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<p>The southeastern Nigerian Basement Complex, a key segment of the Trans-Saharan Orogenic Belt (TSOB), preserves magmatic and tectonic records critical to understanding late Neoproterozoic crustal evolution in West Africa. Despite extensive studies on the Pan-African granitoids, the timing and tectonomagmatic transition from subduction-related magmatism to crustal reworking remain debated. The study investigates five petrographically distinct granitoid types from Njua and adjoining areas, southeastern Nigeria basement: aplitic granite, biotite granite, hornblende granite, leucogranite, and granodiorite. Geochemical classification indicates that these granitoids are shoshonitic to low-K, peraluminous, and comprise both S- and I-type, calc-alkaline suites. Zr-in-titanite thermometry yields crystallization temperatures ranging from 654 to 719&#xa0;°C, indicating emplacement under upper crustal conditions (&lt; 15&#xa0;km depth). Trace-element compositions of titanite, integrated with whole-rock geochemistry, document a magmatic evolution from subduction-related arc magmatism to post-collisional crustal anatexis. Chondrite-normalized REE patterns in titanite reveal distinct magmatic, recrystallized, and anatectic signatures, reflecting progressive thermal and compositional changes within the magmatic system. LA-ICP-MS U–Pb dating of idiomorphic, inclusion-free titanite grains constrains granitoid emplacement to 631.7 ± 7.5&#xa0;Ma, with a lower intercept age of 623 ± 15&#xa0;Ma. These ages correspond to syn- to late-orogenic stages of the Pan-African Orogeny. The granitoids therefore record a tectonomagmatic transition from subduction-related arc magmatism to late-orogenic and incipient post-collisional crustal reworking, linked to regional processes such as lithospheric delamination and transpressional shearing, consistent with broader Pan-African tectonic evolution across the Trans-Saharan and Central African orogenic domains.</p> Graphic Abstract <p></p>

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Titanite as a recorder of Pan-African magmatism: an example from granitoids from Njua and adjoining areas, southeastern Nigeria Basement complex

  • 期刊论文

  • 发表日期：

    2026年2月20日

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  • Chinedu Uduma Ibe,
  • Ifeoma Chinwendu Aghaebita,
  • Johnson Ogonna Amobi

摘要

The southeastern Nigerian Basement Complex, a key segment of the Trans-Saharan Orogenic Belt (TSOB), preserves magmatic and tectonic records critical to understanding late Neoproterozoic crustal evolution in West Africa. Despite extensive studies on the Pan-African granitoids, the timing and tectonomagmatic transition from subduction-related magmatism to crustal reworking remain debated. The study investigates five petrographically distinct granitoid types from Njua and adjoining areas, southeastern Nigeria basement: aplitic granite, biotite granite, hornblende granite, leucogranite, and granodiorite. Geochemical classification indicates that these granitoids are shoshonitic to low-K, peraluminous, and comprise both S- and I-type, calc-alkaline suites. Zr-in-titanite thermometry yields crystallization temperatures ranging from 654 to 719 °C, indicating emplacement under upper crustal conditions (< 15 km depth). Trace-element compositions of titanite, integrated with whole-rock geochemistry, document a magmatic evolution from subduction-related arc magmatism to post-collisional crustal anatexis. Chondrite-normalized REE patterns in titanite reveal distinct magmatic, recrystallized, and anatectic signatures, reflecting progressive thermal and compositional changes within the magmatic system. LA-ICP-MS U–Pb dating of idiomorphic, inclusion-free titanite grains constrains granitoid emplacement to 631.7 ± 7.5 Ma, with a lower intercept age of 623 ± 15 Ma. These ages correspond to syn- to late-orogenic stages of the Pan-African Orogeny. The granitoids therefore record a tectonomagmatic transition from subduction-related arc magmatism to late-orogenic and incipient post-collisional crustal reworking, linked to regional processes such as lithospheric delamination and transpressional shearing, consistent with broader Pan-African tectonic evolution across the Trans-Saharan and Central African orogenic domains.

Graphic Abstract