Three-dimensional shape and emplacement of the Cardenchosa deformed pluton (Variscan Orogen, southwestern Iberian Massif)

Abstract

The Cardenchosa pluton is a Lower Carboniferous Variscan granite located in the southwestern Iberian Massif. It intruded along the contact between the Sierra Albarrana and Azuaga tectonic units. To the northwest the pluton connects with the leftlateral Azuaga fault. The pluton appears in the footwall of the low-angle normal Casa del Cafe fault, which crops out to the west of the granite. Gravimetric modelling shows the pluton to have a¯at bottom at a depth of 2 km. Strain analysis of postemplacement deformation of the pluton indicates that: (a) the deformation of the pluton accommodates the displacement of the Azuaga fault; and (b) the pluton prior to the solid state deformation was a lens-shaped laccolith of approximately 10 km diameter and 2 km thickness. The Cardenchosa pluton was a single pulse of magma trapped in a rheological discontinuity of the upper crust (the contact between the Sierra Albarrana and Azuaga units). The magma would ascend through dikes since no root has been detected. The tectonic scenario during the intrusion was one of regional extension. #

Polyphase tectonic reworking of serpentinites and chlorite‐tremolite‐talc rocks (SW Spain) from the subduction forearc to intracontinental emplacement

“…They form intrusive massifs with apophyses and satellite dykes emplaced along the mechanical anisotropies provided by D1 foliations and tectonic contacts. Country rock metamorphic xenoliths with D1 fabrics are also included near their rims (Ábalos, 1992; Azor et al, 2016; Simancas et al, 2000). These rocks show ductile deformation and were fully transformed into orthogneisses (with penetrative S–C fabrics) during a later D2 event dated in the interval 350–330 Ma (Abranches et al, 1979; Blatrix & Burg, 1981; García‐Casquero et al, 1988; Ordóñez‐Casado, 1998; Quesada & Dallmeyer, 1994).…”

Tectonic setting and isotopic sources (Sm–Nd) of the SW Iberian Autochthon (Variscan Orogen)

“…The Cardenchosa pluton intruded this unit and produced contact metamorphism in its host (Insúa et al, 1991). This pluton is affected by Variscan deformation (Simancas et al, 2000), has been dated at Early Ordovician and interpreted as part of a late-rift episode, related to the Cambrian-Ordovician rift stage of the Iberian Massif (Azor et al, 2016;Sánchez García et al, 2019).…”

“…This gave rise to a normal metamorphic zonation from the biotite zone on top up to partial melting conditions towards the bottom (Garrote, 1976;González del Tánago, 1995). The penetrative metamorphic fabrics formed in this area were considered as formed in relation to a ductile shear zone (Azor and Ballèvre, 1997), while the upright folds that affect the series were interpreted as Variscan and related to strike-slip shear zones (Simancas et al, 2000).…”

Constraints on the crustal structure of the internal Variscan Belt in SW Europe: A magnetotelluric transect along the eastern part of Central Iberian Zone, Iberian Massif

“…The 1:1,000,000 Bouguer anomaly map reveals wide negative anomalies related to the outcropping igneous bodies (Pedroches and Mora batholiths; Figure 3b) and to the sedimentary basins crossed by the MT profile or located in nearby areas. However, the map is not accurate enough to determine in detail the structure of those batholiths and basins; only the geometry of the small-sized Cardenchosa granite (located near the southernmost end of the profile), extending ∼2 km deep and displaying a subhorizontal bottom, is well constrained by a detailed gravity survey [Simancas et al, 2000]. The 1:1,000,000 aeromagnetic map shows numerous WNW-ESE elongated anomalies, parallel to the main Variscan structural trend, which could reflect the presence of hidden mafic/intermediate igneous bodies and/ or local enrichments in (ferro-) magnetic ores ( Figure 3b).…”