The lacustrine Itapema Formation in the Santos Basin locally comprises 102 m thick clinoforms identified seismically and corroborated by several well penetrations. Individual clinoforms, as proven by well penetrations, are composed of 102 m thick successions of basinward-dipping molluscan grainstones and rudstones. Manual dip picking of borehole images show upward increasing dips consistent with seismic geometries and a predominance of longshore sediment transport. Clinoforms are bound at their top and base by strata with significantly lower dips recognizable both on seismic and borehole images. Elevated gamma-ray log responses together with sidewall core samples indicate that these intervals correspond to more argillaceous facies which are interpreted as lake flooding events. While the existence of bona fide clinoforms is demonstrated by a range of subsurface data their precise origin remains enigmatic. The majority of the bivalve genera that make up the grain-supported carbonates appear to be infaunal or semi-infaunal. As such the clinoforms represent large bars produced through the re-working of bivalves from lower energy depositional environments by shore-parallel currents.

The Casa-Berardi gold deposits are located 180 km north of Rouyn-Noranda within Archean rocks of the Abitibi Subprovince. The Casa-Berardi deformation zone (CBDZ), which contains these deposits, is an east–west trending structure that is recognized along a minimum distance of 80 km. Ductile deformation has affected the lithologies in the central portion of the CBDZ. The CBDZ juxtaposes distinct sedimentary and volcanic lithostratigraphic packages which locally display opposite facing directions. Within the CBDZ the Casa-Berardi fault has been recognized; it is a brittle structure with a reverse motion. This fault represents a distinct element associated with the progression of deformation in the CBDZ and appears late in the geodynamical evolution of this deformation zone. Two other deformation zones have been identified in this region: (i) the east–west-trending Boivin-Paradis deformation zone, which has limited lateral extent and is located at the periphery of a granitoid intrusion, and (ii) the Laberge deformation zone, which has a northwest to east–west trend and crosscuts the regional structural grain. Most of the economic gold mineralization in the Casa-Berardi deposits is found in the second set of four recognized vein and fracture sets. The mineralized veins are found within zones of intense deformation which are preferentially developed close to contacts between sedimentary and volcanic units. The geometry of the different sets of quartz veins, their relative chronology, and their respective hydrothermal alterations can be explained by the progression of deformation within the CBDZ and bracket the gold mineralization as syn- to late-tectonic. The CBDZ is distinguished from the other two deformation zones by its greater lateral extent, the juxtaposition of distinct lithological domains, the complexity of its internal fabrics, and the relative length of the deformation event. These features indicate that in contrast with the other two deformation zones, the CBDZ was the site of a major mineralizing event. The recognition of contrasting characteristics between the different deformation zones has repercussions on the understanding of the different criteria that control gold deposition and, ultimately, on gold exploration.

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