Modern and Holocene foraminifera and sediments on the continental shelf off Troms, North Norway

• Published in: Boreas
• Main Authors: HALD, MORTEN, VORREN, TORE O.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1984
• Subjects: Norway; Ice Sheet; North Norway; Troms
• Online Access: http://dx.doi.org/10.1111/j.1502-3885.1984.tb00067.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1502-3885.1984.tb00067.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1502-3885.1984.tb00067.x

Based on studies of gravity cores from two transverse troughs on the shelf and earlier investigations, the surface sediments are divided into three main facies: bouldery and pebbly sand on the banks and the shelf break; sand on the flanks and outer parts of the troughs and sandy mud in the inner parts of the troughs. Besides a depth control, the distribution must have been influenced by relatively rapidly moving bottom currents in the outer parts of the troughs. The distribution and composition of the modern benthic foraminiferal fauna (e.g. C. lobatulus/T. angulosa in the outer reaches and C. obtusalBolivina spp. in the inner reaches) is mainly controlled by the bottom current regime and sediments. The planktic fauna dominated by N. pachyderma (R) correlates well with the winter surface temperatures. The stratigraphi‐cal analysis shows that the 10,000–9,600 years B.P. period experienced high rates of deposition probably due to meltwater runoff from the continental ice sheet. At ca. 9,700 B.P. a minimum in the production of N. pachyderma (R) indicates a temporary cooling of the surface water. During the 9,600–7,800 B.P. period the rate of deposition was reduced. At the end of this period the foraminiferal fauna changed towards one like the modern fauna, reflecting improving ecological conditions. At ca. 7,800 B.P. the sediments became coarser due to reduced input of detrital sediments and an increased production of sand‐sized biogenic material. Since then the shelf environment has been fairly stable up to the present time.