A new discovery of the cretaceous/tertiary boundary from the tethyan belt, hekimhan basin, turkey: Mineralogical and geochemical evidence

Abstract

A Cretaceous/Tertiary (K/T) boundary location within the Tethyan region (present Mediterranean area) has been discovered in the Hekimhan basin, Malatya, Turkey. The K/T transition in a 1.65-m-thick marine evaporitic facies (gypsum and celestite) consists of laminated carbonate rocks (limestone, dolomitic limestone, dolomite) and marl in the upper part, and laminated limestone and marl in the lower part. The K/T boundary is marked by a 6-mm-thick clay layer that is entirely greenish pink in color. The stratum is characterized by a decrease in calcite content, and by an increase in the proportion of smectites and K-feldspar. Palygorskite and rarely serpentine are associated with smectite. A minimum in CaO + MgO content exists at the K/T boundary. The amounts of some transition metals, miscellaneous, low- and high-field-strength, platinum-group, and rare-earth elements reveal a substantial anomaly at the K/T boundary that supports both terrestrial (volcanic) and extraterrestrial (bolide) hypotheses. © 1996 Taylor & Francis Group, LLC.