Abstract

ALVAREZ-ORTIZ, Iris; CRUZ-GAMEZ, Esther M.; COBIELLA-REGUERA, Jorge L.  and  CACERES-GOVEA, Dámaso. Composition and source area of the sandstones of the San Cayetano formation. Min. Geol. [online]. 2023, vol.39, n.2, pp. 65-87.  Epub June 30, 2023. ISSN 1993-8012.

San Cayetano Formation, of Lower Jurassic?- Upper Jurassic (Oxfordian) age, constitutes the oldest and most extensive stratigraphic unit in the Guaniguanico Mountain Range (western Cuba) and is part of: Alturas de Pizarra del Sur (APS) and Sierra del Rosario/Alturas de Pizarra del Norte/Esperanza (SR/APN/E), separated by carbonate sequences. Lithologically, it is composed by shale, siltstone and sandstone, in apparently monotonous and somewhat metamorphosed sections; towards the upper part limestone and conglomerate interbedding is reported. Information on mineralogical composition and sediments source area for sandstones has been limited. A review and reinterpretation of these rocks is carried out, with special attention to the petrographic characterization of quartz, lithoclasts, feldspars and zircon grains (with age reports from the Paleoproterozoic to early Devonian). As a result, it is found that the source area for these rocks classifies as from: internal craton and recycled orogens. Based on these results, and the report of a granitic intrusive recorded at site M0077A with an age of 326 ± 5 Ma (25 km from the Yucatan coastline), it is possible to specify some parts of the Maya block as the source area (northern part, currently under the Chicxulub impact structure and its coverage). It is also shown that the APS sequences resemble flood and shoreline sediments (predominance of pelites) while those of SR/APN/E are more varied: fan, slope and foot-slope sediments (sandstones predominate).

Keywords : Qt/F/Lit content; sandstones; San Cayetano Formation; Pangea.

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