Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Application of the QUILF thermobarometer to the peralkaline trachytes and pantellerites of the Eburru volcanic complex, East African Rift, Kenya.
AU - Ren, Minghua
AU - Omenda, Peter A.
AU - Anthony, Elizabeth A.
AU - White, John C.
AU - MacDonald, Raymond
AU - Bailey, D. K.
PY - 2006/10
Y1 - 2006/10
N2 - The Quaternary Eburru volcanic complex in the south-central Kenya Rift consists of pantelleritic trachytes and pantellerites. The phenocryst assemblage in the trachytes is sanidine + fayalite + ferrohedenbergite + aenigmatite ± quartz ± ilmenite ± magnetite ± pyrrhotite ± pyrite. In the pantellerites, the assemblage is sanidine + quartz + ferrohedenbergite + fayalite + aenigmatite + ferrorichterite + pyrrhotite ± apatite, although fayalite, ferrohedenbergite and ilmenite are absent from more evolved rocks (e.g. with SiO2 > 71%). QUILF temperature calculations for the trachytes range from 709 to 793 °C and for the pantellerites 668–708 °C, the latter temperatures being among the lowest recorded for peralkaline silicic magmas. The QUILF thermobarometer demonstrates that the Eburru magmas crystallized at relatively low oxidation states (ΔFMQ + 0.5 to − 1.6) for both trachytes and pantellerites. The trachytes and pantellerites evolved along separate liquid lines of descent, the trachytes possibly deriving from a more mafic parent by fractional crystallization and the pantellerites from extreme fractionation of comenditic magmas.
AB - The Quaternary Eburru volcanic complex in the south-central Kenya Rift consists of pantelleritic trachytes and pantellerites. The phenocryst assemblage in the trachytes is sanidine + fayalite + ferrohedenbergite + aenigmatite ± quartz ± ilmenite ± magnetite ± pyrrhotite ± pyrite. In the pantellerites, the assemblage is sanidine + quartz + ferrohedenbergite + fayalite + aenigmatite + ferrorichterite + pyrrhotite ± apatite, although fayalite, ferrohedenbergite and ilmenite are absent from more evolved rocks (e.g. with SiO2 > 71%). QUILF temperature calculations for the trachytes range from 709 to 793 °C and for the pantellerites 668–708 °C, the latter temperatures being among the lowest recorded for peralkaline silicic magmas. The QUILF thermobarometer demonstrates that the Eburru magmas crystallized at relatively low oxidation states (ΔFMQ + 0.5 to − 1.6) for both trachytes and pantellerites. The trachytes and pantellerites evolved along separate liquid lines of descent, the trachytes possibly deriving from a more mafic parent by fractional crystallization and the pantellerites from extreme fractionation of comenditic magmas.
KW - Kenya
KW - Eburru volcanic complex
KW - Trachyte
KW - Pantellerite
KW - Peralkaline
KW - QUILF
U2 - 10.1016/j.lithos.2006.03.011
DO - 10.1016/j.lithos.2006.03.011
M3 - Journal article
VL - 91
SP - 109
EP - 124
JO - Lithos
JF - Lithos
SN - 0024-4937
IS - 1-4
ER -