Transformation of kyanite to andalusite in the Benamocarra Unit (Betic Cordillera, S. Spain). Kinetics and petrological significance

Navas, Ana; Macaione, Elisa; Oliveira-Barbosa, Rita de Cassia; Messina, Antonia; Martín‐Algarra, Agustín

doi:10.1127/ejm/2016/0028-2518

Cited by 9 publications

(2 citation statements)

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“…Variscan metamorphism is preserved in graphitic schists of the Alpujárride Complex (and in the other tectonic complexes) [e.g., Martín‐Algarra et al ., ; Gómez‐Pugnaire et al ., ], evidenced by relict garnet cores [ Ruiz Cruz , ; Manjón‐Cabeza Córdoba et al ., ; Ruiz Cruz and Sanz de Galdeano , ] and relict andalusite [ Sánchez‐Navas et al ., , ]. However, in the study area zoned garnet clearly postdates the high‐ P Alpine stage associated with chloritoid + kyanite growth.…”

Section: Tectonic Events In the Alpujárride Complexmentioning

confidence: 76%

Superposed and refolded metamorphic isograds and superposed directions of shear during late orogenic extension in the Alborán Domain, southern Spain

Williams

Platt

2017

Tectonics

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The timing, kinematics, and mode of exhumation within the Alpujárride Complex, the largest tectonic unit of the Alborán Domain, are controversial. Alternative tectonic models include synorogenic exhumation during pre‐Miocene crustal thickening, intraorogenic exhumation during repeated phases of contraction and extension, and late orogenic exhumation during early Miocene crustal thinning. New structural and petrographic relationships documented in this study support the latter model: subhorizontal foliations, stretching lineations, and recumbent folds are associated with early Miocene high‐temperature decompressional metamorphism and vertical condensation of the metamorphic sequence. Relict isograds associated with high‐pressure metamorphism and burial are systematically overprinted by isograds associated with high‐temperature metamorphism and rapid decompression. During the early stages of extensional exhumation and growth of sillimanite, ENE directed shear (D2) overprinted thrusts and foliations associated with crustal thickening (D1). During the later stages of extensional exhumation and growth of andalusite, from ductile to semibrittle conditions, north directed shear (D3) produced kilometer‐scale recumbent folds that refold isograds. Stretching lineations characterize superposed directions of orogen‐parallel (L2) and later orogen‐perpendicular (L3) shear associated with a rapid temporal transition in the kinematics of extensional exhumation. During the final stages of crustal thinning and cooling, ductile structures (D2/D3) were cut by brittle low‐angle normal faults (D4).

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Section: Tectonic Events In the Alpujárride Complexmentioning

confidence: 76%

Superposed and refolded metamorphic isograds and superposed directions of shear during late orogenic extension in the Alborán Domain, southern Spain

Williams

Platt

2017

Tectonics

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“…of Agustin Martin-Algarra). It may be of interest that similar rocks are typical Variscan metamorphites belonging to the Benamocarra Unit in the Betic Cordillera (Spain) [55]. The source areas could be different and complex to identify, because the studied metamorphic lithics could be also cannibalized clasts deriving from different Miocene to Pleistocene siliciclastic sequences of the Calabria-Peloritani Arc.…”

Section: Petrographic Featuresmentioning

confidence: 99%

Petrographic and Textural Characterization of Beach Sands Contaminated by Asbestos Cement Materials (Cape Peloro, Messina, Italy): Hazardous Human-Environmental Relationships

Somma

2024

Geosciences

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In the past fifteen years, the contamination of the Italian marine coastal environments by asbestos cement materials (ACMs) represents a known crux mostly reported or denounced by mass media and environmental associations. A recent research reporting compositional and textural data related to ACMs found in the beach deposits of a protected natural reserve (Cape Peloro, Messina, Italy) induced the author to perform new petrographic and textural analyses on the Cape Peloro beach sands, pebbles, cobbles (BSPC), and technofossils (bricks, tails, slab, concrete), associated with the previously studied ACMs, in order to compare the data with those of the ACMs previously reported in the literature. The petrographic investigations allowed the author to determine that beach sands and weakly gravelly sands were characterized by a quartzo–lithic signature, being mainly composed of metamorphic grains of quartz (50–60%) and metamorphic lithics (40–50%, mainly composed of polymineral quartz + microcline, quartz + plagioclase, quartz + biotite, quartz + muscovite grains, and monomineral opaque minerals, plagioclase, k-feldspar, and almandine garnet grains), whereas the pebbles and cobbles were made of acid intrusive (granitoids) and metamorphic rocks (gneiss, augen gneiss prevailing). Pebbles and cobbles made up of porphyroids could derive from the cannibalization of the underlying lower to middle Pleistocene siliciclastic deposits of the Messina Formation. Differently, the gneiss, augen gneiss, and granitoids forming the beach pebbles and cobbles, being present both in the crystalline rocks of the Aspromonte Unit and in the clasts of the SGMF, could originate from both of them. Textural investigations allowed the author to characterize grain size, shape parameters, and roundness in the beach deposits. These were mostly composed of sands and weakly gravelly sands with medium grains. Parameters, such as elongation and flatness, showed higher values in the BSPC than in the technofossils. The shapes of the BSPC were mostly from oblate to equant, whereas the shapes of the technofossils were mostly from bladed to oblate. The main differences depended on the original shape of the technofossils, being mostly platy, and their softer composition. The roundness was from angular to sub-rounded. In the Ionian coast of the Cape Peloro peninsula, the source areas for the well-rounded ACM found on the beach and in the beach deposits could have at least four different origins: (i) Possible landfills widespread since the 1970s in the intensively urbanized coastal areas. (ii) Direct abandonment in the coastal area. (iii) Direct abandonment in the streams. (iv) Activities to counteract the erosion/lack of sediment using non-conforming materials. Considering the diffused damage caused by the coastal erosion affecting most of the Italian coast and the obvious increasing dispersion of the asbestos fibers from the ACMs over time, effectual counter actions to prevent further contamination and guidelines for clean-up efforts are necessary.

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Paleozoic Basement and Pre-Alpine History of the Betic Cordillera

Martín‐Algarra

García-Casco

Gómez-Pugnaire

et al. 2019

The Geology of Iberia: A Geodynamic Approach

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Transformation of kyanite to andalusite in the Benamocarra Unit (Betic Cordillera, S. Spain). Kinetics and petrological significance

Cited by 9 publications

References 50 publications

Superposed and refolded metamorphic isograds and superposed directions of shear during late orogenic extension in the Alborán Domain, southern Spain

Superposed and refolded metamorphic isograds and superposed directions of shear during late orogenic extension in the Alborán Domain, southern Spain

Petrographic and Textural Characterization of Beach Sands Contaminated by Asbestos Cement Materials (Cape Peloro, Messina, Italy): Hazardous Human-Environmental Relationships

Paleozoic Basement and Pre-Alpine History of the Betic Cordillera

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