A first-order approximation of the lithological make-up of an orogen's middle and lower crust can provide insights into its structure, as well as the tectono-metamorphic and geodynamic processes taking place there. In this study, we investigate the possible lithological and chemical composition of Taiwan's middle and lower crust by matching in situ physical properties measured by the TAIGER tomography data with isotropic wavespeeds, density, and major element composition for a variety of upper amphibolite and granulite facies rocks modelled at ambient pressure and temperature using the AbersHacker Macro. The modelling suggests that Taiwan's middle crust is possibly comprised of some combination of biotite-poor metapelite, garnet-poor felsic granulite, mafic granulite, amphibolite, and marble. The lower crust is likely comprised of mafic granulite, garnet-rich felsic granulite, biotite-free metapelite, and eclogite. Furthermore, the modelling shows that the modal abundance of garnet and/or sillimanite has a significant effect on physical properties, elevating seismic wavespeeds and density of felsic rocks to those of mafic rocks. The modelled wt% major oxide composition suggests that Taiwan's middle and lower crust have a more mafic chemical composition than that of global compilations of the continental crust. Nevertheless, this reflects the choices made when assigning rock types for the lithological mix used to calculate the wt% oxides, since increasing the percentage of garnet-rich metapelite and felsic granulite would result in a more felsic bulk composition.
A petrophysical study of the composition of Taiwan's middle and lower crust / Brown, D.; Camanni, G.; Kuo-Chen, H.; Alvarez-Marron, J.. - In: TECTONOPHYSICS. - ISSN 0040-1951. - 870:(2024), pp. N/A-N/A. [10.1016/j.tecto.2023.230160]
A petrophysical study of the composition of Taiwan's middle and lower crust
Camanni, G.;
2024
Abstract
A first-order approximation of the lithological make-up of an orogen's middle and lower crust can provide insights into its structure, as well as the tectono-metamorphic and geodynamic processes taking place there. In this study, we investigate the possible lithological and chemical composition of Taiwan's middle and lower crust by matching in situ physical properties measured by the TAIGER tomography data with isotropic wavespeeds, density, and major element composition for a variety of upper amphibolite and granulite facies rocks modelled at ambient pressure and temperature using the AbersHacker Macro. The modelling suggests that Taiwan's middle crust is possibly comprised of some combination of biotite-poor metapelite, garnet-poor felsic granulite, mafic granulite, amphibolite, and marble. The lower crust is likely comprised of mafic granulite, garnet-rich felsic granulite, biotite-free metapelite, and eclogite. Furthermore, the modelling shows that the modal abundance of garnet and/or sillimanite has a significant effect on physical properties, elevating seismic wavespeeds and density of felsic rocks to those of mafic rocks. The modelled wt% major oxide composition suggests that Taiwan's middle and lower crust have a more mafic chemical composition than that of global compilations of the continental crust. Nevertheless, this reflects the choices made when assigning rock types for the lithological mix used to calculate the wt% oxides, since increasing the percentage of garnet-rich metapelite and felsic granulite would result in a more felsic bulk composition.File | Dimensione | Formato | |
---|---|---|---|
Brown et al (TECTONO 2024).pdf
Open access
Tipologia:
VOR - Versione pubblicata dall'editore
Dimensione
8.61 MB
Formato
Adobe PDF
|
8.61 MB | Adobe PDF | Visualizza/Apri |
Pubblicazioni consigliate
I metadati presenti in IRIS UNIMORE sono rilasciati con licenza Creative Commons CC0 1.0 Universal, mentre i file delle pubblicazioni sono rilasciati con licenza Attribuzione 4.0 Internazionale (CC BY 4.0), salvo diversa indicazione.
In caso di violazione di copyright, contattare Supporto Iris