科研之友
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摘要
The properties of streamlined glacial landforms and palaeo-flow indicators in the valleys of Vididalur, Vatnsdalur and Svinadalur in northern Iceland were quantified using spatial analyses. Drumlins and mega-scale glacial lineations (MSGL) were visually identified using satellite imagery from Google Earth, the National Land Survey of Iceland (NLSI) Map Viewer and Landsat satellites, and using aerial photographs from the NLSI. A semi-automated technique was developed using ENVI to determine regions in northern Iceland likely to contain streamlined landforms. The outlines of the identified landforms were manually delineated in Google Earth, and all analyses were conducted in ArcGIS using a 20 m digital elevation model (DEM) of Iceland from the NLSI. Smaller features such as flutes, grooves and striations were measured in the field. At least 543 drumlins and 90 MSGL were identified in the three valleys. Average elongation ratios for Vididalur, Vatnsdalur and Svinadalur are 4.3:1, 5.2:1 and 6.7:1, respectively. The average density of streamlined landforms is 2.34 landforms per 1 km(2). Striations and orientation data of the drumlins and MSGL demonstrate ice flow to the northwest into Hunafloi. Parallel conformity is higher in the valley of Svinadalur (9 degrees standard deviation) than in Vididalur (12 degrees) and Vatnsdalur (16 degrees). Packing values are generally higher in the centre of each valley. The properties of streamlined landforms in the valleys of Vididalur, Vatnsdalur and Svinadalur support the presence of palaeo-ice stream activity on northern Iceland. Palaeo-ice streams flowed from these regions into Hunafloi, supplying ice to the margin of the Iceland Ice Sheet during the Last Glacial Maximum. These palaeo-ice streams provide a mechanism for ice centres from the mainland of Iceland to reach the shelf-slope break.
- 出版日期2016-7
