Authigenic and detrital neodymium isotopic compositions of surface sediments in Svalbard fjords: preliminary results

Abstract

The Svalbard Archipelago is located in the eastern Arctic Ocean near the Fram Strait. This region is characterized by several fjords formed during the retreat/advance of glaciers. The behavior of glaciers exerts a strong influence on the sediment transport system and hydrology in Svalbard, and hence tracing of the change in sediment provenance and seawater composition is important to understand the ice dynamics and history. Here we tentatively measured detrital and authigenic Nd isotopes (143Nd/144Nd; εNd) of surface sediments in Svalbard fjords Dicksonfjorden, Hornsund, Isfjorden, Van Mijenfjorden, Wijdefjorden and Woodfjorden to reconstruct spatial variation in lithological sediment provenance and water mass composition at present. Detrital εNd fluctuates widely from -10.1 to -24.9, indicating a large spatial variation in the provenance of Svalbard sediments at present. As expected from various and different rocks surrounding Hornsund area, εNd values of detrital sediments are mostly variable in Hornsund. On the contrary, detrital εNd values in Dicksonfjorden and Woodfjorden are relatively constant with average value of -13.6. Considering the geological setting and overall reddish sediments in Dicksonfjorden and Woodfjorden, Devonian red sandstone seems to be a dominant source for both fjords at present. Authigenic εNd values in Svalbard are also variable ranging from -9.0 to -14.5 and well correlated with detrital εNd (r = 0.62, n = 45), probably resulting from local Nd fluxes such as meltwaters draining rocks and/or sediment-seawater interaction. Again, the oscillation in authigenic εNd is mostly prominent in Hornsund, but the variation in authigenic εNd has a smaller amplitude compared to detrital εNd, indicating that seawater composition in Hornsund is also influenced by the N. Atlantic inflow as well as local fluxes. Likewise, northward increase in authigenic εNd from coastal to pelagic area in Wijdefjorden seems to be an example to show the interplay between local terrestrial input and N. Atlantic inflow.