@misc{10481/92718,
year = {2024},
month = {5},
url = {https://hdl.handle.net/10481/92718},
abstract = {Recent geological mapping conducted in the Ronda Peridotites (Betic Cordillera, S Spain) has revealed a
systematic field correlation between lower crustal metamorphic units and different tectonometamorphic
domains of the ultramafic massif. Mylonitic and highly tectonized Spl ± Grt peridotites
(i.e., Grt-Spl mylonite and Spl tectonite domains), which are considered to be derived from a thick continental
lithosphere, are in contact with garnet-bearing gneisses (i.e., kinzigites) of the Jubrique unit
along a narrow but continuous mylonitic shear zone. Phase equilibrium calculations indicate that the
metamorphic rocks of the Jubrique unit are consistent with an initial continental setting characterized
by normal crustal thicknesses, which underwent two melting events. The first melting occurred at
0.9–1.0 GPa / 770–800 ºC and resulted in 13 %melt, while the second one took place at shallower crustal
conditions (0.4–0.5 GPa and 710–765 ºC) and led to more restricted melt production (2–3 %melt). In contrast,
the Spl ± Pl peridotites (Pl-tectonite domain), which are stable only at shallowest mantle levels
within a highly extended continental lithosphere, are consistently found exposed in contact with heterogeneous
granites and migmatites of the Guadaiza unit. According to new thermodynamic modeling, the
Guadaiza metamorphic rocks record a single melting event characterized by a theoretical melt production
of 6 to 11 % at the base of a very thin continental crust (ca. 0.3 GPa and 675–710 ºC). This process
was likely facilitated by influx of external water, necessary to generate high melt fractions observed in
the diatexites. The systematic correlation observed between crustal metamorphic units, consistently
overlaying the mantle rocks, and specific ultramafic domains of the Ronda massif, suggests that their juxtaposition
primarily resulted from the severe extension of the continental lithosphere.
U-Pb radiometric dating of zircons from gneisses, migmatites, and heterogeneous granites in the middle
crustal rocks of the Guadaiza unit indicates that extensional processes, crustal anatexis, and melt
stagnation occurred at around 280 Ma. Comparison of these new radiometric ages with previous results
from the Jubrique unit suggests that a Permian high-temperature / low- to medium-pressure event uniformly
affected the crustal units over the Ronda Peridotites. This event coincided with the formation of
characteristic ultramafic mineral assemblages within the Ronda massif and provides evidence for the
interaction between upper mantle rocks and lower- to mid-crustal metamorphic rocks during this period.},
organization = {Project by the MCIN/AEI/10.13039/501100011033/. FEDER ‘Una manera de hacer
Europa’ (REViSE-Betics-PID2020-119651RB-I00)},
publisher = {Elsevier},
keywords = {Continental rifting},
keywords = {Lower-crust migmatite},
keywords = {Mantle peridotite},
title = {Tectono-metamorphic interaction of upper mantle peridotites and lower crustal units during continental rifting in the western Betic Cordillera},
doi = {10.1016/j.gr.2024.03.018},
author = {Díaz Alvarado, Juan and González Menéndez, Luis and Hidas, Károly and Azor Pérez, Antonio and Pedrera Parias, Antonio},
}