Dimmuborgir: a rootless shield complex in northern Iceland

• The origin of Dimmuborgir, a shield-like volcanic structure within the Younger Laxa lava flow field near Lake Myvatn, in northern Iceland, has long been questioned. New airborne laser mapping (light detection and ranging (LiDAR)), combined with ground-penetrating radar results and a detailed field study, suggests that Dimmuborgir is a complex of at least two overlapping rootless shields fed by lava erupting from the nearby Ludentarborgir crater row. This model builds upon previous explanations for the formation of Dimmuborgir and is consistent with observations of rootless shield development at Kilauea Volcano, Hawaii. The larger rootless shields at Dimmuborgir, 1-1.5 km in diameter, elliptical in plan view, similar to 30 m in height, and each with a 500-m-wide summit depression, were capable of storing as much as 2-3x10(6) m(3) of lava. They were fed by lava which descended 30-60 min lava tubes along a distance of 3 km from the crater row. The height difference generated pressure sufficient to build rootless shields at Dimmuborgir in a timescale of weeks. The main summit depressions, inferred to be drained lava ponds, could have emptied via a 30-m-wide x 5-m-deep channel, with estimated effusion rates of 0.7-7 m(3) s(-1) and minimum flow durations of 5-50 days. We argue that the pillars for which Dimmuborgir is famed are remnants of lava pond rims, at various stages of disintegration that formed during pond drainage.

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences (hsv//eng)

Nyckelord

Dimmuborgir

Iceland

Rootless shields

LiDAR

Younger Laxa Lava

ground-penetrating radar

lava pillars

pahoehoe

eruption

volcano

hawaii

water

flow

Geology

Dimmuborgir

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)