425°C, according to the reaction calculated by the GEOCALC program (Brown et al., 1988).
The Jubrique Unit consists of a segment of severely thinned middle and upper crust at the end of event 2 (Balanyá et al., 1997), where each metamorphic zone formed an approximately horizontal level whose PT conditions were determined by the geothermal gradient. The metamorphic evolution of four sections was analyzed: the phyllites, the fine-grained schists, the sillimanite-bearing schists, and the garnet gneiss (Fig. 3, Fig. 6A).
The presence of pre-Sp carpholite pseudomorphs in quartz veins from the phyllite, quartzite, and calc-schist sections indicates that event 1 reached high-pressure, low-temperature conditions (Balanyá et al., 1997). The stability field for carpholite depends on the end-member of the solid solution between Fe-carpholite and Mg-carpholite (Vidal et al., 1992). The XMg ratio is 0.75, indicating P > 7 kbar, whereas the absence of kyanite implies a temperature limit of 400°C. The association between chloritoid (XMg = 0.34), kyanite, and chlorite (XMg = 0.75) appears in the fine-grained schists, indicating P = 8 kbar and T 425°C, according to the reaction calculated by the GEOCALC program (Brown et al., 1988).
During Sp development, pyrophyllite, chloritoid, and carpholite were replaced by white mica and chlorite. The white mica, associated with biotite, K-feldspar, and quartz (Massonne and Schreyer, 1987), contains 3.15 atoms per formula (apf) Si, which is indicative of a minimum pressure of ~4 kbar at 400°C (Balanyá et al., 1997).
Syn- and post-Sp sillimanite is the index mineral for the lower part of the metapelites (Fig. 6A; sillimanite-bearing schists). The metamorphic peak in this mineral zone gives temperatures of 600° ± 40°C using the garnet-biotite geothermometer (Perchuk and Larent'eva, 1983; Ganguly and Saxena, 1985) in garnet cores and biotites. A garnet-aluminosilicate-plagioclase (GASP) geobarometer was used at different calibrations (Koziol and Newton, 1988; Powell and Holland, 1988) on garnet cores and pre-Sp plagioclase, yielding a pre-Sp episode pressure of 11 ± 1 kbar for an assumed temperature of 600°C. These results, however, must be considered approximate, because diffusion may have altered core compositions at such high temperatures. The first post-Sp growth of sillimanite in these schists and its subsequent transformation to andalusite indicate that a temperature of >550°C was maintained below a pressure of 3 kbar (Fig. 6A). Andalusite commonly encloses post-Sp staurolite in Z4. Several reactions occurred in the garnet gneisses during event 2 (formation of main foliation): the transformation of rutile to ilmenite (although it is preserved as inclusions in the garnet); the transformation of kyanite to sillimanite; and a late-phase progressive substitution of garnet by cordierite. All these reactions indicate substantial decompression.
The retrograde profiles of the nuclei of large garnets were used to determine the PT conditions for the beginning of event 2 or the end of event 1 (Fig. 6A; garnet gneiss). Temperature was established using the geothermometer mineral pair garnet-clinopyroxene (Ellis and Green, 1979; Powell, 1985) at 770°-790°C. GASP equilibrium (garnet-aluminosilicate-plagioclase) at different calibrations (Koziol and Newton, 1988; Powell and Holland, 1988) was used to determine pressures of 11.5 and 13.5 kbar, in the nuclei of both plagioclase porphyroblasts and plagioclase included in garnet (assuming T = 780°C). These pressures are in accordance with the presence of rutile included in the garnet.
Pressures of 5-7 kbar were determined by applying the same geobarometer to the garnet rims and to post-Sp mylonitic plagioclase (Fig. 6A; garnet gneiss). The temperature for the same episode of mineral growth was estimated at 725°-795°C using the garnet-biotite geothermometer (Perchuk and Larent'eva, 1983; Ganguly and Saxena, 1985). Nevertheless, the presence of post-Sp cordierite and the composition of the adjacent garnet rims indicate that the end of event 2 saw lower-pressure conditions of around 3-4.5 kbar (Fig. 6A; garnet gneiss) at temperatures that were still relatively high (650°-700°C). These pressures and temperatures were obtained assuming a water activity of 0.3 using Phillips' method (1980) and applying the graph geothermobarometers of Martignole and Sisi (1981) and the numerical ones of Bhattacharya (1986). The garnet gneiss, therefore, indicates a practically isothermal decompression trajectory for event 2. No mineral textures provide information on the evolution of event 3 metamorphic conditions. Circumstances were similar for event 4, which saw no significant mineral growth in the garnet gneisses. Final cooling at low pressure, characterized by the substitution of K-feldspar and cordierite by sericite and pinnite, is attributed to events 4 and 5.
The Ojen Unit, a recumbent syncline with abundant granitic intrusive rocks (Fig. 3), is characterized by minimum temperatures of >550°C, even in the higher lithostratigraphic levels (attributed to the Permian-Triassic); well-developed crenulation foliation (Sc) is related to folding. In contrast with the Jubrique Unit, the Ojen Permian-Triassic rocks yield no high-pressure, low-temperature traces. Some relics of the high-pressure metamorphism (eclogites) were found from metabasites located in the lower part of the lithostratigraphic sequence belonging to the reverse limb of the syncline (Tubía and Gil Ibarguchi, 1991; Sánchez-Gómez, 1997).
Two lithologic sections from the upper and lower parts of the lithostratigraphic sequence were selected to present the PT evolution of the Ojen Unit (Fig. 3, Fig. 6B). The highest section stratigraphically consists of high-grade schists and impure marbles, whereas the lowest section stratigraphically consists of migmatite and garnet gneiss.
In the marbles (Triassic protoliths) the mineral association includes diopside + forsterite ± phlogopite ± spinel ± clinohumite ± rutile ± ilmenite, which indicates high-grade metamorphic conditions. In the schists, the structural and metamorphic features of event 1 were not preserved. Event 2 must also have developed in high-grade conditions because K-feldspar and muscovite grew during Sp development. The most interesting mineral association in the schists is quartz + biotite + plagioclase + sillimanite ± K-feldspar ± cordierite ± muscovite (Sánchez-Gómez, 1997), and when the whole chemical composition of the rocks is favorable, other metamorphic minerals such as clinopyroxene, spinel, corundum, tourmaline, and cummingtonite are observed (Westerhof, 1975). All these mineral associations indicate that high-grade conditions were reached in the schists. The presence of syn- to post-Sc K-feldspar, a product of the reaction muscovite + quartz = K-feldspar + biotite + sillimanite + water (ms-out reaction in Fig. 6B), indicates that the Ojen Unit schists reached temperatures of 
700°C during event 3, although the preservation of syn-Sp muscovite may indicate that these reactions were not widely surpassed (Fig. 6B, high-grade schists).
Migmatite and garnet gneiss are similar to the Jubrique Unit ones and have the same mineral association (garnet-potassium feldspar-plagioclase-quartz-cordierite-sillimanite), except that no crystals or kyanite pseudomorphs can be seen. This does not mean, however, that they were never in kyanite conditions (i.e, metamorphic zone 6; see Fig. 3) because the presence of rutile as inclusions in the garnet indicates pressures of >8 kbar (calculated with the GRIPS reaction, grossularite + almandine + rutile = ilmenite + anorthite + quartz; Sánchez-Gómez, 1997). The complete disappearance of kyanite can be attributed to high temperatures during the intermediate-pressure event 3, as may be noted in the remaining levels in the Ojen lithologic sequence. Textural evidence of the reaction garnet + sillimanite + quartz = cordierite + hercynite unequivocally indicates a pressure drop below 5 kbar at high-temperature conditions during the metamorphic evolution of these rocks.
A decompression path has also been obtained from the gneiss using the garnet-biotite geothermometer (Perchuk and Larent'eva, 1983; Ganguly and Saxena, 1985) and the GASP geobarometer (equilibrium at different calibrations; Koziol and Newton, 1988; Powell and Holland, 1988); this path is in accordance with data from Westerhof (1977), Torres-Roldán (1981), and Tubía and Gil Ibarguchi, (1991). Minimum metamorphic conditions reached during event 1 are shown in Figure 6B (migmatite and garnet gneiss), although the pressure conditions must have been similar to those recorded for the eclogites (>14 kbar; Tubía and Gil Ibarguchi, 1991). The end of the Sp development must have taken place at P > 4-5 kbar and T 700°C, which are the conditions for the garnet to cordierite transformation, occurring during event 2 and later. Event 3, poorly defined in these rocks, probably occurred under the same PT conditions because K-feldspar and sillimanite grow along the axial plane foliation of the folds of this event (Fig. 5C). Subsequent decompression and associated cooling, corresponding to event 4, was most likely marked by re-equilibrium of the garnet rims with biotite and plagioclase.
As can be seen in Figure 6B, at the end of event 2 the gneiss surpassed the PT conditions for generation of melts, which was more or less abundant depending on the amount of water available. These H2O-poor rocks produced a limited amount of melt that gave rise to the migmatitic gneiss (metatexites) with S2-parallel differentiates. The gneiss show crenulation folding (event 3) and constitute xenoliths in the granites, granitoids, and diatexites that formed during event 4.
It can be assumed that the evolution of the granitic rocks intruding the Ojen Unit occurred during event 4, because they are not affected by the main Sp foliation (event 2) nor by the crenulation folds (event 3). Indeed, both of these structures are found inside xenoliths or are cut by dikes and granite bodies (Fig. 5E, Fig. 5F).
