Читать книгу Biogeography in the Sub-Arctic - Группа авторов - Страница 29

In the aftermath of the ocean opening there was notable uplift of the adjacent ‘trailing’ continental margins. The uplift is noteworthy in, for example, western Scotland and Norway, but is most extreme in eastern Greenland where ‘plateau lavas’ erupted close to sea‐level (and which were preceded by marine Mesozoic strata) have been raised, while remaining essentially horizontal. Among the uplifted rocks are those of Gunnbjørns Fjeld, which at 3693 m is the highest mountain in the Arctic. How much strata have been eroded from above it is unknown.

The pre‐opening loading, by up to 7 km of basaltic lavas, would be expected to have depressed rather than elevated surfaces. However, the uplift is inferred to be the consequence of intrusion of igneous rocks deep in the crust that more than compensate for the surface loading (Larsen et al. 1998). Despite the huge volume of erupted lavas a much larger volume of magma crystallized deep in the crust as ‘underplating’. The east coast of Greenland presents an elongate area of uplift centred on that part (Kangerdlugssuaq) where the plume axis is deduced to have passed from continent to ocean (Lawver and Müller 1994).

The tilting of the topography in northern Britain from west to east is also attributed to the process of magmatic underplating (Brodie and White 1994). Consequently, the Iceland plume has been instrumental in shaping the landscapes on either side of the ocean (Fitton and Larsen 2001).