<p>The Roches-Genty ignimbrite represents the only documented ignimbrite deposit on Martinique and may represent a large-volume eruption that contrasts with the small-volumes characteristic of the Lesser Antilles eruptions. Despite its significance, it has remained largely understudied. Here, we present a comprehensive stratigraphic, petrological, geochemical, and geochronological analysis of the Dizac and Galocha pyroclastic deposits, based on a 5&#xa0;km transect across the island’s southwestern peninsula. Our study contributes to expanding the catalog of ignimbrite in the Lesser Antilles. Field observations, supported by grain size distributions and component analyses, indicate a sequence of sub-Plinian to Plinian eruption columns transitioning into pyroclastic density currents, lahars, ash-rich, and fallout layers. Massive to poorly sorted pumice-rich and block-and-ash flow deposits display diverse grain size distribution modes, reflecting varying eruptive dynamics. New ⁴⁰Ar/³⁹Ar dates yield a weighted-mean age of 3.38 ± 0.25&#xa0;Ma, marking the onset of volcanism in SW Martinique. Whole-rock geochemistry shows that juvenile and lithic clasts are predominantly andesitic, with more evolved dacitic compositions during the earlier stages (SiO₂ = 55.5–70.7 wt%; total alkalis = 2.7–5.8 wt%). These compositions fall within the range of arc magmas from the Lesser Antilles, suggesting magma differentiation during prolonged storage. This study enhances our understanding of the eruptive history and magmatic evolution of Martinique and raises the possibility that other complex sequences of pyroclastic deposits could be redefined as ignimbrites pending new investigations.</p>