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High‐resolution profile of stable isotopes and iridium across a K/T boundary section from Koshak Hill, Mangyshlak, Kazakhstan
Author(s) -
Sarkar A.,
Bhattacharya S.K.,
Shukla P.N.,
Bhandari N.,
Naidin D.P.
Publication year - 1992
Publication title -
terra nova
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.353
H-Index - 89
eISSN - 1365-3121
pISSN - 0954-4879
DOI - 10.1111/j.1365-3121.1992.tb00600.x
Subject(s) - geology , iridium , excursion , isotopes of carbon , cretaceous , carbonate , boundary (topology) , paleontology , boundary layer , period (music) , isotopes of oxygen , carbon fibers , isotope , oceanography , geochemistry , chemistry , materials science , physics , thermodynamics , catalysis , mathematics , law , mathematical analysis , composite number , acoustics , composite material , biochemistry , political science , organic chemistry , quantum mechanics
Oxygen and carbon isotopes were measured to a high depth resolution in a nannoplankton carbonate sequence spanning the Cretaceous‐Tertiary boundary at Koshak Hill, Mangyshlak Peninsula, Kazakhstan. The boundary is characterized by the presence of a ∼ 1 cm thick clay layer having a sharp peak in iridium concentration with a maximum value of 3.7 ng g ‐1 . The δ 18 O data reveal rapid (∼10 3 years) excursion of sea‐surface temperature at the boundary where an initial cold pulse is followed by a persistent warm period. The δ 13 C data, in contrast, indicate only a gradual change in productivity across the boundary. The observations suggest a biogeochemical scenario for the boundary event pertaining to shallow epicontinental seas.