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40Ar/39Ar age of the onset of high-Ti phase of the Emeishan volcanism strengthens the link with the end-Guadalupian mass extinction.
- Source :
-
International Geology Review . Nov2018, Vol. 60 Issue 15, p1906-1917. 12p. - Publication Year :
- 2018
-
Abstract
- Precise time constraints of the main extrusive phase of the Emeishan large igneous province (ELIP) remain unresolved because basalts commonly do not contain suitable minerals for U-Pb dating, whereas previous 40Ar/39Ar studies on basalts yielded tectonothermal overprint ages. The timing for the ELIP was deduced from indirect dating of minor intrusions of ultramafic/mafic and felsic compositions by geochronological methods and geological correlations. The extrusive part of the ELIP consists of an older low-Ti and younger high-Ti basalt phases. We have found fresh samples of plagioclase-phyric rocks at the lower Qiaojia extrusive section (the Yunnan province of China), which belong to the ELIP unit of the high-Ti basalt series. 40Ar/39Ar dating on plagioclase from two samples conducted at two different laboratories using different age standards yielded statistically indistinguishable results with the weighted mean age of 260.1 ± 1.2 Ma for five individual measurements. This provides the direct constraints on the onset of the ELIP high-Ti basalt extrusive phase. The obtained age is within the error or slightly older than the age of the Guadalupian-Lopingian boundary and felsic ignimbrite capping the ELIP lava succession (both dated at 259.1 ± 0.5 Ma). Our new data are strengthening the short duration of the, at least, high-Ti phase of the ELIP volcanism and its temporal link with the end-Guadalupian mass extinction. Estimation of the total duration of the ELIP volcanism awaits finding of suitable for dating low-Ti basalts. [ABSTRACT FROM AUTHOR]
- Subjects :
- *IGNEOUS provinces
*MASS extinctions
*PHENOCRYSTS
*GEOCHRONOMETRY
*VOLCANISM
Subjects
Details
- Language :
- English
- ISSN :
- 00206814
- Volume :
- 60
- Issue :
- 15
- Database :
- Academic Search Index
- Journal :
- International Geology Review
- Publication Type :
- Academic Journal
- Accession number :
- 132111730
- Full Text :
- https://doi.org/10.1080/00206814.2017.1405748