scholarly journals Elemental fingerprinting of Kenya Rift Valley ochre deposits for provenance studies of rock art and archaeological pigments

2017 ◽  
Vol 430 ◽  
pp. 42-59 ◽  
Author(s):  
Andrew M. Zipkin ◽  
Stanley H. Ambrose ◽  
John M. Hanchar ◽  
Philip M. Piccoli ◽  
Alison S. Brooks ◽  
...  
Keyword(s):  
Rift Valley ◽  
Rock Art ◽  
Kenya Rift ◽  
Provenance Studies ◽  
Elemental Fingerprinting ◽  
Archaeological Pigments ◽  
Kenya Rift Valley

Mixed benmoreite/trachyte flows from Kenya and their bearing on the Daly Gap

1979 ◽  
Vol 116 (6) ◽  
pp. 487-489 ◽  
Author(s):  
W. B. Jones
Keyword(s):  
Rift Valley ◽  
Complete Sequence ◽  
Kenya Rift ◽  
Kenya Rift Valley

SummaryBlebs of anorthoclase-phyric purple rock, usually up to 10 cm but occasionally up to 30 cm in diameter, occur in trachyte lavas of the volcanoes Kilombe and Kapkut, Kenya. The blebs have bulbous outlines and chilled margins and are therefore considered to have been liquid when incorporated in the trachyte. Chemically similar to the benmoreites of Hawaii, Skye and the southern Kenya Rift Valley, they bridge a gap in an otherwise complete sequence of lavas from basalt to trachyte. The failure of benmoreite to erupt as a lava is attributed to viscosity reaching a maximum among intermediate lavas.

The Geology of the Katmaian Volcanics of the Upper Oramutia Valley, Kenya

1962 ◽  
Vol 99 (2) ◽  
pp. 153-163 ◽  
Author(s):  
C. M. Bristow
Keyword(s):  
Rift Valley ◽  
Kenya Rift ◽  
Eastern Flank ◽  
Similar Explanation ◽  
Kenya Rift Valley

AbstractThe Oramutia volcanics consist of a group of ignimbrites overlain by pumice tuffs, which lie in a fault formed valley on the eastern flank of the main Kenya rift valley. The presence of a dyke of ignimbrite suggests that the “claystone ” ignimbrite of this area was erupted from fissures. A similar explanation probably applies to the pumice tuffs. These volcanics are therefore the product of Katmaian type eruptions.

Lemudong'o: a new 6 Ma paleontological site near Narok, Kenya Rift Valley

2003 ◽  
Vol 44 (6) ◽  
pp. 737-742 ◽  
Author(s):  
Stanley H Ambrose ◽  
Leslea J Hlusko ◽  
David Kyule ◽  
Alan Deino ◽  
Martin Williams
Keyword(s):  
Rift Valley ◽  
Kenya Rift ◽  
Kenya Rift Valley

Succession of Cainozoic Vertebrate Assemblages from the Northern Kenya Rift Valley

Nature ◽  
1971 ◽  
Vol 233 (5319) ◽  
pp. 389-394 ◽  
Author(s):  
W. W. BISHOP ◽  
G. R. CHAPMAN ◽  
A. HILL ◽  
J. A. MILLER
Keyword(s):  
Rift Valley ◽  
Kenya Rift ◽  
Northern Kenya ◽  
Kenya Rift Valley

Distribution of gallium between phenocrysts and melt in peralkaline salic volcanic rocks, Kenya Rift Valley

2010 ◽  
Vol 74 (2) ◽  
pp. 351-363 ◽  
Author(s):  
R. Macdonald ◽  
N. W. Rogers ◽  
B. Bagiński ◽  
P. Dzierżanowski
Keyword(s):  
Rift Valley ◽  
Inductively Coupled Plasma ◽  
Magma Mixing ◽  
Volcanic Rocks ◽  
Alkali Feldspar ◽  
Volcanic Complex ◽  
Kenya Rift ◽  
Inductively Coupled ◽  
Plasma Mass Spectrometry ◽  
Kenya Rift Valley

AbstractGallium abundances, determined by laser ablation-inductively coupled plasma-mass spectrometry, are presented for phenocrysts and glassy matrices from a metaluminous trachyte and five peralkaline rhyolites from the Greater Olkaria Volcanic Complex, Kenya Rift Valley. Abundances in the glasses range from 28.9 to 33.3 ppm, comparable with peralkaline rhyolites elsewhere. Phenocryst Ga abundances (in ppm) are: sanidine 31.5–45.3; fayalite 0.02–0.22; hedenbergite 3.3–6.3; amphibole 12; biotite 72; ilmenite 0.56–0.72; titanomagnetite 32; chevkinite-(Ce) 364. The mafic phases and chevkinite-(Ce) are enriched in Ga relative to Al, whereas Ga/Al ratios in sanidine are smaller than in coexisting glass. Apparent partition coefficients range from <0.01 in fayalite to 12 in chevkinite-(Ce). Coefficients for hedenbergite, ilmenite and titanomagnetite decrease as melts become peralkaline. The sharp increase in Ga/Al in the more fractionated members of alkaline magmatic suites probably results from alkali feldspar-dominated fractionation. Case studies are presented to show that the Ga/Al ratio may be a sensitive indicator of such petrogenetic processes as magma mixing, interaction of melts with F-rich volatile phases, mineral accumulation and volatile-induced crustal anatexis.

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