Pressure‐Temperature‐Fluid Evolution in Eburnean Metabasites and Metapelites from Tamanrasset (Hoggar, Algeria)

Abstract

Abstract Tamanrasset (Central Hoggar, Algeria) is part of the 2000 Ma Eburnean terrane in which spectacular examples of granulite‐grade metapelites and metabasites occur. Reactional textures in metabasites, supplemented by geothermobarometry, fluid inclusions, and mineral equilibria indicate a complex metamorphic history, characterized by a strong decompression during postpeak uplift. Peak metamorphic pressure‐temperature (PT) conditions of 800°C and 10 kbar, respectively, were followed by rapidly decreasing pressure (to 700°C and 6 kbar) at nearly constant temperature, during which time the rocks acquired their present mineral assemblages and textures (garnet pyroxenites). This isothermal decompression path was followed by nearly isobaric cooling. Throughout this history, water activity remained consistently low ( \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usep...