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Mantelplymer : realitet eller ad hoc?

Larsson, Alfred LU (2015) In Examensarbeten i geologi vid Lunds universitet GEOL01 20151
Department of Geology
Abstract
Mantle plumes are subject of a great discussion within the field of Geology. Do they really exist, and in that case, from where do they originate? The scope of this Bachelor thesis is to discuss the characteristics of mantle plumes and the arguments in favor of and against their proposed existence. The mantle plume hypothesis was first presented in 1971 by Jason Morgan, suggesting diapirs of hot rock were bringing heat from the Earth’s core to form hot spots on the surface of the Earth. The hypothesis has since that time gradually been elaborated and an increas-ing amount of data confirm that mantle plumes do exist and that they fuel the majority of the intraplate magmatism occurring in e.g. Hawaii, Tristan da Cunha and Reunion. In the... (More)
Mantle plumes are subject of a great discussion within the field of Geology. Do they really exist, and in that case, from where do they originate? The scope of this Bachelor thesis is to discuss the characteristics of mantle plumes and the arguments in favor of and against their proposed existence. The mantle plume hypothesis was first presented in 1971 by Jason Morgan, suggesting diapirs of hot rock were bringing heat from the Earth’s core to form hot spots on the surface of the Earth. The hypothesis has since that time gradually been elaborated and an increas-ing amount of data confirm that mantle plumes do exist and that they fuel the majority of the intraplate magmatism occurring in e.g. Hawaii, Tristan da Cunha and Reunion. In the attempts to evince the existence of mantle plumes, mainly three methods of analysis are used: seismic, geochemical analysis and different types of modelling. This literature review discusses the benefits and drawbacks of the above mentioned methods and the results they have spawned. Some critics consider the mantle plume characteristic magmatism being a consequence of melting in the shallow mantle as a result of varying chemical composition, small-scale convection, tectonic features and chemical stratification of the mantle due to subduction. Conclusively too much evidence agree with the mantle plume hy-pothesis for it to be ruled out. Some igneous provinces are results of mantle plumes while others require a different model of explanation. A working majority of the models produced by sceptics are more or less ad hoc and does not provide satisfying alternative explanations. Continued research should focus on studying the mantle plumes more closely to determine their origin and forming processes. (Less)
Abstract (Swedish)
Mantelplymer är ett mycket omdebatterat fenomen inom geologiämnet. Existerar de och var har de i så fall sitt ursprung? Detta kandidatarbete behandlar mantelplymens karaktäristika och de för- och motargu-ment för dess existens som finns i litteraturen. Hypotesen om mantelplymer uttrycktes första gången 1971 av Jason Morgan där det föreslogs att hett mantelmaterial förs från Jordens kärna till ytan där de bildar hotspots. Efterhand har hypotesen utvecklats och allt mer data pekar på att mantelplymer finns och att de gett upphov till majoriteten av magmatismen som sker inom plattor, exempelvis vid Hawaii, Tristan da Cunha och Reunion. I jakten på att försöka påvisa mantelplymer används främst tre typer av analysmetoder: seismik, geokemiska... (More)
Mantelplymer är ett mycket omdebatterat fenomen inom geologiämnet. Existerar de och var har de i så fall sitt ursprung? Detta kandidatarbete behandlar mantelplymens karaktäristika och de för- och motargu-ment för dess existens som finns i litteraturen. Hypotesen om mantelplymer uttrycktes första gången 1971 av Jason Morgan där det föreslogs att hett mantelmaterial förs från Jordens kärna till ytan där de bildar hotspots. Efterhand har hypotesen utvecklats och allt mer data pekar på att mantelplymer finns och att de gett upphov till majoriteten av magmatismen som sker inom plattor, exempelvis vid Hawaii, Tristan da Cunha och Reunion. I jakten på att försöka påvisa mantelplymer används främst tre typer av analysmetoder: seismik, geokemiska analyser och modelleringar av olika slag. I denna litteraturstudie diskuteras för- och nackdelar med dessa metoder, samt vilka resultat de gett upphov till. Det finns en inte helt oansenlig skara kritiker som anser att den magmatism som anses karaktäristisk för mantelplymer istället beror på uppsmältning i mantelns övre delar som ett resultat av varierande kemisk samman-sättning, småskalig mantelkonvektion, tektoniska svaghetszoner och kemisk stratifiering till följd av subduktion. Sammantaget talar en alltför stor mängd bevis för mantelplymhypotesen för att kunna avfärda den. Vissa magma-tiska provinser har uppkommit genom mantelplymer medan andra områden kräver alternativa förklaringsmodeller. Flertalet förklaringsmodeller framlagda av skeptiker är mer eller mindre ad hoc och ger inga tillfredsställande alter-nativa förklaringar. Fortsatt forskning bör fokusera på att studera mantelplymerna närmare för att kunna avgöra deras härkomst och bildningsprocesser. (Less)
Please use this url to cite or link to this publication:
author
Larsson, Alfred LU
supervisor
organization
course
GEOL01 20151
year
type
M2 - Bachelor Degree
subject
keywords
uppsmältning, seismik, hotspot, litosfär, mantelplym
publication/series
Examensarbeten i geologi vid Lunds universitet
report number
440
language
Swedish
id
5466262
date added to LUP
2015-06-05 17:54:15
date last changed
2015-06-05 17:54:15
@misc{5466262,
  abstract     = {Mantle plumes are subject of a great discussion within the field of Geology. Do they really exist, and in that case, from where do they originate? The scope of this Bachelor thesis is to discuss the characteristics of mantle plumes and the arguments in favor of and against their proposed existence. The mantle plume hypothesis was first presented in 1971 by Jason Morgan, suggesting diapirs of hot rock were bringing heat from the Earth’s core to form hot spots on the surface of the Earth. The hypothesis has since that time gradually been elaborated and an increas-ing amount of data confirm that mantle plumes do exist and that they fuel the majority of the intraplate magmatism occurring in e.g. Hawaii, Tristan da Cunha and Reunion. In the attempts to evince the existence of mantle plumes, mainly three methods of analysis are used: seismic, geochemical analysis and different types of modelling. This literature review discusses the benefits and drawbacks of the above mentioned methods and the results they have spawned. Some critics consider the mantle plume characteristic magmatism being a consequence of melting in the shallow mantle as a result of varying chemical composition, small-scale convection, tectonic features and chemical stratification of the mantle due to subduction. Conclusively too much evidence agree with the mantle plume hy-pothesis for it to be ruled out. Some igneous provinces are results of mantle plumes while others require a different model of explanation. A working majority of the models produced by sceptics are more or less ad hoc and does not provide satisfying alternative explanations. Continued research should focus on studying the mantle plumes more closely to determine their origin and forming processes.},
  author       = {Larsson, Alfred},
  keyword      = {uppsmältning,seismik,hotspot,litosfär,mantelplym},
  language     = {swe},
  note         = {Student Paper},
  series       = {Examensarbeten i geologi vid Lunds universitet},
  title        = {Mantelplymer : realitet eller ad hoc?},
  year         = {2015},
}