Jöns, Niels; Bach, Wolfgang; Schroeder, Timothy (2009): Chemistry of minerals from amphibole-chlorite veins of ODP Site 209-1270. PANGAEA, https://doi.org/10.1594/PANGAEA.772913, Supplement to: Jöns, N et al. (2009): Formation and alteration of plagiogranites in an ultramafic-hosted detachment fault at the Mid-Atlantic Ridge (ODP Leg 209). Mineralogy and Petrology, 157, 625-639, https://doi.org/10.1007/s00410-008-0357-2
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We examined small-scale shear zones in drillcore samples of abyssal peridotites from the Mid-Atlantic Ridge. These shear zones are associated with veins consisting of chlorite + actinolite/tremolite assemblages, with accessory phases zircon and apatite, and they are interpreted as altered plagiogranite melt impregnations, which originate from hydrous partial melting of gabbroic intrusion in an oceanic detachment fault. Ti-in-zircon thermometry yields temperatures around 820°C for the crystallization of the evolved melt. Reaction path modeling indicates that the alteration assemblage includes serpentine of the adjacent altered peridotites. Based on the model results, we propose that formation of chlorite occurred at higher temperatures than serpentinization, thus leading to strain localization around former plagiogranites during alteration. The detachment fault represents a major pathway for fluids through the oceanic crust, as evidenced by extremely low d18O of altered plagiogranite veins (+3.0-4.2 per mil) and adjacent serpentinites (+ 2.6-3.7 per mil). The uniform oxygen isotope data indicate that fluid flow in the detachment fault system affected veins and adjacent host serpentinites likewise.
Median Latitude: 14.721220 * Median Longitude: -44.884760 * South-bound Latitude: 14.721160 * West-bound Longitude: -44.884850 * North-bound Latitude: 14.721400 * East-bound Longitude: -44.884730
Date/Time Start: 2003-05-31T12:00:00 * Date/Time End: 2003-06-02T14:45:00
209-1270C * Latitude: 14.721400 * Longitude: -44.884850 * Date/Time Start: 2003-05-31T12:00:00 * Date/Time End: 2003-06-01T03:00:00 * Elevation: -1821.9 m * Penetration: 18.6 m * Recovery: 1.98 m * Location: South Atlantic Ocean * Campaign: Leg209 * Basis: Joides Resolution * Method/Device: Drilling/drill rig (DRILL) * Comment: 3 cores; 18.6 m cored; 0 m drilled; 10.6 % recovery
209-1270D * Latitude: 14.721160 * Longitude: -44.884730 * Date/Time Start: 2003-06-01T03:00:00 * Date/Time End: 2003-06-02T14:45:00 * Elevation: -1816.9 m * Penetration: 57.3 m * Recovery: 7.68 m * Location: South Atlantic Ocean * Campaign: Leg209 * Basis: Joides Resolution * Method/Device: Drilling/drill rig (DRILL) * Comment: 11 core; 57.3 m cored; 0 m drilled; 13.4 % recovery
Datasets listed in this publication series
- Jöns, N; Bach, W; Schroeder, T (2009): (Table A1) Representative analyses of amphibole from amphibole-chlorite veins of ODP Site 209-1270. https://doi.org/10.1594/PANGAEA.772905
- Jöns, N; Bach, W; Schroeder, T (2009): (Table A2) Representative analyses of chlorite from amphibole-chlorite veins of ODP Site 209-1270. https://doi.org/10.1594/PANGAEA.772907
- Jöns, N; Bach, W; Schroeder, T (2009): (Table 2) Whole-rock geochemical and oxygen isotope analyses of chlorite-amphibole-bearing veins of ODP Site 209-1270. https://doi.org/10.1594/PANGAEA.772901
- Jöns, N; Bach, W; Schroeder, T (2009): (Table A3) Representative analyses of apatite from amphibole-chlorite veins of ODP Hole 209-1270D. https://doi.org/10.1594/PANGAEA.772908
- Jöns, N; Bach, W; Schroeder, T (2009): (Table A4) Ti-in-zircon thermometry and representative analyses of zircon from amphibole-chlorite veins of ODP Site 209-1270D. https://doi.org/10.1594/PANGAEA.772910
- Jöns, N; Bach, W; Schroeder, T (2009): (Table A5) Analyses of orthopyroxene inclusions in zircon of ODP Hole 209-1270D. https://doi.org/10.1594/PANGAEA.772912