40Ar/39Ar dating of the Siberian Traps, USSR: Evaluation of the ages of the two major extinction events relative to episodes of flood-basalt volcanism in the USSR and the Deccan Traps, India

Journal Article · Wed May 01 00:00:00 EDT 1991 · Geology; (USA)

DOI:https://doi.org/10.1130/0091-7613(1991)019<0461:ADOTST>2.3.CO;2· OSTI ID:5667584

Baksi, A K ^[1]; Farrar, E ^[2]

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1. Louisiana State Univ., Baton Rouge, LA (USA)
2. Queen's Univ., Kingston, Ontario (Canada)

{sup 40}Ar/{sup 39}Ar incremental-heating studies have been carried out on three whole-rock specimens from the Siberian Traps. A basalt lava flow from the lowermost horizon yields and age of 238.4 {plus minus} 1.4 Ma (1{sigma} error). A second basalt lava flow from the top of the section, {approximately}800 m above the first specimen, yields an age of 229.9 {plus minus} 2.3 Ma, indicating that the duration of volcanism was {approximately}5{minus}10 m.y. A doleritic dike intrusive into the lower parts of the Siberian Traps contains excess argon and yields an isochron age of 234 {plus minus} 7 Ma. Critical reexamination of relevant radiometric data relating two separate episodes of flood-basalt volcanism to global faunal extinctions suggests the volcanic event forming the most voluminous sections of the Deccan Traps, India, was coincident to within {plus minus}1 m.y. with the time of the Cretaceous/Tertiary boundary. However, the onset of volcanism in the Siberian Traps apparently occurred at a time postdating that of the Permian/Triassic boundary.

• OSTI ID: 5667584
• Journal Information: Geology; (USA), Vol. 19:5; ISSN 0091-7613
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
USSR
VOLCANIC REGIONS
AGE ESTIMATION
ARGON 39
ARGON 40
BASALT
BOUNDARY CONDITIONS
COMPARATIVE EVALUATIONS
CRETACEOUS PERIOD
DEPTH
DIKES
GEOLOGIC FORMATIONS
GEOLOGIC HISTORY
INDIA
ISOTOPE DATING
ISOTOPE RATIO
LAVA
PERMIAN PERIOD
PLUTONIC ROCKS
TERTIARY PERIOD
TRIASSIC PERIOD
VOLCANISM
ARGON ISOTOPES
ASIA
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CENOZOIC ERA
DEVELOPED COUNTRIES
DEVELOPING COUNTRIES
DIMENSIONS
EUROPE
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
GEOLOGIC AGES
GEOLOGIC STRUCTURES
IGNEOUS ROCKS
ISOTOPES
LIGHT NUCLEI
MESOZOIC ERA
NUCLEI
PALEOZOIC ERA
RADIOISOTOPES
ROCKS
STABLE ISOTOPES
VOLCANIC ROCKS
YEARS LIVING RADIOISOTOPES
580000* - Geosciences