Cordierite andalusite-bearing micaschist from the Garabonc-1 borehole (Central Transdanubia, W. Hungary) Geothermo-barometry and fluid inclusion study
European Journal of Mineralogy Volume 4 Number 5 (1992), p. 1125 - 1136
published: Oct 14, 1992
manuscript accepted: Jan 21, 1992
ArtNo. ESP147050405019, Price: 29.00 €
Abstract Folymetamorphic 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 °C). Finally, contact metamorphism (100-150 Mpa and 600-640 °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 ai, 1981). The most dense CO2±CH4±N2 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 CO2±CH4±N2 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 CH4± CO2 inclusions.