Two-stage crustal growth in the Arabian-Nubian shield: Initial arc accretion followed by plume-induced crustal reworking
Island-arc accretion during the assembly of Gondwana has been widely regarded as the main mechanism for Neoproterozoic crustal growth in the Arabian-Nubian Shield (ANS). However, processes involved to transform the newly accreted juvenile terranes into a typical continental crust remain unclear. Her...
| Main Authors: | , , , , , , , |
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| Format: | Journal Article |
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2021
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| Online Access: | http://purl.org/au-research/grants/arc/LE150100013 http://hdl.handle.net/20.500.11937/83408 |
| _version_ | 1848764581220974592 |
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| author | Gamal El Dien, Hamed Li, Zheng-Xiang Abu Anbar, Mohamed Doucet, Luc S Murphy, J Brendan Evans, Noreen Xia, Xiao-Ping Li, Jiangyu |
| author_facet | Gamal El Dien, Hamed Li, Zheng-Xiang Abu Anbar, Mohamed Doucet, Luc S Murphy, J Brendan Evans, Noreen Xia, Xiao-Ping Li, Jiangyu |
| author_sort | Gamal El Dien, Hamed |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | Island-arc accretion during the assembly of Gondwana has been widely regarded as the main mechanism for Neoproterozoic crustal growth in the Arabian-Nubian Shield (ANS). However, processes involved to transform the newly accreted juvenile terranes into a typical continental crust remain unclear. Here, we present geochemical, isotopic, and U-Pb geochronological data from the El-Shadli volcanic province (80 km × 35 km and > 10 km thick) in the Eastern Desert of Egypt, which lies in the north-western part of the ANS, and overlies strongly deformed, previously accreted arc terranes. The El-Shadli volcanic province consists mainly of a mafic-felsic bimodal suite and subordinate intermediate rocks that intrude the mafic rocks of the suite. The bimodal suite rocks are tholeiitic, whereas the intermediate rocks have a calc-alkaline affinity. The bimodal suite and the intermediate rocks both yield U-Pb zircon ages of ~ 700 Ma implying they are coeval. High zircon εHf(t) values for the bimodal suite (average εHf(t) = +11.46) as well as the intermediate rocks (average εHf(t) = +9.76) indicate they were either magmatic extractions derived directly from a depleted mantle source, or the products of remelting of juvenile crust. Oxygen isotope data for zircon yield similar δ18O values for both the bimodal suite (average δ18O = 4.94‰) and intermediate rocks (average δ18O = 4.79‰). These are lower than typical mantle values indicating the parental magma in both cases interacted with hydrothermal fluids. Based on the petrological, geochemical, and isotopic data, we suggest that the El-Shadli bimodal suite and the intermediate rocks were produced by reworking of MORB-like and arc-like oceanic lithosphere, respectively, most likely driven by a mantle plume during the break-up of Rodinia. The recognition of the El-Shadli volcanic province as a likely mantle plume-induced post-kinematic magmatism provides a mechanism for the transformation of newly accreted juvenile crustal terranes into a chemically stratified normal continental crust. In addition, such plume events may result in new mantle extractions that are converted into new continental crust. |
| first_indexed | 2025-11-14T11:21:38Z |
| format | Journal Article |
| id | curtin-20.500.11937-83408 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T11:21:38Z |
| publishDate | 2021 |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-834082023-05-03T04:36:25Z Two-stage crustal growth in the Arabian-Nubian shield: Initial arc accretion followed by plume-induced crustal reworking Gamal El Dien, Hamed Li, Zheng-Xiang Abu Anbar, Mohamed Doucet, Luc S Murphy, J Brendan Evans, Noreen Xia, Xiao-Ping Li, Jiangyu Island-arc accretion during the assembly of Gondwana has been widely regarded as the main mechanism for Neoproterozoic crustal growth in the Arabian-Nubian Shield (ANS). However, processes involved to transform the newly accreted juvenile terranes into a typical continental crust remain unclear. Here, we present geochemical, isotopic, and U-Pb geochronological data from the El-Shadli volcanic province (80 km × 35 km and > 10 km thick) in the Eastern Desert of Egypt, which lies in the north-western part of the ANS, and overlies strongly deformed, previously accreted arc terranes. The El-Shadli volcanic province consists mainly of a mafic-felsic bimodal suite and subordinate intermediate rocks that intrude the mafic rocks of the suite. The bimodal suite rocks are tholeiitic, whereas the intermediate rocks have a calc-alkaline affinity. The bimodal suite and the intermediate rocks both yield U-Pb zircon ages of ~ 700 Ma implying they are coeval. High zircon εHf(t) values for the bimodal suite (average εHf(t) = +11.46) as well as the intermediate rocks (average εHf(t) = +9.76) indicate they were either magmatic extractions derived directly from a depleted mantle source, or the products of remelting of juvenile crust. Oxygen isotope data for zircon yield similar δ18O values for both the bimodal suite (average δ18O = 4.94‰) and intermediate rocks (average δ18O = 4.79‰). These are lower than typical mantle values indicating the parental magma in both cases interacted with hydrothermal fluids. Based on the petrological, geochemical, and isotopic data, we suggest that the El-Shadli bimodal suite and the intermediate rocks were produced by reworking of MORB-like and arc-like oceanic lithosphere, respectively, most likely driven by a mantle plume during the break-up of Rodinia. The recognition of the El-Shadli volcanic province as a likely mantle plume-induced post-kinematic magmatism provides a mechanism for the transformation of newly accreted juvenile crustal terranes into a chemically stratified normal continental crust. In addition, such plume events may result in new mantle extractions that are converted into new continental crust. 2021 Journal Article http://hdl.handle.net/20.500.11937/83408 10.1016/j.precamres.2021.106211 http://purl.org/au-research/grants/arc/LE150100013 http://purl.org/au-research/grants/arc/FL150100133 http://creativecommons.org/licenses/by-nc-nd/4.0/ fulltext |
| spellingShingle | Gamal El Dien, Hamed Li, Zheng-Xiang Abu Anbar, Mohamed Doucet, Luc S Murphy, J Brendan Evans, Noreen Xia, Xiao-Ping Li, Jiangyu Two-stage crustal growth in the Arabian-Nubian shield: Initial arc accretion followed by plume-induced crustal reworking |
| title | Two-stage crustal growth in the Arabian-Nubian shield: Initial arc accretion followed by plume-induced crustal reworking |
| title_full | Two-stage crustal growth in the Arabian-Nubian shield: Initial arc accretion followed by plume-induced crustal reworking |
| title_fullStr | Two-stage crustal growth in the Arabian-Nubian shield: Initial arc accretion followed by plume-induced crustal reworking |
| title_full_unstemmed | Two-stage crustal growth in the Arabian-Nubian shield: Initial arc accretion followed by plume-induced crustal reworking |
| title_short | Two-stage crustal growth in the Arabian-Nubian shield: Initial arc accretion followed by plume-induced crustal reworking |
| title_sort | two-stage crustal growth in the arabian-nubian shield: initial arc accretion followed by plume-induced crustal reworking |
| url | http://purl.org/au-research/grants/arc/LE150100013 http://purl.org/au-research/grants/arc/LE150100013 http://hdl.handle.net/20.500.11937/83408 |