Pulses in silicic arc magmatism initiate end-Permian climate instability and extinction

Chapman, Timothy; Milan, Luke; Metcalfe, Ian; Blevin, Phillip L.; Crowley, Jim

doi:10.1038/s41561-022-00934-1

Cited by 20 publications

(11 citation statements)

References 87 publications

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“…Moreover, the sharp decrease of pyrite sulfur isotope (δ 34 S) values coinciding with the extinction interval in the Bunnerong core provides evidence for increasing atmospheric sulfate concentrations, which have been previously linked to aerosol production by the STLIP 32 . Similarly, the 1783–1784 eruptions of the Laki volcano in Iceland (~70°N) caused coeval climate perturbations in the Southern Hemisphere 33 .…”

Section: Discussionmentioning

confidence: 99%

Mercury evidence from southern Pangea terrestrial sections for end-Permian global volcanic effects

Shen

Chen

et al. 2023

Nat Commun

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The latest Permian mass extinction (LPME) was triggered by magmatism of the Siberian Traps Large Igneous Province (STLIP), which left an extensive record of sedimentary Hg anomalies at Northern Hemisphere and tropical sites. Here, we present Hg records from terrestrial sites in southern Pangea, nearly antipodal to contemporaneous STLIP activity, providing insights into the global distribution of volcanogenic Hg during this event and its environmental processing. These profiles (two from Karoo Basin, South Africa; two from Sydney Basin, Australia) exhibit significant Hg enrichments within the uppermost Permian extinction interval as well as positive Δ199Hg excursions (to ~0.3‰), providing evidence of long-distance atmospheric transfer of volcanogenic Hg. These results demonstrate the far-reaching effects of the Siberian Traps as well as refine stratigraphic placement of the LPME interval in the Karoo Basin at a temporal resolution of ~105 years based on global isochronism of volcanogenic Hg anomalies.

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Section: Discussionmentioning

confidence: 99%

Mercury evidence from southern Pangea terrestrial sections for end-Permian global volcanic effects

Shen

Chen

et al. 2023

Nat Commun

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“…Samples GA1954029 (Parlour Mountain Leucomonzogranite) and GA1954030 (Gwydir River Monzogranite, originally called an adamellite in Cross and Blevin, 2010) both intrude the Wandsworth Volcanic Group, and thus they provide a youngest constraint for that group (Cross and Blevin, 2010). CA-ID-TIMS data for all these samples appear in Chapman et al (2022).…”

Section: Sample Descriptionsmentioning

confidence: 99%

Examination of the accuracy of SHRIMP U–Pb geochronology based on samples dated by both SHRIMP and CA-TIMS

Magee

Bodorkos²,

Lewis³

et al. 2023

Geochronology

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Abstract. Estimations of the reproducibility of U–Pb ages from SHRIMP (Sensitive High-Resolution Ion MicroProbe) instruments are based on data from studies that are nearly 2 decades old. Since that time, refinement of analytical procedures and operational improvements have reduced the historically identified uncertainties of SHRIMP U–Pb analysis. This paper investigates 36 SHRIMP thermal ionisation mass spectrometry (TIMS) double-dated “real-world” geologic samples from a variety of igneous rock types to better understand both geological and analytical sources of disagreement between the two dating methods. Geoscience Australia's (GA) use of high-precision chemical abrasion thermal ionisation mass spectrometry (CA-TIMS) for chronostratigraphy in Australian sedimentary basins has produced a substantial selection of precisely dated zircons, which we can use to cross-correlate the SHRIMP and CA-TIMS ages throughout the Phanerozoic. A total of 33 of the 36 ages were reported with external SHRIMP uncertainties less than 1 % (95 % confidence). Six of eight cases where the CA-TIMS age was outside the SHRIMP uncertainty envelope were in samples where the 95 % confidence interval of the reported SHRIMP age was below 0.66 % uncertainty, suggesting that SHRIMP analyses of untreated zircon with smaller uncertainties are probably overoptimistic. The mean age offset between SHRIMP and TIMS ages is 0.095 %, but the distribution appears bimodal. Geological explanations for age discrepancies between SHRIMP and CA-TIMS are suggested by considering intrusive and extrusive age results separately. All but one sample where the SHRIMP age is more than 0.25 % older are volcanic. This offset could be explained by the better single-grain age resolution of TIMS, allowing identification and exclusion of antecrysts from the eruptive population, while SHRIMP does not have a sufficient single-grain precision to deconvolve these populations – leading to an apparent older SHRIMP age. In contrast, SHRIMP ages from plutonic rocks – particularly plutonic rocks from the early Paleozoic – are typically younger than the CA-TIMS ages from the same samples, most likely reflecting Pb loss from non-chemically abraded SHRIMP zircons, while chemical abrasion of zircons prior to TIMS analysis destroyed or corrected these areas of Pb loss.

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“…Samples GA1954029, Parlour Mountain Leucomonzogranite and GA1954030, the Gwydir River Monzogranite (originally called an adamellite in Cross and Blevin (2010)) both intrude the Wandsworth Volcanics, and thus provide a youngest constraint for that group (Cross and Blevin 2010). CA-ID-TIMS data for all these samples appear in Chapman et al (2022).…”

Section: Sample Descriptionsmentioning

confidence: 99%

“…An additional sample of the Emmaville Volcanics, also part of the Wandsworth Volcanic Group, had a SHRIMP date published by Cross and Blevin (2013). The CA-ID-TIMS data for all Wandsworth Volcanic Group samples are in Chapman et al (2022).…”

Section: Sample Descriptionsmentioning

confidence: 99%

Examination of SHRIMP U-Pb zircon geochronology accuracy from samples dated by both SHRIMP and CA-TIMS

Magee

Bodorkos

Crowley

et al. 2022

Preprint

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Abstract. Estimations of the reproducibility of U-Pb ages from SHRIMP instruments are based on data from studies nearly two decades old. Since that time, refinement of analytical procedures and manufacturing and installation improvements may have reduced the fundamental uncertainties of SHRIMP U-Pb analysis. This paper investigates 35 SHRIMP-TIMS double-dated “real-world” geologic samples from a variety of igneous rock types to better understand both geological and analytical sources of disagreement between the two dating methods. Geoscience Australia’s (GA) use of high-precision chemical abrasion thermal ionization mass spectrometry (CA-TIMS) for chronostratigraphy in Australian sedimentary basins has produced a substantial selection of precisely dated zircons, which we can use to cross-correlate the SHRIMP and CA-TIMS ages throughout the Phanerozoic. Thirty-two of the 35 ages were reported with external SHRIMP uncertainties less than 1 % (95 % confidence), below previous estimates of the reproducibility limits of the SHRIMP. Six of eight cases where the CA-TIMS age was outside the SHRIMP uncertainty envelope were in samples where the reported SHRIMP age had a sub-0.66 % uncertainty, suggesting that SHRIMP analyses of untreated zircon which report smaller uncertainties are probably overoptimistic. The mean age-offset between SHRIMP and TIMS is 0.097 %, but the distribution is bimodal. Geological explanations for SHRIMP-CA-TIMS age discrepancies are uncovered by considering intrusive and extrusive age results separately. All but one sample where the SHRIMP age is more than 0.25 % older are volcanic. This offset could be explained by the better single-grain age-resolution of TIMS, allowing identification and exclusion of antecrysts from the eruptive population, while SHRIMP does not have a sufficient single-grain precision to deconvolve these populations – leading to an apparent older SHRIMP age. In contrast, SHRIMP ages from plutonic rocks- particularly plutonic rocks from the early Paleozoic- are typically younger than the CA-TIMS ages from the same samples, most likely reflecting Pb loss from non-chemically-abraded SHRIMP zircons, while chemical abrasion of zircons prior to TIMS analysis destroyed or corrected these areas of Pb loss.

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Pulses in silicic arc magmatism initiate end-Permian climate instability and extinction

Cited by 20 publications

References 87 publications

Mercury evidence from southern Pangea terrestrial sections for end-Permian global volcanic effects

Mercury evidence from southern Pangea terrestrial sections for end-Permian global volcanic effects

Examination of the accuracy of SHRIMP U–Pb geochronology based on samples dated by both SHRIMP and CA-TIMS

Examination of SHRIMP U-Pb zircon geochronology accuracy from samples dated by both SHRIMP and CA-TIMS

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