The kinematic interpretation of natural transpressional deformation remains limited by strain partitioning in three dimensions. This prompts multiscale data integration to extract tectonically meaningful information on the role of strike-slip fault systems in orogen building processes. Here, we investigate the kinematics of mid-crustal deformation in an archetypal wide transpressional orogen from the mesoscale (kilometers) to the regional scale (similar to 1000 km), based on an exhaustive compilation of structural data, the construction of an integrative structural map, and the computation of the orogen's strain field. We document a pervasive crustal flow mode, termed bulk inhomogeneous transpressional flow, which accommodates convergence through a self-similar anastomozed fabric-shear zone network that converts crustal shortening into lateral and vertical escape. This flow pattern may exhibit local complexity due to partial annealing or recovery of shear zones and fabrics during a prolonged (tens of Myr), cumulative deformation history. As a result, local kinematic observations or relative deformation chronologies within the structural network may not capture bulk flow and thus have limited tectonic significance. Transpressional flow is pure-shear dominated and produces distributed crustal thickening combined with orogen-parallel escape, the latter involving a component of extension. Regional flow patterns follow the convex shape of the boundaries of stiff crustal domains and oroclines. Distributed flow implies crust-mantle coupling facilitated by lithospheric mantle attenuation beneath the orogen. Orogen-scale transcurrent shear zones primarily act as transfer structures accommodating flow heterogeneities rather than plate-scale displacements. Crustal flow therefore leads the kinematics of wide transpressional orogens and must operate in the hot portions of most orogens. These results challenge fault-driven escape tectonics models and support vertically coupled, distributed deformation across lithospheric layers.

The Bissa orogenic gold deposit is located at the contact between basic (basalt) and felsic (dacite) volcanic formations through intermediates (andesite) and graphite-intercalated sandstone-pelitic sedimentary formations. This green schist facies metamorphosed ensemble is hosted by the 15-km-long Sabcé shear zone within the Goren greenstone belt. Field investigations combined with fine microscopy enable us to define the mineralization host formations, deformation phases, and hydrothermal alteration in the Sabcé zone. The host formations (metabasalt, metasediments, metagabbro, metadacite) are affected by two deformation phases. The first deformation phase, D1B, is a shear-type deformation that globally controls mineralization. It is taken up by the D2B, which has a ductile-breaking deformation. The hydrothermal alteration with which the mineralization is associated is white quartz-mica-pyrite ± carbonate ± arsenopyrite, crystallization of which was manifested by veins/veinlets subparallel to parallel to D1B. Various electron microprobe, scanning electron microscope, and LA-ICP-MS analyses show that visible gold is present in type I and II pyrites as inclusions or as microfracture fillers. LA-ICP-MS shows that in type I and II pyrites, where no visible gold is present, invisible gold is present in their distorted crystal structure as nanoparticles. The chemical association between Au-As controls the distribution of this couple in type I and II pyrites. This clearly shows that the limpid parts of arsenic-rich pyrites are where visible and invisible gold like to concentrate.

In a gold deposit near Nassara, southern Burkina Faso, gold occurs closely associated with pyrite within a network of veins hosted by metavolcanic and metasedimentary rocks. Using SEM and LA-ICP-MS analyses, we identified three generations of pyrite with distinct roles in gold mineralization. Pyrite 1 (Py1) formed early during mineralization, replacing alteration minerals like ankerite in metabasalt. Pyrite 2 (Py2) developed around Py1 in pressure shadows caused by localized micro-shear zone reactivation during successive micro-seismic events. Pyrite 2 is enriched in As and Au, unlike Py1. Pyrite 3 (Py3), unrelated to mineralization, formed at a later stage. Gold occurs in pyrite as micro-inclusions (in Py1 and Py2), fracture-fillings (mainly in Py2), and within the pyrite structure as invisible gold, including nanoparticles (predominantly in Py2). Combining electron backscatter diffraction (EBSD) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) analysis reveals that deformation-induced misorientation of pyrite facilitated the remobilization of invisible gold, which subsequently re-precipitated as colloidal particles along sub-grain boundaries and within fractures, mimicking visible inclusions. These findings demonstrate that gold perceived as inclusions (visible or invisible) often precipitates within micro/nano-fissures and sub-grain boundaries during remobilization. This highlights the critical importance of thorough ore characterization for accurately determining gold deportment. Such insights advance our understanding of mineralization processes and support the development of more efficient recovery strategies.

South of Godé, in the central-western region of Burkina Faso, granitoids of Paleoproterozoic age are similar to those of the Man/Leo shield.This study focused on the petrographic and geochemical characteristics of these granitoids, with the following results: 1) The tonalite that outcrops in the south-west of the study area belongs to the TTG group or first generation granitoids.They are most often ribboned at outcrop and have a geochemical signature close to that of Archean TTGs.Tonalite has a metaluminous character and the REE spectrum indicates that it may be derived from partial melting of basic magmatic rocks.2) Biotite granites have no outcrop structure.They are weakly metaluminous to peraluminous and potassic to highly potassic.Their rare earth spectra indicate that they may be derived from the partial melting of TTG granitoids.3) Geotectonic diagrams show that the granitoids studied to the south of Godé were emplaced in an active tectonic context similar to that of present-day subduction zones.

This study, carried out in the Léo square degree (west-central Burkina Faso) in the Palaeoproterozoic domain of the Man/Léo ridge, aims to define the shapes and positions of granitic plutons and the organisation of deformation structures using aeromagnetic data. These data have shown that there are small sub-circular granitic bodies to the north of the granitic masses in this region, and a large sub-circular granitic body to the south, around which are other smaller granitic bodies. The lineament map shows that the deformation structures are organised along three main directions and largely form these sub-circular plutonic bodies. We suggest that the granitic plutons are coalescent, pending identification of the internal structures of these granites to further refine the geodynamic model.

The Pouni area is made up of basalts belonging to the Boromo belt, lamprophyres and granitoids. These geological formations are similar to geological formations of the same type in other regions of the Palaeoproterozoic domain of the Man/Leo shield. This study, which focused on the petrographic and geochemical characteristics of these geological formations, led to the following main conclusions: The lamprophyres are basic plutonic rocks that cut through other geological formations. The basalt belongs to the northern part of the Borormo belt and is thought to be a relic of overthickened oceanic plateaus. There are two groups of granitoid rocks. The granodiorite has a geochemical signature close to that of Archean TTGs and is metaluminous in character. It has a low potassium content. The minor element and rare earth element spectra indicate that it could be derived from partial melting of basic magmatic rocks. Biotite granites are peraluminous and highly potassic. Minor element contents and rare earth spectra indicate that they could be derived from partial melting of felsic materials. Geotectonic diagrams show that the granitoids identified in the Pouni zone were emplaced in an active tectonic context, similar to that of present-day subduction zones.

The purpose of this study is to assess the magnetic fabrics and anisotropy of magnetic susceptibility (AMS) of the Yoli anorogenic microgranite to infer its emplacement mechanism. The Yoli massif is one of the numerous Cenozoic plutons of the Cameroon Magmatic Line cutting across the Central African Pan-African Fold Belt. The pluton, emplaced as result of the reactivation of the N–S oriented Pan-African Mayo Nolti major shear zone, is made of fine-grained and porphyritic microgranite showing evidence of magmatic and submagmatic state deformations. It mostly shows ferromagnetic behavior marked by the presence of the pure magnetite crystals as susceptibility carrier. The pluton internal geometry inferred from magnetic fabrics allows to distinguish two main domains: domain I shows steep plunges and dips magnetic fabrics suggesting fan-like vertical ascent of the magma whereas magnetic fabrics in domain II indicate multidirectional moderate to low plunging lineation suggesting horizontal magma flow following steep dipping planes. These structural features suggest that the magma ascended in domain I through the reactivated N–S fault and flowed toward the south and east. Low P j values (≤1.20) is inferred to magmatic flow, whereas the AMS oblate shapes suggest internal high stress flowing condition during emplacement, probably due to forceful emplacement through ballooning.

The reconstitution of the geodynamic processes of the Eburnean orogeny in the time span around 2.1 Ga in Dori area is here carried out through the examination of the internal structures and microstructures of the Dori, Gorom-Gorom and Touka Baye`l granitic plutons. The radiometric ages of these plutons vary between 2164 Ma and 2148 Ma. The internal structures have been evidenced using the Anisotropy of Magnetic Susceptibility (AMS) method and the examination of microstructures through thin sections under optical microscope. The organization of the internal fabrics strongly suggests a diapiric emplacement for the Dori and the Touka Baye`l plutons in a still soften crust. The pluton of Gorom-Gorom seems to be constituted of four small plutons. Three of them, coalescent in the southern part, are emplaced by the diapirism and the fourth in the northern part can be interpreted as emplaced in a tension gash. The overall disposition of the fabrics lets suggest a synchronous emplacement in accordance with the dextral sense of the Tie ' be ' le '-Dori-Markoye (TDM) shear zone in a regional E-W shortening context responsible of a crustal thickening. The two emplacement mechanisms (diapirism and tension gash) identified through the internal fabrics testify a rheological contrast of the crust during this early period of the Eburnean Orogeny.

The characterization of the relationships between mineralization and hydrothermal alteration is an essential element in understanding gold deposits.In south-west Burkina Faso, the Napélépéra mineralisation, the mobility of chemical elements and alteration-mineralization relationships were studied by means of selected core drilling and geochemical analyses using ICP-MS (Inductively Coupled Plasma Mass Spectrometry) and ICP-AES (Inductively coupled plasma atomic emission spectroscopy).The mineralised granodiorite is grey porphyroid with quartz, plagioclase, biotite and amphibole.It is metaluminous and located in the tholeiitic series.The Na 2 O + CaO versus Fe 2 O 3 + MgO alteration diagram divides the samples according to alteration dominance.Chloritisation and carbonation are the main alterations.There is a relationship between gold mineralisation at Napélépéra and alteration, and the paragenesis of gold + pyrite ± carbonate ± silica ± sericite is the main characteristic.Carbonation is the result of fluid input in the shear corridor of the mineralised zone.The mass balance of comparative metals in the proximal and distal zones of the mineralisation shows the absence of metals, while As, Hg, Ag and Bi are strongly enriched from the distal zone to the mineralised zone.The oxides associated with the mineralisation are mainly NaO, SrO and CaO.

Mineralization at the Nassara and Torkera gold deposits is situated at the contact between volcanic rocks (basalt-andesite) and volcanosedimentary rocks (pyroclastite, black shale) within the echelon faults of the large West Batié shear zone (WBZ).Along the mineralized body, shear deformation is intense, accompanied by significant hydrothermal fluid circulation.The objective of this study is to determine the direction of hydrothermal fluid creep in the Nassara-Torkera shear zone.To achieve this, we have integrated direct field measurements with Anisotropy of Magnetic Susceptibility (AMS) measurements and microstructure analysis.Magnetic foliation data align with direct field measurements.Additionally, the lineation data indicate that, during the deformation phase, the material or mineralizing fluids exhibit a southeastward creep, following the contemporaneous structures of deformation.These structures are observed to govern the gold mineralization.Furthermore, the gold content increases in the vicinity of lamprophyre, dacite, and diorite dykes.This observation suggests that the mineralizing fluid and the dykes were emplaced along the same structures of deformation.The drainage of the mineralizing fluid to the southeast explains the occurrence of the seven gold deposits (Djikando, Poni, Nassara, Torkera, Wadaradoo, Konkera and Napelepera) identified along the shear corridor.Identifying the direction of material creep in shear zones serves as a potent prospecting guide for mining explorers, enabling them to strategically position various drill holes efficiently.