Abstract The Late Cretaceous fill of the Oman Mountains foredeep is subdivided into four sub-sequences using seismic stratigraphic principles based on seismic, well and outcrop data. Sub-sequence FD-a (Late Coniacian to Early Santonian) was overriden by the Hawasina allochthon on the sea bed of the foredeep. FD-b (Early to Late Santonian) was deposited during thrusting and slices of foredeep sediment were tectonically accreted onto the allochthon during the final stages of thrusting. FD-c and FD-d (Late Santonian to Late Coniacian) were deposited after the emplacement of the allochthon into the foredeep. Subsidence curves for the foredeep area show that an emergent peripheral bulge bounded the cratonic side of the foredeep throughout the Late Cretaceous. There is no evidence that the forebulge migrated with time ahead of the advancing Hawasina thrust sheets. Instead the bulge remained in situ while the basin narrowed during thrusting. During the Maastrichtian, after infill of the foredeep, the Oman Mountains area subsided beneath sea level. Clastic supply from the drowned hinterland ceased and carbonate deposition followed. The main Oman Mountain building episode was during the Late Miocene when continent-continent collision occurred in the Zagros Mountains.
Summary Fallot’s ‘intercutaneous’ Tinée Nappes are interpreted as gravity slides initiated by uplift of the Argentera Massif and emplaced partly by the ductile deformation of slate horizons, and partly by movement on discrete shear planes. Together, the structures stack between 8 and 11 km of Jurassic and Lower Cretaceous strata—the telescoped cover of the Argentera Massif. The lowest nappe is the furthest travelled. Sliding on a larger scale may have contributed to shortening in the more external parts of Provence.
Abstract Evaporites play a major role in the evolution of an orogenic wedge, modifying the shape and the deformation kinematics inside the wedge. Salt tectonics can occur at various stages, but early salt activity can create a structural inheritance which compartmentalizes the building of the sedimentary succession and the mechanical architecture of the orogenic wedge. Sub‐Alpine fold‐and‐thrust belts commonly show evidence of inherited salt‐related structures, which were mostly described as having been initiated during the Liassic Tethyan rifting. However, even though a few authors tried to introduce salt tectonics as a major factor in the Alpine history, most of the interpretations underestimate the phenomenon. In this paper, we show that the Digne Nappe area presents many salt‐controlled structures within both the Digne and the Authon‐Valavoire thrust sheets. Salt activity began during the Hettangian and continued through the whole Jurassic. At a larger scale, our observations show alignments of salt‐controlled structures following NW–SE and NNE–SSW directions, as well as preferential locations at tectonic unit boundaries. Distribution of salt structures seems to follow a well‐defined pattern directly inherited from the rifting, and this strongly influences deformation of the sub‐Alpine domain.
<p>The understanding of the evolution of salt structures in passive margins has increased significantly in recent decades, largely driven by advances in seismic reflection imaging in offshore passive margin salt basins. This has provided a new perspective with which to view analogous settings in outcrop. The Subalpine Chains of southeast France is one of these places. This region has undergone a complex tectonic history involving Early to Middle Jurassic rifting related to the opening of the Ligurian Tethys, Late Jurassic to Late Cretaceous passive margin subsidence, and Late Cretaceous to Miocene Alpine shortening. The structures and stratigraphic variations in the area strongly suggest that all of these have provided driving mechanisms for, or been associated with, halokinesis.</p><p>This study investigates the role that salt has played in the tectonic evolution of the Subalpine Chains since its deposition in the Triassic using field observations, structural cross sections and drone photography. The period of Early-Middle Jurassic rifting was associated with reactive salt rise, and halokinesis continued during the subsequent passive margin phase driven by sedimentation in the Vocontian basin. Triassic salt reached the sea bed to form salt glaciers during the Aptian-Albian when salt rise outpaced sedimentation rate.</p><p>Later, during Alpine shortening, SW directed compression was partly partitioned as sinistral strike-slip deformation along a pre-existing salt wall, forming the Rouaine-Daluis fault system. There is a discrepancy between the amounts of thin skinned shortening northwest and southeast of the strike slip system which can probably be attributed to the interplay of Jurassic Provence carbonate platform geometry, subsurface salt distribution and basement architecture. In the thin skinned domain of the Digne arc, salt diapirs and walls, formed during the rifting and passive margin phases, such as those at Chasteuil and Cr&#234;te du Teillon, were tightened and displaced up the slope of the Provence Platform margin. Alpine shortening also squeezed salt to surface to form canopies such as the diapir at G&#233;vaudan.</p><p>Halokinesis has influenced, and has been influenced by the tectonic history of the region. While previous regional shortening estimates have acknowledged the role of Triassic salt as a decollement layer, they do not account for the presence of salt walls and diapirs during Alpine shortening. Consequentially, the amount of strain in the Digne arc has likely been underestimated.</p>
'%3e%3cpath fill='%23012169' d='M0 0v30h60V0z'/%3e%3cpath stroke='%23fff' stroke-width='6' d='m0 0 60 30m0-30L0 30'/%3e%3cpath stroke='%23C8102E' stroke-width='4' d='m0 0 60 30m0-30L0 30' clip-path='url(%23b)'/%3e%3cpath stroke='%23fff' stroke-width='10' d='M30 0v30M0 15h60'/%3e%3cpath stroke='%23C8102E' stroke-width='6' d='M30 0v30M0 15h60'/%3e%3c/g%3e%3c/svg%3e)
