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During continental collision, crustal rocks are buried, deformed, transformed and exhumed. The rates, timescales and tectonic implications of these processes are constrained through the sequence and conditions of metamorphic reactions in major and accessory phases. Petrographic, isotopic and elemental data from metabasite samples in NW Bhutan, eastern Himalaya, suggest initial equilibration under high‐pressure (plagioclase‐absent and rutile‐present) conditions, followed by decompression to lower pressure conditions at high‐temperatures that stabilized plagioclase, orthopyroxene and ilmenite. Field observations and chemical indicators suggest equilibration under the lower pressure conditions is likely linked to the infiltration of melt from the host metasedimentary rocks. The metabasites preserve two metamorphic growth stages of chemically‐and petrographically distinct allanite that temporally overlap two stages of zircon growth. Allanite cores and zircon mantles grew at c. 19 ± 2 and 17–15.5 Ma respectively, linked texturally and chemically to the high‐pressure evolution. Symplectitic rims on embayed allanite cores, wholly symplectized Aln–Ilm and Aln–Cpx grains, and high U zircon rims grew at c. 15.5–14.5 Ma, linked chemically to the presence of melt and lower pressure, high‐temperature conditions. A single garnet Lu–Hf date is interpreted as geologically meaningless, with the bulk rock composition modified by melt infiltration after garnet formation. The open system evolution of these rocks precludes precise determination of the reactive bulk composition during metamorphic evolution and thus absolute conditions, especially during the early high‐pressure evolution. Despite these limitations, we show that combined geochemical and petrographic datasets are still able to provide insights into the rates and timescales of deep orogenic processes. The data suggest a younger and shallower evolution for the NW Bhutan metabasites compared to similar rocks in the central and eastern Himalayas. [ABSTRACT FROM AUTHOR]

It is my pleasure to announce the winners of the 2021 B Mike Brown Annual Early Career JMG Research Paper Prize b and B Douglas Robinson JMG annual reviewer award. b Congratulations go to B Alexander T. De Vries Van Leeuwen b , currently a PhD Student at the University of South Australia, for the 2021 I Mike Brown Annual Early Career JMG Research Paper Prize i for the publication: A. T. De Vries Van Leeuwen, M. Hand, L. J. Morrissey & T. Raimondo, 2021. The work very nicely integrates a range of field, petrological, thermodynamic, geochemical, geochronological, and geodynamic approaches to provide a comprehensive model for high-T-low-P metamorphism in the Flinders Ranges of South Australia. The approach taken is impressively comprehensive going beyond most papers in pursuing a driving cause for the metamorphism using regional heat flow data. [Extracted from the article]

An introduction to articles published within the issue is presented, including one on quartz and amphibole lamellae formation in clinopyroxene from the Greek Rhodope and another on the study of the exsolution lamellae of garnet in clinopyroxene and orthopyroxene porphyroclasts.

Presents a list of papers to be published in the 'Journal of Metamorphic Geology.'

Lists the articles for future publication of the "Journal of Metamorphic Geology."

Introduces several studies published in the 'Journal of Metamorphic Geology.' 'Timing of High-Grade Metamorphism: Early Palaeozoic U-Pb Formation Ages of Titanite Indicate Long-Standing High-T Conditions at the Western Margin of Gondwana (Argentina, 26-29°S),' by F. Lucassen and R. Becchio; 'Prograde and Retrograde History of Eclogites From the Eastern Blue Ridge, North Carolina, USA,' by F. Z. Page, E. J. Essene and S. B. Mukasa; 'Lawsonite Growth in the Epidote Blueschists From the Ile de Groix (Armorican Massif, France): A Potential Geobarometer,' by M. Ballavre, P. Pitra and M. Bohn.