Shrimp U-Pb age and Sr-Nd isotopes of the Morro do Baú mafic intrusion: implications for the evolution of the Arenópolis volcano-sedimentary sequence, Goiás Magmatic Arc
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Academia Brasileira de Ciências
2003
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| author | Maria Helena B.M. Hollanda |
| author_facet | Maria Helena B.M. Hollanda |
| contents | Shrimp U-Pb age and Sr-Nd isotopes of the Morro do Baú mafic intrusion: implications for the evolution of the Arenópolis volcano-sedimentary sequence, Goiás Magmatic Arc Maria Helena B.M. Hollanda Richard Armstrong Márcio M. Pimentel Multidisciplinaria (Ciencias Naturales y Exactas) Pb SHRIMP Arenópolis basic magmatism Goiás Magmatic Arc crustal contamination The Arenópolis volcano-sedimentary sequence is located in the southern part of the Goiás Magmatic Arc andincludes a ca. 900 Ma calc-alkaline arc sequence made of volcanic rocks ranging in composition from basaltsto rhyolites, metamorphosed under greenschist to amphibolite facies. Small calc-alkaline gabbro to granitesub-volcanic bodies are also recognized. The Morro do Baú intrusion is the largest of these intrusions, andis made of gabbros and diorites. Zircon grains separated from one gabbro sample and analyzed by SHRIMPI yielded the mean 206Pb/238U age of 890 +/ 8 Ma, indicating that the intrusion is roughly coeval or onlyslightly younger than the Arenópolis volcanics.Contrary to the metavolcanics, which are juvenile, the Nd isotopic composition of the Morro do Baú gabbroindicates strong contamination with archean sialic material (TDM of 2.8 Ga and EpsilonNd(T) of 9.7),represented in the area by an allochthonous sliver of archean/paleoproterozoic gneisses (Ribeirão gneiss)which are the country-rocks for the gabbro/dioritic intrusion. The emplacement age of ca. 890 Ma representsa minimum age limit for the tectonic accretion of the gneiss sliver to the younger rocks of the Arenópolissequence. The data suggest that this happened early in the evolution of the Goiás Magmatic Arc, betweenca. 920 and 890 Ma. 2003 artículo científico 0001-3765 https://www.redalyc.org/articulo.oa?id=32775306 en http://www.redalyc.org/revista.oa?id=327 Anais da Academia Brasileira de Ciências application/pdf Academia Brasileira de Ciências Anais da Academia Brasileira de Ciências (Brasil) Num.3 Vol.75 |
| format | Artículo científico |
| id | redalyc_32775306 |
| institution | Redalyc |
| language | en |
| publishDate | 2003 |
| publisher | Academia Brasileira de Ciências |
| spellingShingle | Shrimp U-Pb age and Sr-Nd isotopes of the Morro do Baú mafic intrusion: implications for the evolution of the Arenópolis volcano-sedimentary sequence, Goiás Magmatic Arc Maria Helena B.M. Hollanda Multidisciplinaria (Ciencias Naturales y Exactas) Pb SHRIMP Arenópolis basic magmatism Goiás Magmatic Arc crustal contamination Shrimp U-Pb age and Sr-Nd isotopes of the Morro do Baú mafic intrusion: implications for the evolution of the Arenópolis volcano-sedimentary sequence, Goiás Magmatic Arc Maria Helena B.M. Hollanda Richard Armstrong Márcio M. Pimentel Multidisciplinaria (Ciencias Naturales y Exactas) Pb SHRIMP Arenópolis basic magmatism Goiás Magmatic Arc crustal contamination The Arenópolis volcano-sedimentary sequence is located in the southern part of the Goiás Magmatic Arc andincludes a ca. 900 Ma calc-alkaline arc sequence made of volcanic rocks ranging in composition from basaltsto rhyolites, metamorphosed under greenschist to amphibolite facies. Small calc-alkaline gabbro to granitesub-volcanic bodies are also recognized. The Morro do Baú intrusion is the largest of these intrusions, andis made of gabbros and diorites. Zircon grains separated from one gabbro sample and analyzed by SHRIMPI yielded the mean 206Pb/238U age of 890 +/ 8 Ma, indicating that the intrusion is roughly coeval or onlyslightly younger than the Arenópolis volcanics.Contrary to the metavolcanics, which are juvenile, the Nd isotopic composition of the Morro do Baú gabbroindicates strong contamination with archean sialic material (TDM of 2.8 Ga and EpsilonNd(T) of 9.7),represented in the area by an allochthonous sliver of archean/paleoproterozoic gneisses (Ribeirão gneiss)which are the country-rocks for the gabbro/dioritic intrusion. The emplacement age of ca. 890 Ma representsa minimum age limit for the tectonic accretion of the gneiss sliver to the younger rocks of the Arenópolissequence. The data suggest that this happened early in the evolution of the Goiás Magmatic Arc, betweenca. 920 and 890 Ma. 2003 artículo científico 0001-3765 https://www.redalyc.org/articulo.oa?id=32775306 en http://www.redalyc.org/revista.oa?id=327 Anais da Academia Brasileira de Ciências application/pdf Academia Brasileira de Ciências Anais da Academia Brasileira de Ciências (Brasil) Num.3 Vol.75 |
| title | Shrimp U-Pb age and Sr-Nd isotopes of the Morro do Baú mafic intrusion: implications for the evolution of the Arenópolis volcano-sedimentary sequence, Goiás Magmatic Arc |
| topic | Multidisciplinaria (Ciencias Naturales y Exactas) Pb SHRIMP Arenópolis basic magmatism Goiás Magmatic Arc crustal contamination |
| url | https://www.redalyc.org/articulo.oa?id=32775306 |