Chromatographic fractionation of bitumen from sediments and presence of glycerol ethers in immature sediments (Table 2)

Alkanes having unusual saturated isoprenoidal and methyl-branched structures have been isolated from the bitumen of several sediments. The methanogenic biomarkers 2,6,10,15,19-pentamethyleicosane and squalane were found in sediments which also contained bacteriogenic glycerol ethers. However, in one ether-containing sediment, 2,6,10,13,17,21-hexamethyldocosane was tentatively identified and this compound was found in place of the established alkane biomarkers. Other hydrocarbons found were regular C21 and C23 isoprenoid alkanes, compounds which cannot be derived from phytol; two isoprenoids of the type 3,7,11.-polymethylalkane, previously reported only in petroleums; 8-methylheptadecane, a probable biomarker for cyanobacteria and a number of its homologs and other methyl-branched alkanes. Ubiquitous branched-chain alkylbenzenes and a homology of trimethylalkylbenzenes were also isolated. Most, or all, of the compounds reported here are probably not catagenetic products but may represent direct algal or bacterial bioinputs.

(Table 2) Presence of plant remains in sediment core GIK14973, northern Kattegat

For the first time detailed physical properties were measured in addition to sedimentological parameters of near surface sediments of Kattegat channel system. This study has been accomplished on two sediment cores of different waterdepth of each Alkor-deep and Littorina-deep. The sediments of Littorina-deep, which have been dated with 210Pb-method, turned out to be surprisingly recent, with sedimentation rates up to 3,2 cm/year. Differences in physical properties lead to the assumption of lower sedimentation rates in Alkor-deep, the velocities of bottom and deepwater currents could be the cause of these differences in sedimentation rates. In Alkor-deep, the morphology runs parallel to the main direction of the bottom current. Therefore higher current velocities can be reached, which favor the erosion of fine sediment particles. Littorina-deep is located rectangular to the main direction of bottom currents. This might lead to an 'overflow' situation instead of a 'flow through'.