Provenance of Cape Supergroup sediments and timing of Cape Fold Belt orogenesis: Constraints from high-precision 40Ar/39Ar dating of muscovite

Blewett, Scarlett C.J.; Phillips, David; Matchan, Erin

doi:10.1016/j.gr.2019.01.009

Cited by 15 publications

(2 citation statements)

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“…Moreover, analyses of low-K phases such as latest Pleistocene plagioclase phenocrysts (e.g., Carrasco-Nuñez et al, 2018) and Cenozoic pyroxene (e.g., Ware and Jourdan, 2018;Konrad et al, 2019) are now feasible. Higher precision on smaller and younger detrital grains is improving our understanding of progressive, grain size-specific detrital signal dilution in rivers, and our ability to provide robust provenance signals obtained for sediments located many hundreds of kilometers away from their source rocks (e.g., Blewett et al, 2019;Gemignani et al, 2019;Hereford et al, 2016).…”

Section: Modern Magnetic Sector Mass Spectrometrymentioning

confidence: 99%

Interpreting and reporting 40Ar/39Ar geochronologic data

et al. 2020

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The 40Ar/39Ar dating method is among the most versatile of geochronometers, having the potential to date a broad variety of K-bearing materials spanning from the time of Earth’s formation into the historical realm. Measurements using modern noble-gas mass spectrometers are now producing 40Ar/39Ar dates with analytical uncertainties of ∼0.1%, thereby providing precise time constraints for a wide range of geologic and extraterrestrial processes. Analyses of increasingly smaller subsamples have revealed age dispersion in many materials, including some minerals used as neutron fluence monitors. Accordingly, interpretive strategies are evolving to address observed dispersion in dates from a single sample. Moreover, inferring a geologically meaningful “age” from a measured “date” or set of dates is dependent on the geological problem being addressed and the salient assumptions associated with each set of data. We highlight requirements for collateral information that will better constrain the interpretation of 40Ar/39Ar data sets, including those associated with single-crystal fusion analyses, incremental heating experiments, and in situ analyses of microsampled domains. To ensure the utility and viability of published results, we emphasize previous recommendations for reporting 40Ar/39Ar data and the related essential metadata, with the amendment that data conform to evolving standards of being findable, accessible, interoperable, and reusable (FAIR) by both humans and computers. Our examples provide guidance for the presentation and interpretation of 40Ar/39Ar dates to maximize their interdisciplinary usage, reproducibility, and longevity.

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Section: Modern Magnetic Sector Mass Spectrometrymentioning

confidence: 99%

Interpreting and reporting 40Ar/39Ar geochronologic data

et al. 2020

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“…The transport and deposition of K-bearing minerals can mean the 40 Ar/ 39 Ar signature of minerals within sedimentary rocks is representative of events in the source region, rather than indicative of new mineral growth or resetting. This principle has been applied in many settings to reconstruct the early history of orogenic regions now eroded (Stuart, 2002;Blewett et al, 2019), including in the continental foreland basin of the Himalayas (Najman et al, 1997), and the Lachlan Orogen of eastern Australia (Fergusson and Phillips, 2001). As discussed by Fergusson and Phillips (2001) the relative input of different detrital minerals in a whole rock analysis will depend on the abundance, grain size, argon retentivity and respective ages of the different detrital components.…”

Section: Detrital 40 Ar/ 39 Ar Signaturesmentioning

confidence: 99%

Complex ⁴⁰Ar/³⁹Ar age spectra from low metamorphic grade rocks: resolving the input of detrital and metamorphic components in a case study from the Delamerian Orogen

Reid

Forster

Preiss

et al. 2021

Preprint

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Abstract. Low metamorphic grade rocks contain both detrital minerals and minerals newly grown or partly recrystallised during diagenesis and metamorphism. However, rocks such as these typically yield complex 40Ar/39Ar age spectra that can be difficult to interpret. In this study, we have analysed a suite of variably deformed rocks from a region of low metamorphic grade within the c. 514–490 Ma Delamerian Orogen, South Australia. The samples analysed range from siltstone and shale to phyllite and all contain either muscovite or phengite determined by hyperspectral mineralogical characterisation. Furnace step heating 40Ar/39Ar analysis produced complex apparent age spectra with multiple age components. Using the concept of asymptotes that define minimum and maximum ages for different components, we interpret the age spectra to preserve a range of detrital mineral ages, along with younger components related to either cooling or deformation- induced recrystallisation. Two samples contain Mesoproterozoic detrital age components, up to c. 1170 Ma, while the c. 515 Ma Heatherdale Shale which has both c. 566 Ma and c. 530 Ma detrital components. All samples contain younger lower (younger) asymptotes in the age spectra defined from multiple heating steps that range from c. 476 to c. 460 Ma. One interpretation of these younger ages is that they are caused by post-metamorphic cooling. However, the shape of the age spectra and the degree of deformation in the phyllites suggest the ages may record recrystallisation of detrital minerals and/or new mica growth during deformation. Potentially these c. 476 to c. 460 Ma ages suggest deformation in the upper portion of the orogen was facilitated by movement along regional faults and shear zones up to around 20 million years after the cessation of deformation in the high-metamorphic grade regions of the Delamerian Orogen.

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Early Triassic Legoupil Formation in Schmidt Peninsula, Antarctic Peninsula: Provenance and Depositional Settings

Zhang,

Cui,

Liu

et al. 2024

J. Earth Sci.

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Provenance of Cape Supergroup sediments and timing of Cape Fold Belt orogenesis: Constraints from high-precision 40Ar/39Ar dating of muscovite

Cited by 15 publications

References 80 publications

Interpreting and reporting 40Ar/39Ar geochronologic data

Interpreting and reporting 40Ar/39Ar geochronologic data

Complex ⁴⁰Ar/³⁹Ar age spectra from low metamorphic grade rocks: resolving the input of detrital and metamorphic components in a case study from the Delamerian Orogen

Early Triassic Legoupil Formation in Schmidt Peninsula, Antarctic Peninsula: Provenance and Depositional Settings

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Provenance of Cape Supergroup sediments and timing of Cape Fold Belt orogenesis: Constraints from high-precision 40Ar/39Ar dating of muscovite

Cited by 15 publications

References 80 publications

Interpreting and reporting 40Ar/39Ar geochronologic data

Interpreting and reporting 40Ar/39Ar geochronologic data

Complex 40Ar/39Ar age spectra from low metamorphic grade rocks: resolving the input of detrital and metamorphic components in a case study from the Delamerian Orogen

Early Triassic Legoupil Formation in Schmidt Peninsula, Antarctic Peninsula: Provenance and Depositional Settings

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Complex ⁴⁰Ar/³⁹Ar age spectra from low metamorphic grade rocks: resolving the input of detrital and metamorphic components in a case study from the Delamerian Orogen