Available online
Description
'Ray Macdonald and Richard Thorpe visit the Rift Valley in Kenya, this video documents their findings as they piece together the story of crustal and mantle processes thought to occur under the rif...t. The formation of Menegai Crater, some 200 kilometres north of Nairobi, is described with field evidence of pre-Caldera lavas and the post caldera eruption that formed the crater. Suswa has carbonate rich ash flows and syenite nodules have been found on its flanks. This remarkable field evidence from the Magma Chamber beneath Suswa suggests fractional crystalisation processes occuring at the top of the chamber, which is zoned with basalts forming the dome connecting part. Evidence for basalts underlying the whole area and for magma mixing under the crust comes from an exploration of the Badlands and the Olcaria Dome Field, site of Kenya's geothermal power station. In conclusion, the possible processes are summarised and Dr. MacDonald speculates on how, with dykes running the length of the Rift system, the processes are linked, one event triggering others in this part of Africa.'
'Ray Macdonald and Richard Thorpe visit the Rift Valley in Kenya, this video documents their findings as they piece together the story of crustal and mantle processes thought to occur under the rif...t. The formation of Menegai Crater, some 200 kilometres north of Nairobi, is described with field evidence of pre-Caldera lavas and the post caldera eruption that formed the crater. Suswa has carbonate rich ash flows and syenite nodules have been found on its flanks. This remarkable field evidence from the Magma Chamber beneath Suswa suggests fractional crystalisation processes occuring at the top of the chamber, which is zoned with basalts forming the dome connecting part. Evidence for basalts underlying the whole area and for magma mixing under the crust comes from an exploration of the Badlands and the Olcaria Dome Field, site of Kenya's geothermal power station. In conclusion, the possible processes are summarised and Dr. MacDonald speculates on how, with dykes running the length of the Rift system, the processes are linked, one event triggering others in this part of Africa.'
| Module code and title: | S339, Understanding the continents |
|---|---|
| Item code: | S339; 06 |
| First transmission date: | 1990 |
| Published: | 1990 |
| Rights Statement: | |
| Restrictions on use: | |
| Duration: | 00:27:39 |
| Note: | The UK version is FOUS528S, VF 3177 |
| + Show more... | |
| Producer: | Andrew Crilly |
| Contributors: | Ray MacDonald; Richard Thorpe |
| Publisher: | BBC Open University |
| Keyword(s): | Ash flows; Basalts; Domal uprising; East Africa; Flow fields; Lithosphere; Magma chamber; Menengai; Suswa; Syenite nodules |
| Subject terms: | Geology--Africa; Plate tectonics; Rifts (geology)--Africa; Volcanoes--Kenya |
| Master spool number: | HOU6147 |
| Production number: | HOU6147 |
| Available to public: | no |
