Late Pennsylvanian-Permian sedimentary successions are exposed in Central-Eastern Sardinia (Italy). Here, the sandstone detrital modes of several scattered basins (Mulargia-Escalaplano, Ingurtipani, Perdasdefogu, and Montarbu basins) have been investigated to highlight how the tectono-magmatic processes influenced the sedimentation. Sandstones were collected along well-characterized stratigraphic sections that usually start with a Upper Pennsylvanian - Early Permian dark limnic succession (Rio Su Luda Fm, Ronchi & Falorni, 2004; Costamagna & Criniti, 2024) lying unconformably on the Variscan basement, and continue upward with red bed successions (Mulargia and Pegulari Fms: Costamagna, 2022; Costamagna & Criniti, 2024) until the Lower- Middle(?) Permian. The sandstone composition testifies a changing nature of the source areas feeding since it is quartzolithic metamorphiclastic in the Upper Pennsylvanian sedimentary strata of the Mulargia basin, abruptly passing to volcaniclastic sandstones upward in the Early-Middle(?) Permian of all studied basins. In particular, the Upper Pennsylvanian strata always display low-grade metamorphic detritus, including metaradiolarite (lydite) and phyllite fragments deriving from the Variscan chain. An increasing metamorphic grade of the feeding is supported in the upward successions. The disappearance or dilution upward of this metamorphic detritus suggests the emplacement of the volcanic activity during a progressive tectonic fragmentation of the basins and more in general of large portions of the supercontinent Pangaea. In fact, the Lower -Middle Permian successions of all studied basins display an increasing content and variety of neovolcanic detritus (Critelli et al., 2023) revealing frequently andesitic, and rhyodacitic-rhyolitic coeval sources, while spots of basaltic and basaltic andesite lavas and pyroclastic rocks; whereas, andesitic-dacitic neovolcanic sources, are rarely encountered in the Perdasdefogu and Mulargia basins. Costamagna L.G. (2022) - Sedimentary evolution of the Pennsylvanian-Permian MulargiaeEscalaplano molassic basin (Sardinia, Italy): The most complete record in the Southern Variscan Realm. Geol. Magazine, 159, 1529-1568, https:// doi.org/10.1017/S001675682200036X. Costamagna L.G. & Criniti S. (2024) - Interpreting siliciclastic sedimentation in the upper Paleozoic Mulargia-Escalaplano Basin (Sardinia, Italy): influence of tectonics on provenance. J. Palaeog., 13, 18-34, https://doi.org/10.1016/j. jop.2023.10.005. Critelli S. et al., (2023) - Temporal and Spatial significance of volcanic particles in sand (stone): implications for provenance and paleotectonics. In: Di Capua A., De Rosa R., Kereszturi G., Le Pera E., Rosi M., Watt S.F.L. (Eds), Volcanic Processes in the Sedimentary Record: When Volcanoes Meet the Environment, Geological Society of London Special Publication, 520, 311-325, https://doi.org/10.1144/SP520-2022-99. Ronchi A. & Falorni P. (2004) - Formazione di Rio su Luda. Carta Geologica d’Italia scala 1:50.000. Catalogo delle Formazioni, Unità validate (a cura della Commissione Italiana di Stratigrafia). I Quaderni, serie III, del SGI 7 (fasc. V), 155-9.
Detrital modes of the Pennsylvanian-Permian sandstones in Central-Eastern Sardinia (Italy)
Criniti Sara
;
2024-01-01
Abstract
Late Pennsylvanian-Permian sedimentary successions are exposed in Central-Eastern Sardinia (Italy). Here, the sandstone detrital modes of several scattered basins (Mulargia-Escalaplano, Ingurtipani, Perdasdefogu, and Montarbu basins) have been investigated to highlight how the tectono-magmatic processes influenced the sedimentation. Sandstones were collected along well-characterized stratigraphic sections that usually start with a Upper Pennsylvanian - Early Permian dark limnic succession (Rio Su Luda Fm, Ronchi & Falorni, 2004; Costamagna & Criniti, 2024) lying unconformably on the Variscan basement, and continue upward with red bed successions (Mulargia and Pegulari Fms: Costamagna, 2022; Costamagna & Criniti, 2024) until the Lower- Middle(?) Permian. The sandstone composition testifies a changing nature of the source areas feeding since it is quartzolithic metamorphiclastic in the Upper Pennsylvanian sedimentary strata of the Mulargia basin, abruptly passing to volcaniclastic sandstones upward in the Early-Middle(?) Permian of all studied basins. In particular, the Upper Pennsylvanian strata always display low-grade metamorphic detritus, including metaradiolarite (lydite) and phyllite fragments deriving from the Variscan chain. An increasing metamorphic grade of the feeding is supported in the upward successions. The disappearance or dilution upward of this metamorphic detritus suggests the emplacement of the volcanic activity during a progressive tectonic fragmentation of the basins and more in general of large portions of the supercontinent Pangaea. In fact, the Lower -Middle Permian successions of all studied basins display an increasing content and variety of neovolcanic detritus (Critelli et al., 2023) revealing frequently andesitic, and rhyodacitic-rhyolitic coeval sources, while spots of basaltic and basaltic andesite lavas and pyroclastic rocks; whereas, andesitic-dacitic neovolcanic sources, are rarely encountered in the Perdasdefogu and Mulargia basins. Costamagna L.G. (2022) - Sedimentary evolution of the Pennsylvanian-Permian MulargiaeEscalaplano molassic basin (Sardinia, Italy): The most complete record in the Southern Variscan Realm. Geol. Magazine, 159, 1529-1568, https:// doi.org/10.1017/S001675682200036X. Costamagna L.G. & Criniti S. (2024) - Interpreting siliciclastic sedimentation in the upper Paleozoic Mulargia-Escalaplano Basin (Sardinia, Italy): influence of tectonics on provenance. J. Palaeog., 13, 18-34, https://doi.org/10.1016/j. jop.2023.10.005. Critelli S. et al., (2023) - Temporal and Spatial significance of volcanic particles in sand (stone): implications for provenance and paleotectonics. In: Di Capua A., De Rosa R., Kereszturi G., Le Pera E., Rosi M., Watt S.F.L. (Eds), Volcanic Processes in the Sedimentary Record: When Volcanoes Meet the Environment, Geological Society of London Special Publication, 520, 311-325, https://doi.org/10.1144/SP520-2022-99. Ronchi A. & Falorni P. (2004) - Formazione di Rio su Luda. Carta Geologica d’Italia scala 1:50.000. Catalogo delle Formazioni, Unità validate (a cura della Commissione Italiana di Stratigrafia). I Quaderni, serie III, del SGI 7 (fasc. V), 155-9.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
