The Cenozoic stratigraphy and structure of the western part of the Rift Valley in southern Kenya
作者： Robert Crossley
关键词: Period (geology) 、 Volcano 、 Seismology 、 Volcanic rock 、 Flood basalt 、 Rift 、 Geology 、 Trachyte 、 Paleontology 、 Rift valley 、 Cenozoic
摘要: Mapping, K–Ar dating and palaeomagnetic polarity measurements were used to study the geological history of predominantly volcanic sequences in western part Kenya rift valley S 1o309S. The was initiated as a downwarp which later infilled by melanephelinitic agglomerates lavas (15–12 Ma ago). Major faulting (12–7 ago) downthrew these volcanics E flood trachytes (7–5 erupted onto newly-formed floor. Minor volcanism preceded second period major (5–3 Extensive basalts (3–2.5 resulting structure. Later subsidiary depressions floor infiIled two large porphyritic trachyte flows N (the older one 2.1 ago), (2.1–1.7 (1.4–0.7 E. sequence from represents substantial Matuyama epoch. A (most it post-0.6 created much present topography Magadi–Natron basin flooded an extensive temporary lake.
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