Active Deformation along the Southern End of the Tosco-Abreojos Fault System: New Insights from Multibeam Swath Bathymetry

Abstract

The relative motion of the Pacific plate with respect to the North America plate is partitioned between transcurrent faults located along the western margin of Baja California and transform faults and spreading ridges in the Gulf of California. However, the amount of right lateral offset along the Baja California western margin is still debated. We revisited multibeam swath bathymetry data along the southern end of the Tosco-Abreojos fault system. In this area the depths are less than 1,000 m and allow a finer gridding at 60 m cell spacing. This improved resolution unveils several transcurrent right lateral faults offsetting the seafloor and canyons, which can be used as markers to quantify local offsets. The seafloor of the southern end of the Tosco-Abreojos fault system (south of 24°N) displays NW-SE elongated bathymetric highs and lows, suggesting a transtensional tectonic regime associated with the formation of pull-apart basins. In such an active tectonic context, submarine canyon networks are unstable. Using the deformation rate inferred from kinematic predictions and pull-apart geometry, we suggest a minimum age for the reorganization of the canyon network.

Farallon slab detachment and deformation of the Magdalena Shelf, southern Baja California

“…In this model, transtensional faulting in the BC forearc occurs much later in time (8 Ma versus 12 Ma) than suggested by Stock and Hodges [1989]. If these faults systems formed ∼8 Ma and accommodated 3–7 mm/yr of slip since their initiation [ Michaud et al , 2011; Plattner et al , 2007], their cumulative displacement would be 24–56 km, in agreement with estimates by Fletcher et al [2007]. Since 12.3 Ma the total displacement between the Magdalena microplate and North America is ∼610 km.…”

Coexistence of Adjacent Siliciclastic, Carbonate, and Mixed Sedimentary Systems: An Example From Seafloor Morphology in the Northern Lesser Antilles Forearc

“…Tectonics can play an important role in sediment transfer and destabilization, particularly along active margins, where vertical motions can deflect or dam transfer axis, modify the availability of sediment supply or drive the failure of over-steepened slopes (Laursen and Normark, 2002;Mountjoy et al, 2009;Michaud et al, 2011;Ratzov et al, 2012;Collot et al, 2019;Seibert et al, 2020;Claussmann et al, 2021a). Subsidence outlined by the presence of two tilted carbonate paleo-platforms at 700 mbsl and 1,600 mbsl (Figure 8) is consistent with the drastic subsidence of the forearc identified by Boucard et al, 2021.…”

Reducing the residual error of multibeam sounding data through empirical mode decomposition based on cubic Bessel interpolation

“…In Figure 2, the solid line represents a part of the original data that was removed, the symbol "o" represents the minimum value point extracted from the original data, and the symbol "*" represents a control point; notably, the control points were calculated according to formula (8). Based on Figure 2, two control points are added between every two adjacent minimum points according to the above formula.…”

“…These methods have displayed good performance in decreasing the error of multibeam measurements and improving the precision of water depth measurements. [7][8][9][10][11] However, errors inevitably remain in the processed sounding results; these are referred to as residual errors, which cannot be fully eliminated, even with the employment of extremely precise instruments, strict operations, and sophisticated postprocessing schemes. Moreover, the comprehensive effects of residual errors on sounding data can become increasingly significant as the beam depth and incident angle increase with distance, resulting in low-quality sounding measurements; consequently, distortions form in the area of overlap between adjacent bands.…”