Petrogenesis of TTG veins in oceanic gabbro: constraints from partial melting experiments in the presence of NaCl-rich H2O-CO2 fluids
Final Report Abstract
The role of the "sea water-derived fluid" during partial melting of gabbro was investigated for the wide range of initial gabbro starting compositions, and thermodynamic conditions (100-200 MPa, 800 - 1040°C, oxidized and reduced redox conditions). Partial melting in the presence of single aqueous fluid of lower salinity (< 20 wt %NaCl) does not show any significant differences from the hydrous partial melting. Only SiO2 concentrations in residual melts tend to decrease slightly with the increase of chlorine melt contents. In contrast, the presence of large amounts of NaCl (>20 wt %, brine present) in the course of hydrous partial melting of gabbro is characterized by a dramatic SiO2 decrease, and is not required to produce natural plagiogranites. However the presence of NaCl may have played an important role at much lower temperatures above the hydrous (only H2O-bearing fluid) solidus of the system in the presence of more complex fluids (saline and with low aH2O).
Publications
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(2012). Partial melting of gabbro in the presence of NaCl-rich hydrous fluid - implications for the genesis of oceanic plagiogranites. EMPG-XIV. Kiel, Germany, 35
Almeev, R. R., Koepke, J., Silantyev, S. A., Strube, N., Portnyagin, M. V., Garbe-Schönberg, D. & Holtz, F.
