Early diageneitc isotopic signal at the Cretaceous/Tertiary boundary, Israel

Carbon and oxygen isotope records from carbonate fractions in marls overlying the K/T boundary in southern Israel are used to interpret paleoenvironmental changes and the history of early diagenetic events in the earliest Tertiary. The δ¹³C record of the whole rock does not significantly depart from the original values and reflects the global productivity drop shortly after the K/T boundary and the subsequent recovery. Fine fraction oxygen isotope values reflect the addition of carbonate cement highly depleted in ¹⁸O throughout the profile. The δ¹⁸O record demonstrates two main episodes in which contact with fresh water affected the sediments. One is below a short hiatus at planktic foraminiferal subzone transition PO/P1a (Guembelitria cretacea/Parvularugoglobigerina eugubina) and the other at an pyrite- rich clay layer near the top to planktic foraminiferal subzone P1b ('Globigerina' taurica). The latter event suggests introduction of sapropelic bottom conditions in the oceanic paleoenvironment.