The widely distributed granitic intrusions in the Nubian Shield can provide comprehensive data for understanding its crustal evolution. We present new bulk-rock geochemistry and isotopic (zircon U-Pb and Lu-Hf) data from the Haweit granodiorites in the Gabgaba Terrane (NE Sudan). The dated zircons presented a ²⁰⁶Pb/²³⁸U Concordia age of 718.5 ± 2.2 Ma, indicating that they crystallized during the Cryogenian. The granodiorites contain both biotite and amphibole as the main mafic constituents. The samples exhibit metaluminous (A/CNK = 0.84–0.94) and calc-alkaline signatures. Their mineralogical composition and remarkable low P₂O₅, Zr, Ce, and Nb concentrations confirm that they belong to I-type granites. They exhibit subduction-related magma geochemical characters such as enrichment in LILEs and LREEs and depletion in HFSEs and HREEs, with a low (La/Yb)_N ratio (3.0–5.9) and apparent negative Nb anomaly. The positive Hf(t) values (+7.34 to +11.21) and young crustal model age (T_DM^C = 734–985 Ma) indicates a juvenile composition of the granodiorites. The data suggest that the Haweit granodiorites may have formed from partially melting a juvenile low-K mafic source. During subduction, the ascending asthenosphere melts might heat and partially melt the pre-existing lower crust mafic materials to generate the Haweit granodiorites in the middle segment of the Nubian Shield.

Gabal El-Ineigi fluorite-bearing rare-metal granite with A-type affinity, located in the Central Eastern Desert of Egypt, is distinguished by its abundance of large fluorite-quartz veins and mafic enclaves. Plagioclase (labradorite to oligoclase), Mg-rich biotite, and Mg-rich hornblende are the main components of mafic enclaves, with significant amounts of fluorite as essential phases, and titanite and Fe-Ti oxides (Nb-free rutile and ilmenite-rutile solid solution) as the main accessories. These enclaves are monzodioritic in composition, Si-poor, and highly enriched in Ca, Fe, Mg, and F compared to the host alkali feldspar F-poor Si-rich granites. Given the conflicting evidence for a restitic, xenolithic, magma mixing/mingling, cumulate, or bimodal origin for these enclaves, we propose that the mafic enclaves and felsic host granites are two conjugate liquids, with contrasting compositions, of a single parental melt. This is inferred by the normalized REE patterns that are similar. As a result, liquid immiscibility is proposed as a probable explanation for this mafic–felsic rock association. These enclaves can be interpreted as transient melt phases between pure silicate and calcium-fluoride melts that are preserved from the early stages of separation before evolving into a pure fluoride (Ca-F) melt during magma evolution. Due to element partitioning related to melt unmixing, the enclaves are preferentially enriched in Ca, F, Li, Y, and REE and depleted in HFSE (such as Zr, U, Th, Ta, Nb, Hf, and Ga) in comparison to the host granites. Furthermore, mafic enclaves exhibit W-type tetrad effects, while host granites exhibit M-type tetrad effects, implying that the REE partitioning, caused by liquid immiscibility, is complementary.

The Markersbach intrusion (Erzgebirge, Germany) is a late Variscan, early post-collisional, highly evolved, autometasomatically and hydrothermally altered F-rich, P-poor, aluminous A-type granite. It ranges from coarse-grained biotite monzogranite to fine-grained leucosyenogranite. The rich accessory mineral assemblage comprises, in addition to diverse Nb–Ta–Sn–W–Ti–Fe species, abundant zircon, thorite, topaz fluorite and fluocerite-(Ce), rare xenotime-(Y) and chernovite-(Y), synchysite-(Y) enriched in thorbästnasite component, synchysite-(Ce) and extremely rare monazite-(Ce). Lithium-rich siderophyllite commonly hosts annular radiohaloes developed around Th-rich zircon and thorite. These consist of Th-rich, metamict cores surrounded by a clay-rich alteration zone and a non-stoichiometric Th–Y–Si rim that locally is rimmed by goethite (± limonite). Their textures reflect alpha-recoil damage and localised element redistribution. The dimensions of the haloes and mineral compositions indicate radiation damage controlled predominantly by the ²³²Th decay chain. Zircon, thorite and xenotime form complex Zr(Hf)–Th(U)–Y(REE) solid-solutions (with REE – rare earth elements), which commonly experienced strong metamictisation, hydration and fluorination [≤ 6.8 wt% F in thorite, ≤ 3.8 wt% F in zircon, ≤ 1.1 wt% F in xenotime-(Y)]. Zircon and thorite are the principal hosts of immobile Th, whereas U is largely sequestered in secondary pyrochlore. Interaction with late fluids gave rise to local destabilisation of monazite-(Ce) and promoted various dissolution–reprecipitation reactions, producing Y-poor fluorite II, synchysite-(Y), and sporadic Ca _0.5 Th _0.5 F ₃ micro-inclusions in re-equilibrated fluocerite-(Ce). Rare chernovite-(Y) and As-bearing zircon–thorite assemblages further imply the involvement of oxidising, As-rich fluids. The evolution of REE–Zr–Th–U mineral phases records both the fractionation history of the halogen-enriched, P-poor parental melt and the subsequent subsolidus fluid-mediated re-equilibration in an F-rich environment, resulting in multi-stage LILE and HFSE redistribution within the granite, postdated by widespread U removal from the granite in the Cretaceous.