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Sökning: id:"swepub:oai:DiVA.org:su-186475" > New gravity data an...

  • Scarponi, M.Univ Lausanne UNIL, Inst Earth Sci, Batiment Geopolis, CH-1015 Lausanne, Switzerland. (författare)

New gravity data and 3-D density model constraints on the Ivrea Geophysical Body (Western Alps)

  • Artikel/kapitelEngelska2020

Förlag, utgivningsår, omfång ...

  • 2020-05-30
  • Oxford University Press (OUP),2020
  • printrdacarrier

Nummerbeteckningar

  • LIBRIS-ID:oai:DiVA.org:su-186475
  • https://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-186475URI
  • https://doi.org/10.1093/gji/ggaa263DOI
  • https://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-421524URI

Kompletterande språkuppgifter

  • Språk:engelska
  • Sammanfattning på:engelska

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Klassifikation

  • Ämneskategori:ref swepub-contenttype
  • Ämneskategori:art swepub-publicationtype

Anmärkningar

  • We provide a high-resolution image of the Ivrea Geophysical Body (IGB) in the Western Alps with new gravity data and 3-D density modelling, integrated with surface geological observations and laboratory analyses of rock properties. The IGB is a sliver of Adriatic lower lithosphere that is located at shallow depths along the inner arc of the Western Alps, and associated with dense rocks that are exposed in the Ivrea-Verbano Zone (IVZ). The IGB is known for its high seismic velocity anomaly at shallow crustal depths and a pronounced positive gravity anomaly. Here, we investigate the IGB at a finer spatial scale, merging geophysical and geological observations. We compile existing gravity data and we add 207 new relative gravity measurements, approaching an optimal spatial coverage of 1 data point per 4–9 km2 across the IVZ. A compilation of tectonic maps and rock laboratory analyses together with a mineral properties database is used to produce a novel surface rock-density map of the IVZ. The density map is incorporated into the gravity anomaly computation routine, from which we defined the Niggli gravity anomaly. This accounts for Bouguer Plate and terrain correction, both considering the in situ surface rock densities, deviating from the 2670 kg m–3 value commonly used in such computations. We then develop a 3-D single-interface crustal density model, which represents the density distribution of the IGB, including the above Niggli-correction. We retrieve an optimal fit to the observations by using a 400 kg m–3 density contrast across the model interface, which reaches as shallow as 1 km depth below sea level. The model sensitivity tests suggest that the ∼300–500 kg m–3 density contrast range is still plausible, and consequently locates the shallowest parts of the interface at 0 km and at 2 km depth below sea level, for the lowest and the highest density contrast, respectively. The former model requires a sharp density discontinuity, the latter may feature a vertical transition of densities on the order of few kilometres. Compared with previous studies, the model geometry reaches shallower depths and suggests that the width of the anomaly is larger, ∼20 km in west–east direction and steeply E–SE dipping. Regarding the possible rock types composing the IGB, both regional geology and standard background crustal structure considerations are taken into account. These exclude both felsic rocks and high-pressure metamorphic rocks as suitable candidates, and point towards ultramafic or mantle peridotite type rocks composing the bulk of the IGB.

Ämnesord och genrebeteckningar

Biuppslag (personer, institutioner, konferenser, titlar ...)

  • Hetényi, G.Univ Lausanne UNIL, Inst Earth Sci, Batiment Geopolis, CH-1015 Lausanne, Switzerland. (författare)
  • Berthet, T.Uppsala universitet,Institutionen för geovetenskaper (författare)
  • Baron, L.Univ Lausanne UNIL, Inst Earth Sci, Batiment Geopolis, CH-1015 Lausanne, Switzerland. (författare)
  • Manzotti, PaolaStockholms universitet,Institutionen för geologiska vetenskaper,University of Lausanne, Switzerland,Univ Lausanne UNIL, Inst Earth Sci, Batiment Geopolis, CH-1015 Lausanne, Switzerland.;Stockholm Univ, Dept Geol Sci, SE-10691 Stockholm, Sweden.(Swepub:su)pama8085 (författare)
  • Petri, B.Univ Lausanne UNIL, Inst Earth Sci, Batiment Geopolis, CH-1015 Lausanne, Switzerland.;Univ Strasbourg, CNRS, IPGS UMR 7516, F-67000 Strasbourg, France. (författare)
  • Pistone, M.Univ Lausanne UNIL, Inst Earth Sci, Batiment Geopolis, CH-1015 Lausanne, Switzerland.;Univ Georgia UGA, Dept Geol, Franklin Coll Arts & Sci, Geog Geol Bldg,210 Field St, Athens, GA 30602 USA. (författare)
  • Müntener, O.Univ Lausanne UNIL, Inst Earth Sci, Batiment Geopolis, CH-1015 Lausanne, Switzerland. (författare)
  • Univ Lausanne UNIL, Inst Earth Sci, Batiment Geopolis, CH-1015 Lausanne, Switzerland.Institutionen för geovetenskaper (creator_code:org_t)

Sammanhörande titlar

  • Ingår i:Geophysical Journal International: Oxford University Press (OUP)222:3, s. 1977-19910956-540X1365-246X

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