The Koulekoun Gold project is the most important prospect of Avocet Mining plc. It is one of the projects within the TriK-block in Guinea (West Africa) for which an exploration permit has been granted. The Koulekoun deposit is located within the Siguiri basin of Birimian age in the Eastern Guinea region; where most Guinea’s gold mines are situated. The present study involves the investigation of structural elements (S₀, S₁, S₂, intrusive contacts, faults and veins) from selected drill cores from drill sections that intersect the Koulekoun orebody in four parts of the deposit; characterizes the principal orientations of measured structures and determines their relationships using stereonet; in order to predict important intersections to focus on in exploration programs within the TriK-block and suggests a possible structural model of the Koulekoun deposit. Raw data used for the present research was collected from half-core samples due to the absence of surface outcrop from which direct measurements could have been made. Measured data were interpreted using stereographic projection. Often no preferred orientations of structural elements exist in the area, suggesting a complex structural situation, particularly with regard to hydrothermal vein attitudes. Thus, it has been illustrated from structural data analysis and S₀ data 3d interpolation of the four sub-structural domains (North-East, North-West, Central and South) that NE-SW structures (S₂, intrusive contact, fault and vein) have controlled the occurrency of gold mineralization in the Koulekoun deposit area. Geometrical relationships between structure main cluster orientation from stereonet analysis show the majority of S₀ moderately E-dipping; intrusive contacts dip at moderate angle to the SE in all zones, except in the North-East zone where they are sub-vertical and SE-dipping. Fault planes show variable orientation of NE-SW, NW-SE and E-W, and steeply SE-dipping. Vein planes correspond to fault systems and show high variability in their orientation with numerous orders of vein direction in each domain. The cross-cutting relationships suggest two principal generations of faults: the NE-SW fault (F1) and the NW-SE fault (F2). These two fault systems and their associated vein intersection areas preferably define the ore shoot zones within the Koulekoun deposit. The proposed structural model of the Koulekoun deposit suggests the intersection and interference of major NW-SE and minor NE-SW structures. The interference of folds formed basin-dome structures with oval shape geometries striking NW-SE and that dominantly occur in North-East, North-West and Central zones. The South Zone is characterized by NE-SW gently plunging and moderately inclined folds with NW-SE striking axial surface. Gold mineralization occurs at the edges of basin-dome structures in North-East, North-West and Central zones. Mineralized porphyry intrusions are likely located within the axial surface of the South zone folds and extend toward the Central zone. The proposed model is compliant with the earlier model of the Koulekoun deposit presented by Tenova (2013); Fahey et al. (2013) describing the Koulekoun deposit as an auriferous NE-SW trending fault zone, intersecting a major NW-striking and steeply E-dipping porphyry units. The model also fits within the regional structural context suggested by Lahondere et al. (1999a) related to the E-W vein structures attributed to NW-SE fractures and to the conjugated fault of NE-SW direction. Comparatively to the three industrial gold deposits (Siguiri, Lero, Kiniero) being currently mined in the Siguiri Basin, and defined as mesothermal vein and lode mineralization hosted in Birimian meta-sedimentary rocks (Lalande, 2005), the Koulekoun gold deposit appears to be a porphyry hosted orogenic disseminated style mineralization system (Fahey et al., 2013). Although, similarities between the Koulekoun gold deposit and these three industrial deposits (Siguiri, Lero, Kiniero) constitute of the intensive extends of the weathering profile and at some stages, by the existence of numerous ring-shaped and curved lineaments enhanced by drag folding (Lero deposit for instance). It is therefore recommended that targets selection around the Koulekoun deposit and within the TriK-block for further exploration programs be concentrated along NW-SE structures, in objective to determine possible intersection zones with NE-SW structures.

Italian Trap Allochthon is a rare upper-plate exposure of Paleozoic metasedimentary and Precambrian to Tertiary crystalline tectonites in the Santa Catalina-Rincon metamorphic core complex. Elsewhere in the complex, metasedimentary tectonite is usually restricted to an autochthononous position. The internal structures of the allochthon consist of numerous low-angle faults, tear faults, and overturned asymmetric and upright folds. Close association of the low-angle faults and asymmetric folds, and vergence of the folds, indicates that these folds were formed during westward transport along the low-angle faults. The structures of the allochthon are truncated and rotated to the northeast by a listric (?) normal fault. The probable shape of the fault surface, together with the northeastward rotation of the internal structures, suggests translation of the allochthon from the northeast to the southwest. The fact that metasedimentary tectonites are found in upper- plate position indicates that the listric (?) normal faulting post-dates the metamorphism of the Paleozoic and Mesozoic strata. Metamorphism in turn was part of the development of the Santa Catalina-Rincon metamorphic core complex. It is inferred that the Italian Trap Allochthon was emplaced in the final stages of profound regional extension which prevailed during the mid-Tertiary in southern Arizona.

[Truncated abstract] The southwest of Western Australia is an intraplate area classified as a stable continental region. It comprises predominantly Archaean and Proterozoic geology and has generally subdued topography. The region currently experiences significant seismicity in the Southwest Seismic Zone (SWSZ), which is one of the most seismically active areas in Australia and is thought to represent the highest seismic hazard of the region. In recent years, numerous scarps, potentially related to large palaeoearthquakes have been recognised not only within the SWSZ, but also in a broader region of the southwest of Australia. Palaeoseismological investigations of two of these scarps, the Dumbleyung and the Lort River scarps, confirm their association with surface-rupturing palaeoearthquakes and indicate events with likely maximum magnitudes of ~Mw 7.0 on faults of low to medium slip rates. Two trenches across the Dumbleyung Fault scarp revealed a thrust fault in alluvial sediments with two associated earthquakes in the last ca 24-60 ka. A possible Holocene age was recognised for the last recorded earthquake event exposed in these trenches. Two trenches across the Lort River Scarp show that this feature results from thrust faulting in the weathered gneissic country rock. These trenches exposed evidence of two events in the last ca 35 ka, with a likely late Pleistocene age for the last earthquake. On both sites, the earthquakes are interpreted as associated with the last phase of fault activity, which was likely been preceded by a long period of quiescence. Assessment of the earthquake hazard associated with large earthquakes at the Dumbleyung and Lort River Faults resulted in calculated peak ground accelerations of up to 2 g in the near-fault fields. Such earthquakes would significantly affect nearby towns such as Dumbleyung, Wagin, Katanning, and Esperance, but they are unlikely to cause any significant damage in Perth. The palaeoseismological investigations show that the earthquake activity in the southwest of Western Australia is not only confined to the SWSZ, as it has been considered in previous assessments of the seismic hazard, but that there is also potential for strong earthquakes across much of the region. The seismicity in the southwest of Western Australia appears to be transient and migratory. This is suggested by the lack of local relief associated with places of current seismicity and fault scarps, the widespread distribution of the fault scarps across the region, the increase in seismicity in the SWSZ following strong recent events, and the apparent long periods of earthquake recurrence at fault sites. Accordingly, the current seismicity in the SWSZ is inferred to be transient and probably associated with stress changes produced by the recent earthquakes. '...' This uplift could be associated with dynamic topography effects resulting from processes along the plate margins. The uplift is probably enhanced by a flexural response of the lithosphere to local differential loads and density contrast along the southern margin, a mechanism that may also help explain the occurrence of some earthquake activity. The results from this study, complemented by additional palaeoseismological studies must be included in future probabilistic assessments of the seismic hazard of the southwest of Western Australia.

The present study provides the results of detailed mapping and analysis of structures encountered in Seguelen pit of Siguiri gold mine, Guinea, where the Siguiri mine is geo-tectonically located in the Baoulé-Mossi domain of Man Shield in West African craton. The gold deposit is hosted in low-grade metamorphic sediments of turbidites sequences which form part of the Lower Proterozoic of Birimian Super group. Three rock formations of Balato, Fatoya and Kintinian underlay the overall pits. The Siguiri gold mine is characterized by the deep weathering profile, developed over the rocks reaching 200 m below the surface in some areas and often capped by the lateritic gravel or duricrust. The rock formations at Seguelen area are characterised by strong bedding monotonously dipping towards SW and trending NW-SE. The lithology of the host rocks has strong control on the disseminated mineralisation throughout the deposit. Two domains of rock formations are clearly distinguished at Seguelen:  Fatoya Formation(Ffm) domain ; and  Kintinian Formation (Kfm) domain. The two domains are separated by a contact zone of 1.7 m wide parallel to bedding and characterised by the presence of quartz fragments as well as thinly sheeted shale and black shale. This contact zone is identified as disconformity. The major tectonic deformation which has affected the region is known as D2 corresponding to the Eburnean orogeny. The major D2 related structures is the regional thrust striking N-S over an area of 12 km long and 3 km wide and within which corridors all Siguiri gold Mine open pits are located. In the N-S trending structures, there is east-northeast shortening and north-northwest extension. There is pervasive hydrothermal alteration (carbonatization and sideritization) and supergene alteration in the all pits. The hydrothermal alteration attests the intensity of hydrothermal fluid-flow over the host rocks. The hydrothermal fluids flowed along the fractures and within the wall rocks through bedding plans to form numerous auriferous quartz veins bearing disseminated sulphides through chemical reaction between fluids and wall rocks, which are remarkable at Seguelen pit. Three quartz vein sets are distinguished at Seguelen:  NNE-SSW quartz vein set  NE-SW quartz vein set  NW-SE quartz vein set The NE-SW and NNE-SSW quartz veins are often lenticular and associated with the bulk mineralisation.