Figure F4. Pressure-temperature path for the gabbro and diabase from Sites 1118, 1109, and 1117. The evolution shows the magmatic crystallization (dated at 66.4 ± 1.5 Ma) followed by cooling and retrograde greenschist alteration (dated at 31 ± 0.9 Ma) and, finally, the subgreenschist deformation and metamorphism (undated) related to rifting. Pressure conditions during intrusion were determined with the Nimis and Pulmer (1998) barometer. Reactions used in the diagram are from Powell et al., (1993): (1) Zo + Grt + Qtz + H2O = Phr; (2) Czo + Act + H2O = Pump + Chl + Qtz; (3) Act + Pump + Ep + H2O = Phr + Chl; (4) Phr + Ep + Chl + H2O = Pump + Qtz; and (5) Act + Pump + Ep + Qtz = Phr + Chl. Epi-out and Sph-out are after Apted and Liou (1983); Cpx-in is after Spear (1981) for QFM (quartz-fayalite-magnetite) buffer; Chl-out is after Liou (1971), after Winkler (1979). The Altot-Hbl barometer is after Plyusnina (1982). Dashed lines = temperatures obtained using the hornblende-plagioclase thermometer of Holland and Blundy (1994), solid lines = temperatures obtained with the Otten (1984) hornblende thermometer. I, II, and III = temperature conditions obtained using the Cathelineau and Nieva (1985) thermometer on the third generation of chlorites. Chl = chlorite, ab = albite, act = actinite, qtz = quartz, pl = plagioclase, Cc = calcite, hbl = hornblende, zo = zoisite, V = vapor, ep = epidotite, sph = sphalerite, cpx = clinopyroxene. Grt = garnet, Czo = clinozoisite, Phr = prehnite, Act = actinolite, Pump = pumpellinite, Ep = epidote, Chl = chlorite.

Figure F4. Pressure-temperature path for the gabbro and diabase from Sites 1118, 1109, and 1117. The evolution shows the magmatic crystallization (dated at 66.4 ± 1.5 Ma) followed by cooling and retrograde greenschist alteration (dated at 31 ± 0.9 Ma) and, finally, the subgreenschist deformation and metamorphism (undated) related to rifting. Pressure conditions during intrusion were determined with the Nimis and Pulmer (1998) barometer. Reactions used in the diagram are from Powell et al., (1993): (1) Zo + Grt + Qtz + H₂O = Phr; (2) Czo + Act + H₂O = Pump + Chl + Qtz; (3) Act + Pump + Ep + H₂O = Phr + Chl; (4) Phr + Ep + Chl + H₂O = Pump + Qtz; and (5) Act + Pump + Ep + Qtz = Phr + Chl. Epi-out and Sph-out are after Apted and Liou (1983); Cpx-in is after Spear (1981) for QFM (quartz-fayalite-magnetite) buffer; Chl-out is after Liou (1971), after Winkler (1979). The Al_tot-Hbl barometer is after Plyusnina (1982). Dashed lines = temperatures obtained using the hornblende-plagioclase thermometer of Holland and Blundy (1994), solid lines = temperatures obtained with the Otten (1984) hornblende thermometer. I, II, and III = temperature conditions obtained using the Cathelineau and Nieva (1985) thermometer on the third generation of chlorites. Chl = chlorite, ab = albite, act = actinite, qtz = quartz, pl = plagioclase, Cc = calcite, hbl = hornblende, zo = zoisite, V = vapor, ep = epidotite, sph = sphalerite, cpx = clinopyroxene. Grt = garnet, Czo = clinozoisite, Phr = prehnite, Act = actinolite, Pump = pumpellinite, Ep = epidote, Chl = chlorite.