The long-lived Chiltepe volcanic complex, Nicaragua: magmatic evolution at an arc offset.
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| Title: | The long-lived Chiltepe volcanic complex, Nicaragua: magmatic evolution at an arc offset. |
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| Authors: | Freundt, A.1 (AUTHOR) afreundt@geomar.de, Kutterolf, S.1 (AUTHOR) |
| Source: | Bulletin of Volcanology. Oct2019, Vol. 81 Issue 10, pN.PAG-N.PAG. 1p. |
| Subject Terms: | *Metasomatism, *Volcanic eruptions, *Subduction zones, *Plagioclase, *Fluid flow, *Andesite, *Magmas |
| Geographic Terms: | Nicaragua |
| Abstract: | The NW-SE striking volcanic front in Nicaragua is dissected into a western and an eastern segment separated by 20 km of N-S offset. The Chiltepe volcanic complex lies at the eastern end of the western segment and at the northern tip of the Nejapa-Miraflores tectonic and volcanic lineament that traces the arc offset. The Chiltepe peninsula attained its present shape and composition during highly explosive and effusive volcanic activity through the Late Pleistocene and Holocene, which formed the Chiltepe Formation (CF) and culminated in the 1.9 ka plinian eruption of the Chiltepe tephra. The previous evolution of this volcanic system is recorded in the volcaniclastic Mateare Formation (MF) exposed west (downwind) of the peninsula and separated from the CF by a large regional erosional unconformity. We divide the MF into the lower MF-1 member (22 volcaniclastic units) and the upper MF-2 member (17 volcaniclastic units), which are separated by a major erosional unconformity. The MF-1 was formed by variably evolved (basalt to dacite) magmas from a mantle source that was moderately metasomatized by fluids derived from subducted sediments. These high-Al moderately hydrous magmas fractionated in a tholeiitic fashion, with early plagioclase but delayed magnetite fractionation (initial Fe-Ti enrichments). Apart from the variable degree of differentiation, magmatic conditions during MF-1 remained fairly constant. While MF-1 contains several erosional unconformities suggesting tectonic activity, MF-2 is conformably stratified and the tholeiitic magmas persisted during this time. However, during MF-2, Al-poor tholeiitic compositions gradually replaced the Al-rich of MF-1 without significant changes in metasomatism or degree of melting at their mantle sources. At the same time, a different mantle source was tapped that was richer in the sediment components, and which produced more hydrous magmas that differentiated in a calc-alkaline fashion with early fractionation of both plagioclase and magnetite. Hence, two mantle source compositions were active during MF-2. The erosional interval between MF and CF, associated with strike-slip motion at the Mateare Fault, correlates with initiation of Nejapa-Miraflores volcanism. We postulate that extension along the Najapa-Miraflores fault system facilitated rapid ascent of mafic magmas from a mantle source laterally away from the arc axis that was less metasomatized than sources directly below the arc. On the Chiltepe peninsula, the Nejapa-Miraflores and Chiltepe magma systems interacted to form tholeiitic, less hydrous types of magmas (andesite to dacite) that erupted intermittently with the dominant calc-alkaline hydrous dacites. While associations of tholeiitic and calc-alkaline magmas at other subduction zones have often been attributed to variable intracrustal processes, we here argue for changes in the mantle source, particularly hydration by slab-derived fluids, as the main control on subsequent differentiation behavior. We further attribute the long-term changes in mantle source conditions through MF and CF, possibly over about 1 My, to result from temporal heterogeneity caused by mantle wedge solid flow and possibly variable fluid flow from the slab. [ABSTRACT FROM AUTHOR] |
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| Header | DbId: enr DbLabel: Energy & Power Source An: 139365804 AccessLevel: 6 PubType: Academic Journal PubTypeId: academicJournal PreciseRelevancyScore: 0 |
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| Items | – Name: Title Label: Title Group: Ti Data: The long-lived Chiltepe volcanic complex, Nicaragua: magmatic evolution at an arc offset. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Freundt%2C+A%2E%22">Freundt, A.</searchLink><relatesTo>1</relatesTo> (AUTHOR)<i> afreundt@geomar.de</i><br /><searchLink fieldCode="AR" term="%22Kutterolf%2C+S%2E%22">Kutterolf, S.</searchLink><relatesTo>1</relatesTo> (AUTHOR) – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Bulletin+of+Volcanology%22">Bulletin of Volcanology</searchLink>. Oct2019, Vol. 81 Issue 10, pN.PAG-N.PAG. 1p. – Name: Subject Label: Subject Terms Group: Su Data: *<searchLink fieldCode="DE" term="%22Metasomatism%22">Metasomatism</searchLink><br />*<searchLink fieldCode="DE" term="%22Volcanic+eruptions%22">Volcanic eruptions</searchLink><br />*<searchLink fieldCode="DE" term="%22Subduction+zones%22">Subduction zones</searchLink><br />*<searchLink fieldCode="DE" term="%22Plagioclase%22">Plagioclase</searchLink><br />*<searchLink fieldCode="DE" term="%22Fluid+flow%22">Fluid flow</searchLink><br />*<searchLink fieldCode="DE" term="%22Andesite%22">Andesite</searchLink><br />*<searchLink fieldCode="DE" term="%22Magmas%22">Magmas</searchLink> – Name: SubjectGeographic Label: Geographic Terms Group: Su Data: <searchLink fieldCode="DE" term="%22Nicaragua%22">Nicaragua</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: The NW-SE striking volcanic front in Nicaragua is dissected into a western and an eastern segment separated by 20 km of N-S offset. The Chiltepe volcanic complex lies at the eastern end of the western segment and at the northern tip of the Nejapa-Miraflores tectonic and volcanic lineament that traces the arc offset. The Chiltepe peninsula attained its present shape and composition during highly explosive and effusive volcanic activity through the Late Pleistocene and Holocene, which formed the Chiltepe Formation (CF) and culminated in the 1.9 ka plinian eruption of the Chiltepe tephra. The previous evolution of this volcanic system is recorded in the volcaniclastic Mateare Formation (MF) exposed west (downwind) of the peninsula and separated from the CF by a large regional erosional unconformity. We divide the MF into the lower MF-1 member (22 volcaniclastic units) and the upper MF-2 member (17 volcaniclastic units), which are separated by a major erosional unconformity. The MF-1 was formed by variably evolved (basalt to dacite) magmas from a mantle source that was moderately metasomatized by fluids derived from subducted sediments. These high-Al moderately hydrous magmas fractionated in a tholeiitic fashion, with early plagioclase but delayed magnetite fractionation (initial Fe-Ti enrichments). Apart from the variable degree of differentiation, magmatic conditions during MF-1 remained fairly constant. While MF-1 contains several erosional unconformities suggesting tectonic activity, MF-2 is conformably stratified and the tholeiitic magmas persisted during this time. However, during MF-2, Al-poor tholeiitic compositions gradually replaced the Al-rich of MF-1 without significant changes in metasomatism or degree of melting at their mantle sources. At the same time, a different mantle source was tapped that was richer in the sediment components, and which produced more hydrous magmas that differentiated in a calc-alkaline fashion with early fractionation of both plagioclase and magnetite. Hence, two mantle source compositions were active during MF-2. The erosional interval between MF and CF, associated with strike-slip motion at the Mateare Fault, correlates with initiation of Nejapa-Miraflores volcanism. We postulate that extension along the Najapa-Miraflores fault system facilitated rapid ascent of mafic magmas from a mantle source laterally away from the arc axis that was less metasomatized than sources directly below the arc. On the Chiltepe peninsula, the Nejapa-Miraflores and Chiltepe magma systems interacted to form tholeiitic, less hydrous types of magmas (andesite to dacite) that erupted intermittently with the dominant calc-alkaline hydrous dacites. While associations of tholeiitic and calc-alkaline magmas at other subduction zones have often been attributed to variable intracrustal processes, we here argue for changes in the mantle source, particularly hydration by slab-derived fluids, as the main control on subsequent differentiation behavior. We further attribute the long-term changes in mantle source conditions through MF and CF, possibly over about 1 My, to result from temporal heterogeneity caused by mantle wedge solid flow and possibly variable fluid flow from the slab. [ABSTRACT FROM AUTHOR] |
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| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.1007/s00445-019-1321-x Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 1 StartPage: N.PAG Subjects: – SubjectFull: Metasomatism Type: general – SubjectFull: Volcanic eruptions Type: general – SubjectFull: Subduction zones Type: general – SubjectFull: Plagioclase Type: general – SubjectFull: Fluid flow Type: general – SubjectFull: Andesite Type: general – SubjectFull: Magmas Type: general – SubjectFull: Nicaragua Type: general Titles: – TitleFull: The long-lived Chiltepe volcanic complex, Nicaragua: magmatic evolution at an arc offset. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Freundt, A. – PersonEntity: Name: NameFull: Kutterolf, S. IsPartOfRelationships: – BibEntity: Dates: – D: 01 M: 10 Text: Oct2019 Type: published Y: 2019 Identifiers: – Type: issn-print Value: 02588900 Numbering: – Type: volume Value: 81 – Type: issue Value: 10 Titles: – TitleFull: Bulletin of Volcanology Type: main |
| ResultId | 1 |
