Deep to shallow crustal differentiation of within-plate alkaline magmatism at Mt. Bambouto volcano, Cameroon Line

At Mt. Bambouto, a continental stratovolcano of the Cameroon Line, magmatic activity lasted for over 20. Ma and was characterized by at least two caldera formation events. Here we present detailed mineral and whole-rock compositions of Mt. Bambouto basanites, hawaiites, trachytes and phonolites, wit...

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Main Authors: Marzoli, A., Aka, F., Merle, Renaud, Callegaro, S., N'ni, J.
Format: Journal Article
Published: Elsevier 2015
Online Access:http://hdl.handle.net/20.500.11937/13630
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author Marzoli, A.
Aka, F.
Merle, Renaud
Callegaro, S.
N'ni, J.
author_facet Marzoli, A.
Aka, F.
Merle, Renaud
Callegaro, S.
N'ni, J.
author_sort Marzoli, A.
building Curtin Institutional Repository
collection Online Access
description At Mt. Bambouto, a continental stratovolcano of the Cameroon Line, magmatic activity lasted for over 20. Ma and was characterized by at least two caldera formation events. Here we present detailed mineral and whole-rock compositions of Mt. Bambouto basanites, hawaiites, trachytes and phonolites, with emphasis on caldera related volcanic rocks. These data show that differentiation took place within a complex magma plumbing system, with magma chambers occurring at different depths within the crust. Though differentiation was chiefly dominated by fractional crystallization, chemical mineral zoning of olivines, clinopyroxenes, and feldspars is also indicative of open-system processes such as magma mixing and magma chamber recharge. Chemical zoning is evident mainly in the outer 100 microns of the analyzed crystals, suggesting that magma mixing occurred shortly before eruption. The last caldera collapse at about 15. Ma also marked a clear change in the magma plumbing system. Before caldera collapse, Mt. Bambouto was characterized by a dominant production of peralkaline quartz trachytic magmas in shallow magma chambers. During this phase, evolved basic magmas (hawaiites) and strongly evolved alkaline magmas were formed in middle and upper crustal magma chambers, respectively. After emptying of the shallow quartz trachytic magma chamber and caldera collapse, magmas from the deep magmatic plumbing system were mobilized and partially mixed. This triggered eruptions of magmas on the caldera rims.
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spelling curtin-20.500.11937-136302017-09-13T15:00:25Z Deep to shallow crustal differentiation of within-plate alkaline magmatism at Mt. Bambouto volcano, Cameroon Line Marzoli, A. Aka, F. Merle, Renaud Callegaro, S. N'ni, J. At Mt. Bambouto, a continental stratovolcano of the Cameroon Line, magmatic activity lasted for over 20. Ma and was characterized by at least two caldera formation events. Here we present detailed mineral and whole-rock compositions of Mt. Bambouto basanites, hawaiites, trachytes and phonolites, with emphasis on caldera related volcanic rocks. These data show that differentiation took place within a complex magma plumbing system, with magma chambers occurring at different depths within the crust. Though differentiation was chiefly dominated by fractional crystallization, chemical mineral zoning of olivines, clinopyroxenes, and feldspars is also indicative of open-system processes such as magma mixing and magma chamber recharge. Chemical zoning is evident mainly in the outer 100 microns of the analyzed crystals, suggesting that magma mixing occurred shortly before eruption. The last caldera collapse at about 15. Ma also marked a clear change in the magma plumbing system. Before caldera collapse, Mt. Bambouto was characterized by a dominant production of peralkaline quartz trachytic magmas in shallow magma chambers. During this phase, evolved basic magmas (hawaiites) and strongly evolved alkaline magmas were formed in middle and upper crustal magma chambers, respectively. After emptying of the shallow quartz trachytic magma chamber and caldera collapse, magmas from the deep magmatic plumbing system were mobilized and partially mixed. This triggered eruptions of magmas on the caldera rims. 2015 Journal Article http://hdl.handle.net/20.500.11937/13630 10.1016/j.lithos.2015.02.005 Elsevier restricted
spellingShingle Marzoli, A.
Aka, F.
Merle, Renaud
Callegaro, S.
N'ni, J.
Deep to shallow crustal differentiation of within-plate alkaline magmatism at Mt. Bambouto volcano, Cameroon Line
title Deep to shallow crustal differentiation of within-plate alkaline magmatism at Mt. Bambouto volcano, Cameroon Line
title_full Deep to shallow crustal differentiation of within-plate alkaline magmatism at Mt. Bambouto volcano, Cameroon Line
title_fullStr Deep to shallow crustal differentiation of within-plate alkaline magmatism at Mt. Bambouto volcano, Cameroon Line
title_full_unstemmed Deep to shallow crustal differentiation of within-plate alkaline magmatism at Mt. Bambouto volcano, Cameroon Line
title_short Deep to shallow crustal differentiation of within-plate alkaline magmatism at Mt. Bambouto volcano, Cameroon Line
title_sort deep to shallow crustal differentiation of within-plate alkaline magmatism at mt. bambouto volcano, cameroon line
url http://hdl.handle.net/20.500.11937/13630