Seismological evidence for a fossil subduction zone in the East Greenland Caledonides

Schiffer, Christian; Balling, Niels; Jacobsen, Bo Holm; Stephenson, Randell; Nielsen, Søren B.

doi:10.1130/g35244.1

Cited by 49 publications

(41 citation statements)

References 38 publications

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“…Our results suggest that the deep structure of the GIFR is not fully symmetric: The major high‐density anomaly is along the Greenland margin, where it is apparently associated with the North Atlantic LIP. We speculate that the anomaly is compositional in origin and, similar to continental mantle, may be caused by partial eclogitization of basaltic magmas associated with the LIP, facilitated by mantle hydration at the paleosubduction system (Schiffer et al, ). Therefore, the apparent absence of the anomaly at Iceland and along the GIFR may be caused by the counter‐play of a negative low‐density anomaly of thermal origin and a positive high‐density anomaly of compositional origin.…”

Section: Density Of Oceanic Upper Mantlementioning

confidence: 95%

Thermochemical Heterogeneity and Density of Continental and Oceanic Upper Mantle in the European‐North Atlantic Region

Shulgin

Artemieva

2019

JGR Solid Earth

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We present a new model, EUNA‐rho, for the density structure of the continental and oceanic upper mantle based on 3‐D tesseroid gravity modeling. On continent, there is no clear difference in lithospheric mantle (LM) density between the cratonic and Phanerozoic Europe, yet an ~300‐km‐wide zone of a high‐density LM along the Trans‐European Suture Zone may image a paleosubduction. Kimberlite provinces of the Baltica and Greenland cratons have a low‐density (3.32 g/cm3) mantle where all non‐damondiferous kimberlites tend to a higher‐density (3.34 g/cm3) anomalies. LM density correlates with the depth of sedimentary basins implying that mantle densification plays an important role in basin subsidence. A very dense (3.40–3.45 g/cm3) mantle beneath the superdeep platform basins and the East Barents shelf requires the presence of 10–20% of eclogite, while the West Barents Basin has LM density of 3.35 g/cm3 similar to the Variscan massifs of western Europe. In the North Atlantics, south of the Charlie Gibbs fracture zone (CGFZ) mantle density follows half‐space cooling model with significant deviations at volcanic provinces. North of the CGFZ, the entire North Atlantics is anomalous. Strong low‐density LM anomalies (< −3%) beneath the Azores and north of the CGFZ correlate with geochemical anomalies and indicate the presence of continental fragments and heterogeneous melting sources. Thermal anomalies in the upper mantle averaged down to the transition zone are 100–150 °C at the Azores and can be detected seismically, while a <50 °C anomaly around Iceland is at the limit of seismic resolution.

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Section: Density Of Oceanic Upper Mantlementioning

confidence: 95%

Thermochemical Heterogeneity and Density of Continental and Oceanic Upper Mantle in the European‐North Atlantic Region

Shulgin

Artemieva

2019

JGR Solid Earth

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“…Interpolated Moho depth map based on all available data from the region, including the new RFs described here and data from Mandler (), Schmidt‐Aursch and Jokat (), Schiffer et al (), and Shulgin and Thybo ().…”

Section: Discussionmentioning

confidence: 99%

“…Only very recently the first regional seismological studies in onshore Greenland were carried out. Schiffer et al () interpret an eastward dipping interface detected by seismic receiver functions as a fossil subduction zone close to the east coast at around 73°N based on P receiver functions. Kraft et al () image the fine structure of the mantle transition zone and interpret it in terms of the thermal structure.…”

Section: Introductionmentioning

confidence: 99%

Crustal Structure in Central‐Eastern Greenland From Receiver Functions

et al. 2019

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The crustal structure in the interior of Greenland is largely unknown because of its remote location below the up to 3.4‐km‐thick ice sheet. We present a model of the crustal velocity structure in central‐eastern Greenland based on simultaneous inversion of P and S receiver functions for data acquired at 23 broadband stations between the coast and the center of the ice sheet. The area is believed to mainly include Precambrian basement and includes a part covered by Tertiary volcanic rocks and some sedimentary basins. Our results show a westward deepening Moho from less than 20 km at the coast to 50 km below central Greenland. Crustal S wave velocities are generally 3.75 km/s through the whole crust which may be relatively small for Precambrian areas, and Vp/Vs is generally around 1.73, although slightly higher in central Greenland. In the coastal area we observe anomalously low velocities at the top of the crust. In the volcanic area south of Scoresbysund Fjord this layer has very high Vp/Vs (>2), which indicates a high mafic content and the presence of water‐filled cracks in the basaltic material. In the north, outside the volcanic area, Vp/Vs is normal and the low‐velocity layer probably is instead related to the presence of sedimentary basins. At stations in the center of our study area we find low Vs and high Vp/Vs in the lower crust. Based on the Moho topography, our results do not support Airy type isostasy as explanation of the high topography in eastern Greenland.

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“…We therefore have an irregular spatial distribution of information, which means that a lot of rays cross some regions, whereas other regions suffer from very poor ray coverage or maybe have no rays at all. This, or similar aspects, applies to several projects carried out worldwide, for example, Hi-CLIMB project in Tibet (Zhang et al, 2012), GAMSEIS in Antarctica (Lloyd et al, 2013), SCAN-LIPS in Norway and Sweden (England and Ebbing, 2012), and the central Fjord array in East Greenland (Schiffer et al, 2014). The method presented in this paper is particularly suited for such datasets.…”

Section: Introductionmentioning

confidence: 87%