Velero Basin

Stratigraphic and structural controls on submarine mass wasting in the Velero Basin, Outer California Borderland

Paper: https://doi.org/10.1016/j.margeo.2026.107822

Data: https://doi.org/10.7284/909885 

Abstract

Submarine mass wasting in the active California Continental Borderland is controlled by strike-slip tectonics and stratigraphic heterogeneity, producing recurrent slope failure and mass transport deposits (MTDs) in structurally confined basins. In the Velero Basin, Outer California Borderland (OCB), new high-resolution geophysical data reveal two adjacent but morphologically distinct mass transport complexes (MTCs), reflecting different failure styles. The southern MTC is characterized by canyon-controlled sediment transport and deposition of overlapping debris lobes and rockfalls on the basin floor. The northern MTC shows a stepped slope profile defined by multiple scarps, indicating basinward-progressive failure and structural control by faulting and mechanically weak stratigraphic horizons. Seismic stratigraphy documents multiple MTDs spanning Late Miocene to Recent, including a >200 m-thick Late Miocene–Pliocene slide (>3.7 Ma), a ~35 m Early Pleistocene deposit (~1.3 Ma), and recent events up to ~72 m thick on the seafloor. A regionally continuous reflector, interpreted as a turbidite (~721.4 ± 6 ka), likely acted as a weak layer facilitating recent mass wasting. A coeval but distinct turbidite is identified in the adjacent Cortes Basin. The correlation between these deposits suggests potential synchronicity in MTD emplacement, implying that large-magnitude earthquakes can trigger extensive slope failures across the OCB.