Overblog
Editer l'article Suivre ce blog Administration + Créer mon blog

Earth of fire

Actualité volcanique, Articles de fond sur étude de volcan, tectonique, récits et photos de voyage

Publié le par Bernard Duyck
Publié dans : #Eruptions historiques

An Interuniversity research (St.Andrews Univ., Uppsala Univ., Durham Univ., Scottish Environmental Research Center Kilbride) reviews a large-scale explosive eruption in Scotland.

Pitchstone (pechstein), retinite, a vitreous rhyolitic volcanic rock, similar to obsidian, but with a higher water content, and no conchoidal fracture, from a single strong eruption (determined by isotopic geochemistry), was found at two places distant of 30 km in the Inner Hebrides: Sgürr of Eigg and Skerry of Òigh-sgeir (Hyskeir).

Map of the Inner Hebrides (in pink) off the coast of Scotland (in green)

Map of the Inner Hebrides (in pink) off the coast of Scotland (in green)

Neist Point lighthouse on the Isle of Skye - picture Isle of Skye

Neist Point lighthouse on the Isle of Skye - picture Isle of Skye

It would have been formed during a 58 million year old eruption, in a place corresponding to the present Isle of Skye ... and which is linked to a global warming during prehistory, the PETM / Thermal Maximum Paleocene-Eocene.

This global warming, of the order of + 8 ° C, has long been related to volcanic activity in the North Atlantic : Greenland, the British Isles and the North Sea.

An explosion on Skye's current position would have contributed to the global warming of the time because millions of tons of greenhouse gases, including carbon dioxide, were released into the atmosphere.

An Sgùrr is the highest hill on the island of Eigg - photo James Gray

An Sgùrr is the highest hill on the island of Eigg - photo James Gray

An Sgùrr is the highest hill on Eigg Island in Lochaber, Highlands, Scotland. It was formed 58.72 ± 0.07 million years ago, following one of the last eruptions of a volcano whose nucleus now forms the island of Rùm.

A thick viscous lava of rhyodacitic composition has flowed, filling a river valley. The lava cooled and formed columnar structures, similar to those of Giant's Causeway, updated following erosion.

Canna - Small isles / Scotland - photo Scotland info

Canna - Small isles / Scotland - photo Scotland info

Hyskeir (Gael. Oigh Sgeir) is one of the basaltic rock islands that emerge at low tide. It is part of the Inner Hebrides in the Highlands Council Area, located 6 km southwest of the island of Canna and 14 km west of Rum. A lighthouse was established on the largest of these islets in 1904.

Isle of Skye - Talisker - picture Isle of Skye

Isle of Skye - Talisker - picture Isle of Skye

Is there a Krakatau 1883 type eruption in the northern hemisphere, or is that just a hypothesis to be tested further?

 

Sources:

- Skye volcanic eruption 'changed climate' / BBC News

- Geology of Eigg

- McInerney, F.A., & Wing, S.L. (2011). The maximum Paleocene-Eocene thermal: a disturbance of carbon cycle, climate, and biosphere with implications for the future. Annual Review of Earth and Planetary

- Mineralienatlas - Pechstein

Commenter cet article

Articles récents

Hébergé par Overblog