ALBERT

Description: The Rungwe Volcanic Province (RVP) is the southernmost volcanically active region in the East African Rift (EAR), with three active-dormant volcanoes and several extinct centres. Together, they represent a long history of magmatism and volcanism in a complex structural setting between the Malawi and Rukwa-Tanganyika Rifts, and the less seismically active or inactive NE-SW trending Usangu and Luangwa Rifts. Early possible carbonatite volcanism at ~ 24.5-26 Ma and emplacement of phonolite domes at ~ 17-18 Ma suggest prolonged thermal perturbation of the lithosphere well before initiation of rifting. The main episode of volcanism and rifting is thought to have initiated at ~9 Ma and continues to the present, including large-scale explosive eruptions of mostly phonolitic magma. Tuffs and other volcanic rocks provide constraints on the timing of rift initiation and propagation in the southern EAR. However, they have been poorly described in terms of their physical volcanology and chemistry and have, in some cases, inconsistent chronology, in contrast with some of the youngest (Holocene) deposits. We revisit the long-term history of these large explosive eruptions in the RVP and present new field observations, providing descriptions and interpretations of emplacement mechanisms of the large-scale pyroclastic deposits. Chemical and mineralogical fingerprinting of tephra provides insight into magmatic sources and will facilitate correlation and synchronization of volcano-sedimentary records locally within the RVP, and regionally. Geochronological studies will place constraints on eruptive rates throughout the developmental history of the RVP, and link to intrusive volumes imaged in geophysical data.