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Eruption of the Continental Flood Basalts at ∼259 Ma in the Emeishan Large Igneous Province, SW China: Evidence from Laser Microprobe 40 Ar/ 39 Ar Dating
Author(s) -
Zengqian HOU,
Wen CHEN,
Jiren LU
Publication year - 2006
Publication title -
acta geologica sinica ‐ english edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.444
H-Index - 61
eISSN - 1755-6724
pISSN - 1000-9515
DOI - 10.1111/j.1755-6724.2006.tb00271.x
Subject(s) - flood basalt , large igneous province , geology , basalt , geochemistry , mantle plume , mafic , isochron , igneous rock , deccan traps , volcanism , paleontology , magmatism , tectonics , lithosphere
A suite of continental flood basalts sampled over a vast exposure and stratigraphic thickness in the Emeishan large igneous province (LIP), SW China was investigated for laser microprobe 40 Ar/ 39 Ar dating. There are two 40 Ar/ 39 Ar age groups for these basalts, corresponding to 259–246 Ma and 177–137 Ma, respectively. A well‐defined isochron gives an eruption age of huge quantities of mafic magmas at 258.9±3.4 Ma, which is identical to previous dating and paleontological data. Much younger 40 Ar/ 39 Ar ages for some basalts with low‐greenschist metamorphic facies probably recorded a late thermo‐tectonic event caused by collision between the Yangtze and Qiangtang continental blocks during the Mesozoic, which resulted in the reset of argon isotope system. The 40 Ar/ 39 Ar age data, we present here, combined with previous dating and paleontological data, suggest relatively short duration (about 3 Ma) of mafic volcanism, which have important implication on mantle plume genesis of the Emeishan continental flood basalts in the LIP.