Criteria for Recognit

Recognition of Extension-Rifting Environments inAncient SuccessionsGeological CriteriaAncient rift successions have definitive geological characteristicsand a predictable stratigraphy related to extension, these include:1. A pre-rift succession that could be part of an oceanic, transitional orcontinental margin arc succession, followed by a bimodal rift successiondominated either by basalts or rhyolites, and in some deposit types(Bimodal-felsic and Siliciclastic-felsic) a post-rift ,thermal subsidencesuccession dominated by deep marine sedimentary rocks2. Evidence from volcanic and sedimentary facies of rapid subsidenceand restriction of lithofacies within fault blocks e.g. megabeccias - graben,cauldron, calderas3. Synvolcanic dike swarms and/or sill complexes4. High-level, comagmatic subvolcanic pluton comprised of sill-like intrusionsof tonalite, trondhjemite and gabbro whose composition matches that ofthe associated volcanic succession5. Pervasive zones of high-temperature, semiconformable alteration