Description: Re-examination of marine geophysical data from the continental margin of West Morocco reveals a broad zone characterized by deformation, active faults and updoming offshore the High Atlas (Morocco margin), situated next to the Tafelney Plateau. Both seismic reflection and swath-bathymetric data, acquired during Mirror marine geophysical survey in 2011, indicate recent uplift of the margin including uplift of the basement. This deformation, which we propose to name the Atlantic Atlas tectonic arch, is interpreted to result largely through uplift of the basement, which originated during the Central Atlantic rifting stage - or even during phases of Hercynian deformation. This has produced a large number of closely spaced normal and reverse faults, “piano key faults”, originating from the basement and affecting the entire sedimentary sequence, as well as the seafloor. The presence of four terraces in the Essaouira canyon system at about 3500 meters water depth and “piano key faults” and the fact that these also affect the seafloor, indicate that the Atlantic Atlas is still active north of Agadir canyon. We propose that recent uplift is causing morphogenesis of four terraces in the Essaouira canyon system. In this paper the role of both Canary plume migration and ongoing convergence between the African and Eurasian plates in the formation of the Atlantic Atlas are discussed as possibilities to explain the presence of a tectonic arch in the region. The process of reactivation of passive margins is still not well understood. The region north of Agadir canyon represents a key area to better understand this process.

Description: We present seismic, core, log, and chronologic data on three early to middle Miocene sequences (m5.8, m5.4, and m5.2; ca. 20–14.6 Ma) sampled across a transect of seismic clinothems (prograding sigmoidal sequences) in topset, foreset, and bottomset locations beneath the New Jersey shallow continental shelf (Integrated Ocean Drilling Program Expedition 313, Sites M27–M29). We recognize stratal surfaces and systems tracts by integrating seismic stratigraphy, lithofacies successions, gamma logs, and foraminiferal paleodepth trends. Our interpretations of systems tracts, particularly in the foresets where the sequences are thickest, allow us to test sequence stratigraphic models. Landward of the clinoform rollover, topsets consist of nearshore deposits above merged transgressive surfaces (TS) and sequence boundaries overlain by deepening- and fining-upward transgressive systems tracts (TST) and coarsening- and shallowing-upward highstand systems tracts (HST). Drilling through the foresets yields thin (〈18 m thick) lowstand systems tracts (LST), thin (〈26 m) TST, and thick HST (15–90 m). This contrasts with previously published seismic stratigraphic predictions of thick LST and thin to absent TST. Both HST and LST show regressive patterns in the cores. Falling stage systems tracts (FSST) are tentatively recognized by seismic downstepping, although it is possible that these are truncated HST; in either case, these seismic geometries consist of uniform sands in the cores with a blocky gamma log pattern. Parasequence boundaries (flooding surfaces) are recognized in LST, TST, and HST. TS are recognized as an upsection change from coarsening- to fining-upward successions. We find little evidence for correlative conformities; even in the foresets, where sequences are thickest, there is evidence of erosion and hiatuses associated with sequence boundaries. Sequence m5.8 appears to be a single million-year-scale sequence, but sequence m5.4 is a composite of 3 ~100-k.y.-scale sequences. Sequence m5.2 may also be a composite sequence, although our resolution is insufficient to demonstrate this. We do not resolve the issue of fractal versus hierarchical order, but our data are consistent with arrangement into orders based on Milankovitch forcing on eccentricity (2.4 m.y., 405 and 100 k.y. cycles) and obliquity scales (1.2 m.y. and 41 k.y.).