Deep-Sea Record of Cenozoic Explosive Volcanism in the North Atlantic

Sigurdsson, Haraldur; Loebner, Benny

doi:10.1007/978-94-009-8537-7_18

Cited by 40 publications

(74 citation statements)

References 35 publications

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“…4) have a distinct higher A1 2 O 3 and K 2 O and lower SiO 2 content compared to the Miocene tephra. Sigurdsson and Loebner (1981) distinguish two series of Cenozoic tephra in the North Atlantic region: a high potassium series (K 2 O >3.8 wt%) that ranges from quartz trachytes to alkali rhyolites and a low potassium series (K 2 O >3.8 wt%) that ranges from icelandites to rhyolites. The majority of the rhyolitic glass shards analyzed belong to the low potassium series.…”

Section: Rhyolitic and Trachytic Tephramentioning

confidence: 98%

“…During this time, the Greenland Basin was much smaller than it is today, and the distance of the site to the ancient active spreading center was around half of the recent distance to the Mohns Ridge (around 500 km). East of the site, some poorly known volcanic explosive activities (related to the rifting of the Jan Mayen Ridge from East Greenland during the Oligocene), which produced rhyolitic material, were estimated by Sigurdsson and Loebner (1981). The ashes of Hole 913B may correlate with these activities.…”

Section: Stratigraphymentioning

confidence: 99%

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Distribution, Chemical Composition, and Sources of Oligocene to Miocene Volcanic Ashes from Sites 907, 908, and 913

Werner¹,

Wallrabe-Adams²,

Lacasse³

et al. 1996

Proceedings of the Ocean Drilling Program

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The volcanogenic component of 54 ash layers and ash-bearing sediments recovered at Sites 907, 908, and 913 (Ocean Drilling Program Leg 151) in the Greenland-Iceland-Norwegian Seas (Iceland Plateau, Greenland Basin, Hovgàrd Ridge) consists mainly of colorless and/or light to dark brown glass particles with an average medium grain size of 100 µm (±60 µm); crystals and lithics are minor constituents. Colorless glass shards are primarily bubble wall shards and pumice fragments. Most light to dark-brown glass shards are slightly vesicular or dense blocky shards, but highly vesicular or pumice-like fragments also occur. The compositions of glass shards comprise subalkalic and low-K subalkalic basaltic (27% of all analyzed shards), basalticandesitic (9%), andesitic (6%), dacitic (<1%), and trachytic (4%), as well as low-K and high-K rhyolitic (47% and 7%, respectively).The rhyolitic and trachytic tephra deposits can be attributed to highly explosive Plinian eruptions. Some mafic or intermediate ash deposits of Hole 907 A show the influence of hydroclastic fragmentation processes, suggesting submarine or subglacial/ sublacustrine eruption environments. Major element compositions suggest that most ash layers are derived from Iceland and to a lesser extent from the Jan Mayen System. The oldest basaltic ashes of Hole 907A possibly originate from submarine eruptions at the ancient Kolbeinsey Ridge as indicated by their particle shape and the low degree of degassing.The well-preserved record of middle to late Miocene ash deposits in Hole 907A indicates a short but strong increase in explosive volcanic activity during the late middle Miocene but relatively low activity rates for early middle Miocene and late Miocene.

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Section: Rhyolitic and Trachytic Tephramentioning

confidence: 98%

Section: Stratigraphymentioning

confidence: 99%

Distribution, Chemical Composition, and Sources of Oligocene to Miocene Volcanic Ashes from Sites 907, 908, and 913

Werner¹,

Wallrabe-Adams²,

Lacasse³

et al. 1996

Proceedings of the Ocean Drilling Program

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“…The remaining shards in this layer form a second homogeneous population with significantly higher FeO* (2.8−3.2 wt%), and lower in SiO 2 concentrations. All rhyolitic tephra drilled on Site 918 belong to the low potassium series (K 2 O <3.8 wt%) as defined by Sigurdsson and Loebner (1981).…”

Section: Geochemistrymentioning

confidence: 99%

“…This hypothesis is also supported by the lack of (dense) crystals and the relatively small grain size of the shards (<<100 µm). Possible sources for middle Miocene rhyolite tephra are Iceland (Sigurdsson and Loebner, 1981), the Jan Mayen magmatic province (Bitschene et al, 1989), and volcanic centers near the Iceland-Faeroe Ridge (Sigurdsson and Loebner, 1981). Jan Mayen and the Iceland-Faeroe Ridge, however, produced high-K alkali rhyolites and therefore can be excluded as a source for the low-K rhyolitic tephra of Layer 20.…”

Section: Mgo (Wt%)mentioning

confidence: 99%

“…Using piston and Deep Sea Drilling Project (DSDP) cores, Donn and Ninkovich (1980) inferred a middle Eocene episode of abundant volcanism in the North Atlantic, the main volcanic source area being the subaerial Iceland-Faeroes ridge (Sigurdsson and Loebner, 1981). The relatively high amount of middle Eocene ash layers in Unit IV probably reflects this peak in volcanic activity.…”

Section: Ash Layersmentioning

confidence: 99%

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Chemical composition, age, and sources of volcaniclastic sediments from Sites 917 and 918

Werner¹,

Bogaard²,

Lacasse³

et al. 1998

Proceedings of the Ocean Drilling Program

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Volcaniclastic deposits drilled at Leg 152 Sites 917 (East Greenland Shelf) and 918 (Irminger Basin) comprise 21 Neogene ash-bearing intervals and numerous Paleogene ash layers, tuffs, lapillistones, breccias, and conglomerates. The volcanogenic components of the Neogene ash deposits consist mainly of brown to colorless glass particles with an average median grain size of 30 µm (± 20 µm). Colorless glass particles are bubble wall shards and pumice fragments. Brown glass shards are slightly vesicular or dense blocky shards, rarely highly vesicular or pumiceous. The glass shards have subalkalic and low-K subalkalic basaltic, as well as low-K rhyolitic compositions. Rhyolitic ash layers are attributed to highly explosive plinian eruptions. Textural criteria and degree of sulfur degassing of most mafic shards suggest an origin from hydroclastic explosive fragmentation processes in a subglacial/sublacustrine eruption environment. Major element compositions indicate that most ash deposits are derived from Iceland. Only a few mafic deposits may have originated at the Reykjanes Ridge.Abundant, highly altered Paleogene ash layers in the middle Eocene sequence of Hole 918D confirm a peak in the volcanic activity in the North Atlantic area at this period of time, as postulated in the literature. Polymict volcanic breccias and conglomerates immediately overlying flood basalts of the East Greenland Shelf are interpreted as lahars and fluvial deposits that mark the end of the intense volcanic activity in East Greenland. Altered tuffs and lapillistones within the flood basalt sequence of Site 917 are primary or reworked hydroclastic and pyroclastic deposits, reflecting rare explosive phases during the effusive eruption of the flood basalts.Laser probe 40 Ar/ 39 Ar dating of anorthoclase and plagioclase crystals from two successions of Paleogene tuffs and lapillistones intercalated with the lavas of the Middle Series at Site 917 give mean apparent ages from 60.5 ± 0.2 Ma to 60.3 ± 0.2 Ma.

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The tephrochronology of Iceland and the North Atlantic region during the Middle and Late Quaternary: a review

2000

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Deep-Sea Record of Cenozoic Explosive Volcanism in the North Atlantic

Cited by 40 publications

References 35 publications

Distribution, Chemical Composition, and Sources of Oligocene to Miocene Volcanic Ashes from Sites 907, 908, and 913

Distribution, Chemical Composition, and Sources of Oligocene to Miocene Volcanic Ashes from Sites 907, 908, and 913

Chemical composition, age, and sources of volcaniclastic sediments from Sites 917 and 918

The tephrochronology of Iceland and the North Atlantic region during the Middle and Late Quaternary: a review

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