A simple recipe for red bole formation in continental flood basalt provinces: weathering of flow-top and flow-bottom breccias

摘要: Continental flood basalt (CFB) provinces such as the Deccan Traps show numerous inter-flow horizons called boles, most commonly red or brown. These have been variably interpreted altered glassy bases of flows, paleosols developed on exposed flow tops, volcanic ash beds, local sediments. We believe that each these mechanisms may apply, singly in combination, to specific and propose an additional mechanism, namely weathering flow-top flow-bottom breccias. The breccias are inherently highly prone weathering, evidence for mechanism is a close observed correspondence between breccia zones boles. explains absence boles compound pāhoehoe flows which characteristically lack breccias, their abundance rubbly ‘a’a lava flows. latter observation has misinterpreted indicating significant eruptive hiatuses low eruption frequency. Importantly, even all breccia-derived do not same significance: those derived from paleosols, formed by subaerial during breaks. Those thus contact with atmosphere, were due groundwater ingress along contacts fractures. slowly over long time periods. Significant development bole types must also occurred post-volcanism arguably ongoing today unexposed parts CFB sequences. Recognizing multiple complex origins superficially similar-looking critical importance volcanology stratigraphy, warning sign straightforward application mineral chemical, magnetic, geochemical, similar data interpreting paleoweathering, paleoclimates, paleoenvironments.