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Pyroxene 40 Ar/ 39 Ar Dating of Basalt and Applications to Large Igneous Provinces and Precambrian Stratigraphic Correlations
Author(s) -
Zi JianWei,
Haines Peter W.,
Wang XuanCe,
Jourdan Fred,
Rasmussen Birger,
Halverson Galen P.,
Sheppard Stephen,
Li ChaoFeng
Publication year - 2019
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.983
H-Index - 232
eISSN - 2169-9356
pISSN - 2169-9313
DOI - 10.1029/2019jb017713
Subject(s) - geology , basalt , precambrian , igneous rock , large igneous province , pyroxene , flood basalt , geochemistry , deccan traps , mafic , felsic , volcanic rock , geochronology , lava , paleontology , volcano , magmatism , volcanism , olivine , tectonics
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 40 Ar/ 39 Ar dating to pyroxene from a Neoproterozoic basalt unit, the Keene Basalt in the Officer Basin of central Australia. 40 Ar/ 39 Ar analyses of igneous pyroxene crystals yielded an age of 752 ± 4 Ma (mean squared weighted deviation = 0.69, p = 72%), which is underpinned by 40 Ar/ 39 Ar 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 × 10 5 km 2 ) related to breakup of the supercontinent Rodinia. This study demonstrates the potential of pyroxene 40 Ar/ 39 Ar geochronology to date ancient flood basalts and to provide pivotal time constraints for stratigraphic correlations of Precambrian basins.