Unravelling the role of crust-mantle processes in the evolution of large silicic-intermediate magmatic systems is a major contemporary research frontier. Magmatic enclaves (MEs), common in granitoid, may provide important information and bring additional constraints in this endeavour. Critical to this is whether the MEs represent earlier rock (xenoliths) or cumulates (and restites) or contemporaneous magma(s) to host granitoid integral to the same tectono-magmatic system. Using new field, petrography and microstructural evidence, and detailed bulk geochemical compositions (major and trace element compositions including REE), we recognize for the first time MEs of felsic-intermediate lower crustal litholgies, e.g. magmatic charnockites (730°C–855°C), TTG (∼817°C) and felsic granulites (∼616°C), and mafic MEs (enriched basalts/picro-basalt: 1170°C–1217°C) in the ∼2.7–2.3 Ga Bundelkhand granitoid (India). We show that MEs represent coeval magmas that experienced variable extents of crustal-mantle melt interactions, yet coexisted in the same reservoir as that of the host granitoid and incorporated into the mush at deeper crustal levels (∼5–10 kbar) in the NeoArchaean-Palaeoproterozic tectono-magmatic system. Our study highlights transcrustal Bundelkhand granitoid not only exposes lower crustal lithologies, including TTG, but the role of hydrated OIB-like mantle was critical to Archaean mid-to lower-crustal anatexis in fluid-present conditions. The fluid-present lithospheric melting may explain the production of sodic crust, including TTG in the ancient Earth, irrespective of geodynamic setting.

The main parts of the 1.7–1.6 Ga bedrock in the Fennoscandian segment of continent Baltica were reworked and tectonically displaced during the 1.1–0.9 Ga Sveconorwegian and 0.5–0.4 Ga Caledonian orogenies. As a consequence, the late Paleoproterozoic evolution of Fennoscandia is poorly understood, and present models are limited by biased sampling in the interiors of the continent that escaped post-1.7 Ga reworking. In this study, igneous crystallization of felsic porphyries and orthogneisses in the east-central Caledonian allochthons are dated at between 1685 ± 8 Ma and 1649 ± 5 Ma (U-Pb zircon). Felsic porphyries in the autochthon beneath the nappe complex, accessed at 1.2–2.3 km depth by the Collisional Orogeny Scandinavian Caledonides drilling project, are dated at between 1656 ± 5 Ma and 1649 ± 5 Ma. The chemistry of the dated samples supports correlation with granite to syenitoid rocks of the 1.87–1.66 Ga Transscandinavian Igneous Belt (TIB) in the Fennoscandian shield. They are, however, in part, significantly younger and represent a prolonged stage of TIB magmatism not present in the shield. Together, the post-1.74 Ga TIB rocks in the Caledonides and in the Sveconorwegian province are the remains of an extensive crustal scale accretionary orogenic system formed along the active Fennoscandian margin at 1.74–1.62 Ga, to be accounted for in models of the orogenic evolution of Fennoscandia. These rocks demonstrate a shift in the composition of the magmatism along the evolving Fennoscandian active margin towards a more syenitoid character over time and contradicts a quiescence of orogenic activity upon entering the Statherian and the so called ‘boring billion’.