Pressure–temperature evolution of the late Hercynian Calabria continental crust: compatibility with post‐collisional extensional tectonics

Abstract

The late Hercynian tectonic evolution of the Calabria crust is characterized by peak metamorphic conditions up to 800 °C and 1000 MPa, and coeval mid‐crustal granitoid emplacement at 304–300 Ma. To check if a post‐collisional extensional framework, similar to that of other Hercynian massifs, can explain petrologic data, we model the pressure–temperature evolution of the crust during extension following granitoid emplacement. Model parameters are constrained by petrologic, geochemical and structural data. Computed P–T paths are characterized by nearly isothermal decompression followed by isobaric cooling, which show a good fit to petrologic P–T paths for duration of extension between 5 and 10 Ma. The model results, therefore, support an interpretation of the magmatic and metamorphic evolution of the Calabria crust in terms of the late Hercynian extension. In this framework, slab break‐off is a reasonable explanation for the common evolution of the southern European Hercynian massifs.

Diachronic and different metamorphic evolution in the fossil Variscan lower crust of Calabria

“…Their tectonic interpretations, too, are different: (1) contraction and subsequent extensional tectonics accompanied by granitic plutonism (Acquafredda et al 2006); (2) a continent-continent collision in which the Variscan plutonism and tectonic uplift of the lower crustal segment took place (Schenk 1989). Numerical simulation of P-T-t paths for different levels of the lower crust of the Serre (Caggianelli et al 2007) supports an interpretation of the magmatic and metamorphic evolution in terms of Late-Hercynian extension. However, similar debates about the tectonic regime affecting south European Variscides (Burg et al 1994;Gardien et al 1997;Lardeaux et al 2001;Kruhl and Vernon 2005) are being conducted.…”

“…Curves (5) and (6) for the lower and upper part of the section, respectively, derived from Schenk (1989). c Numerical simulations of P-T paths relative to the top (A) and bottom (B) of the Serre section, from Caggianelli et al (2007). d Temperature-time diagram for the metagabbros (black squares) and the upper metapelites (white squares) of the Serre Massif.…”

“…Since the ages of the Variscan metamorphic zircon in the rocktypes of the section concentrate between *350 and *270 Ma, such time-period has been considered, as happens for other peri-mediterranean Variscan blocks. Comparisons with large (Jamieson et al 2004) and local (Caggianelli et al 2007) scale model predictions have been made.…”

Age constraints on Late Paleozoic evolution of continental crust from electron microprobe dating of monazite in the Peloritani Mountains (southern Italy): another example of resetting of monazite ages in high-grade rocks

“…Despite the absence of detailed geochronological constraints, clockwise P-T-(t) paths inferred for the medium-to high-grade rocks of the Aspromonte Massif and Peloritani Mountains have been considered to be consistent with processes of crustal thickening during early-and middle-Hercynian collisional stages, followed by crustal thinning, granitoid intrusion and unroofing during lateHercynian extensional stages (Festa et al 2004;Caggianelli et al 2007). In particular, Atzori and Ferla (1992) proposed distinct peaks for P and T in the northern Peloritani Mountains, with eo-Hercynian, or pre-Hercynian, P peak (at ca.…”

“…70% of the exposed rocks) metaluminous to weakly peraluminous calc-alkaline batholitic suite, and a strongly peraluminous suite, which is composed of a number of small scale intrusions (Rottura et al 1993 and references therein). The granitoids are lateto post-tectonic and were probably emplaced along ductile shear zones connected to an extensional regime Caggianelli et al 2000Caggianelli et al , 2007. Only relatively small plutons, mostly composed of weakly to strongly peraluminous granitoids, are exposed within the mediumhigh-grade basement of the Aspromonte-Peloritani Unit.…”