Trace Element Geochemistry and Tectonic Setting of the Kerang Twin Volcanoes Within the Panyam Volcanic Line, Jos Plateau, Nigeria

Abstract

This study presents the geochemical characteristics of basalts of Kerang twin 
volcanoes within the Panyam Volcanic Line with a focus on their evolution and 
tectonic setting. The Kerang twin volcanoes, as the name implies, are made of 2 
large volcanoes, which are major landmarks in the southeastern portion of Jos 
Plateau Volcanic Province of central Nigeria. Like other volcanoes along the Panyam 
volcanic line, they are well-preserved volcanic cones built of product of eruptive 
lapilli, scoria, breccias, basalts and pyroclastic materials (ash, granitic, lava flow, 
etc.). The volcanic edifices extruded the Precambrian migmatite-gneiss and Pan 
African biotite granite. The traverse mapping method was used to map the area. A 
total of 30 fresh samples collected from the volcanic cones and surrounding areas 
were analyzed for trace elements using the Inductively Coupled Plasma Mass 
Spectrometry. The constituent composition of these basaltic rocks displayed clear 
enrichment in both their Large-Ion-Lithophile Elements (≥100X chondrite) and High 
Field Strength Elements (>10–80X chondrite) relative to chondrite. Similarly, their 
enrichment in incompatible element ratios Zr/Nb (3.20–3.47); Ba/La (10.24–12.85); 
La/Nb (0.76–0.85) and Ba/Nb (8.51–9.91) speak for an Oceanic Island Basalt (OIB) 
source rather than Mid-Oceanic-Ridge Basalts (MORB). All of these mentioned 
geochemical features shown by the basaltic rocks of the Kerang twin volcanoes, 
imply that they were derived from a deep mantle source that is enriched in 
incompatible elements with partial melting playing a significant role in their 
evolution. Furthermore, their trace element compositions reveal that they are 
“within plate’s alkaline basalts” emplaced along major NNW–SSE lineament within 
the pre-existing basement complex rocks.