The Cenomanian to early Santonian interval is usually considered a time of postrifting tectonic quiescence around the northern margins of Iberia that preceded the onset of the Pyrenean convergence by crustal thrusting in the latest Santonian. However, plate kinematic models of the Mesozoic evolution of Iberia poorly constrain the Turonian-Santonian position of Iberia relative to Eurasia. This study reconstructs changes in the sedimentary facies and architecture of the Iberian carbonate platform throughout the Late Cretaceous and sheds new light on the geodynamic evolution of the Iberia-Eurasia relationship at that time. Sixteen outcrop sections were described and 24 sedimentary facies identified that define 5 depositional environments ranging from the basin to the continental setting. From these and previously published field data we reconstruct the evolution of the Pyrenean carbonate platform, on an east-west transect nearly 400 km long, on the basis of 11 short-term depositional sequences and 5 long-term systems tracts. In our interpretation, the Cenomanian and Turonian correspond to a postrift stage during which the European and Iberian margins, together with the deep basin between them, subside gently, as shown by accommodation rates varying from ~15 to 30 m/My in the margins and ~100 to 150 m/My in the basin. The Coniacian and early Santonian are characterized by a large-scale flexural response consisting of (1) uplift of the southern Iberian margin, with negative accommodation rates, karstified surfaces and paleosols, and (2) increasing subsidence rates in the basin and its edges (the northern Iberian margin and eastern Aquitaine platform), with accommodation rates several times greater than during the Turonian. We propose that far-field stress associated with slight northward motion of the Iberia plate led to the incipient large-scale flexural deformation in the Pyrenean domain. The late Santonian and Campanian are an early orogenic stage marked by rapid subsidence throughout the Pyrenean domain, except at its western end. We argue that the initiation of the Pyrenean convergence, usually considered to occur during the latest Santonian, occurred in the Coniacian.

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<p>Reservoir rocks, such as carbonates, are rapidly becoming key elements for the energy transition. The damage of these reservoir rocks when placed under a stress field must be characterized, to better predict storage capacity distribution. In the shallow subsurface, carbonate rocks accommodate the stress by developing structures at the mesoscale, such as fractures, deformation bands or stylolites, depending on porosity or fluid content. Those are localized, showing a finite damaged area, outside which the relative host rock can accommodate the applied stress in a different way, usually overlooked in low temperature and pressure conditions.</p> <p>In this study, we highlight a new marker of accommodation of shortening, characterized by heterogeneous quartz grain rotation in non-porous carbonate matrix. The studied rock is an upper Cretaceous bioclastic calcarenite from the Cotiella Massif (Spain). This rock is composed of 85% carbonate (micrite and recrystallized microsparite), 10% quartz, and <5% of nanometric porosity. It hosts a fracture pattern including fractures, stylolites and deformation bands that correspond to different tectonic stages. However, we focus on investigating the quartz grain orientation in the grains outside the deformation bands, in both the far-field and near-field host rock. We investigated the fabric (typology, distribution and orientation) of thousands of quartz grains using X-ray microtomography on cylindrical cores of 8-26 mm diameter. Each segmented quartz grain is approximated with a best-fit ellipsoid whose major axis (L1) and minor axis (L3) give us information about the average orientation of the quartz grain. We show that the typology of the quartz grains, namely the size and average shape is similar in all our samples.</p> <p>The average orientation of all quartz grains at the core scale reveals subtle preferences, without clear correlation to the orientation of neither the stylolites nor the deformation bands. We observe that in half of the samples studied, the quartz grain fabric is not controlled by the bedding. Instead, there are two distinct patterns of grain orientation, with the quartz grain fabric either reflecting the early burial stage or revealing a later reorientation perpendicular to one of the major shortening directions. These directions are either striking parallel to the local shortening flow (NE-SW) or to the regional orogenic flow (N-S), that is attributed to the Pyrenean orogeny. Evidence of dissolution-recrystallization are observed in quartz, but the diagenetic conditions constrainthis mechanism from being a robust hypothesis to explain the change of quartz fabric, but rather favour the rigid rotation of quartz in a micritic matrix. The examination of both the quartz grains and the carbonate matrix with EBSD suggests a local strain accumulation within the carbonates in the vicinity of quartz grains. Although the mechanisms causing this rotation need to be better understood, measuring the grain typology and orientation on a considerable number of grains with the aid of X-ray microtomography could result in a new method of deformation quantification in carbonate rocks.</p>

<p>Salt tectonics is responsible for typical structures associated with salt structures margins development: (i) minibasin subsidence, (ii) basin edge backfolding of basin margins, forming plurikilometric steep or overturned structures along the salt structures or their equivalent welds, called megahooks and megaflaps and (iii) smaller-scale halokinetic drape folding and composite halokinetic sequences (CHS). Mega-halokinetic structures like the megaflaps are of particular interest to us as they have been recently defined and their kinematics are poorly understood compared to those of CHS. They develop either during halokinetic drape folding, or during contractional squeezing of the diapirs or during some combination of both processes. It seems megaflaps form early in the salt reliefs development as opposed to more mature structures allowing the CHS development. Because of their geometry, megaflaps have also implications for reservoirs geometries and fluid pressures distribution, critical for successful exploration or potential storage. Megaflaps seem to have the same behaviour as detachment folds and could present same kinematics and deformations. Characterizing the multi-scale damage records, using fracturation network and matrix damage analyses, may allow us to reconstruct the megaflaps formation dynamics and to establish relationships between reservoir properties and structural evolution.</p><p>In the Cotiella Basin, recent studies have shown the role of salt tectonics associated with gravity in the creation of various minibasins during the post-rift system between the Cenomanian and the Santonian. The Cotiella minibasin <em>s.s.</em> presents a megaflap with vertical to completely overturned layers. The calcarenites composing this megaflap present numerous joints, veins and stylolites. The first observations and analyses show several stages of deformation, from Layer Parallel Shortening (LPS) to Late Stage Fold Tightening (LSFT) as observed in the folds. Moreover, preliminary results of matrix damage, using AMS, also indicate a record of LPS and even late deformation, LSFT, in the rocks. A detailed scenario of the damage acquisition chronology, from the multi-scale damage, is under contruction to understand the formation of this megaflap. We will then be able to compare the damage, the type of megaflap and the causal relationships such as geodynamic context and lithology with others such as the Sivas megaflap (Turkey).</p>