Sets of flat joints controlling barren or SnW mineralized veins with aplite-pegmatite and/or quartz fillings form an interesting but difficult and controversial problem. In fact, at least three more-or-less independent parameters influence the formation of these vein-type deposits: (1) the creation of flat sets; (2) the origin of opening(s); and (3) their filling(s).Relatively few studies have been made of these domains and even if their authors did determine similar successions of events (i.e., creation, opening, and filling of the joints) they disagreed and even came to drastically contrary conclusions concerning the mode of the origin and the opening of flat joints.These different hypotheses are summarized and compared with our own results; the latter were obtained from observations of flat joint sets and of mineralized (or unmineralized) quartz and/or aplite-pegmatite veins occupying parts of these sets on the southern flank of the Serra de Estrêla, and by comparison with already known flat sets (locally with veins) of the Iberian Variscan belt.The following conclusions are drawn: 1.(1) Sets of flat joints are very common structures in the Iberian Variscan chain.2.(2) The sets are locally opened and filled by veins, either with or without mineralization (which is present only in close proximity of granitic intrusions, especially near late well-differentiated leucogranitic cupolas), elsewhere the joints remain closed and barren.3.(3) The genetic history of the flat joints is clearly independent of their opening(s) and filling(s); these joints originated long before the opening and infilling, the later having been two sub-synchronous or penecontemporaneous mechanisms, namely the consequence of shrinkage of the granites and hydraulic over-pressuring of different fluids. Clearly several genetic stages were involved.4.(4) The origin of flat joint systems can be related to shearing movements associated with weak to very weak tectonics which developed when the main structuration of the belt by the first syn-metamorphic phase of folding was already achieved and when the belt was partially uplifted and eroded.5.(5) The formation of the flat joints terminated just before the intrusion of the latest granites (Stephanian leucogranites) and thus before the injection of the residual magmatic liquids (aplites-pegmatites) or of hydrothermal SnW mineralizing fluids; in fact, some late biotitic leucogranites filled some scarcely opened joints.

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{{Explor lien
   |wiki=    Wicri/Terre
   |area=    NickelMaghrebV1
   |flux=    Main
   |étape=   Exploration
   |type=    RBID
   |clé=     ISTEX:CCDEDAF65604FC3DCEE7BA591FADE01F8F0EFBBA
   |texte=   Tectonics, magmatism, hydrothermalism and sets of flat joints locally filled by SnW aplite-pegmatite and quartz veins; southeastern border of the Serra de Estrela granitic massif (Beira Baixa, Portugal)
}}