence of chemical weathering on the composition of the continental crust: Insights from Li and Nd isotopes in bauxite profiles developed on Columbia River Basalts

Liu

Rudnick

McDonough

et al. 2013

Geochimica et Cosmochimica Acta

100

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Glacial diamictites, with ages ranging from $2900 to 0.01 Ma, record the changing composition of the upper continental crust through time (Gaschnig et al., 2014). Li concentrations and isotopic compositions, combined with Pb isotopic compositions, chemical index of alteration (CIA) values and relative Sr concentrations are used here to assess the degree of chemical weathering recorded in these deposits and the origin of this signature. The d Li values of most of the diamictites (ranging from À3.9 to +3.5) are lower than those of mantle-derived basalts (+3.7 ± 2, 2r), and the low d7 Li values are generally accompanied by high CIA and low Sr/Sr * values (or Sr depletion factor, Sr/Sr * = Sr/(Ce * Nd) 0.5 ), reflecting a weathering signature that may have derived from pre-depositional, syn-depositional, and/or post-depositional weathering processes. Profiles through three glacial diamictites with relatively high CIA (a fresh road cut of the Neoproterozoic Nantuo Formation (CIA = 62-69), and drill cores through the Paleoproterozoic Timeball Hill (CIA = 66-75) and Duitschland Formations (CIA = 84-91)) do not show evidence of significant post-depositional weathering. High Th/U, reflecting loss of uranium during oxidative weathering, is seen in all Paleozoic and Neoproterozoic diamictites and a few Paleoproterozoic deposits. Pb isotopic systematics suggest that this signature was largely inherited from preexisting crust, although a subset of samples (the Neoproterozoic Konnarock, Paleozoic Dwyka, and several of the Paleoproterozoic Duitschland samples) appears to have experienced postdepositional U loss. Modern glaciomarine sediments record little weathering (CIA = 47, Sr/Sr * = 0.7, d7 Li = +1.8), consistent with the cold temperatures accompanying glacial periods, and suggesting that limited syn-depositional weathering has occurred. Thus, the chemical weathering signature observed in ancient glacial diamictites appears to be largely inherited from the upper continental crust (UCC) over which the glaciers traversed. The strength of this weathering signature, based on the CIA, is greatest in the Mesoarchean and some of the Paleoproterozoic diamictites and is weaker in the Neoproterozoic and Phanerozoic glacial diamictites. Combining these data with data for Archean shales and other types of post-Paleoproterozoic sedimentary rocks (i.e., shales, mudstones, etc.), it appears that post-Paleoproterozoic upper continental crust experienced less intense chemical weathering, on average, than Archean and Paleoproterozoic upper continental crust.

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Section: Syn-depositional Weatheringmentioning

confidence: 99%

Influence of chemical weathering on the composition of the continental crust: Insights from Li and Nd isotopes in bauxite profiles developed on Columbia River Basalts

Liu

Rudnick

McDonough

et al. 2013

Geochimica et Cosmochimica Acta

100

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“…725 Ma for the Rapitan Group. Using regional correlations with the Shaler Supergroup, Young (1992) suggested that the iron formation is younger than 723 Ma (also see Rainbird et al 1996), which is supported by U-Pb zircon ages of interbedded tuffs and dropstones in correlative strata in Idaho (<717 Ma; >685 Ma; Lund et al 2003;Fanning and Link 2004) and a ca. 716 Ma interbedded tuff from correlated rocks in Yukon (Macdonald et al 2010).…”

Section: Stratiform Iron Formationmentioning

confidence: 90%

“…3A; Eisbacher 1978Eisbacher , 1981Yeo 1981Yeo , 1986Klein and Beukes 1993;Baldwin et al 2012). The Rapitan Group unconformably overlies either the Coates Lake Group, or Little Dal Group and was deposited after 750 Ma, the age of a granitic dropstone in tillite (Ross and Villeneuve 1997) and prior to 685 Ma, deduced by correlation to glacial equivalents in Idaho (Lund et al 2003;Fanning and Link 2004). Park (1997) used paleomagnetic poles and ages of the Franklin Sills to indicate deposition at low paleolatitudes at ca.…”

Section: Stratiform Iron Formationmentioning

confidence: 99%

“…716 Ma interbedded tuff from correlated rocks in Yukon (Macdonald et al 2010). On a grand scale, these glacial marine rocks are associated with the contested Sturtian snowball Earth episode (e.g., Hoffman and Schrag 2002;Young 2002;Eyles and Januszczak 2004;Harland 2007;Macdonald et al 2010), the nature of which has been questioned as the result of recent radiometric agedating (e.g., Lund et al 2003;Kendall et al 2006;Azmy et al 2008).…”

Section: Stratiform Iron Formationmentioning

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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“…Unradiogenic Hf-isotope compositions are observed in ca. 100-70 Ma Idaho Batholith zircons (Toth and Stacey, 1992;Lund et al, 2003;Gaschnig et al, 2009Gaschnig et al, , 2011Gaschnig et al, , 2013 (Fig. 7A and Table 3); however, WMB zircons also include more radiogenic grains and require an additional source.…”

Section: Upper Cretaceous Unitsmentioning

confidence: 99%

Evolution of the Jura-Cretaceous North American Cordilleran margin: Insights from detrital-zircon U-Pb and Hf isotopes of sedimentary units of the North Cascades Range, Washington

et al. 2017

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The U-Pb age and Hf-isotope composition of detrital zircons from Jurassic to Upper Cretaceous sedimentary rocks adjacent to the southern North Cascades-Coast Plutonic Complex continental magmatic arc document shifting provenance, the tectonic evolution of the arc system, and translation along the continental margin. Systematic changes in the detrital-zircon data provide insight that the western margin of North America evolved from: marginal basins adjacent to continent-fringing oceanic arcs (ca. 160-140 Ma); forearc basins adjacent to mid-Cretaceous (ca. 120-90 Ma) Andean-type continental arcs; and addition of a cratonic source to forearc and accretionary wedge units to Cordilleran arc systems in the mid-Late Cretaceous (ca. 85 Ma). Jurassic Methow terrane, Nooksack Formation, and western mélange belt units dominantly contain detrital zircons derived from accreted oceanic terranes, whereas Lower Cretaceous strata from the same units have age peaks that correspond to known pulses of magmatism in Cordilleran continental magmatic arc systems. The age peaks and Hf-isotope signature of the Jurassic and Lower Cretaceous strata are comparable to multiple sources exposed along the margin. In contrast, the Upper Cretaceous western mélange belt has distinct Precambrian zircon populations and unradiogenic Late Cretaceous zircons that are more similar to southwestern than northwestern Laurentian sources. Statistical comparisons confirm provenance similarities between rocks of the North Cascades and those 700-2000 km to the south and, thus, support marginparallel translation from as far as the latitude of southern California.

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SHRIMP U-Pb geochronology of Neoproterozoic Windermere Supergroup, central Idaho: Implications for rifting of western Laurentia and synchroneity of Sturtian glacial deposits

Cited by 179 publications

References 62 publications

Influence of chemical weathering on the composition of the continental crust: Insights from Li and Nd isotopes in bauxite profiles developed on Columbia River Basalts

Influence of chemical weathering on the composition of the continental crust: Insights from Li and Nd isotopes in bauxite profiles developed on Columbia River Basalts

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

Evolution of the Jura-Cretaceous North American Cordilleran margin: Insights from detrital-zircon U-Pb and Hf isotopes of sedimentary units of the North Cascades Range, Washington

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