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Kaolin is a widespread authigenic clay mineral in the Permo-Triassic sandstones from the marginal areas of the SE Iberian Basin. However, relatively more extensive illitization of kaolin occurs in the SW basin margin compared with the slight occurrence in the NE margin. SEM analysis of sandstones reveals that illite replaced small kaolinite crystals while blocky dickite remained unaltered. Kaolin illitization is suggested to take place in relation to the maximum burial depth reached during Late Cretaceous post-rift stage. Vitrinite reflectance data denotes a maximum burial temperature of 118 °C and 144 °C in the NE basin margin and in the SW basin margin, respectively. Thus, the extent of illitization in the SW margin is attributed to the higher T peak reached by the Permo-Triassic succession. Regarding the lack of K-feldspars observed in the sandstones and interbedded mudrocks, the source of K + is mainly related to the alteration of detrital mica.

Fe and Mn occur in calcite cements depending on the oxidizing–reducing conditions of cementing waters, which may change according to depositional and diagenetic environments. In red beds, Mn and Fe are available from the ferruginous matrix. Thus, it is possible to know the oxidizing–reducing conditions of fluids that precipitated calcite as a function of Mn and Fe content in calcite cement. A detailed petrological (with special attention to cathodoluminescence) and geochemical analysis of these cements is a useful tool to constrain the diagenetic evolution of red beds and the history of the basin where they deposited.

The Valles-Penedes half-graben developed during a Neogene extensive period as part of the Catalan Coastal Ranges in the northwestern edge of the Valencia Trough. The Neogene deposits of the Valles-Penedes half-graben consist of, from base to top, three lithostratigraphic complexes: i) a lower continental complex of Aquitanian?–early Langhian age; ii) a continental to marine complex with reefal carbonate platforms of Langhian age and; iii) an upper continental complex of middle Serravallian–Tortonian age. This study focuses on the calcite cements of the lower continental complex consisting of red beds (mudstones, sandstones and conglomerates) and lacustrine limestones deposited in alluvial fan environments. The studied materials are cemented by calcite precipitated from meteoric waters that circulated through the sediments during the early diagenesis at shallow burial depths. The calcite cement was studied by means of petrographic, cathodoluminescence, microprobe and δ18O and δ13C isotopic analysis. The petrographic and geochemical results show that these cements vary according to the sedimentary environment: (i) sandstones deposited in proximal alluvial fan environments cemented by calcite with low contents of Mg, Fe, Mn, Sr and Na, δ13C values of − 7,4‰PDB and δ18O values from − 6.5 to − 6.2‰PDB; (ii) sandstones sedimented in medium to distal alluvial fan environments cemented by Mn-rich and Mg, Fe, Sr and Na-poor calcite with δ13C values from − 7.9 to − 6.9‰PDB and δ18O values from − 10.5 to − 8.6‰PDB; and (iii) lacustrine limestones of distal alluvial fan environments cemented by Fe-rich calcite with variable contents of Mn and low contents of Mg, Sr and Na. The distribution of these calcite cements allows us to propose a model of fluid circulation and early calcite cementation within an alluvial fan indicating spatial and temporal variations in chemical composition of meteoric water during migration from proximal to distal alluvial fan environments. Residence time of waters, Eh–pH conditions, and the degree of sediment–water interactions, influenced by the mineral composition of the host sediments, are the most important parameters controlling variations in calcite cement composition.