Index

Page numbers in italic denote figures. Page numbers in bold denote tables. aa lava, Oldoinyo Lengai 61, 61 Mosonik 41 exploration, early European 3, 5 Afar triple junction 2 Oldoinyo Lengai 57, 59 extension, crustal 18 African Plate 1, 18 Shombole 40 Extrusives see Older Extrusives; African rift valleys, discovery 3, 5 see also calcite carbonatite; natrocarbonatite Younger Extrusives African Superswell 2, 18 Chyulu Hills Volcanic Province 79 Eyasi Basin 23, 34,35 Amboseli Basin 37 petrogenesis 85–86 faulting 30 Amboseli Beds 37 xenoliths 17 magnetic data 17, 35 Angata Salei 50 cirques, Mawenzi 56 Eyasi fault see Sonjo-Eyasi fault Angata Salei Fault 27 combeite 46, 59, 61, 64, 69 Eyasi half-graben 9, 21 anisotropy, seismic 15 comendite 86 faulting 29 Archaean, northern Tanzania 9, 12 conductivity, southern Kenya 17 Eyasi trend 29, 30 heat flow 17 contamination, crustal 12, 83–84 Ardai Basin 28,35 Crater Highlands volcanoes 21, 39, 42–44, faulting 26 43,50 faulting lava plateau 70 faulting 27, 30 early, northern Tanzania 21 Armykon Hill 66, 67 lava 26, 27, 42, 50 Neogene-Recent 10–11 Arusha radiometric data 94 southern extension 29 faulting 28,30 crust, extension 18 Olduvai Basin 35 lava plateau 70 Crystalline Limestone Series 9 Plio-Pleistocene 23–29 ash crystallization, fractional 83–84, 85, 87 Upper Pleistocene–Recent 29–30 Meru 68 faults Oldoinyo Lengai 50, 57–59 listric 29 debris flow asthenosphere, density 14 relationship with basement 29–30 Eastern Chasm 46, 58, 59 Aswa-Nandi-Loita shear zone 30 Fischer, Gustav, early exploration 5, 57 Kerimasi 64 Australopithecus cf. boisei 2, 36 Fischer’s Tower 5 Meru 68 Footprint Tuff 61 Oldoinyo Lengai 46, 58, 59 fossils Balangida Basin 34, 35, 72 Decken, Count von der, early exploration 3, 5 Laetoli 35–37 faulting 23, 26 Deeti cone 65, 67 Lake Manyara 35 magnetic data 17 discontinuities, seismic 15 Olduvai Gorge 6, 35, 36 Balangida Lelu Basin 35 Dodoman Archaean fold belt 30 faulting 23, 26 Dodoman Formation 9 basalt 39 drainage, redirection 23, 33, 36 Gallapo 71 Gelai 41–42 dyke injection 13 Gelai volcano 41–42 Kilimanjaro 54, 56 dyke swarms geophysics 13–18 Lemagrut 44 Eyasi trend 29 modelling 14 Loolmalasin 44 Mbulu Plateau 15 glaciation Monduli 54 Shira cone 56 Kibo cone 56, 57 Ngorongoro 44 Kilimanjaro 56, 57 Oldeani 50 gravity studies 13–14 earthquakes 15–16, 16 Oldoinyo Sambu 40–41 Gregory, John Walter, work on rift valleys 5 East Africa Plateau 2 south Kenya 79 Gregory Rift Valley 2, 9 East African Rift system 1, 4 Tarosero 51 earthquakes 15 discovery 3, 5 basalt-trachyte volcanoes, petrogenesis 84–86 southern extension 29 Eastern Rift, extension 18 basins, sedimentary 33–37 gregoryite 62, 63 Elanairobi volcano 42, 43 Basotu maars and craters 30, 70 grid-faulting, Kibangaini 29, 41–42 faulting 27 Basso Ebor see Lake Stephanie Eledoi crater 66, 67 Basso Narok see Lake Rudolph xenoliths 80, 81 halite 33, 35 Bast Hills 41 Elunata Basin 28,35 Hami River 72 Bouguer anomalies 13, 14, 23, 35, 44 Elunata fault 68 Hanang volcano 35, 71–72 Bubu cataclasites 29–30 Embagai caldera 42, 45 radiometric data 94 Bubu trend 30 Embulu Sabuk crater 66 Hans Meyer Peak 56 Burko volcano 28, 30, 67–68, 68 Engare Nyiro River 33 heat flow 9, 12, 16–17 radiometric data 94 Engare Sero River 33 helium ratio, xenoliths 81 Burton, Sir Richard Francis 3 Engaruka Basin 23, 34, 42 High Natron Beds 33 faulting 25, 28,30 Ho¨hnel, Ludwig von, early exploration 5 calcite carbonatite magnetic data 17 hominids 2, 36–37 ‘corduroy’, Kerimasi 64–66 see also Natron-Engaruka tuff-cone area Homo erectus 36 Hanang 72 Engaruka Block 50–51 Homo habilis 36 Kwaraha 71 Engaruka-Manyara area hornitos, Oldoinyo Lengai 46, 58, 59, 61, 64 calcrete, radiometric data 93 Humbu Formation 33 Olduvai Basin 35, 50 volcanoes 50–57 Monduli 70 Engelosin plug 50 Igwisi Hills 73 calderas 39 Engitati Hill 44 tuff-cones 72–73 Embagai 42, 45 Essimingor volcano 21, 28,51 xenoliths 15, 17, 49,80 Kibo 45,56 eruption 21 isotope variation, xenoliths 80–81 Ngorongoro 44, 45 lava 51 Olmoti 45 radiometric data 94 Cameron’s Crater 70 Ethiopia Afar Geophysical Lithosphere Kavirondian Formation 9 carbon dioxide, Oldoinyo Lengai 64 Experiment 13 Kenya carbonatite Ethiopia Dome 1,2 early exploration 3 Kerimasi 64–66 Euler deconvolution technique 17, 35 early rift structure 21 100 INDEX

Kenya (Continued) salts 33, 40 Mbulu Plateau faulting 21 Lake Nyanza 4 dyke swarms 15, 16 southern discovery 3 faulting 26–27, 30 conductivity 17 Lake Nyasa, discovery 3 maars and craters 70 petrogenesis 84–85 Lake Rudolph 4,5 magnetic data 17 volcanism 79, 80 Lake Stephanie 5 melilitite 39, 84–85, 86–87 Kenya Dome 1,2 Lake Tanganyika 4 Meru 68–69, 79 Bouguer anomaly 13 discovery 3 Monduli 70 Kenya Rift International Seismic Project 13, 30 Lake Turkana, gravity anomaly 14 Natron-Engaruka 66–67 Kerimasi volcano 25, 64–66, 65, 66, 67 Lake Victoria, discovery 3 Oldoinyo Lengai 59 faulting 29 Lalarasi Hill 67 Sadiman 50 magma 65 Lashaine tuff cone 70 Menengai volcano 79 tephra 36 Lashaine volcano, xenoliths 9, 15, 17, 80, 87 Meru area, radiometric data 94–95 Ketumbeine volcano 42, 42 lava, mantle composition, northern Meru volcano 28, 30, 49, 68–70, 69,79 faulting 26 Tanzania 81, 82,83 gravity anomaly 13 Kibangaini lead, isotope variation 83, 84 petrography and mineralogy 68–69 grid-faulting 29, 41–42 Leakey, Louis Seymour Bazett metamorphism, Usagaran 9 trachytes 79 Laetoli fossils 37 metasomatism 14, 80–81, 87 Kibo cone 39, 45, 54, 55,56 Olduvai Gorge fossils 6, 35 Miamoja Hill 64, 67 glaciation 57 Leakey, Mary 36, 37 Moho depth 13, 14 lava 56, 79 Leletema Hills 9 Moinik Formation 33 Kilimanjaro 30, 45, 54–57, 54 Lemagrut volcano 22, 43, 44, 50 Moinik River 33 early exploration 3, 5 lava 37 Momella Lakes 68, 69 eruption 37 Lembolos graben 23, 24, 26, 68 Monduli area basins 35 geological survey 6 Lenderut volcano 79 lava plateau 70 Great Barranco 56 Lengai Trend 87 Monduli volcano 28, 30, 52, 54 glaciation 57 Lengitoto trachytes 79 faulting 26 Kibo cone 39, 45, 54, 55, 56, 79 lithosphere, strength 17–18 radiometric data 94 lava 39 Livingstone, David 3 xenoliths 80 Mawenzi cone 54,56 Loliondo 9 Mosonik volcano 41, 79 parasitic minor cones 56 Loluni crater 67 Mozambique Belt 2, 9 petrochemistry 56–57 Longido 9 heat flow 17 radiometric data 95 Longonot volcano 5, 79 Tertiary–Recent rift fractures 29–30 Shira cone 54,55–56 Loolmalasin volcano 42, 43–44 seismic data 13, 14, 15 Kilimanjaro Depression 21, 22,23 Loolmurwak crater 59, 66, 67 Mozambique orogenic fold belt 9 Kilimatinde, faulting 29 Lorngabolo River 42 Mponde graben 26, 29 Kilombero rift zone 29 Losimingori see Essimingor volcano gravity anomaly 13 kimberlite 49 Msasa River Gorge 26 Kirikiti-Lengitoto faulting 23, 79 maars, Basotu 30, 70 Mt Kenya, first sighting 3 Kisetey crater 66 Maasai Block Kisima ya Mungu 70 early rift structure 21 Naisiusiu Beds 36, 50, 59 Kitingiri Basin, gravity anomaly 13 faulting 26–27, 30 Namorod Ash 59 Klute Peak 55 magnetic data 17 natrocarbonatite 33 Kondoa, earthquakes 15, 16,29 Maasailand, exploration by Joseph Thomson 3, 5 Oldoinyo Lengai 46, 48, 57, 59, 61–64, 63 Kondoan trend 30 Magadi Basin 33 alteration 63–64 KRISP see Kenya Rift International magma formation 64 Seismic Project crustal contamination 83–84 gas species 64 Kwaraha volcano 71 parent, Younger Extrusives 86–87 Olduvai Basin 35 radiometric data 94 paradox 87–88 Natron Basin 23, 33, 34 magmatism 2, 9, 15, 39, 57 boundary fault system 23, 25–26, 27, Labait volcano, xenoliths 15, 17, magnesite 33 30, 41, 64, 65 80, 81, 87 magnetic anomaly data 17 gravity anomaly 13 Laetoli Basin 34 magnetotelluric data, southern Kenya 17 magnetic data 17 Laetoli Beds 36–37, 50 mantle structure 33 first mapping 6 anaomalous 14, 67 Natron-Engaruka tuff-cone area 66–67, 67 fossils 36–37 density 13–14 Ndonyo Engai, first sighting 3 lahar plume 1–2, 15, 18, 87 Ndutu Beds 36, 50, 59 Kibo 56 replenishment 60, 87–88 neodymium isotope variation 80–81, 83 Meru 68 seismic data 13–14 Neogene–Recent Oldoinyo Lengai 66 upper, northern Tanzania 79–83 faults, northern Tanzania 10–11 Laikipia Plateau 5 heterogeneity 79–81 volcanic rocks 39–73 Lake Albert, discovery 3 lava composition 81, 82,83 nomenclature 39, 40 Lake Babati, seismicity 15 Manyara Basin 34–35 nephelinite 39, 46 Lake Baringo 4,5 boundary fault system 23, 25, 26, 27, 28,30 Burko 67–68 Lake Burungi 35 fossils 35 Essimingor 51 Lake Eyasi 35 gravity anomaly 13 Hanang 72 Lake Magad 43, 44, 45 magnetic data 17 Kerimasi 64–65 Lake Magadi 9, 33 seismicity 15, 16 Kibo cone 56 gravity anomaly 14 Manyara Group 21, 34 Kwaraha 71 Lake Malawi 3, 4 Masasi Series 9 Lemagrut 44, 50 Lake Manyara 4,5,35 Masek Beds 36 Meru 68–69, 79 magnetic data 17 Matisiwi fault 26 Mosonik 41 seismicity 15, 16 Matuffa crater 69 Natron-Engaruka area 66–67 Lake Naivasha 4,5 Matunginini fault escarpment 24,26,28 Older Extrusives 84–85 Lake Natron 4,5,27,33 Mautia Hill 9 Oldoinyo Lengai 46, 59–61, 86–87 olivine basalt dates 96 Mawenzi cone 45, 54 Oldoinyo Sambu 41 proto-lake 23, 25, 33 glaciation 57 Sadiman 50 radiometric data 93 lava 56 Shombole 40 INDEX 101

Neumann Tower 56 Peninj Group sediments 23, 33 Tanganyika-Rukwa-Malawi rift 29 Ngaloba Beds 37 Peninj River 33 Tanzania, early exploration 5–6 Ngong volcano 79 delta 40 Tanzania Broadband Seismic Experiment 13, 15 Ngong-Turoka fault 23 peridotite 49, 67, 70 Tanzania Craton 1,2,9 Ngorongoro caldera 43, 44, 45 mantle 14, 72 heat flow 17 faulting 27 petrochemistry, Kilimanjaro 56–57 plume 15 seismicity 15 petrogenesis 84–88 relationship to Tertiary–Recent rift Ngurdoto crater 69 basalt-trachyte volcanoes 84–86 fractures 29–30 Nguruman fault 21 Older Extrusives 84–86 seismic anisotropy 15 Nile, source of 3 Tarosero trachytes and comendites 86 seismic data 13, 14, 15 niobium 83, 84 Younger Extrusives 86–88 thermal anomaly 15 Njorowa Gorge 5 phonolite Tanzania, northern 2 North Tanzania Divergence 1, 2, 21, 29, 30 Elanairobi 42 early faulting 21 Nubian Plate 1,2,18 Essimingor 51 early rift structure 21 Nutcracker Man 2, 36 Kilimanjaro 54, 56 late Tertiary depression 21–23 Nyangea-Athi-Ikutha shear zone 30 Meru 68–69, 79 petrogenesis 84–85 Nyanzian Formation 9 Mosonik 41 regional geology 9–12 nyerereite 62, 63 Oldoinyo Lengai 59, 86 rock analyses 97–98 Sadiman 50 upper mantle composition 79–83 Tarosero 51, 52 volcanism 79, 80 Ogol Hills 22 phosphates 35 Tanzanian Geological Survey, mapping 9, 39 Ogol lava 50 plate tectonics tanzanite 9 Ol Esayeti volcano 79 development 21–30 Tarosero volcano 23, 26, 51–52, 51 Ol Keja Nero basalt 79 modelling 18 lava 51–52, 53 Ol Tepesi basalt 79 Pleistocene radiometric data 94 Olbalbal Depression 22, 27, 36 Lower, faulting 23–29 trachytes and comendites, petrogenesis 86 Oldeani volcano 43,50 Upper–Recent, faulting 29–30 Tarosero fault 26 faulting 27 Pliocene-Pleistocene, faulting 23–29 TBSE see Tanzania Broadband Seismic Experiment Older Extrusives 23, 24, 39, 40–42 plume, mantle 18 tectonics see plate tectonics petrogenesis 84–86 Tanzania Craton 1–2, 15, 87 Teleki, Count, early exploration 5 Oldoinyo Lengai volcano 46, 57–64, 58 Project EAGLE see Ethiopia Afar Geophysical teleseismic experiments 14–15 activity 57–58 Lithosphere Experiment Tertiary, late, depression 21–23, 39 ash 57–59 thermal anomaly 15 early exploration 3, 5, 6, 57 thermonatrite 33 Eastern Chasm 46, 58, 59 Recent, faulting 29 Thomson, Joseph, early exploration 3, 5 geology 59 Reck, Hans 6, 35 trachybasalt 42, 43, 54, 55, 56 lava 59–64, 86 replenishment, mantle 60, 87–88 trachyte minerals 46, 47, 48,59–61 rhyolite Gelai 41, 42 morphology 58–59 Olkaria 86 Ketumbeine 42 parent magma 87 peralkaline 5 Kibangaini 79 petrogenesis 86 rifting 18 Kibo cone 56 seismicity 15 rubidium isotope variation 83, 84 Kilimanjaro 54, 56 tephra 36 Ruhuhu graben 29 Lengitoto 79 xenoliths 80 Rungwe volcanics, work of Joseph Loolmalasin 44 Oldoinyo Sambu volcano 39, 40–41, 40 Thomson 3 Monduli 54 lava 23 Ngorongoro 44 Olduvai Basin 22, 34,35–37 Oldeani 50 drainage reversal 23, 36 S-wave velocity variation 15 Olmoti 43 Olduvai Beds 36 Sadiman volcano 43,50 petrogenesis 84–86 Olduvai Gorge Salei Plain 50 Tarosero 51, 52, 53 faulting 29 salts, Lake Natron 33 trona 33, 35, 40, 63, 64 fossils 2, 6, 36 Sambu volcanics 33 tuff radiometric data 94 Sanjan Fault 25, 41 Laetoli Basin 37 sediments 36 Sea of Unyamwezi see Lake Nyanza Oldoinyo Lengai 59 Oljoro graben 26, 68 sedimentary basins 33–37 Olduvai Basin 35 lava plateau 70 seismic experiments 13, 14–15 Salei and Serengeti plains 50 Olkaria rhyolites 86 seismicity 15–16, 16 tuff cones Olmani cinder cone 69,70 Serengeti Plain 21, 22, 50 Hanang 72 xenoliths 80 shear zones 29–30 Igwisi Hills 72–73 Olmoti volcano 43, 45 Shira cone 54,55–56 Kwaraha 71 faulting 27 Shombole Trend 87 Natron-Engaruka area 66–67, 67 Olorgesaile Formation 29 Shombole volcano 40, 40,79 Younger Extrusives 57 Olorgesaile volcano 79 Singaraini basalt 79 tuff rings Olsirwa volcano 43,44 Somali Plate 1,2 Basotu maars 70 Orkandira Hill 51 rifting 18 Lashaine 70 Sonjo-Eyasi fault 13, 21–22, 27, 30 Turkwell Fault 21 Speke, John Hanning 3 P-waves, low velocity layer 9, 13 springs pahoehoe lava, Oldoinyo Lengai 61, 61, 62 freshwater 44 Pan-African orogenic event 9 Ufiome 71 hot 73 Pangani graben 9, 13, 21 Uhlig, Carl, Manyara-Natron sector 5–6 stromatolites, Lake Manyara 35 Uhuru Peak 45, 55,56 boundary faults 30 strontium isotope variation 80–81, 83 seismicity 16 uplift, domal 18, 21 Suess, Eduard, early work on rift valleys 3, 5 Parangan trend 30 uranium 83, 84 Suswa volcano 79 Pare Mountains 9 Usagara Mountains 9 folding 30 Usagaran metamorphic event 9 seismicity 16 Tanganyika Geological Survey Pello Hill tuff cone 67 mapping 6, 22 volcanism 2 xenoliths 14, 49, 80, 81, 87 see also Tanzanian Geological Survey early 21, 39 102 INDEX volcanism (Continued) earthquakes 15 Olmani 80 northern Tanzania 10–11, 79, 80 extension 18 Pello Hill 14, 49, 67, 80, 81, 87 Older Extrusives 23, 24, 39, 40–42 wollastonite 46, 47, 59, 60, 64, 69 Oldoinyo Lengai 57–59 south Kenya 79, 80 xenoliths Yaida Basin 34,35 Younger Extrusives 25, 39, Burko 67 Yaida graben 21 57–73 Chyulu Hills 17 faulting 30 volcanoes Eledoi 67, 80, 81 Yayai Basin 28,35 linearity 30 Igwisi Hills 15, 17, 49,80 Younger Extrusives 25, 39, 57–73 peralkaline 39, 59, 79 isotope variation 80–81 parent magma 86–87 shield 39, 40, 41, 42–44, 50, 54 Labait 15, 17, 80, 81, 87 paradox 87–88 Lashaine tuff 9, 15, 17, 80, 81, 87 petrogenesis 86–88 mantle composition 79–80 water 64, 80 Meru 68 zeolite, Olduvai Basin 36 Wembere Basin 35 Monduli 80 Zinjanthropus boisei see Australopithecus Western Rift Oldoinyo Lengai 60, 67, 80 cf. boisei