An attempt to constrain the age, duration, and eruptive history of the Karoo flood basalt: Naude's Nek section (South Africa)
M. Moulin,M. Moulin,Frédéric Fluteau,Frédéric Fluteau,V. Courtillot,V. Courtillot,Julian S. Marsh,Guillaume Delpech,Guillaume Delpech,Xavier Quidelleur,Xavier Quidelleur,Martine Gérard,Anne E. Jay +12 more
TLDR
In this paper, the authors carried out paleomagnetic sampling of a similar to 750 m sequence of the Karoo large igneous province (Naude's Nek Pass, South Africa).Abstract:
We have carried out paleomagnetic sampling of a similar to 750 m sequence of the Karoo large igneous province (Naude's Nek Pass, South Africa). K-Ar dating (Cassignol-Gillot) has been performed on four samples from the 650 m upper unit (mean age 179.2 +/- 1.8 Ma) and a sample from the lower unit (184.8 +/- 2.6 Ma). A succession of two phases of volcanism is suggested. The lower 25 flows (115 m thick) have recorded a reversed polarity; the next 23 flows (135 m thick) are transitional and contribute a detailed record of the "Van Zijl" (1962) Jurassic reversal. The upper 38 flows (500 m thick) have normal polarity. Directional groups (DGs) of lava flows with quasi-identical remanence directions indicate eruption durations too short to have recorded geomagnetic secular variation and hence are interpreted as single eruptive events. Altogether, 19 DGs and 10 sheet lobes yield a sequence of 29 distinct directions. This could correspond to a total eruptive activity shorter than 3000 years, less than one per mil of the total duration over which the section was emplaced. We obtain a new paleomagnetic pole for South Africa at similar to 180 Ma (lambda = 75.2 degrees N, phi = 276.4 degrees E, A(95) = 5.8 degrees, N = 19), which is consistent with earlier reports.read more
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Large Igneous Provinces
TL;DR: Large igneous provinces (LIPs) are intraplate magmatic events, involving volumes of mainly mafic magma upwards of 100,000 km3, and often above 1 million km3 as discussed by the authors.
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Rapid magma emplacement in the Karoo Large Igneous Province
TL;DR: In this paper, the authors present U-Pb zircon (and baddeleyite) ages for fourteen new samples of Karoo LIP sills and dykes spaced by as much as 1100 km across the half million square kilometer Karoo Basin.
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A review of Wilson Cycle plate margins: A role for mantle plumes in continental break-up along sutures?
TL;DR: In this article, the authors review the passive margins of the Atlantic and Indian oceans with the aim to evaluate the extent in which oceanic openings used former sutures and analyse the potential role of mantle plumes in continental break-up.
On the possible occurrence of "archaeomagnetic jerks" in the geomagnetic field over the last three millennia
TL;DR: In this article, the authors demonstrate a remarkable coincidence between sharp cusps in geomagnetic field direction and intensity maxima (two clear ones at ∼AD 200 and 1400; two presently less well constrained at ∼800 BC and AD 800).
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Dynamics of a stepped carbon-isotope excursion: Ultra high-resolution study of Early Toarcian environmental change
Michaël Hermoso,Fabrice Minoletti,Rosalind E. M. Rickaby,Stephen P. Hesselbo,François Baudin,Hugh C. Jenkyns +5 more
TL;DR: The Toarcian Oceanic Anoxic Event (T-OAE) was accompanied by a negative carbon-isotope excursion (CIE) caused by massive injection of isotopically light carbon into the ocean-atmosphere system, possibly from destabilisation of gas hydrates as mentioned in this paper.
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