The Koshak section located on the northeastern margin of the Tethyan
ocean reveals a distinctive oxygen and carbon isotope pattern from
surface and bottom water dwellers. Trends in partial derivative(18)O are
similar in bulk samples as well as planktonic and benthic foraminifera.
Concentration of selected trace elements from bulk carbonate indicate
enriched Na. Fe, Ba, Mn and depleted Sr contents compared with average
concentrations in recent pelagic carbonates. The Sr-87/Sr-86 ratios at
Koshak are comparatively low to values reported from other K/T sections.
Carbon and oxygen isotope records show no drastic changes at the K/T
boundary. throughout the section benethics show more positive partial
derivative(13)C values than planktonic and bulk samples. We assume that
the surface water carbon record is imprinted by an admixture of fresh
water which was possibly reduced during the early Danian zone Pla. This
input of fresh water may be related to a major climatic change
(warming?) during the terminal Maastrichtian possibly associated with
intensified volcanic activity (Deccan traps).
Carbon isotopes show similar values to other high latitude sites in
Denmark (Nye Klov) and the southern Indian Ocean (ODP Site 738) with
only minor depletion of -0.5% across the K/T boundary. Geochemical
analyses from the Koshak section record changes which have to be
attributed to postdepositional processes on the external platform and in
basinal environments. Changes in trace element concentrations and
partial derivative(18)O are related to dissolution-precipitation
processes. However, these processes did not affect the primary partial
derivative(13)C and Sr isotope patterns.