| 14960 |
Creator |
4989dd10527e94ef140e45e8c9fb07e6 |
| 14960 |
Creator |
d031e8048206102a070ef3064a0a75b0 |
| 14960 |
Creator |
ext-1c31f7e1f7c7fbb1ceb56cf793da7955 |
| 14960 |
Creator |
ext-0d931c629087d0199ec0a4d3f885bbee |
| 14960 |
Creator |
ext-eb93b630c0dd6e95ad611fd37e16ea37 |
| 14960 |
Creator |
ext-38e1c90fe38a64f22522cdcbcbc07c41 |
| 14960 |
Creator |
ext-accaa0e3a0c10da8d17facb28604f3f6 |
| 14960 |
Date |
2008 |
| 14960 |
Is Part Of |
p00223530 |
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Is Part Of |
repository |
| 14960 |
abstract |
The Greater Olkaria Volcanic Complex is a young ( 20 ka) multi-centred lava and dome
field dominated by the eruption of peralkaline rhyolites. Basaltic and trachytic magmas
have been erupted peripherally to the complex and also form, with mugearites and benmoreites,
an extensive suite of magmatic inclusions in the rhyolites. The eruptive rocks commonly
represent mixed magmas and the magmatic inclusions are themselves two-, three- or
four-component mixes. All rock types may carry xenocrysts of alkali feldspar, and
less commonly plagioclase, derived from magma mixing and by remobilization of crystal
mushes and/or plutonic rocks. Xenoliths in the range gabbro–syenite are common in
the lavas and magmatic inclusions, the more salic varieties sometimes containing silicic
glass representing partial melts and ranging in composition from anorthite ± corundum-
to acmite-normative. The peralkaline varieties are broadly similar, in major element
terms, to the eruptive peralkaline rhyolites. The basalt–trachyte suite formed by
a combination of fractional crystallization, magma mixing and resorption of earlier-formed
crystals. Matrix glass in metaluminous trachytes has a peralkaline rhyolitic composition,
indicating that the eruptive rhyolites may have formed by fractional crystallization
of trachyte. Anomalous trace element enrichments (e.g. 2000 ppm Y in a benmoreite)
and negative Ce anomalies may have resulted from various Na- and K-enriched fluids
evolving from melts of intermediate composition and either being lost from the system
or enriched in other parts of the reservoirs. A small group of nepheline-normative,
usually peralkaline, magmatic inclusions was formed by fluid transfer between peralkaline
rhyolitic and benmoreitic magmas. The plumbing system of the complex consists of several
independent reservoirs and conduits, repeatedly recharged by batches of mafic magma,
with ubiquitous magma mixing. |
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authorList |
authors |
| 14960 |
issue |
8 |
| 14960 |
status |
peerReviewed |
| 14960 |
uri |
http://data.open.ac.uk/oro/document/12172 |
| 14960 |
uri |
http://data.open.ac.uk/oro/document/12490 |
| 14960 |
uri |
http://data.open.ac.uk/oro/document/4630 |
| 14960 |
uri |
http://data.open.ac.uk/oro/document/9067 |
| 14960 |
volume |
49 |
| 14960 |
type |
AcademicArticle |
| 14960 |
type |
Article |
| 14960 |
label |
Macdonald, R.; Belkin, H. E.; Fitton, J. G.; Rogers, N. W. ; Nejbert, K.; Tindle,
A. G. and Marshall, A. S. (2008). The roles of fractional crystallization, magma
mixing, crystal mush remobilization, and volatile-melt interactions in the genesis
of a young basalt- peralkaline rhyolite suite, the Greater Olkaria volcanic complex,
Kenya rift valley. Journal of Petrology, 49(8) pp. 1515–1547. |
| 14960 |
label |
Macdonald, R.; Belkin, H. E.; Fitton, J. G.; Rogers, N. W. ; Nejbert, K.; Tindle,
A. G. and Marshall, A. S. (2008). The roles of fractional crystallization, magma
mixing, crystal mush remobilization, and volatile-melt interactions in the genesis
of a young basalt- peralkaline rhyolite suite, the Greater Olkaria volcanic complex,
Kenya rift valley. Journal of Petrology, 49(8) pp. 1515–1547. |
| 14960 |
Title |
The roles of fractional crystallization, magma mixing, crystal mush remobilization,
and volatile-melt interactions in the genesis of a young basalt- peralkaline rhyolite
suite, the Greater Olkaria volcanic complex, Kenya rift valley |
| 14960 |
in dataset |
oro |