Sedimentological and clay mineralogical analysis of ODP sites in the central Fram Strait

• Main Author: Winkler, Amelie
• Format: Other/Unknown Material
• Language: English
• Published: PANGAEA 1999
• Subjects: 151-908; 151-908A; 151-909; 151-909A; 151-909C; COMPCORE; Composite Core; DRILL; Drilling/drill rig; Joides Resolution; Leg151; North Greenland Sea; Ocean Drilling Program; ODP; Berichte zur Polarforschung; Fram Strait; Greenland; Greenland Sea; Greenland-Scotland Ridge; North Atlantic; North Greenland; Polar Research; Polarforschung; Reports on polar research; Sea ice
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.712694; https://doi.org/10.1594/PANGAEA.712694

This study presents the results of high-resolution sedimentological and clay mineralogical investigations on sediments from ODP Sites 908A and 909AlC located in the central Fram Strait. The objective was to reconstruct the paleoclimate and paleoceanography of the high northern latitudes since the middle Miocene. The sediments are characterised in particular by a distinctive input of ice-rafted material, which most probably occurs since 6 Ma and very likely since 15 Ma. A change in the source area at 1 1.2 Ma is clearly marked by variations within clay mineral composition and increasing accumulation rates. This is interpreted as a result of an increase in water mass exchange through the Fram Strait. A further period of increasing exchange between 4-3 Ma is identified by granulometric investigations and points to a synchronous intensification of deep water production in the North Atlantic during this time interval. A comparison of the components of coarse and clay fraction clearly shows that both are not delivered by the Same transport process. The input of the clay fraction can be related to transport mechanisms through sea ice and glaciers and very likely also through oceanic currents. A reconstruction of source areas for clay minerals is possible only with some restrictions. High smectite contents in middle and late Miocene sediments indicate a background signal produced by soil formation together with sediment input, possibly originating from the Greenland- Scotland Ridge. The applicability of clay mineral distribution as a climate proxy for the high northern latitudes can be confirmed. Based on a comparison of sediments from Site 909C, characterised by the smectite/illite and chlorite ratio, with regional and global climatic records (oxygen isotopes), a middle Miocene cooling phase between 14.8-14.6 Ma can be proposed. A further cooling phase between 10-9 Ma clearly shows similarities in its Progress toward drastic decrease in carbonate sedimentation and preservation in the eastern equatorial Pacific. The ...