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

Abstract

Triassic evaporites represent the regional décollement of the Pyrenees and form two salt provinces north and south of the South Pyrenean Central Salient (SPCS). We present an updated Bouguer and residual Bouguer anomaly map built upon the homogenization of available gravity data of the SPCS together with four new and representative cross-sections, constrained by geological data acquired in the field, seismic, well, and gravity data (gravity forward modeling). Gravity anomaly maps and cross-sections are used to characterize the present-day uneven distribution of Triassic evaporites. Outcropping Triassic evaporites is not necessarily associated with an underlying evaporite accumulation and the absence of it at surface does not involves its non-existence at depth. Northwest of the salient, a major accumulation of Triassic evaporites floors a thick syn-orogenic Upper Cretaceous basin. South of it, Triassic rocks core salt-detached anticlines related to the Pyrenean orogeny. Along the southernmost (and youngest) thrust sheet of the salient, diapirs, and evaporite accumulations are associated with a salt-inflated area.