PETROGRAPHIC AND GEOCHEMICAL STUDY OF NYIRAGONGO VOLCANIC FLOWS FROM THE 2002 AND 2021 ERUPTIONS: A COMPARATIVE ANALYSIS

Abstract

Context: One of the volcanoes on the East African Rift’s Virunga chain is the Nyiragongo. It is recognized for its Hawaiian-style eruptive dynamism and is especially interesting for studies aimed at comprehending the dynamics of the East African Rift. Objectives: In order to close the geochemistry gap, comprehend the evolution of the Nyiragongo magmas over a 20-year period, and enhance our knowledge of the southern region of the Nyiragongo volcanic field, this paper examines the significance of comparative research on the petrography and geochemistry of Nyiragongo volcano flows from 2002 and 2021. Approaches: A field campaign was conducted using the Hammer Survey method to characterize available outcrops macroscopically. Samples were taken to identify unnoticed size and propose relative words. Four out of fifteen samples underwent microscopic examination. Results: The 2021 and 2002 Nyiragongo volcano eruptions have similar mineralogical compositions, dominated by nepheline phenocrysts. However, the 2021 lava has a porphyritic to microlithic texture, with undersaturated silica and enriched alkalis. Olivine microlith is present in the 2002 flow, but not in the 2021 lava. In conclusion, the persistence of dispersive features linked to the East African rift is demonstrated by the geochemical description of geotectonic locations. The alkaline series is geochemically suited to both flows.