Data/hora: 09/06/2024 03:30:50

Provedor de dados: | 5
País: | France
Título: | Assessing Origins of End-Triassic Tholeiites From Eastern North America Using Hafnium Isotopes
Autores: | Elkins, Lynne J.; Meyzen, Christine M.; Callegaro, Sara; Marzoli, Andrea; Bizimis, Michael.
Data: | 2020-06
Ano: | 2020
Palavras-chave: | Basalt; CAMP; Hafnium; Rift; LIP; Isotope.
Resumo: | The driving processes responsible for producing the Central Atlantic Magmatic Province, the Large Igneous Province associated with end-Triassic rifting of Pangea, remain largely debated. Because their compositions encompass most of the Central Atlantic basalt spectrum, tholeiites from southern Eastern North America are considered pivotal for identifying magma origins. New(176)Hf/Hf-177 measurements for 201 Ma Eastern North American tholeiites dominantly record a local petrogenetic history. Their epsilon(Hf)ratios, corrected to an emplacement age of 201 Ma (-7.85 to +5.86), form a positive but shallowly sloped array slightly deviating from the terrestrial array on a epsilon(Hf)versus epsilon(Nd)diagram. Comparison of(176)Hf/Hf-177 to other isotope ratios and trace elements helps to rule out several petrogenetic scenarios, particularly mixing of melts from global depleted or enriched mantle components. In contrast, partial melting of subduction-metasomatized mantle can explain the parental magma composition for southern Eastern North America. Such metasomatism likely occurred during Paleozoic subduction around Pangea and may have been dominated by sediment-derived fluid reactions. The observed(176)Hf/Hf-177 versus(143)Nd/Nd-144 array may reflect subsequent assimilation of lower continental crust, perhaps together with limited direct melting of recycled continental crust in the asthenosphere. The proposed recycling scenario does not specifically support or preclude a mantle plume origin for the Central Atlantic Magmatic Province but instead points toward the presence of a distinct local mantle source and crustal assimilation processes during magma transport. Detailed understanding of these local effects is needed in order to more accurately understand the origins of Large Igneous Provinces.
Tipo: | Text
Idioma: | Inglês

Identificador:

https://archimer.ifremer.fr/doc/00687/79862/82716.pdf

https://archimer.ifremer.fr/doc/00687/79862/82717.pdf

https://archimer.ifremer.fr/doc/00687/79862/82718.xlsx

DOI:10.1029/2020GC008999

https://archimer.ifremer.fr/doc/00687/79862/

Editor: | Amer Geophysical Union
Formato: | application/pdf
Fonte: | Geochemistry Geophysics Geosystems (1525-2027) (Amer Geophysical Union), 2020-06 , Vol. 21 , N. 6 , P. e2020GC008999

Fonte:

info:eu-repo/semantics/openAccess

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