Magmatic Processes Beneath the East African Rift System (EARS): Insights From Melt Inclusions in Lavas of Turkana, Kenya

Details Magmatic Processes Beneath the East African Rift System (EARS): Insights From Melt Inclusions in Lavas of Turkana, Kenya Magmatic Processes Beneath the East African Rift System (EARS): Insights From Melt Inclusions in Lavas of Turkana, Kenya

May 2004

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2004agusm.v43b..05w&link_type=abstract

American Geophysical Union, Spring Meeting 2004, abstract #V43B-05

Other

1010 Chemical Evolution

Scientific paper

The EARS is an ideal site to study the magmatic processes relevant to continental basaltic volcanism. Within the EARS, the Turkana Depression exhibits maximum extension and crustal thinning [1, 2]. Whole rock elemental and isotopic analyses of Turkana lavas demonstrate heterogeneity that is unlikely due to crustal assimilation during magma transport or storage and is instead attributed to mixing between mantle sources (plume and lithosphere) [3]. In other sites of continental basaltic volcanism, compositional studies of olivine-hosted melt inclusions (MIs) lend perspective on magma chamber processing and source diversity (e.g., [4,5]). MIs hosted in primitive olivine (ol) phenocrysts often sample numerous, discrete melts that existed prior to melt aggregation and homogenization within the continental lithosphere. Thus, ol-hosted MIs from Turkana may also provide insight into magmatic processes beneath continental rifts. Furthermore, Turkana lavas afford an unusual opportunity to study MIs that are likely unaffected by crustal assimilation and provide direct evidence of mantle heterogeneity. We present major element compositional data on ol-hosted MIs from a suite of lavas from the Turkana Depression. To test for geographical control on source heterogeneity beneath the Turkana Rift, analyses in progress encompass basaltic lavas that have been sampled from South and Central Islands and the Barrier. Olivine-hosted MIs in a South Island transitional basalt (MgO= 14.10 wt%, K2O/TiO2= 0.37, K2O/P2O5= 2.08; data from [3]) are dominantly alkaline in composition. Incompatible element ratios between MIs in separate, primitive ol grains (Fo= 83.8-86.7) display significant variability (K2O/TiO2= 0.32-0.63, K2O/P2O5= 1.02-4.36). Also, primitive ol grains (e.g., Fo= 86.2) host multiple MIs that consistently display similar incompatible element variability (e.g., K2O/TiO2= 0.33-0.59, K2O/P2O5=1.27-2.04). These data suggest that melt homogenization occurs at relatively shallow levels even for primitive continental lavas erupted through thin (<20 km) continental crust. Ongoing major and trace element analyses of MIs from Turkana lavas may provide more information and constraints on source variability and melt aggregation processes within the EARS. [1] Morley, C.K., Tectonophysics 236, 81-91, 1994. [2] Simiyu and Keller, Tectonophysics 278, 291-313, 1997. [3] Furman, et al., Journal of Petrology 2004, in press. [4] Kent et al., Earth and Planetary Science Letters 202, 577-594, 2002. [5] Kamenetsky and Clochiatti, Earth and Planetary Science Letters 142, 53-572, 1996.

Affiliated with

Also associated with

No associations

Rating

Magmatic Processes Beneath the East African Rift System (EARS): Insights From Melt Inclusions in Lavas of Turkana, Kenya does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Magmatic Processes Beneath the East African Rift System (EARS): Insights From Melt Inclusions in Lavas of Turkana, Kenya, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Magmatic Processes Beneath the East African Rift System (EARS): Insights From Melt Inclusions in Lavas of Turkana, Kenya will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1178163