Origin and tectonic significance of the metavolcanic rocks and mafic enclaves from the Palaeoproterozoic Birimian Terrane, SE West African Craton, Ghana
The Palaeoproterozoic Birimian Supergroup of the West African Craton (WAC) consists of volcanic belts composed predominantly of basaltic and andesitic rocks and intervening sedimentary basins composed predominantly of wackes and argillites. Mafic metavolcanic rocks and granitoid-hosted enclaves from...
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| Veröffentlicht in: | Geological magazine 2020-08, Vol.157 (8), p.1349-1366 |
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| creator | Sakyi, Patrick Asamoah Su, Ben-Xun Manu, Johnson Kwayisi, Daniel Anani, Chris Y. Alemayehu, Melesse Malaviarachchi, Sanjeewa P.K. Nude, Prosper M. Su, Ben-Can |
| description | The Palaeoproterozoic Birimian Supergroup of the West African Craton (WAC) consists of volcanic belts composed predominantly of basaltic and andesitic rocks and intervening sedimentary basins composed predominantly of wackes and argillites. Mafic metavolcanic rocks and granitoid-hosted enclaves from the Palaeoproterozoic Lawra Belt of Ghana were analysed for geochemical and Sr–Nd isotopic data to constrain the geological evolution of the southeastern part of the WAC. The metavolcanic rocks display mainly tholeiitic signatures, whereas the enclaves show calc-alkaline signatures. The high SiO2 contents (48.6–68.9 wt%) of the enclaves are suggestive of their evolved character. The high Th/Yb values of the samples relative to that of the mantle array may indicate derivation of their respective magmas from subduction-modified source(s). The rocks show positive εNd values of +0.79 to +2.86 (metavolcanic rocks) and +0.79 to +1.82 (enclaves). These signatures and their Nd model ages (TDM2) of 2.31–2.47 Ga (metavolcanic rocks) and 2.39–2.47 Ga (enclaves) suggest they were probably derived from juvenile mantle-derived protoliths, with possible input of subducted pre-Birimian (Archean?) rocks in their source(s). Their positive Ba–Th and negative Nb–Ta, Zr–Hf and Ti anomalies may indicate their formation through subduction-related magmatism consistent with an arc setting. We propose that the metavolcanic rocks and enclaves from the Lawra Belt formed in a similar island-arc setting. We infer that the granitoids developed through variable degrees of mixing/mingling between basic magma and granitic melt during subduction, when blobs of basic to intermediate parental magma became trapped in the granitic magma to form the enclaves. |
| doi_str_mv | 10.1017/S001675681900150X |
| format | Article |
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Mafic metavolcanic rocks and granitoid-hosted enclaves from the Palaeoproterozoic Lawra Belt of Ghana were analysed for geochemical and Sr–Nd isotopic data to constrain the geological evolution of the southeastern part of the WAC. The metavolcanic rocks display mainly tholeiitic signatures, whereas the enclaves show calc-alkaline signatures. The high SiO2 contents (48.6–68.9 wt%) of the enclaves are suggestive of their evolved character. The high Th/Yb values of the samples relative to that of the mantle array may indicate derivation of their respective magmas from subduction-modified source(s). The rocks show positive εNd values of +0.79 to +2.86 (metavolcanic rocks) and +0.79 to +1.82 (enclaves). These signatures and their Nd model ages (TDM2) of 2.31–2.47 Ga (metavolcanic rocks) and 2.39–2.47 Ga (enclaves) suggest they were probably derived from juvenile mantle-derived protoliths, with possible input of subducted pre-Birimian (Archean?) rocks in their source(s). Their positive Ba–Th and negative Nb–Ta, Zr–Hf and Ti anomalies may indicate their formation through subduction-related magmatism consistent with an arc setting. We propose that the metavolcanic rocks and enclaves from the Lawra Belt formed in a similar island-arc setting. We infer that the granitoids developed through variable degrees of mixing/mingling between basic magma and granitic melt during subduction, when blobs of basic to intermediate parental magma became trapped in the granitic magma to form the enclaves.</description><identifier>ISSN: 0016-7568</identifier><identifier>EISSN: 1469-5081</identifier><identifier>DOI: 10.1017/S001675681900150X</identifier><language>eng</language><publisher>Cambridge, UK: Cambridge University Press</publisher><subject>Africa ; alkaline earth metals ; andesitic composition ; Anomalies ; basaltic composition ; Belts ; Birimian ; Birimian Terrane ; calc-alkalic composition ; Cratons ; Evolution ; geochemical anomalies ; Geochemistry ; Geological time ; Geology ; Ghana ; granites ; ICP mass spectra ; igneous and metamorphic rocks ; Igneous rocks ; Island arcs ; isotopes ; Lava ; Lawra Belt ; mafic composition ; mafic enclaves ; Magma ; magmas ; major elements ; mantle ; mass spectra ; metals ; metamorphic rocks ; metavolcanic rocks ; mixing ; neodymium ; Niobium ; Original Article ; Paleoproterozoic ; Petrogenesis ; Petrology ; Plate tectonics ; plutonic rocks ; Precambrian ; Proterozoic ; protoliths ; rare earths ; Rock ; rock, sediment, soil ; Rocks ; Sedimentary basins ; Signatures ; Silica ; Silicon dioxide ; spectra ; strontium ; Subduction ; Subduction (geology) ; Tantalum ; Tectonics ; tholeiitic composition ; trace elements ; upper Precambrian ; Volcanic belts ; West Africa ; West African Craton ; X-ray fluorescence spectra ; Zirconium</subject><ispartof>Geological magazine, 2020-08, Vol.157 (8), p.1349-1366</ispartof><rights>Cambridge University Press 2020</rights><rights>GeoRef, Copyright 2020, American Geosciences Institute. Reference includes data from GeoScienceWorld @Alexandria, VA @USA @United States. Abstract, Copyright, Cambridge University Press</rights><lds50>peer_reviewed</lds50><woscitedreferencessubscribed>false</woscitedreferencessubscribed><citedby>FETCH-LOGICAL-a376t-3e7cde08b05f16d65892f35eb3cf722b7869f2a8a7880d46e522e3fee50a83c73</citedby><cites>FETCH-LOGICAL-a376t-3e7cde08b05f16d65892f35eb3cf722b7869f2a8a7880d46e522e3fee50a83c73</cites><orcidid>0000-0002-7536-6264</orcidid></display><links><openurl>$$Topenurl_article</openurl><openurlfulltext>$$Topenurlfull_article</openurlfulltext><thumbnail>$$Tsyndetics_thumb_exl</thumbnail><linktohtml>$$Uhttps://www.cambridge.org/core/product/identifier/S001675681900150X/type/journal_article$$EHTML$$P50$$Gcambridge$$H</linktohtml><link.rule.ids>164,314,776,780,27901,27902,55603</link.rule.ids></links><search><creatorcontrib>Sakyi, Patrick Asamoah</creatorcontrib><creatorcontrib>Su, Ben-Xun</creatorcontrib><creatorcontrib>Manu, Johnson</creatorcontrib><creatorcontrib>Kwayisi, Daniel</creatorcontrib><creatorcontrib>Anani, Chris Y.</creatorcontrib><creatorcontrib>Alemayehu, Melesse</creatorcontrib><creatorcontrib>Malaviarachchi, Sanjeewa P.K.</creatorcontrib><creatorcontrib>Nude, Prosper M.</creatorcontrib><creatorcontrib>Su, Ben-Can</creatorcontrib><title>Origin and tectonic significance of the metavolcanic rocks and mafic enclaves from the Palaeoproterozoic Birimian Terrane, SE West African Craton, Ghana</title><title>Geological magazine</title><addtitle>Geol. Mag</addtitle><description>The Palaeoproterozoic Birimian Supergroup of the West African Craton (WAC) consists of volcanic belts composed predominantly of basaltic and andesitic rocks and intervening sedimentary basins composed predominantly of wackes and argillites. Mafic metavolcanic rocks and granitoid-hosted enclaves from the Palaeoproterozoic Lawra Belt of Ghana were analysed for geochemical and Sr–Nd isotopic data to constrain the geological evolution of the southeastern part of the WAC. The metavolcanic rocks display mainly tholeiitic signatures, whereas the enclaves show calc-alkaline signatures. The high SiO2 contents (48.6–68.9 wt%) of the enclaves are suggestive of their evolved character. The high Th/Yb values of the samples relative to that of the mantle array may indicate derivation of their respective magmas from subduction-modified source(s). The rocks show positive εNd values of +0.79 to +2.86 (metavolcanic rocks) and +0.79 to +1.82 (enclaves). These signatures and their Nd model ages (TDM2) of 2.31–2.47 Ga (metavolcanic rocks) and 2.39–2.47 Ga (enclaves) suggest they were probably derived from juvenile mantle-derived protoliths, with possible input of subducted pre-Birimian (Archean?) rocks in their source(s). Their positive Ba–Th and negative Nb–Ta, Zr–Hf and Ti anomalies may indicate their formation through subduction-related magmatism consistent with an arc setting. We propose that the metavolcanic rocks and enclaves from the Lawra Belt formed in a similar island-arc setting. We infer that the granitoids developed through variable degrees of mixing/mingling between basic magma and granitic melt during subduction, when blobs of basic to intermediate parental magma became trapped in the granitic magma to form the enclaves.</description><subject>Africa</subject><subject>alkaline earth metals</subject><subject>andesitic composition</subject><subject>Anomalies</subject><subject>basaltic composition</subject><subject>Belts</subject><subject>Birimian</subject><subject>Birimian Terrane</subject><subject>calc-alkalic composition</subject><subject>Cratons</subject><subject>Evolution</subject><subject>geochemical anomalies</subject><subject>Geochemistry</subject><subject>Geological time</subject><subject>Geology</subject><subject>Ghana</subject><subject>granites</subject><subject>ICP mass spectra</subject><subject>igneous and metamorphic rocks</subject><subject>Igneous rocks</subject><subject>Island arcs</subject><subject>isotopes</subject><subject>Lava</subject><subject>Lawra Belt</subject><subject>mafic composition</subject><subject>mafic enclaves</subject><subject>Magma</subject><subject>magmas</subject><subject>major elements</subject><subject>mantle</subject><subject>mass spectra</subject><subject>metals</subject><subject>metamorphic rocks</subject><subject>metavolcanic rocks</subject><subject>mixing</subject><subject>neodymium</subject><subject>Niobium</subject><subject>Original Article</subject><subject>Paleoproterozoic</subject><subject>Petrogenesis</subject><subject>Petrology</subject><subject>Plate tectonics</subject><subject>plutonic rocks</subject><subject>Precambrian</subject><subject>Proterozoic</subject><subject>protoliths</subject><subject>rare earths</subject><subject>Rock</subject><subject>rock, sediment, soil</subject><subject>Rocks</subject><subject>Sedimentary basins</subject><subject>Signatures</subject><subject>Silica</subject><subject>Silicon dioxide</subject><subject>spectra</subject><subject>strontium</subject><subject>Subduction</subject><subject>Subduction (geology)</subject><subject>Tantalum</subject><subject>Tectonics</subject><subject>tholeiitic composition</subject><subject>trace elements</subject><subject>upper Precambrian</subject><subject>Volcanic belts</subject><subject>West Africa</subject><subject>West African Craton</subject><subject>X-ray fluorescence 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Birimian Terrane, SE West African Craton, Ghana</title><author>Sakyi, Patrick Asamoah ; Su, Ben-Xun ; Manu, Johnson ; Kwayisi, Daniel ; Anani, Chris Y. ; Alemayehu, Melesse ; Malaviarachchi, Sanjeewa P.K. ; Nude, Prosper M. ; Su, Ben-Can</author></sort><facets><frbrtype>5</frbrtype><frbrgroupid>cdi_FETCH-LOGICAL-a376t-3e7cde08b05f16d65892f35eb3cf722b7869f2a8a7880d46e522e3fee50a83c73</frbrgroupid><rsrctype>articles</rsrctype><prefilter>articles</prefilter><language>eng</language><creationdate>2020</creationdate><topic>Africa</topic><topic>alkaline earth metals</topic><topic>andesitic composition</topic><topic>Anomalies</topic><topic>basaltic composition</topic><topic>Belts</topic><topic>Birimian</topic><topic>Birimian Terrane</topic><topic>calc-alkalic composition</topic><topic>Cratons</topic><topic>Evolution</topic><topic>geochemical anomalies</topic><topic>Geochemistry</topic><topic>Geological time</topic><topic>Geology</topic><topic>Ghana</topic><topic>granites</topic><topic>ICP mass spectra</topic><topic>igneous and metamorphic rocks</topic><topic>Igneous rocks</topic><topic>Island arcs</topic><topic>isotopes</topic><topic>Lava</topic><topic>Lawra Belt</topic><topic>mafic composition</topic><topic>mafic enclaves</topic><topic>Magma</topic><topic>magmas</topic><topic>major elements</topic><topic>mantle</topic><topic>mass spectra</topic><topic>metals</topic><topic>metamorphic rocks</topic><topic>metavolcanic rocks</topic><topic>mixing</topic><topic>neodymium</topic><topic>Niobium</topic><topic>Original Article</topic><topic>Paleoproterozoic</topic><topic>Petrogenesis</topic><topic>Petrology</topic><topic>Plate tectonics</topic><topic>plutonic rocks</topic><topic>Precambrian</topic><topic>Proterozoic</topic><topic>protoliths</topic><topic>rare earths</topic><topic>Rock</topic><topic>rock, sediment, soil</topic><topic>Rocks</topic><topic>Sedimentary basins</topic><topic>Signatures</topic><topic>Silica</topic><topic>Silicon dioxide</topic><topic>spectra</topic><topic>strontium</topic><topic>Subduction</topic><topic>Subduction (geology)</topic><topic>Tantalum</topic><topic>Tectonics</topic><topic>tholeiitic composition</topic><topic>trace elements</topic><topic>upper Precambrian</topic><topic>Volcanic belts</topic><topic>West Africa</topic><topic>West African Craton</topic><topic>X-ray fluorescence spectra</topic><topic>Zirconium</topic><toplevel>peer_reviewed</toplevel><toplevel>online_resources</toplevel><creatorcontrib>Sakyi, Patrick Asamoah</creatorcontrib><creatorcontrib>Su, Ben-Xun</creatorcontrib><creatorcontrib>Manu, Johnson</creatorcontrib><creatorcontrib>Kwayisi, Daniel</creatorcontrib><creatorcontrib>Anani, Chris Y.</creatorcontrib><creatorcontrib>Alemayehu, Melesse</creatorcontrib><creatorcontrib>Malaviarachchi, Sanjeewa P.K.</creatorcontrib><creatorcontrib>Nude, Prosper M.</creatorcontrib><creatorcontrib>Su, Ben-Can</creatorcontrib><collection>CrossRef</collection><collection>ProQuest Central 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Academic UKI Edition</collection><collection>Engineering Collection</collection><collection>ProQuest Central Basic</collection><collection>University of Michigan</collection><jtitle>Geological magazine</jtitle></facets><delivery><delcategory>Remote Search Resource</delcategory><fulltext>fulltext</fulltext></delivery><addata><au>Sakyi, Patrick Asamoah</au><au>Su, Ben-Xun</au><au>Manu, Johnson</au><au>Kwayisi, Daniel</au><au>Anani, Chris Y.</au><au>Alemayehu, Melesse</au><au>Malaviarachchi, Sanjeewa P.K.</au><au>Nude, Prosper M.</au><au>Su, Ben-Can</au><format>journal</format><genre>article</genre><ristype>JOUR</ristype><atitle>Origin and tectonic significance of the metavolcanic rocks and mafic enclaves from the Palaeoproterozoic Birimian Terrane, SE West African Craton, Ghana</atitle><jtitle>Geological magazine</jtitle><addtitle>Geol. Mag</addtitle><date>2020-08</date><risdate>2020</risdate><volume>157</volume><issue>8</issue><spage>1349</spage><epage>1366</epage><pages>1349-1366</pages><issn>0016-7568</issn><eissn>1469-5081</eissn><abstract>The Palaeoproterozoic Birimian Supergroup of the West African Craton (WAC) consists of volcanic belts composed predominantly of basaltic and andesitic rocks and intervening sedimentary basins composed predominantly of wackes and argillites. Mafic metavolcanic rocks and granitoid-hosted enclaves from the Palaeoproterozoic Lawra Belt of Ghana were analysed for geochemical and Sr–Nd isotopic data to constrain the geological evolution of the southeastern part of the WAC. The metavolcanic rocks display mainly tholeiitic signatures, whereas the enclaves show calc-alkaline signatures. The high SiO2 contents (48.6–68.9 wt%) of the enclaves are suggestive of their evolved character. The high Th/Yb values of the samples relative to that of the mantle array may indicate derivation of their respective magmas from subduction-modified source(s). The rocks show positive εNd values of +0.79 to +2.86 (metavolcanic rocks) and +0.79 to +1.82 (enclaves). These signatures and their Nd model ages (TDM2) of 2.31–2.47 Ga (metavolcanic rocks) and 2.39–2.47 Ga (enclaves) suggest they were probably derived from juvenile mantle-derived protoliths, with possible input of subducted pre-Birimian (Archean?) rocks in their source(s). Their positive Ba–Th and negative Nb–Ta, Zr–Hf and Ti anomalies may indicate their formation through subduction-related magmatism consistent with an arc setting. We propose that the metavolcanic rocks and enclaves from the Lawra Belt formed in a similar island-arc setting. We infer that the granitoids developed through variable degrees of mixing/mingling between basic magma and granitic melt during subduction, when blobs of basic to intermediate parental magma became trapped in the granitic magma to form the enclaves.</abstract><cop>Cambridge, UK</cop><pub>Cambridge University Press</pub><doi>10.1017/S001675681900150X</doi><tpages>18</tpages><orcidid>https://orcid.org/0000-0002-7536-6264</orcidid></addata></record> |
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| ispartof | Geological magazine, 2020-08, Vol.157 (8), p.1349-1366 |
| issn | 0016-7568 1469-5081 |
| language | eng |
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| source | Cambridge Journals |
| subjects | Africa alkaline earth metals andesitic composition Anomalies basaltic composition Belts Birimian Birimian Terrane calc-alkalic composition Cratons Evolution geochemical anomalies Geochemistry Geological time Geology Ghana granites ICP mass spectra igneous and metamorphic rocks Igneous rocks Island arcs isotopes Lava Lawra Belt mafic composition mafic enclaves Magma magmas major elements mantle mass spectra metals metamorphic rocks metavolcanic rocks mixing neodymium Niobium Original Article Paleoproterozoic Petrogenesis Petrology Plate tectonics plutonic rocks Precambrian Proterozoic protoliths rare earths Rock rock, sediment, soil Rocks Sedimentary basins Signatures Silica Silicon dioxide spectra strontium Subduction Subduction (geology) Tantalum Tectonics tholeiitic composition trace elements upper Precambrian Volcanic belts West Africa West African Craton X-ray fluorescence spectra Zirconium |
| title | Origin and tectonic significance of the metavolcanic rocks and mafic enclaves from the Palaeoproterozoic Birimian Terrane, SE West African Craton, Ghana |
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