Preliminary results of detrital muscovite 40Ar/39Ar geochronology from the eastern Mackenzie Mountains and Mackenzie Plain, Northwest Territories

Powell, JH; Schneider, D A

doi:10.4095/292712

Cited by 3 publications

(2 citation statements)

References 1 publication

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“…The age of the Little Dal Group is bracketed between ca. 0.817 Ga (Ar-Ar detrital muscovite; Powell & Schneider, 2013) and 0.779 Ga (U-Pb on cross-cutting igneous rocks; Heaman et al, 1992;Jefferson & Parrish, 1989).…”

Section: Middle Neoproterozoic Stone Knife Formation and Snail Springmentioning

confidence: 99%

In situ trace metal analysis of Neoarchaean – Ordovician shallow‐marine microbial‐carbonate‐hosted pyrites

2015

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Pre-Cambrian atmospheric and oceanic redox evolutions are expressed in the inventory of redox-sensitive trace metals in marine sedimentary rocks. Most of the currently available information was derived from deep-water sedimentary rocks (black shale/banded iron formation). Many of the studied trace metals (e.g. Mo, U, Ni and Co) are sensitive to the composition of the exposed land surface and prevailing weathering style, and their oceanic inventory ultimately depends on the terrestrial flux. The validity of claims for increased/decreased terrestrial fluxes has remained untested as far as the shallow-marine environment is concerned. Here, the first systematic study of trace metal inventories of the shallow-marine environment by analysis of microbial carbonate-hosted pyrite, from ca. 2.65-0.52 Ga, is presented. A petrographic survey revealed a first-order difference in preservation of early diagenetic pyrite. Microbial carbonates formed before the 2.4 Ga great oxygenation event (GOE) are much richer in pyrite and contain pyrite grains of greater morphological variability but lesser chemical substitution than samples deposited after the GOE. This disparity in pyrite abundance and morphology is mirrored by the qualitative degree of preservation of organic matter (largely as kerogen). Thus, it seems that in microbial carbonates, pyrite formation and preservation were related to presence and preservation of organic C. Several redox-sensitive trace metals show interpretable temporal trends supporting earlier proposals derived from deep-water sedimentary rocks. Most notably, the shallow-water pyrite confirms a rise in the oceanic Mo inventory across the pre-Cambrian-Cambrian boundary, implying the establishment of efficient deep-ocean ventilation. The carbonate-hosted pyrite also confirms the Neoarchaean and early Palaeoproterozoic ocean had higher Ni concentration, which can now more firmly be attributed to a greater proportion of magnesian volcanic rock on land rather than a stronger hydrothermal flux of Ni. Additionally, systematic trends are reported for Co, As, and Zn, relating to terrestrial flux and oceanic productivity.

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Section: Middle Neoproterozoic Stone Knife Formation and Snail Springmentioning

confidence: 99%

In situ trace metal analysis of Neoarchaean – Ordovician shallow‐marine microbial‐carbonate‐hosted pyrites

2015

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“…The Imperial Formation was deposited in the Ellesmerian clastic wedge (Beranek et al, 2010;Lemieux et al, 2011), which blanketed much of the Canadian Arctic and northwest Laurentian margin during the Late Devonian and Early Mississippian. Although the Ellesmerian clastic wedge units are lithologically similar and have comparable detrital zircon (e.g., Beranek et al, 2010;Anfinson et al, 2012;Gehrels and Pecha, 2014) and muscovite ages (Powell and Schneider, 2013), the deposition of the Clarence River group predates Ellesmerian clastic wedge sedimentation, as it was deformed in the Early-Middle Devonian Romanzof event (Anderson et al, 1994;Lane, 2007;Lane et al, 2016). Furthermore, the Clarence River group is crosscut by regional Late Devonian plutonic rocks, which are thought to be a principal source of detritus in Ellesmerian Clastic wedge units (Beranek et al, 2010;Anfinson et al, 2012).…”

Section: N O R T H L a U R E N T I A N O R T H L A U R E N T I Amentioning

confidence: 99%

Detrital geochronology of pre-Mississippian strata in the northeastern Brooks Range, Alaska: Insights into the tectonic evolution of northern Laurentia

et al. 2016

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The Arctic Alaska terrane of northern Alaska and Yukon is one of several exotic terranes in the North American Cordillera with putative early Paleozoic connections to the northern Caledonian-Appalachian orogen. The U-Pb and 40 Ar/ 39 Ar isotopic data from detrital minerals in pre-Mississippian sedimentary units of the northeastern Brooks Range are presented here to investigate the consequences of Caledonian orogenesis on sediment dispersal trends and the paleogeography of northern Laurentia. Neoproterozoic-Cambrian siliciclastic rocks of the informal Firth River group and the Neruokpuk Formation were most likely deposited along a passive margin that sourced Archean and Paleoproterozoic basement rocks of the Canadian shield and reworked Mesoproterozoic and younger sedimentary units. These strata are overlain by a Lower Ordovician-Lower Devonian succession of fine-grained siliciclastic turbidites, herein referred to as the Clarence River group, which records a prominent shift in provenance most likely associated with the onset of the Caledonian-Appalachian orogeny in northeast Laurentia. U-Pb detrital zircon age populations of ca. 470-420 and 990-820 Ma, along with 40 Ar/ 39 Ar detrital muscovite ages of ca. 470-430 Ma, support provenance connections with the East Greenland Caledonides, Pearya, and Svalbard. Partially reset 40 Ar/ 39 Ar ages in these sedimentary successions are linked to low-grade metamorphism associated with the Early-Middle Devonian Romanzof orogeny, a poorly understood tectonic event in the Brooks Range that is possibly associated with the emplacement of an allochthonous oceanic assemblage, herein named the Whale Mountain allochthon.

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Orogens and detritus: unravelling the Mesoproterozoic tectonic geography of northern Australia through coupled detrital thermo- and geo-chronometers

Yang

Collins

Blades

et al. 2023

Australian Journal of Earth Sciences

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Preliminary results of detrital muscovite 40Ar/39Ar geochronology from the eastern Mackenzie Mountains and Mackenzie Plain, Northwest Territories

Cited by 3 publications

References 1 publication

In situ trace metal analysis of Neoarchaean – Ordovician shallow‐marine microbial‐carbonate‐hosted pyrites

In situ trace metal analysis of Neoarchaean – Ordovician shallow‐marine microbial‐carbonate‐hosted pyrites

Detrital geochronology of pre-Mississippian strata in the northeastern Brooks Range, Alaska: Insights into the tectonic evolution of northern Laurentia

Orogens and detritus: unravelling the Mesoproterozoic tectonic geography of northern Australia through coupled detrital thermo- and geo-chronometers

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