Studying magmatic systems through chemical analyses on clinopyroxene - a look into the history of the Teno ankaramites, Tenerife
(2020) In Dissertations in Geology at Lund University GEOR02 20201Department of Geology
- Abstract
- Clinopyroxenes have the ability to crystallize over and respond to a large range of temperatures, pressures and chemical compositions, and thus, they are ideal for studies regarding the history of magmatic systems. In this thesis, the chemistry and zoning of four clinopyroxene crystals from an ankaramite sample from the Teno massif, Tenerife, were analysed. The ankaramites in Teno massif were, according to previous studies, erupted following mass wasting events, and at least two mass wasting events have occurred in the history of the massif. The aim of the thesis was to link the chemistry and crystal features to possible processes affecting the magmatic system during their growth, to evaluate possible open system processes and eruption... (More)
- Clinopyroxenes have the ability to crystallize over and respond to a large range of temperatures, pressures and chemical compositions, and thus, they are ideal for studies regarding the history of magmatic systems. In this thesis, the chemistry and zoning of four clinopyroxene crystals from an ankaramite sample from the Teno massif, Tenerife, were analysed. The ankaramites in Teno massif were, according to previous studies, erupted following mass wasting events, and at least two mass wasting events have occurred in the history of the massif. The aim of the thesis was to link the chemistry and crystal features to possible processes affecting the magmatic system during their growth, to evaluate possible open system processes and eruption triggers related to the mass wasting events, and to gain an understanding for how clinopyroxenes can be used to study magmatic systems. The crystals were analysed using optical microscopy, scanning electron microscopy (SEM), and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS).
The results show that the four clinopyroxene crystals can be divided into two groups: sector zoned crystals displaying different compositions in different faces of the crystal, and concentrically zoned crystals. The widely different crystal features, with the concentrically zoned crystals being inferred to have experienced a longer and more complex growth history, indicate that they belong to different generations or origins, indicating that magma mixing occurred in the system. On the other hand, the rims of all four crystals share enough similarities to be interpreted to have grown simultaneously, reflecting the eruption event. Furthermore, a band of deviant chemical composition is present inside the rim of all crystals, perhaps related to the mass wasting event and eruption trigger. Open system processes are inferred by Cr spikes in all four crystals, interpreted to represent events of recharge of primitive magma. These Cr spikes are located in the rims of the sector zoned crystals and in the interior of the concentrically zoned crystals. If the mass wasting event is to be considered the eruption trigger, the location of the Cr spikes close to the rim in the sector zoned crystals points to the possibility that the magma recharge and the mass wasting event are related, most likely that the magma recharge destabilized the system and caused the mass wasting event to occur. However, further work needs to be done to confirm this hypothesis.
To acquire a better understanding for the magmatic history of these clinopyroxene crystals and the magmatic system in which they grew, more chemical analyses have to be made on a larger number of samples; preferably sampled systematically in order to know which ankaramite formation is being studied. Furthermore, geothermobarometry should be carried out in order to constrain the crystallization depth and temperature of the crystals and determine their respective origin. (Less) - Abstract (Swedish)
- Klinopyroxen har förmågan att kristallisera över ett stort intervall av temperatur, tryck och kemisk sammansättning; därför är de optimala för att studera historien för ett magmatiskt system. I den här uppsatsen analyserades fyra klinopyroxenkristaller i en ankaramit med fokus på kemi och zonering. Ankaramitprovet härstammar från Tenomassivet, Teneriffa, och bildades troligtvis i ett utbrott som skedde till följd av massrörelse. Syftet med uppsatsen var att koppla kemi och zonering till möjliga processer som kan ha påverkat det magmatiska systemet under klinopyroxenkristallernas kristallisation, att utvärdera eventuella processer relaterade till ett öppet system, utbrottstriggers och massrörelse, samt att få en förståelse för hur... (More)
- Klinopyroxen har förmågan att kristallisera över ett stort intervall av temperatur, tryck och kemisk sammansättning; därför är de optimala för att studera historien för ett magmatiskt system. I den här uppsatsen analyserades fyra klinopyroxenkristaller i en ankaramit med fokus på kemi och zonering. Ankaramitprovet härstammar från Tenomassivet, Teneriffa, och bildades troligtvis i ett utbrott som skedde till följd av massrörelse. Syftet med uppsatsen var att koppla kemi och zonering till möjliga processer som kan ha påverkat det magmatiska systemet under klinopyroxenkristallernas kristallisation, att utvärdera eventuella processer relaterade till ett öppet system, utbrottstriggers och massrörelse, samt att få en förståelse för hur klinopyroxen kan användas för att studera magmatiska system. Kristallerna analyserades med optiskt mikroskop, svepelektronmikroskop (SEM) och laserablation-induktivt kopplad plasma-masspektrometri (LA-ICP-MS).
Resultaten visar att de fyra klinopyroxenkristallerna kan delas in i två grupper: sektorzonerade kristaller med olika kemisk sammansättning i olika facetter av kristallen, och koncentriskt zonerade kristaller. De olika zoneringstyperna, samt hypotesen att de koncentriskt zonerade kristallerna har genomgått en längre och mer komplex kristallisation, indikerar att de tillhör olika generationer eller olika ursprung. Detta, i sin tur, indikerar att magmamixing har förekommit i systemet. Kristallernas kanter, däremot, är så pass lika att de troligtvis kristalliserade samtidigt och representerar själva utbrottet. Vidare, ett band med avvikande kemisk sammansättning var identifierat innanför kanten i alla kristaller, möjligen relaterat till massrörelserna och utbrottstriggern. Cr-spikar observerades i alla fyra kristaller och indikerar ett öppet system, då dessa troligen representerar tillskott av ny primitiv magma i systemet. Cr-spikarna observerades nära kanterna i de sektorzonerade kristallerna och närmre mitten i de koncentriskt zonerade kristallerna. Om massrörelsen betraktas som utbrottstriggern kan Cr-spikarna nära kanterna i de sektorzonerade kristallerna indikera en koppling mellan massrörelsen och tillskottet av primitiv magma. I detta fall är det mest troligt att tillskottet av magma destabiliserade systemet och orsakade massrörelsen. Det krävs dock mer analyser för att bekräfta denna hypotes.
För att få en bättre förståelse för kristallisationshistorien för dessa klinopyroxenkristaller och det magmatiska system som de kristalliserade i behöver fler kemiska analyser genomföras på en större mängd prov; gärna systematiskt provtagna så att det är säkert vilken ankaramitformation som studeras. Vidare skulle geotermobarometri kunna användas för att avgöra kristallernas kristallisationsdjup- och temperatur och därmed avgöra deras respektive ursprung. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/9018831
- author
- Haag, Vendela LU
- supervisor
- organization
- course
- GEOR02 20201
- year
- 2020
- type
- H2 - Master's Degree (Two Years)
- subject
- keywords
- clinopyroxene, sector zoning, concentric zoning, mass wasting, magma recharge
- publication/series
- Dissertations in Geology at Lund University
- report number
- 595
- language
- English
- id
- 9018831
- date added to LUP
- 2020-06-16 14:44:49
- date last changed
- 2020-06-16 14:44:49
@misc{9018831,
abstract = {{Clinopyroxenes have the ability to crystallize over and respond to a large range of temperatures, pressures and chemical compositions, and thus, they are ideal for studies regarding the history of magmatic systems. In this thesis, the chemistry and zoning of four clinopyroxene crystals from an ankaramite sample from the Teno massif, Tenerife, were analysed. The ankaramites in Teno massif were, according to previous studies, erupted following mass wasting events, and at least two mass wasting events have occurred in the history of the massif. The aim of the thesis was to link the chemistry and crystal features to possible processes affecting the magmatic system during their growth, to evaluate possible open system processes and eruption triggers related to the mass wasting events, and to gain an understanding for how clinopyroxenes can be used to study magmatic systems. The crystals were analysed using optical microscopy, scanning electron microscopy (SEM), and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS).
The results show that the four clinopyroxene crystals can be divided into two groups: sector zoned crystals displaying different compositions in different faces of the crystal, and concentrically zoned crystals. The widely different crystal features, with the concentrically zoned crystals being inferred to have experienced a longer and more complex growth history, indicate that they belong to different generations or origins, indicating that magma mixing occurred in the system. On the other hand, the rims of all four crystals share enough similarities to be interpreted to have grown simultaneously, reflecting the eruption event. Furthermore, a band of deviant chemical composition is present inside the rim of all crystals, perhaps related to the mass wasting event and eruption trigger. Open system processes are inferred by Cr spikes in all four crystals, interpreted to represent events of recharge of primitive magma. These Cr spikes are located in the rims of the sector zoned crystals and in the interior of the concentrically zoned crystals. If the mass wasting event is to be considered the eruption trigger, the location of the Cr spikes close to the rim in the sector zoned crystals points to the possibility that the magma recharge and the mass wasting event are related, most likely that the magma recharge destabilized the system and caused the mass wasting event to occur. However, further work needs to be done to confirm this hypothesis.
To acquire a better understanding for the magmatic history of these clinopyroxene crystals and the magmatic system in which they grew, more chemical analyses have to be made on a larger number of samples; preferably sampled systematically in order to know which ankaramite formation is being studied. Furthermore, geothermobarometry should be carried out in order to constrain the crystallization depth and temperature of the crystals and determine their respective origin.}},
author = {{Haag, Vendela}},
language = {{eng}},
note = {{Student Paper}},
series = {{Dissertations in Geology at Lund University}},
title = {{Studying magmatic systems through chemical analyses on clinopyroxene - a look into the history of the Teno ankaramites, Tenerife}},
year = {{2020}},
}