Abstract Basin modelling tools are now more efficient to reconstruct palinspastic structural cross sections and compute the history of temperature, pore-fluid pressure and fluid flow circulations in complex structural settings. In many cases and especially in areas where limited erosion occurred, the use of well logs, bottom hole temperatures (BHT) and palaeo-thermometers such as vitrinite reflectance (Ro) and Rock-Eval (Tmax) data is usually sufficient to calibrate the heat flow and geothermal gradients across a section. However, in the foothills domains erosion is a dominant process, challenging the reconstruction of reservoir rocks palaeo-burial and the corresponding calibration of their past thermal evolution. Often it is not possible to derive a single solution for palaeo-burial and palaeo-thermal gradient estimates in the foothills, if based solely on maturity ranks of the organic matter. Alternative methods are then required to narrow down the error bars in palaeo-burial estimates, and to secure more realistic predictions of hydrocarbon generation. Apatite fission tracks (AFT) can provide access to time–temperature paths and absolute ages for the crossing of the 120 °C isotherm and timing of the unroofing. Hydrocarbon-bearing fluid inclusions, when developing contemporaneously with aqueous inclusions, can provide a direct access to the pore-fluid temperature and pressure of cemented fractures or reservoir at the time of cementation and hydrocarbon trapping, on line with the tectonic evolution. Further attempts are also currently made to use calcite twins for constraining reservoir burial and palaeo-stress conditions during the main deformational episodes. Ultimately, the use of magnetic properties and petrographical measurements can also document the impact of tectonic stresses during the evolution of the layer parallel shortening (LPS). The methodology integrating these complementary constraints will be illustrated using reference case studies from Albania, sub-Andean basins in Colombia and Venezuela, segments of the North American Cordillera in Mexico and in the Canadian Rockies, as well as from the Middle East.

Abstract A structural analysis and petrographic investigation has been performed on veins in Cretaceous carbonates in the Cordoba Platform in eastern Mexico, which is part of the Laramide foreland fold and thrust belt (FFTB). This chapter focuses on the different episodes of vein formation, vein morphology, and possible mechanisms of vein formation. Vein (fracture) formation is interpreted in relation to the kinematic evolution of the FFTB. Evidence for the development of hydrofractures during this evolution is given. This study documents veins (fractures) related to Laramide FFTB development in the Cordoba Platform. These veins (fractures) are related to the kinematic evolution of the area and the inferred paleostress conditions. The kinematic evolution can be split up into three major stages: a precompression phase with platform development; a Laramide compressional stage, during which the FFTB developed; and finally, a late Basin and Range-related extension phase. Compound veins and densely spaced microveins record multiple fracturing events in a cyclic stress field during burial, most probably caused by changes in fluid pressure. They are interpreted in relation with early foreland flexuring. With rising compressional stress, less well-oriented veins and breccia veins develop because of a lowered differential stress in the prefolding stage. Progressive layer-parallel shortening (LPS) leads to a caterpillar-type scenario of fluid migration toward the foreland, eventually causing hydrofracturing, succeeded by pressure solution and development of vertical stylolitic planes. These LPS stylolites have the potential to be reopened during subsequent folding of the strata. In addition, older LPS-parallel planes and extrados fractures may open in anticlinal hinges. Shear-associated, shallow-dipping veins develop after LPS development, possibly because of bedding-parallel shear and/or thrust migration. Other post-LPS veins are steeply dipping and commonly reuse older vein orientations. Dark, banded veins, which are filled with a silt-sized and clay-sized material and lack significant cementation, are interpreted to reflect fracture planes along which recrystallization of matrix occurred. Many post-LPS dissolution-enlarged veins and breccias relate to telogenetic karstification. Post-LPS multiple brecciation just above a major thrust plane in the buried tectonic front area is interpreted to reflect the damage zone of that fault.

Abstract Selectively oil-impregnated limestones from the Upper Cretaceous Guzmantla Formation, outcropping in the Cordoba Platform of eastern Mexico, were studied to determine the factors controlling the porosity and hydrocarbon distribution and to reconstruct the fluid-flow history. In the two exposed upward-coarsening (i.e., upward-shoaling) sequences, three limestone lithotypes were distinguished, based on sedimentary, diagenetic, and oil-impregnation characteristics. Lithotype I is comprised of mud-dominated low-energy deposits, which have been affected strongly by compaction. These strata are oil impregnated only along stylolites. Lithotype II consists of bioclastic wackestones to packstones deposited in an open-platform lagoonal environment. This lithotype is pervasively oil impregnated. The preservation of porosity is explained by the development of framework-stabilizing, interparticular, early diagenetic (marine and meteoric) calcite cements. Furthermore, secondary porosity was created after layer-parallel shortening (LPS), when LPS-related structures were opened during subsequent folding of the strata. Lithotype III consists of bioclastic shoal grainstones that have been cemented pervasively during early-marine and later meteoric diagenesis, occluding primary porosity and thus preventing oil impregnation. However, Lithotype III strata display an important modern macroporosity, related to a telogenetic phase of karst development that postdates oil migration. Due to the lack of driving forces, the oil did not migrate into these karst-related pores. In Lithotype II, the presence of oil reduced the effective porosity and hindered further fluid migration. Lithotype II strata thus were less affected by the telogenetic karstification. Lithotype I was less affected because of the completely compacted matrix. This late-stage (postoil migration) dissolution phase is not important in this specific history, but it may be very important in similar deposits in the subsurface, where it can enhance appreciably the reservoir capacity. Factors controlling porosity-permeability are, first, the sedimentary environment, which influenced early and, thus also, later diagenetic evolution. Furthermore, stylolite development (compactional as well as tectonic), which exerts a negative effect on porosity-permeability because of pressure-dissolution and related matrix cementation, also is an important factor. However, because of tectonic opening of some of the stylolites and channelling of meteoric fluids, with porosity development as a result, these stylolites also may increase permeability and total porosity. Finally, fracturing of the strata, whereby tectonic opening and/or cementation can take place, exerts a major influence on reservoir characteristics.