Acoustic mapping of the Ilulissat Ice Fjord mouth, West Greenland
- 作者：Kai Schumann ; kaschumann@geomar.desolely ; kaschumann@geomar.de ; David Vö ; lker dvoelker@geomar.de ; Wilhelm R. Weinrebe wweinrebe@geomar.de
- 关键词：Pockmarks ; Gas hydrate release ; Gas hydrate stability ; Marine glaciomorphology ; Ilulissat Glacier
- 刊名：Quaternary Science Reviews
- 出版年：2012
- 期刊代码：78_02773791
- 类别：ear
- 出版时间：27 April, 2012
- 卷：40
- 期：Complete
- 页码：78-88
- 文件大小：2837 K
摘要
A ship-based acoustic mapping campaign was conducted at the exit of Ilulissat Ice Fjord of West Greenland and in the sedimentary basin of Disko Bay west of the fjord mouth. Submarine landscape and sediment distribution patterns represented by five acoustic facies types represent glaciomarine sediment facies types that are related to variations in the past position and relative motion of the glacier front. Asymmetric ridges on the shelf that form a curved entity and a large sill at the fjord mouth represent moraines that depict at least two relatively stable positions of the ice front in the Disko Bay and at the fjord mouth. Comparable ice-end features are not observed seaward of the East Greenland Kangerdlugssuaq Glacier, although both glaciers are comparable in their latitudinal position, present size and present role for the ice discharge from the Inland Ice sheet. Apparently, the retreat of the Greenland Inland Ice after the last maximum expansion was a more discontinuous process on the West Greenland Shelf than on the East Greenland Shelf. The Iceberg Bank, a prominent sill at the fjord exit appears to play an important role for the sedimentation after the retreat of the ice front from the shelf was completed. The retreat of the glacier behind the Iceberg Bank into the inner fjord is marked by a reorganization of sediment delivery in Disko Bay, as most of the till is now deposited within the fjord. Two linear clusters of pockmarks in the center of the sedimentary basin seem to be linked to methane release due to dissociation of gas hydrates, a process driven by fast crustal uplift of the Greenland Shelf. The orientation of these clusters appears to reflect a migration path that is defined by a buried structure which we could not resolve.