Petrogenesis of Late Permian Mafic Rocks in the Western Guangxi Area, SW China: Implications for the Emeishan Mantle Plume Magmatism

Mafic rocks in western
Guangxi exhibit pronounced spatiotemporal
correlation with the Emeishan Large Igneous Province (ELIP), providing
critical constraints on its magmatic distribution, petrogenetic mechanisms,
and evolutionary history. This study presents zircon U–Pb geochronology,
whole-rock geochemistry, and Sr–Nd isotopic data for Tianlin
mafic rocks from the outer zone of the ELIP. These rocks yield a concordant
zircon U–Pb age of 258.3 Ma, contemporaneous with the main
eruptive phase of the ELIP. Geochemically, they comprise a high-Ti
series (TiO2 = 2.79–4.74 wt %; Ti/Y = 507–1229),
exhibiting ocean-island basalt (OIB)-like chondrite-normalized REE
patterns but subtle negative Nb–Ta–Zr-Hf anomalies on
primitive mantle-normalized diagrams. Moderately enriched Sr–Nd
isotopic signatures [(87Sr/86Sr)i = 0.705522–0.705891; εNd(t) = +0.43 to +0.81] indicate
derivation from an enriched mantle source. Integrating regional geology
with these data, we propose that interaction between the Late Permian
Emeishan mantle plume and Neoproterozoic oceanic slab generated the
ELIP’s compositional diversity.