Gravity data on the Central Pyrenees: a step forward to help a better understanding of the Pyrenean structures

Salt Distribution in the South Pyrenean Central Salient: Insights From Gravity Anomalies

“…The gravity data we have used in this investigation comes from a compilation of available terrestrial gravity data acquired over the last 30 years (Ayala et al., 2016; Ayala, Rey‐Moral, Rubio, et al, 2021 and references therein). Within the study area, the data set comprises 12,727 gravity measurements (Figure 3a) of which 3,048 measurements were acquired in the past few years and led to a significant increase of the gravity resolution of the SPCS, from c. 1 measurement per 2–3 km 2 to c. 1 measurement per less than 1 km 2 (Ayala, Rey‐Moral, Rubio, et al., 2021; Ayala, Rey‐Moral, Rubio Sánchez‐Aguililla, et al., 2021; Clariana et al., 2022; Santolaria et al., 2016, 2020; Soto et al., 2022). As described in the referred papers, all the measurements were taken with relative gravimeters (mainly Scintrex CG5 and Lacoste & Romberg, with an accuracy of 0.001 and 0.005 mGal respectively).…”

“…This along‐strike asymmetry is overprinted by several lower wavelength anomalies as described below. The Cotiella‐Bóixols Thrust Sheet shows a 40 km‐long and 22 km‐wide minimum (−18 mGal, Figure 4c, labeled CB2, Ayala, Rey‐Moral, Rubio, et al., 2021; Ayala, Rey‐Moral, Rubio Sánchez‐Aguililla, et al., 2021; Clariana et al., 2022; Soto et al., 2022). This minimum does not have a direct correlation with cropping out rocks but is likely related to low density rocks in the subsurface.…”

“…Observed residual Bouguer anomalies range from −34 to 14 mGal (Figure 4c). The gravity signal in the Axial Zone is characterized by a dominant gravity maximum with relative minima coinciding with the outcrop of Late Paleozoic granitoids or with buried granitoids and gneiss (Ayala, Rey‐Moral, Rubio, et al., 2021; Ayala, Rey‐Moral, Rubio Sánchez‐Aguililla, et al., 2021; Clariana et al., 2022; Soto et al., 2022). This large‐scale regional maximum can be associated with the usually higher density of Paleozoic rocks in the NE Iberian setting (Izquierdo‐Llavall et al., 2019; Pueyo et al., 2016; Toro et al., 2021) and the antiformal stack of the Axial Zone.…”

“…To the west, it is flanked by a prominent maximum (7 mGal, Figure 4c, labeled CB1) that coincides with the western termination of the Cotiella‐Bóixols and Peña Montañesa‐Montsec Thrust Sheets. Toward the east, gentle gravity highs and lows occur (Figure 4c, labeled CB3, Ayala, Rey‐Moral, Rubio, et al., 2021; Ayala, Rey‐Moral, Rubio Sánchez‐Aguililla, et al., 2021; Soto et al., 2022). In this area, gravity lows extend along the contact with the Axial Zone, where Middle‐Upper Triassic evaporites, shales and carbonates are exposed (Figure 1).…”

“…During the past few years, some new densely sampled gravimetric surveys were focused on the SPCS and closer areas (Ayala et al., 2016; Ayala, Rey‐Moral, Rubio, et al, 2021; Carrillo et al., 2020; Pueyo et al., 2021; Santolaria et al., 2016, 2020) and have provided more than 3,000 new gravimetric measurements. Gravity anomalies are here used to unravel the qualitative distribution of evaporitic horizons in the SPCS.…”