Abstract
We present a 3-D shear wave velocity model of the Mauléon and Arzacq Basins from the surface down to 10 km depth, inverted from phase velocity maps at periods between 2 and 9 s. These phase velocity maps were obtained by analyzing coherent surface wave fronts extracted from ambient seismic noise recorded by the large-N Maupasacq seismic array with a matched filtering approach. This new model is in good agreement with a local earthquake tomography study performed on the same acquisition dataset. Our passive imaging models reveal the upper crustal architecture of the Mauléon and Arzacq Basins, with new details on the basement and its relationship with the overlying sedimentary cover. Combining these new tomographic images with surface and subsurface geological information allows us to trace major orogenic structures from the surface down to the basement. In the basin, the models image the first-order basin architecture with a kilometric resolution. At depth, high velocity anomalies suggest the presence of dense deep crustal and mantle rocks in the hanging wall of north-vergent Pyrenean Thrusts. These high velocity anomalies spatially coincide with a positive gravity anomaly in the western Mauléon Basin. In addition, our models reveal major changes from the Chaînons Béarnais to the western Mauléon Basin across a set of orogen-perpendicular structures, the Saison and the Barlanès transfer zones. These changes reflect the along-strike variation of the orogenic evolution that led to the preservation of the former rifted domain and its underlying mantle in the orogenic wedge of the Western Pyrenees. We discuss the implications of these results for the 3-D architecture of the Mauléon Basin and its underlying basement.
Highlights
Imaging crustal structures with a fine spatial resolution is an important goal of modern seismology, with major implications in domains such as georesources and seismic hazard
The advantages related to this passive source of seismic waves i.e., continuity of sources and reduced acquisition costs compared to active seismic methods, did motivate focused applications on sedimentary basins for example for the characterization of an oil and gas field (e.g., Mordret et al, 2013), the subsurface imaging for the exploration of deep geothermal resources (e.g., Lehujeur et al, 2018; Planès et al, 2019) or the monitoring of CO2 underground storage sites (e.g., Gassenmeier et al, 2014)
The inversion of surface wave dispersion curves to determine the vertical variations of elastic parameters is a classical nonlinear inverse problem commonly encountered in earthquake or ambient noise tomography
Summary
Imaging crustal structures with a fine spatial resolution is an important goal of modern seismology, with major implications in domains such as georesources and seismic hazard. The advantages related to this passive source of seismic waves i.e., continuity of sources and reduced acquisition costs compared to active seismic methods, did motivate focused applications on sedimentary basins for example for the characterization of an oil and gas field (e.g., Mordret et al, 2013), the subsurface imaging for the exploration of deep geothermal resources (e.g., Lehujeur et al, 2018; Planès et al, 2019) or the monitoring of CO2 underground storage sites (e.g., Gassenmeier et al, 2014) Another recent advance came from the recognition that large-N node deployments such as those commonly used in controlled-source acquisitions for the oil and gas industry provide rich and valuable datasets for passive imaging studies (e.g., Schmandt and Clayton, 2013). These two recent developments have opened important new perspectives for crustal-scale tomography, and to get valuable insights on the 3-D geometry of sedimentary basins in structurally complex areas to complement active seismic reflection surveys
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
