Geochemical study of Cretaceous-Teratiary (K-T) boundary layers in Turkey

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In this study, we summarize the element and Sr isotope profiling of K-T boundary layers in Medetli and other sectins in Turkey. Combining the results of 1999 and 2000 researches, we made element and Sr isotope profiles in Medetli section. Medetli section is composed of A, B and C layers : A is latest, Cretaceous and C is earliest Tertiary, and B is K-T boundary. In layer B thin goethite-rich layers are included and metal elements such as Fe, Mn, Cr, Ni, V, Cu, Co are enriched in goethite-rich layer. Also As, Sb and Zn concentrations are high in the layers. These element characteristics in goethite-rich layers in Medetli is very similar to famous K-T boundary sections in the world. We also tried to measure the Ir concentration in the goethite-rich layers, but no high concentrations of Ir was not determined. The concentrations are 0.07-0.08 ppb. This result is not consistent that this layer is just K-T bundary layer. However, it is also probable that Ir was diluted during diagenesis after sedimentation. Sr isotope results show that the ratios in layer A is high(0.710-0.711), but decrease 0.7078 to 0.7080 in layer B. The Sr isotope ratios in goethite-rich layers are the same in layer B(0.7078-0.7080). These values are close to sea water Sr isotope value of end of Cretaceous. This means that sea water Sr was much precipitated particular in layer B and goethite-rich layer. In this study strong evidence as enrichment of Ir was not obtained, but it is possible that Ir was diluted or disapeared during the diagenesis after sedimentation. We have to have further research in this problem. In Haymana and Devrekani sections metal elements are concentrated in the K-T boundaries.As related studies, we have studied geochemical studies for the mafic igneous rocks in Oki Dogo Island, SW Japan and late Paleozoic granitoids in central Mongolia. We reported the results in the published paper.