​40Ar/39Ar geochronology of terrestrial pyroxene

Ware, Bryant; Jourdan, Fred

doi:10.1016/j.gca.2018.04.002

Cited by 26 publications

(33 citation statements)

References 69 publications

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“…In both analyses, the K/Ca ratios of the pyroxene display a similar trend (Figures a and b), that is, largely constant in the range of 0.1–0.2 and 0.02–0.04, respectively, at the low heating steps until about 50% of the 39 Ar released, after which the ratios steadily decrease and diminish toward the end of the heating processes. This spectrum is analogous to that observed in pyroxene from Phanerozoic dolerites and basalts (Ware & Jourdan, ). These authors demonstrated that the high K/Ca ratios shown by the pyroxene samples are readily attributed to the coexisting clinopyroxene varieties (i.e., high‐Ca augite vs. low‐Ca pigeonite) being analyzed.…”

Section: Resultssupporting

confidence: 80%

“…The new age constraint from the Keene Basalt supports the correlation of much of the Buldya Group in the western Officer Basin with the Burra Group in the Adelaide Rift Complex and is consistent with available age constraints on the timing of onset of the Cryogenian glaciations (e.g., Macdonald et al, ; Rooney et al, ). As demonstrated by Ware and Jourdan () and the present study, 40 Ar/ 39 Ar dating of pyroxene and plagioclase from the same sample can yield robust and matching crystallization ages of the host rocks when pure crystals of each mineral are dated. Mineral alteration and presence of exsolution lamellae within pyroxene are possible complications that may cause failure of obtaining meaningful plateau ages.…”

Section: Discussionsupporting

confidence: 78%

“…These authors demonstrated that the high K/Ca ratios shown by the pyroxene samples are readily attributed to the coexisting clinopyroxene varieties (i.e., high‐Ca augite vs. low‐Ca pigeonite) being analyzed. Ware and Jourdan () also hypothesized that presence of exsolution lamellae within pyroxene may induce argon loss through recoil redistribution. However, the exsolution process usually occurs during cooling of intrusive rocks, and exsolution lamellae is not observed in thin sections of the Keene Basalt samples.…”

Section: Resultsmentioning

confidence: 99%

“…The raw data were processed using the ArArCALC software (Koppers, ). An extended description of analytical parameters and data processing procedures is given in Text S1, and readers are referred to Ware and Jourdan () for further details.…”

Section: Methodsmentioning

confidence: 99%

“…Dating terrestrial pyroxene has proven more challenging largely due to excess 40 Ar and exceedingly low 39 Ar signal in such samples, which results in difficulties in acquiring precise and meaningful results (Harrison & McDougall, ; Lanphere & Dalrymple, ). However, a recent study by Ware and Jourdan () has shown that pyroxene can now be precisely dated using a new generation of multi‐collector noble gas mass spectrometers. This paper focuses on a basaltic lava, the Keene Basalt, in the Neoproterozoic Officer Basin of central Australia, and represents the first successful application of the new 40 Ar/ 39 Ar pyroxene approach to a Precambrian basaltic lava.…”

Section: Introductionmentioning

confidence: 99%

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Pyroxene ⁴⁰Ar/³⁹Ar Dating of Basalt and Applications to Large Igneous Provinces and Precambrian Stratigraphic Correlations

Haines

Wang

et al. 2019

JGR Solid Earth

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Correlations within and between Precambrian basins are heavily reliant on precise dating of volcanic units (i.e., tuff beds and lava flows) in the absence of biostratigraphy. However, felsic tuffs and lavas are rare or absent in many basins, and direct age determinations of Precambrian basaltic lavas have proven to be challenging. In this paper, we report the first successful application of 40Ar/39Ar dating to pyroxene from a Neoproterozoic basalt unit, the Keene Basalt in the Officer Basin of central Australia. 40Ar/39Ar analyses of igneous pyroxene crystals yielded an age of 752 ± 4 Ma (mean squared weighted deviation = 0.69, p = 72%), which is underpinned by 40Ar/39Ar plagioclase age (753.04 ± 0.84 Ma) from the basalt. This age is significant because the Keene Basalt is one of the very few extrusive igneous rocks identified within the Neoproterozoic successions of central Australia and is potentially an important time marker for correlating the Neoproterozoic stratigraphy within, and beyond, the central Australian basins. Our geochronological and geochemical data show that the Keene Basalt, which is characterized by enriched elemental and Nd‐Pb isotopic signatures, is strikingly similar to, and coeval with, the 755 ± 3 Ma Mundine Well Dolerite in northwestern Australia. Here we suggest that both are part of the same large igneous province (~6.5 × 105 km2) related to breakup of the supercontinent Rodinia. This study demonstrates the potential of pyroxene 40Ar/39Ar geochronology to date ancient flood basalts and to provide pivotal time constraints for stratigraphic correlations of Precambrian basins.

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Section: Resultssupporting

confidence: 80%

Section: Discussionsupporting

confidence: 78%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Pyroxene ⁴⁰Ar/³⁹Ar Dating of Basalt and Applications to Large Igneous Provinces and Precambrian Stratigraphic Correlations

Haines

Wang

et al. 2019

JGR Solid Earth

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Was the Kalkarindji Continental Flood Basalt Province a Driver of Environmental Change at the Dawn of the Phanerozoic?

Marshall

Faggetter

Widdowson

2021

Geophysical Monograph Series

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The Kalkarindji continental flood basalt province of Northern Australia is the oldest basaltic LIP in the Phanerozoic having erupted in the mid-Cambrian. At this time, during the Cambrian Explosion, the global environment suffered a series of mass extinctions and biotic turnover. Kalkarindji had the potential to release 1.65 x 10 6 Tg of CO 2 , approximately 1.72% of the total Cambrian atmospheric carbon reservoir. It has there fore been implicated as a driver of the environmental changes in the Cambrian Series 2. However, temporal discrepancies between Kalkarindji eruptions and biotic turnover may prevent this LIP from being attributed as the sole cause of the Botomian-Toyonian Extinction, which wiped out up to 45% of all genera in the fossil record; while environmental factors such as sea-level change causing ocean anoxia are implicated in the Redlichiid-Olenellid Extinction. It is certainly possible that Kalkarindji could have played a part in forcing these environmental changes, but further advances in geochronology and sedimentary volcanic proxies are needed to confidently define a direct causational link between these events at the dawn of the Phanerozoic.

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Radiometric Constraints on the Timing, Tempo, and Effects of Large Igneous Province Emplacement

Kasbohm

Schoene

Burgess

2021

Large Igneous Provinces

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There is an apparent temporal correlation between large igneous province (LIP) emplacement and global environmental crises, including mass extinctions. Advances in the precision and accuracy of geochronology in the past decade have significantly improved estimates of the timing and duration of LIP emplacement, mass extinction events, and global climate perturbations, and in general have supported a temporal link between them. In this chapter, we review available geochronology of LIPs and of global extinction or climate events. We begin with an overview of the methodological advances permitting improved precision and accuracy in LIP geochronology. We then review the characteristics and geochronology of 12 LIP/event couplets from the past 700 Ma of Earth history, comparing the relative timing of magmatism and global change, and assessing the chronologic support for LIPs playing a causal role in Earth's climatic and biotic crises. We find that (1) improved geochronology in the last decade has shown that nearly all well-dated LIPs erupted in < 1 Ma, irrespective of tectonic setting; (2) for well-dated LIPs with correspondingly well-dated mass extinctions, the LIPs began several hundred ka prior to a relatively short duration extinction event; and (3) for LIPs with a convincing temporal connection to mass extinctions, there seems to be no single characteristic that makes a LIP deadly. Despite much progress, higher precision geochronology of both eruptive and intrusive LIP events and better chronologies from extinction and climate proxy records will be required to further understand how these catastrophic volcanic events have changed the course of our planet's surface evolution.

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40Ar/39Ar geochronology of terrestrial pyroxene

Cited by 26 publications

References 69 publications

Pyroxene ⁴⁰Ar/³⁹Ar Dating of Basalt and Applications to Large Igneous Provinces and Precambrian Stratigraphic Correlations

Pyroxene ⁴⁰Ar/³⁹Ar Dating of Basalt and Applications to Large Igneous Provinces and Precambrian Stratigraphic Correlations

Was the Kalkarindji Continental Flood Basalt Province a Driver of Environmental Change at the Dawn of the Phanerozoic?

Radiometric Constraints on the Timing, Tempo, and Effects of Large Igneous Province Emplacement

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​40Ar/39Ar geochronology of terrestrial pyroxene

Cited by 26 publications

References 69 publications

Pyroxene 40Ar/39Ar Dating of Basalt and Applications to Large Igneous Provinces and Precambrian Stratigraphic Correlations

Pyroxene 40Ar/39Ar Dating of Basalt and Applications to Large Igneous Provinces and Precambrian Stratigraphic Correlations

Was the Kalkarindji Continental Flood Basalt Province a Driver of Environmental Change at the Dawn of the Phanerozoic?

Radiometric Constraints on the Timing, Tempo, and Effects of Large Igneous Province Emplacement

Contact Info

Product

Resources

About

40Ar/39Ar geochronology of terrestrial pyroxene

Pyroxene ⁴⁰Ar/³⁹Ar Dating of Basalt and Applications to Large Igneous Provinces and Precambrian Stratigraphic Correlations

Pyroxene ⁴⁰Ar/³⁹Ar Dating of Basalt and Applications to Large Igneous Provinces and Precambrian Stratigraphic Correlations