Geological deformation of Iceland | |
|---|---|
Land deformation | |
.jpg) Extensional structure, Þingvellir Graben, provides evidence for plate divergence in Iceland. | |
 Fig 1. This figure shows the locations of the major deformation zones in Iceland and the vectors of the North American Plate movement relative to the Eurasian Plate. Legend: RR, Reykjanes Ridge; RVB, Reykjanes volcanic belt; WVZ, West volcanic zone; MIB, Mid-Iceland belt; SISZ, South Iceland seismic zone; EVZ, East volcanic zone; ; SIVZ, South Iceland volcanic zone; NVZ, North volcanic zone; TFZ, Tjörnes fracture zone; KR, Kolbeinsey Ridge; ÖVB, Öræfajökul volcanic belt; SVB, Snæfellsnes volcanic belt. The legend for the basalt regions is the same as below. | |
| Age | |
| Formed by | Tectonic forces |
| Area | |
| • Total | 102,775 km2 (39,682 sq mi) |
| Volcanic arc/belt | Mid-Atlantic Ridge, Iceland hotspot |
| Last eruption | 2024 |
The geological deformation of Iceland is the way that the rocks of the island of Iceland are changing due to tectonic forces. The geological deformation help to explain the location of earthquakes, volcanoes, fissures, and the shape of the island. Iceland is the largest landmass (102,775 km2 (39,682 sq mi)) situated on an oceanic ridge.[1]: 35 It is an elevated plateau of the sea floor, situated at the crossing of the Mid-Atlantic Ridge and the Greenland-Iceland-Scotland ridge.[2]: 59 It lies along the oceanic divergent plate boundary of North American Plate and Eurasian Plate. The western part of Iceland sits on the North American Plate and the eastern part sits on the Eurasian Plate. The Reykjanes Ridge of the Mid-Atlantic ridge system in this region crosses the island from southwest and connects to the Kolbeinsey Ridge in the northeast.[1]: 39, 40, 49
Iceland is geologically young: all rocks there were formed within the last 25 million years.[2] It started forming in the Early Miocene sub-epoch, but the oldest rocks found at the surface of Iceland are from the Middle Miocene sub-epoch. Nearly half of Iceland was formed from a slow spreading period from 9 to 20 million years ago (Ma).[2]
The geological structures and geomorphology of Iceland are strongly influenced by the spreading plate boundary and the Iceland hotspot. Although some have questioned if a hotspot is necessary to explain the observed deformations of Iceland this is currently felt to best explain observations of rock composition and age obtained by modern techniques.[3] The buoyancy of the deep-seated mantle plume underneath has uplifted the Iceland basalt plateau to as high as 3,000 m (9,800 ft). The crust over the plume is also up to 40 km (25 mi) thick which is much thicker than elsewhere in Iceland and a contrast to the minimum thickness of 8 km (5.0 mi) which is a thickness more typical of oceanic divergent plate boundaries.[4] The central part of Iceland is still lifting but the current rate of crustal lifting of 3 cm/year (1.2 in/year) is mainly explained by glacial isostatic adjustment in response to the retreat of ice since 1890 which has removed much weight from the thick icesheet.[4] The hotspot also produces high volcanic activity on the plate boundary.[1]: 50
There are two major geologic and topographic structural trends in Iceland. One strikes north-east in southern Iceland and strikes nearly north in northern Iceland. The other one strikes approximately west to north-west. Altogether they produce a zigzag pattern. The pattern is shown by faults, volcanic fissures, valleys, dikes, volcanoes, grabens and fault scarps.[2]
- ^ a b c Einarsson, P. (2008). "Plate boundaries, rifts and transforms in Iceland". Jökull. 58 (12): 35–58. doi:10.33799/jokull2008.58.035.
- ^ a b c d Árnadóttir, T.; Geirsson, H.; Jiang, W. (2008). "Crustal deformation in Iceland: Plate spreading and earthquake deformation". Jökull. 58: 59–74. doi:10.33799/jokull2008.58.059.
- ^ Árnadóttir, S.; Thordarson, T.; Hjartarson, Á.; Gautason, B. (2023). "U–Pb zircon age and chronology of the Torfufell central volcano: implications for timing of rift relocation in North Iceland". Bulletin of Volcanology. 85 (10): 52. Bibcode:2023BVol...85...52A. doi:10.1007/s00445-023-01667-8.: Introduction
- ^ a b Sigmundsson, F.; Einarsson, P.; Hjartardóttir, Á.R.; Drouin, V.; Jónsdóttir, K.; Arnadottir, T.; Geirsson, H.; Hreinsdottir, S.; Li, S.; Ofeigsson, B.G. (2020). "Geodynamics of Iceland and the signatures of plate spreading". Journal of Volcanology and Geothermal Research. 391: 106436. Bibcode:2020JVGR..39106436S. doi:10.1016/j.jvolgeores.2018.08.014.