Magnetostratigraphy of eastern Iceland

Watkins, N. D.; Walker, G. P. L.

doi:10.2475/ajs.277.5.513

Cited by 140 publications

(106 citation statements)

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“…Saemundsson, 1978Saemundsson, , 1979Jóhannesson, 1980;Kristjánsson, 1982;Óskarsson et al, 1985), although the oldest rocks exposed on land in Iceland are only 14-16 million years old (e.g. Moorbath et al, 1968;McDougall et al, 1984;Watkins and Walker, 1977). The present and past geological architecture of Iceland is a representation of this interaction and the most obvious manifestation is the elevation of the plateau above the surrounding sea floor as well as the configuration of active volcanic zones and belts (Fig.…”

Section: Geologic Settingmentioning

confidence: 99%

Volcanism in Iceland in historical time: Volcano types, eruption styles and eruptive history

Thordarson

Larsen

2007

Journal of Geodynamics

511

454

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The large-scale volcanic lineaments in Iceland are an axial zone, which is delineated by the Reykjanes, West and North Volcanic Zones (RVZ, WVZ, NVZ) and the East Volcanic Zone (EVZ), which is growing in length by propagation to the southwest through pre-existing crust. These zones are connected across central Iceland by the Mid-Iceland Belt (MIB). Other volcanically active areas are the two intraplate belts ofÖraefajökull (ÖVB) and Snaefellsnes (SVB). The principal structure of the volcanic zones are the 30 volcanic systems, where 12 are comprised of a fissure swarm and a central volcano, 7 of a central volcano, 9 of a fissure swarm and a central domain, and 2 are typified by a central domain alone.Volcanism in Iceland is unusually diverse for an oceanic island because of special geological and climatological circumstances. It features nearly all volcano types and eruption styles known on Earth. The first order grouping of volcanoes is in accordance with recurrence of eruptions on the same vent system and is divided into central volcanoes (polygenetic) and basalt volcanoes (monogenetic). The basalt volcanoes are categorized further in accordance with vent geometry (circular or linear), type of vent accumulation, characteristic style of eruption and volcanic environment (i.e. subaerial, subglacial, submarine).Eruptions are broadly grouped into effusive eruptions where >95% of the erupted magma is lava, explosive eruptions if >95% of the erupted magma is tephra (volume calculated as dense rock equivalent, DRE), and mixed eruptions if the ratio of lava to tephra occupy the range in between these two end-members. Although basaltic volcanism dominates, the activity in historical time (i.e. last 11 centuries) features expulsion of basalt, andesite, dacite and rhyolite magmas that have produced effusive eruptions of Hawaiian and flood lava magnitudes, mixed eruptions featuring phases of Strombolian to Plinian intensities, and explosive phreatomagmatic and magmatic eruptions spanning almost the entire intensity scale; from Surtseyan to Phreatoplinian in case of "wet" eruptions and Strombolian to Plinian in terms of "dry" eruptions. In historical time the magma volume extruded by individual eruptions ranges from ∼1 m 3 to ∼20 km 3 DRE, reflecting variable magma compositions, effusion rates and eruption durations.All together 205 eruptive events have been identified in historical time by detailed mapping and dating of events along with extensive research on documentation of eruptions in historical chronicles. Of these 205 events, 192 represent individual eruptions and 13 are classified as "Fires", which include two or more eruptions defining an episode of volcanic activity that lasts for months to years. Of the 159 eruptions verified by identification of their products 124 are explosive, effusive eruptions are 14 and mixed eruptions are 21. Eruptions listed as reported-only are 33. Eight of the Fires are predominantly effusive and the remaining five include explosive activity that produced extensive tephra layers...

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Section: Geologic Settingmentioning

confidence: 99%

Volcanism in Iceland in historical time: Volcano types, eruption styles and eruptive history

Thordarson

Larsen

2007

Journal of Geodynamics

511

454

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show abstract

“…Each succession of strata, roughly 1-3 km in thickness, that formed by central volcanic activity can be divided into alternating sequences of proximal and distal facies lavas. These sequences accumulated either rapidly The magnetostratigraphy of eastern Iceland is well documented through combined magnetic, stratigraphic, and whole rock K-Ar radiometric dating studies of a 9 km thick section, consisting of over 700 successive lava flows that range in age between 13.6 and 2 Ma [e.g., Watkins and Walker, 1977;Helgason, 1982;Kristjansson et al, 1995]. Several Tertiary tuff horizons serve as excellent regional stratigraphic markers.…”

Section: Introductionmentioning

confidence: 99%

Precise dating of the Holmatindur cooling event in eastern Iceland: Evidence for mid‐Miocene bipolar glaciation

Duncan¹,

Helgason²

1998

J. Geophys. Res.

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“…Thus basalt flow sequences, although they have the necessary directional resolution, do not have the necessary time resolution to document low inclination/low variation field behavior lasting 102 to 103 years. There is the suggestion, however, in WATKINS and WALKER'S (1977) data from eastern Iceland of an episode of low inclination approximately 7-8my BP during a normal polarity epoch (Table 1). Most of the low VGP results in WATKINS and WALKER'S (1977) data show dramatic motion of the field vector or are basalt flows.…”

Section: Discussionmentioning

confidence: 93%

“…There is the suggestion, however, in WATKINS and WALKER'S (1977) data from eastern Iceland of an episode of low inclination approximately 7-8my BP during a normal polarity epoch (Table 1). Most of the low VGP results in WATKINS and WALKER'S (1977) data show dramatic motion of the field vector or are basalt flows. WATKINS and WALKER'S (1977) estimate of the time between flows (16,000 years) would make the episode more than 30,000 years long, but since the age of the flows is not accurately known the time represented could be longer or shorter.…”

Section: Discussionmentioning

confidence: 93%

“…Most of the low VGP results in WATKINS and WALKER'S (1977) data show dramatic motion of the field vector or are basalt flows. WATKINS and WALKER'S (1977) estimate of the time between flows (16,000 years) would make the episode more than 30,000 years long, but since the age of the flows is not accurately known the time represented could be longer or shorter. The small directional scatter for this anomalous direction may suggest that a shorter time period is represented.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Anomalous geomagnetic field behavior recorded by glacial sediments from northwestern Patagonia, Argentina.

Kodama¹,

Evenson²,

Clinch³

et al. 1985

J. geomagn. geoelec

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Magnetostratigraphy of eastern Iceland

Cited by 140 publications

References 0 publications

Volcanism in Iceland in historical time: Volcano types, eruption styles and eruptive history

Volcanism in Iceland in historical time: Volcano types, eruption styles and eruptive history

Precise dating of the Holmatindur cooling event in eastern Iceland: Evidence for mid‐Miocene bipolar glaciation

Anomalous geomagnetic field behavior recorded by glacial sediments from northwestern Patagonia, Argentina.

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