The Triassic platform of the Gador-Turon unit (Alpujarride complex, Betic Cordillera, southeast Spain): climate versus tectonic factors controlling platform architecture

Abstract

A litho-biostratigraphic analysis has been carried out in the Gador-Turon unit of the Sierra de Gador (Alpujarride complex, Betic Cordillera, SE Spain). The Triassic succession of this unit is composed of a lower meta-detrital formation overlain by an upper meta-carbonate formation divided in six members. In the latter, a Ladinian-Carnian-rich fossil association has been found (foraminifers, algae, bivalves, microproblematica, trace fossils). Facies analysis has enabled the recognition of 22 facies of platform origin. This succession accumulated as a subsiding margin-type carbonate platform with homoclinal ramp geometry (Anisian?-Ladinian) evolving into a faultblock-type platform with a steeper-margined geometry (Ladinian-Carnian). Slope deposits of this latter platform show a prism-like geometry with progradational patterns and include syn-sedimentary structures associated with normal faults capped by younger beds. The results of the present research indicate that the architecture of the platform studied has been controlled mainly by climate and oceanic factors during the development of the ramp, and by syn-sedimentary extensional tectonics during the development of the steeper-margined platform. The LadinianCarnian tectonic activity was probably also responsible for the siliciclastic input and the shift to a mixed terrigenouscarbonate platform.

Global, regional and local controls on the development of a Triassic carbonate ramp system, Western Balkanides, Bulgaria

“…2003), and some recent researches have greatly improved our knowledge about Phanerozoic examples of different ages (Martin-Rojas et al . 2012; Pomar et al . 2012; Chow et al .…”

“…2010; Martin-Rojas et al . 2012; Delpomdor, Kant & Préat, 2014). Also, the intrabed gradation between isolated limestone nodules in marly matrix and compact nodular structure implies reworking of early lithified nodules that may be due to oversteepened slope.…”

“…2010; Martin, Montañez & Bishop, 2012; Martin-Rojas et al . 2012; Delpomdor, Kant & Préat, 2014; Thomson, Rainbird & Dix, 2014). To sum up, the lack of any evidence for tidal, wave or storm reworking in the strata of Zgorigrad Mb reinforces the interpretation of gravity-influenced transport as a result of slope instability, i.e.…”

“…Martin-Rojas et al . 2012).

Figure 16. Depositional model for the Zgorigrad Mb in section 8 showing locally developed distal steepening of the ramp profile as an effect of synsedimentary tectonics.

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Pre‐Alpine discordant granitic dikes in the metamorphic core of the Betic Cordillera: tectonic implications

“…The Alpujarride Complex is stacked in lower, intermediate and upper Alpine nappes (Figs B, C) affected by late‐orogenic extension (Azañón and Crespo‐Blanc, ; Vera, ; Alonso‐Chaves and Orozco, ). Typical Alpujarride successions consist of: (i) pre‐Permian metasediments (dark‐coloured, graphitic schists, and quartzites) and, locally, gneisses; (ii) Permian‐Triassic metasediments (light‐coloured schists and quartzites with local metabasites); and (iii) metacarbonates, locally bearing Triassic marine fossils (Delgado et al ., ; Martín‐Rojas et al ., , ).…”