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Accurate characterization of hydrocarbon reservoirs requires a good understanding of the paleostress history of their host sedimentary basin. This study aims at reconstructing the paleoburial and paleostress history of the syn-rift Barremian TOCA Fm. in the Lower Congo basin (West African margin). Two oriented borehole cores drilled offshore Congo were investigated using stress inversion techniques applied to calcite mechanical twins to constrain paleostress orientations and magnitudes. The inversion of calcite twins was performed on a widespread early diagenetic cement (~129 to ~113 Ma) and revealed that the TOCA Fm. has undergone a complex polyphase stress history, including (1) extensional stress regimes with vertical σ 1 and horizontal σ 3 trending NE-SW and WNW-ESE (N100) associated with the rifting episode preceding the opening of the South Atlantic (130 to 112 Ma), and with mean differential stresses of ~47 MPa for (σ 1 -σ 3) and ~ 20 MPa for (σ 2 -σ 3). The early N100 extension is associated with the development of normal faults striking N-S that likely reactivated inherited basement structures. The direction of extension evolved during the Barremian into the main NE-SW extension marked by the dominant normal faults striking NW-SE. (2) Compressional and strike-slip stress regimes with horizontal σ 1 oriented ~N-S possibly related to the far-field intraplate transmission of orogenic stresses generated at the distant Africa-Eurasia plate boundary at ~67–60 Ma, and with mean differential stresses of 40 MPa for (σ 1 -σ 3) and 28 MPa for (σ 2 -σ 3). (3) Compressional and strike-slip stress regimes with horizontal σ 1 oriented ENE-WSW to ~E-W that we tentatively relate to the mid-Atlantic ridge push and prevailing since ~15 Ma onwards, associated with mean differential stresses of ~45 MPa for (σ 1 -σ 3) and ~ 18 MPa for (σ 2 -σ 3). Our results reveal that the TOCA Fm. recorded mainly far-field stress effects that could be related to interactions between the African plate and surrounding plates, and that divergent passive margins may experience a complex tectonic history including both extensional and compressional events. • Calcite twin inversion is used to reconstruct paleostress history on the West Africa passive margin. • The orientations and magnitudes of paleostresses affecting the syn -rift TOCA Fm. are characterized from two offshore cores in the Lower Congo basin. • The timing of the successive stress regimes in the TOCA Fm. is constrained. • The influence of far-field tectonic and gravitational lithospheric stresses transferred from distant plate boundaries on the post-rift history on the West Africa passive margin is demonstrated. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents a new approach to constrain paleoburial and subsequent uplift by folding in fold–thrust belts, combining differential stress estimates from mechanically-induced calcite twins with the assumption that stress in the upper crust is in frictional equilibrium. Calcite twin data were collected from pre-folding veins in late Cretaceous limestones from the Ionian zone in Albania in order to (1) determine Paleogene–Neogene stresses associated with the development of the major vein sets in the frontal anticlines of the Outer Albanides and (2) estimate paleoburial of the Cretaceous reservoir rocks during pre-folding flexural subsidence of the foreland. The first vein set (set I) trends N140 (±20) and the second set (set II) is oriented N060 (±20). Calcite twinning analysis from set I veins reveals a pre-folding N030° extension likely related to foreland flexure; a later pre-folding, NE-directed compression (LPS) is identified either from one or from both vein sets in the samples from the Saranda anticline; this NE compression is instead recorded by twinning in set II veins from the Kremenara anticline during late stage fold tightening. This NE compression well agrees with independent microtectonic data, regional transport direction and contemporary stress. The differential stress values related to this NE compression are combined with the hypothesis of crustal frictional stress equilibrium to derive first-order estimates of paleoburial of the Cretaceous limestones just before they were uplifted by folding. The ~4 km paleoburial of these limestones estimated in the Saranda anticline is consistent with independent paleoburial estimates from stratigraphy, maturity rank of organic matter, paleotemperature/paleogeothermal gradients from fluid inclusions and predictions of kinematic modelling of the Albanian foreland. Our results therefore place reliable constraints on the amount and rate of vertical uplift of these Cretaceous limestones and yield a promising methodology for better constraining paleoburial and therefore erosion and uplift in fold–thrust belts. [Copyright &y& Elsevier]