Joint Geophysical‐Petrological Modeling on the Ivrea Geophysical Body Beneath Valsesia, Italy: Constraints on the Continental Lower Crust

Abstract

Exposed crust-mantle sections are essential archives of the past and contemporary lithosphere (Rudnick & Fountain, 1995; Rudnick & Presper, 1990; Percival et al., 1992) and are fundamental for estimates of the composition of the Earth's crust (Rudnick & Gao, 2003) above the Mohorovičić discontinuity or Moho separating the Earth's crust from the subjacent mantle (Mohorovičić, 1910). While the "geophysical Moho" defines the sudden change in compressional wave velocities from typically <7 km/s to >8 km/s, the "petrological Moho" transition zone corresponds to the level where plagioclase disappears from the crystallizing assemblage within the cumulates of underplated mafic magma (Müntener & Ulmer, 2006). The "petrological

Joint Seismic and Gravity Data Inversion to Image Intra-Crustal Structures: The Ivrea Geophysical Body Along the Val Sesia Profile (Piedmont, Italy)

“…Moreover, when compared with the rock properties of in situ IVZ samples (Zappone et al, 2015) in v S -ρ space, the inversion results show good agreement with several gabbro samples, and also with ultramafic rock and amphibolite samples if the aforementioned density-shift is considered (Figure 9). These align with indications drawn from studies by Pistone et al (2020) and Scarponi et al (2020) on possible rock types. However, we make no further selection of rock types, to avoid potential over-interpretation here, as reality is surely more complex than a single-discontinuity 2D model.…”

Insights Into the Origin and Deformation Style of the Continental Moho: A Case‐Study From the Western Alps (Italy)

“…The amount of anisotropy that we found in our inversion is not compatible with the rocks proposed by Pistone et al. ( 2020 ), so we should assume that the igneous complex these rocks would belong to, has a limited dimension, lower than the tens of km distant from CIFALPS stations.…”

“…serpentinized peridotite) below the proto-continental Moho (Figure 6). Recently Pistone et al (2020), using gravity and seismological evidence, proposed magmatic underplating as a possible hypothesis for petrological reconstruction of the origin of the IB into the European lower crust.…”

“…Recently Pistone et al. ( 2020 ), using gravity and seismological evidence, proposed magmatic underplating as a possible hypothesis for petrological reconstruction of the origin of the IB into the European lower crust. However, in our opinion, this hypothesis is not feasible in our area of interest at least for three reasons: (a) the Pistone et al.…”

“…The DIVE project will address fundamental questions about the origin of the continental crust, its formation and evolution (Pistone et al., 2017 ). However, while the characterization of the northern part of the IB benefits of studies on lower‐crustal rocks of the Ivrea‐Verbano zone (i.e., Pistone et al., 2020 ; Scarponi et al., 2020 ), the extension and definition of the IB in its central and southern parts is not straightforward, due to the difficulties and challenges in mapping subsurface rock volumes (Fountain, 1976 ). A recent modeling of a dense gravity data set in the Ivrea‐Verbano zone has shown that the Moho on top of the IB may be as shallow as 1–2 km below sea level (Scarponi et al., 2020 ).…”