Geochemical Investigation of Forlandsundet Graben, Svalbard : Analysis of core samples from Well 7811/5-1 with a paleoclimate perspective

Sammanfattning

The transition between Eocene and Oligocene (EOT) saw drastic changes in the global climate and is important to understand present climate change. Forlandsundet Graben in Svalbard is an area believed to contain sediments from the EOT. This study investigates this graben using 15 core samples from Well 7811/5-1, analyzing mercury, elemental composition, carbon and nitrogen content. Mercury anomalies as a result of volcanic activity is speculated as a possibility based on mean values from early Eocene, and heightened mercury and Hg/TOC ratios in our samples. This is especially implied for the middle section of our three sections of the core. Possible ages of the samples are implied by comparison with global trends in δ13C to be Eocene. Comparison with δ13C data from dated strata in Central Spitsbergen also implies the same. The lowest section is possibly from early Eocene while the middle and upper from mid- to late Eocene. There is still a high likelihood for presence of the EOT in strata further up in the graben. C/N ratios show that our samples all come from marine sources. Sediment classification from elemental composition results classifies our samples as Shale facies. Oxide ratios confirm this and show variability in feldspar content between the samples. Central Spitsbergen Basin sediments are compared with our data and show a slight possibility of a common sediment source with Forlandsundet.