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Fluid inclusions (FIs) ( n = 34) in spinel lherzolite xenoliths derived from the subcontinental lithospheric mantle from Jeju Island (S. Korea), the Rio Grande Rift (New-Mexico, USA) and Mt. Quincan (Australia) were analysed using confocal Raman spectroscopy. Despite the significant geographical distances, the studied rocks and their FIs show similar petrographic features. We show evidence for the presence of small amounts of nitrogen in extreme high density (≥1 g/cm 3 ) FIs from the deep lithospheric mantle using Raman spectroscopy with a spectral resolution between 0.6 and 0.7 cm −1 . The only nitrogen-bearing species found in the inclusions was N 2 . The N 2 Raman signal appeared as two adjacent, partially overlapping bands. The band at higher Raman shift is identical with the nitrogen-in-air (N 2 air ) band. The band at lower Raman shift is therefore nitrogen within the FIs (N 2 fluid ). The relative amounts of CO 2 and N 2 within the FIs were calculated using the integrated band areas. In the studied ultramafic xenoliths, N 2 concentrations varied between 0.2 and 1.8 mol%, with one exceptionally high concentration of 3.1 mol%. We believe that microthermometric measurements and/or Raman spectroscopy with an inferior spectral resolution may leave N 2 undetected in CO 2- rich upper mantle FIs. Based on our observations, we propose that N 2 may be a minor but common component in subcontinental lithospheric upper-mantle fluids.

High-pressure metapelites with the assemblage kyanite-staurolite-garnet ′ chloritoid-biotite-muscovite-plagioclase-quartz and crosscutting gneiss veins were studied in the Sopron Mountains near Obrennberg (Hungary, Eastern Alps). Different garnet generations were investigated by textural analysis and study of garnet zoning from different textural domains from both the micaschist and the gneiss veins. Thermobarometry of subsequent garnet generations and the surrounding mineral assemblage was used to reconstruct the Alpine P-T path of the metamorphic rocks during the Alpine orogenesis. Peak pressure conditions (1390-1470 MPa) are recorded by high-Si phengites (Si = 7.03 a.p.f.u.) and temperatures by white mica-garnet-albite-quartz assemblage at about 550-600 °C. This is in good agreement with the peak pressures obtained from the massive orthogneisses of the area. Gneiss veins crosscutting the micaschist show slightly lower peak pressures between 1230 and 1280 MPa at similar temperatures (575-590 °C). Subsequent garnet generations and associated mineral assemblages show decreasing pressure with slightly decreasing temperature. Textural observations, white mica chemistry and comparison of garnet zoning trends provided additional evidence on the formation of leucophyllites during retrograde metamorphism.

Polymetamorphic cordierite andalusite-bearing micaschist from the Garabonc-1 borehole has been affected by three metamorphic episodes: Medium-pressure (800-900 Mpa), medium-grade (500-550 C ) Barrovian-type metamorphism occurred first, defined by the appearance of staurolite and kyanite. There are no geochronologic data concerning the age of this episode. Based on certain assumptions it is most probably related to the Caledonian or Early Hercynian orogenies. The second metamorphic episode was low-pressure/medium-grade in character (200-300 Mpa and 560 to 580 o C). Finally, contact metamorphism (100-150 Mpa and 600-640 o C) was caused by an intruding granitoid body. The characteristic minerals are andalusite, cordierite, fibrolite and spinel. The age of the granite intrusion is Carboniferous (Balogh et al., 1981). The most dense CO 2 ±CH 4 ±N e inclusions formed well after the peak P-T conditions. This inclusion type was sealed during all the three stages of metamorphism. There is no significant change in the fluid composition during the second phase. In addition to the pre-existing CO 2 ±CH 4 ±N 2 fluid hypersaline brine was trapped in connection with the third stage. The cooling and uplift of the terrain is recorded by low- to intermediate-salinity aqueous and gaseous CH 4 ±CO 2 inclusions