Triassic redbeds in the Malaguide Complex (Betic Cordillera — Spain): Petrography, geochemistry and geodynamic implications

Sandstone petrography and mudstone mineralogy and geochemistry of Triassic mudstones and sandstones fromcontinental redbeds of the Malaguide Complex (Betic Cordillera, southern Spain) provide useful information onprovenance, palaeoclimate and geodynamics during the early stages of the Pangea break-up, and on their diageneticevolution. The sandstones are quartzarenites to sub-litharenites, with minor lithic fragments and rare feldspars.The mudstone samples show a PAAS like elemental distribution. The samples likely record recyclingprocesses from their metasedimentary basement rocks that significantly affected the weathering indices, andmonitors cumulative effects, including a first cycle of weathering at the source rocks. Sandstone compositionand chemical–mineralogical features of mudstones record a provenance derived from continental block andrecycled orogen that were weathered under warm and episodically wet climate. Source areas were locatedtowards the east of the present-day Malaguide outcrops, and were formed by fairly silicic rock types, made upmainly of Palaezoic metasedimentary rocks, similar to those of the Paleozoic underlying series, with subordinatecontributions from magmatic–metamorphic sources, and a rare supply from mafic metavolcanic rocks. Claymineraldistribution of mudstones is dominated by illite and illite/smectite mixed-layer that result from differencesin provenance,weathering, and burial/temperature history. Illite crystallinity values, illitization of kaolinite,occurrence of typical authigenic minerals and apatite fission-track studies, coupled with a subsidence analysisof the whole Malaguide succession suggest burial depths of at least 4–6 km with temperatures of 140–160 °C,typical of the burial diagenetic stage, and confirm the Middle Miocene exhumation of the Betic Internal Domaintectonic stack topped by the Malaguide Complex.