Magnetic Anomalies Over Iceland and Surrounding Seas (Text to Accompany Map)

Nunns, Alan G.; Talwani, Manik; Lorentzen, G. R.; Vogt, Peter R.; Sigurgeirsson, T.; Kristjánsson, Leó; Larsen, Hans Christian; Voppel, Dietrich

doi:10.1007/978-1-4613-3485-9_33

Cited by 20 publications

(14 citation statements)

References 40 publications

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“…Broken line: basement shelf edge, inferred from magnetic survey results exhibiting a distinct pair of large positive and negative anomalies. Examples of such anomalies occur in the four magnetic survey profiles shown, selected from (in clockwise order) "Project Magnet" line 158 (Nunns et al, 1983), line 9 of Jonsson and Kristjansson (1998), and lines 27 and 13 in Kristjansson (1976b) survey area 2. Solid line: the shelf break as defined from the bathymetry by the authors, usually at 200-400 m depth.…”

Section: The Insular Shelfmentioning

confidence: 98%

“…Parts of the insular shelf were surveyed from ships (e.g. Kristjansson, 1976a,b) and other parts by aircraft (Nunns et al, 1983). The regional data obtained up to 1989 have been reviewed and partly interpreted by Jonsson et al (1991), and additional surveys around the southern half of Iceland were presented by Kristjansson and Jonsson (1998) and Jonsson and Kristjansson (1998).…”

Section: Main Surveysmentioning

confidence: 99%

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Paleomagnetism and magnetic anomalies in Iceland

Kristjánsson

Jónsson

2007

Journal of Geodynamics

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Section: The Insular Shelfmentioning

confidence: 98%

Section: Main Surveysmentioning

confidence: 99%

Paleomagnetism and magnetic anomalies in Iceland

Kristjánsson

Jónsson

2007

Journal of Geodynamics

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“…The top of the C. apiculata Zone of Bukry (1978) is correlated to CP17 by Bukry (1981), which suggests that Core 9 is no younger that 34 Ma. 17 -Age of crust at this site is anomaly 12, according to Nunns et al (1983). The site was drilled 20 km E of the extinct axis on the steep slope of the magnetic anomaly (?= base 12N).…”

Section: Norwegian-greenland Seamentioning

confidence: 99%

“…Fossils were undiagnostic. 20 -Our best estimate from the magnetic anomaly map of Nunns et al (1983).…”

Section: Norwegian-greenland Seamentioning

confidence: 99%

“…My estimate of the magnetic anomaly is from the map of Nunns et al (1983 For this study, a total of 55 samples from Cores 41X to 63X were processed for benthic foraminifera, dinocysts and radiolarians following the methodology outlined in Kaminski et al (in press, d). The taxonomy of benthic foraminifera from the Leg 38 sites in the Norwegian-Greenland Sea was originally developed by Verdenius and Van Hinte (1983).…”

Section: Norwegian-greenland Seamentioning

confidence: 99%

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Cenozoic deep-water agglutinated foraminifera in the North Atlantic

Kaminski¹

1987

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Cenozoic (predominantly Paleogene) "flysch-type" agglutinated foraminiferal assemblages and their modern analogs in the North Atlantic and adjacent areas have been studied to provide an overview of their spatial and temporal distribution and utility for paleoenvironmental analysis. Over 200 species of agglutinated foraminifera have been recognized in Paleogene sediments from North Atlantic and Tethyan basins. This unified taxonomic data base enables the first general synthesis of biostratigraphic, paleobiogeographic and paleobathymetric patterns in flysch-type agglutinated assemblages from upper Cretaceous to Neogene sediments in the North Atlantic. The majority of taxa are cosmopolitan, but latitudinal, temporal and depth-related trends in diversity and species composition are observed among flysch-type assemblages.Modern deep-sea agglutinated foraminiferal faunas provide an analog to fossil flysch-type assemblages and serve as models for paleoecologic studies. Core-top samples from the Panama Basin, Gulf of Mexico and Nova Scotian continental rise were examined in order to determine the habitats of modern species of agglutinated foraminifera. The ecology of modern taxa provides constraints on the paleoenvironmental significance of fossil agglutinated assemblages in the North Atlantic, and their utility for paleoceanography.Towards this end, spade core samples from a 3912 m deep station in the Panama Basin were studied to determine abundance and microhabitat partitioning among living agglutinated foraminiferal populations and the preservation of dead assemblages. The genera Dendrophrya, Cribrostomoides and Ammodiscus have epifaunal habitats and the genus Reophax is predominantly infaunal. Species of Reophax are probably responsible for fine reticulate burrows observed in xradiographs. An experiment using recolonization trays in the Panama Basin was designed to identify opportunistic species of benthic foraminifera, and to assess the rate at which a population can colonize an abiotic substrate. The most successful colonizer at this site is Reophax, while Dendrophrya displays the lowest capability for dispersal. After nine months the abundance of living individuals in sediment trays was one-tenth to one-third that of background abundance, but the faunal diversity did not differ greatly from control samples. Recolonization by benthic foraminifera is more rapid than among macrofaunal invertebrates.Modern agglutinated assemblages from the Louisiana continental slope were examined to determine changes in species composition associated with hydrocarbon seeps. Organic-rich substrates are characterized by a decrease in astror--iihizids and an increase in trochamminids and textulariids. Highly organicenriched substrates with chemosynthetic macrofauna are dominated by Trochammina glabra and Glomospira charoides.The biostratigraphy of fossil agglutinated foraminifera in the North Atlantic is based on detailed analysis of 670 samples from 14 wells and one outcrop section, and examination of additional picked faunal...

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Causes and Consequences of Diachronous V‐Shaped Ridges in the North Atlantic Ocean

et al. 2017

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In the North Atlantic Ocean, the geometry of diachronous V‐shaped features that straddle the Reykjanes Ridge is often attributed to thermal pulses which advect away from the center of the Iceland plume. Recently, two alternative hypotheses have been proposed: rift propagation and buoyant mantle upwelling. Here we evaluate these different proposals using basin‐wide geophysical and geochemical observations. The centerpiece of our analysis is a pair of seismic reflection profiles oriented parallel to flow lines that span the North Atlantic Ocean. V‐shaped ridges and troughs are mapped on both Neogene and Paleogene oceanic crust, enabling a detailed chronology of activity to be established for the last 50 million years. Estimates of the cumulative horizontal displacement across normal faults help to discriminate between brittle and magmatic modes of plate separation, suggesting that crustal architecture is sensitive to the changing planform of the plume. Water‐loaded residual depth measurements are used to estimate crustal thickness and to infer mantle potential temperature which varies by ±25°C on timescales of 3–8 Ma. This variation is consistent with the range of temperatures inferred from geochemical modeling of dredged basaltic rocks along the ridge axis itself, from changes in Neogene deep‐water circulation, and from the regional record of episodic Cenozoic magmatism. We conclude that radial propagation of transient thermal anomalies within an asthenospheric channel that is 150 ± 50 km thick best accounts for the available geophysical and geochemical observations.

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Magnetic Anomalies Over Iceland and Surrounding Seas (Text to Accompany Map)

Cited by 20 publications

References 40 publications

Paleomagnetism and magnetic anomalies in Iceland

Paleomagnetism and magnetic anomalies in Iceland

Cenozoic deep-water agglutinated foraminifera in the North Atlantic

Causes and Consequences of Diachronous V‐Shaped Ridges in the North Atlantic Ocean

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