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Ultrahigh‐temperature (UHT) granulites, a prominent feature of Paleoproterozoic orogenic belts, preserve a record of geodynamic processes during the Precambrian (Archean–Paleoproterozoic). Quantitative pressure–temperature–time (P–T–t) paths of these UHT granulites can constrain the tectonic processes and metamorphic evolution in such a tectonic regime. Here, UHT mafic granulites with a high‐pressure (HP) prograde path are first reported in the Diebusige Complex in the Alxa Block, western part of the Khondalite Belt (KB), North China Craton (NCC). The detailed petrographic studies show that two mafic granulite samples preserve corona textures around relict garnet or garnet pseudomorphs (completely replaced by plagioclase), and a third mafic granulite sample has a relatively simple mineralogy with a granoblastic‐polygonal texture. These mafic granulites have similar peak (Tmax) assemblages of clinopyroxene + orthopyroxene + plagioclase + ilmenite ± garnet ± amphibole ± quartz + melt. Phase equilibrium modelling and Ti‐in‐amphibole and rare earth element (REE)‐based thermometries all constrain similar peak conditions of ~880–950°C/~8.5–10 kbar implying an ~100°C/kbar apparent geothermal gradient for these mafic granulites. Based on the corona textures or pseudomorphs of garnet and mineral assemblages, we identified a Pmax (~14 kbar) prograde stage before the Tmax stage. Thus, a clockwise P–T path with heating and decompression followed by near‐isobaric cooling (IBC) is recorded from these UHT mafic granulites. In addition, zircon and apatite SHRIMP or LA–ICP–MS U–Pb dating yields an age interval of ~1.81–1.7 Ga, which is interpreted as representing the cooling time from ~900–800°C to ~575°C at the middle‐upper crustal levels (<25 km deep) for these mafic granulites, with an ~1.5–2.5°C/Myr cooling rate. The new P–T–t path of these rocks includes high‐pressure prograde, UHT peak, and slow cooling retrograde processes, which implicates a post‐collisional tectonic setting for UHT metamorphism in the KB and the processes of collision, exhumation, and cooling of the KB. [ABSTRACT FROM AUTHOR]

This study presents the results of petrology, SHRIMP zircon U–Pb analysis, conventional Fe–Mg geothermobarometry, REE (rare earth element)‐based geothermobarometry, and phase equilibrium modelling, for newly discovered ultramafic‐mafic granulites (garnet pyroxenite with minor plagioclase and garnet‐bearing granulite) in the Namakkal Block of the southern granulite terrain (SGT), India. Results from this study shed light on the growth, evolution, and thermal state of lower continental crust during the Neoarchean, as a cross‐section of the Archean lower continental crust is well‐exposed in the SGT. SHRIMP zircon U–Pb dating of a garnet pyroxenite sample (18ID‐41) yielded a weighted mean 207Pb/206Pb age of 2531 ± 6 Ma, which is the same within uncertainty as one weighted mean SHRIMP metamorphic zircon 207Pb/206Pb age of 2519 ± 9 Ma from mafic granulite sample (18ID‐43). In addition, zircon U–Pb analyses also yielded an apparent 207Pb/206Pb age of 2474 ± 3 Ma (1σ) for the garnet pyroxenite, and a weighted mean 207Pb/206Pb age of 2489 ± 8 Ma for the mafic granulite. Thus, the timing of metamorphism of the ultramafic‐mafic granulites was constrained to be ca. 2530–2470 Ma. The peak metamorphic phase assemblage of the garnet pyroxenite is grt–cpx–pl–ilm–liq, which was modelled to be stable at 1058–1172°C/7.8–11.6 kbar, whereas the retrograde mineral assemblage of grt–cpx–hbl–pl–qz–ilm–liq occurred at 877–888°C/9.9–11 kbar. The mafic granulite was demonstrated to record similar peak and retrograde metamorphic P–T conditions to those of the garnet pyroxenite but have a relatively small P–T range of the peak mineral assemblage. The ultrahigh temperature metamorphism of these ultramafic‐mafic granulites was further confirmed by the temperature results (1057–1087°C) from the REE‐in‐two‐pyroxene thermometer. As a result, a retrograde metamorphic P–T path characterized by near‐isobaric cooling from ~1080°C at ~10 kbar to ~900°C at ~10 kbar was constructed for these rocks, which is consistent with an extremely high thermal state that persisted for ca. 60 Ma in the lower crust. [ABSTRACT FROM AUTHOR]