Insuring the quality of gravity data

Grandjean, Gilles; Mennéchet, C.; Debeglia, N.; Bonijoly, D.

doi:10.1029/98eo00160

Cited by 11 publications

(9 citation statements)

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“…HF, Hendaya Fault; PF, Pamplona Fault; TC, Torrelavega Canyon. (b) Bouguer anomaly map obtained from our own data and data provided by the Bureau Gravimétrique International and the GeoFrance3D Project [ Grandjean et al , 1998] (reduction density of 2670 kg/m 3 and variable terrain corrections). Note that the trace of the southernmost position of the European‐Cantabrian Margin lower crust follows approximately the southern gradient of the highest anomalies (see text for details).…”

Section: Discussion and Tectonic Implicationsmentioning

confidence: 99%

Seismic evidence of Alpine crustal thickening and wedging from the western Pyrenees to the Cantabrian Mountains (north Iberia)

et al. 2003

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The Alpine collision between the Iberian and European plates resulted in a complex crustal structure beneath the northern Iberian Peninsula, as revealed from a new set of seismic refraction/wide‐angle reflection profiles. The study area is characterized by two major E‐W ranges, the Cantabrian Mountains and the Pyrenees, which are relayed to the south by the Iberian Chain. Important variations in crustal thickness and velocity distribution are found in a 560‐km‐long E‐W transect. In contrast to the typical 30‐ to 32‐km‐thick European Variscan crust of the western end of the profile, a continuous Alpine crustal root is evidenced from the Cantabrian Mountains to the central Pyrenees, with a Moho depth of 46–48 km, locally rising to ∼40 km depth in between, beneath the Basque‐Cantabrian Basin. Another outstanding feature is the inferred presence of high velocities of 6.40–6.75 km/s at midcrustal depths, which can be associated with portions of a lower crustal wedge from the northern (European) domain indenting the southern (Iberian) crust during the Alpine stage of compression. This indentation produces the delamination of the Iberian crust, with northward underthrusting of its lower half and the consequent crustal thickening. The indenting wedge has a discontinuous presence along the longitudinal section, as it was controlled and/or affected by N‐S to NE‐SW structures. Further evidence of the northward subduction of the Iberian plate is provided by another profile toward the Aquitaine Basin, while a N‐S profile across the Iberian Chain reveals an Alpine midcrustal thickening beneath this belt with Moho depths of ∼42 km.

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Section: Discussion and Tectonic Implicationsmentioning

confidence: 99%

Seismic evidence of Alpine crustal thickening and wedging from the western Pyrenees to the Cantabrian Mountains (north Iberia)

et al. 2003

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“…To obtain the Bouguer anomalies, data were reduced to the Hayford 1930 ellipsoid. These data have been integrated within the French National database CGF65 (Grandjean et al, 1998;Martelet et al, 2002). These additional data permit obtaining a regular sampling that reduces interpolation errors.…”

Section: Methodsmentioning

confidence: 99%

“…Each point was measured with a Scintrex CG3M (Seigel et al, 1995) and geo-referenced with a global positioning system. Points of measurements were first combined with measurements made for the French National database CGF65 (Grandjean et al, 1998) (Fig. 3a).…”

Section: Methodsmentioning

confidence: 99%

Impact of gently dipping discontinuities on basement aquifer recharge: An example from Ploemeur (Brittany, France)

Ruelleu

Moreau

Bour

et al. 2010

Journal of Applied Geophysics

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“…For the computation of our Bouguer gravity map, we mainly used ground gravity data from the French gravity database (Grandjean et al 1998; Martelet et al 2002) and particularly from the gravity surveys performed in the western Alps (Masson et al 1999). Italian gravity data are provided by the BGI (Bureau Gravimétrique International).…”

Section: Geophysical Data On the Southwestern Alpsmentioning

confidence: 99%

3-D modelling of Alpine Mohos in Southwestern Alps

Schreiber¹,

Lardeaux²,

Martelet³

et al. 2010

Geophysical Journal International

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International audienceWe present and discuss a 3-D geometrical model of the Moho topography in the Southwestern Alps. To achieve this objective, we used the potential of 3-D modelling software (i.e. a 3-D GeoModeller) to combine gravity, seismic and seismological constraints in a same and coherent 3-D space. A new regional Bouguer gravity anomaly map of the Southwestern Alps was calculated and filtered to isolate the Moho signature in the Southwestern Alps. Then, two alternative 3-D models were computed with data from the literature based on seismic and seismological constraints. The first one represents an European lithospheric mantle decoupled from the European orogenic crust which is back-thrusted by the Ivrea body whereas the second 3-D model illustrates the subduction of a 20-km-thick piece of lower continental crust, coupled with the European upper mantle, beneath the Ivrea body. According to the geological knowledge of these units we then assigned a density value to each modelled layer and we computed their gravity effects to compare them with the filtered Moho map of the Southwestern Alps. First of all, the significant discrepancies of the Moho gravity signature generated by these two geometrical models reveal that subduction of continental crust is no more active in the present-day configuration of the Southwestern Alps. Therefore, the first 3-D model was refined by a stochastic 3-D gravity inversion. Based on this processing, our investigations confirm the presence of three superposed Mohos in the Southwestern Alps and underline that: (i) The crust/mantle European boundary is localized around 50 km depth beneath the Argentera-Mercantour massif, (ii) The European lithospheric mantle is decoupled from the European orogenic crust, (iii) The Adriatic mantle (Ivrea body) is split into two distinct units; the upper unit is located at 10 km depth beneath the Dora-Maïra massif, and the lower unit extends from 20 to 45 km depth. (iv) These two mantle indenters affect differently the European crust and are responsible for the localization of crustal deformation and for strain partitioning in the Southwestern Alps

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Insuring the quality of gravity data

Cited by 11 publications

References 0 publications

Seismic evidence of Alpine crustal thickening and wedging from the western Pyrenees to the Cantabrian Mountains (north Iberia)

Seismic evidence of Alpine crustal thickening and wedging from the western Pyrenees to the Cantabrian Mountains (north Iberia)

Impact of gently dipping discontinuities on basement aquifer recharge: An example from Ploemeur (Brittany, France)

3-D modelling of Alpine Mohos in Southwestern Alps

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