Paleoproterozoic subduction-related metasomatic signatures in the lithospheric mantle beneath NE Brazil: inferences from trace element and Sr–Nd–Pb isotopic compositions of Neoproterozoic high-K igneous rocks

Hollanda, Maria Helena Bezerra Maia de; Pimentel, Márcio Martins; Sá, Emanuel Ferraz Jardim de

doi:10.1016/s0895-9811(03)00014-2

Cited by 59 publications

(22 citation statements)

References 38 publications

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“…Therefore, the Ce/Pb ratios (0.92-19.41) in most of these rocks, which are lower than those of mantle-derived magmas values (e.g., Ce/Pb %25 for average oceanic basalts), may be due to incorporation of Pb into the mantle via subduction fluids (Chung et al, 2001). The lower Pb isotopic ratios excluded the contribution from the subducted sediment because the slight addition of sediment material would significantly alter Pb isotopic ratios toward more radiogenic values (De Hollanda et al, 2003). In fact, subduction occurred along the north margin of the Central Tianshan Block before the Ordovician, and the subduction had been continuing along the south margin of the Central Tianshan Block from the middle-late Silurian to the Early Carboniferous (Han et al, 1998;Chen et al, 2001;Xia et al, 2002;Dong et al, 2006).…”

Section: Mantle Sourcesmentioning

confidence: 83%

Geology, petrology and geochemistry of the Baishiquan Ni–Cu-bearing mafic–ultramafic intrusions in Xinjiang, NW China: Implications for tectonics and genesis of ores

Chai

Zhang

Mao

et al. 2008

Journal of Asian Earth Sciences

105

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Section: Mantle Sourcesmentioning

confidence: 83%

Geology, petrology and geochemistry of the Baishiquan Ni–Cu-bearing mafic–ultramafic intrusions in Xinjiang, NW China: Implications for tectonics and genesis of ores

Chai

Zhang

Mao

et al. 2008

Journal of Asian Earth Sciences

105

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“…It is impossible to obtain significant amounts of granitic magma due to the partial melting of the mantle (Leake, 1990); therefore, granites with positive ε Hf (t) values are generally considered as the products of partial melting of juvenile crust with the addition of mantle components (Taylor & McLennan, 1985;Wu et al 2010). O isotopes can also effectively Zorpi et al (1991) and de Hollanda et al (2003), and data for the samples in Quxu batholith are from Chen (2006), Dong et al (2008) and Huang et al (2010).…”

Section: B1 Genetic Type Of Mmesmentioning

confidence: 99%

Geochemical characteristics of the Nyemo intrusion and crust–mantle interactions in southern Gangdese, Tibet

et al. 2020

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The Gangdese magmatic belt across the southern Tibetan Plateau is juxtaposed with the Indus–Yurlung Zangbo suture zone (IYS), and many mafic microgranular enclaves (MMEs) are exposed in the belt, thus providing a window for observing deep crust–mantle processes related to the Indo-Asian collision. The Nyemo intrusion is located in the middle part of the Gangdese magmatic belt and comprises host diorites with abundant MMEs. Compared with other parts of the Gangdese magmatic belt, the host rock of the Nyemo intrusion has a mineral composition similar to that of the MME, although differences are observed in chemical contents. To explore the genetic type of the MMEs and the deep processes of the Gangdese magmatic belt, the Nyemo intrusion is selected as the research object for this paper. Here, we report zircon U–Pb geochronological and whole-rock geochemical data for host diorites and MMEs, and electron probe data for hornblendes in diorites and MMEs, and combine mineralogy, petrology, petrogeochemistry and isotope geochemistry analyses. Research has shown that diorites in the Nyemo intrusion belong to the medium-K, metaluminous series. The light rare earth elements (LREEs) and heavy rare earth elements (HREEs) are significantly fractionated, and the LREE/HREE values are 5.77–7.71. The (87Sr/86Sr)i values of the diorites range from 0.704260 to 0.704287, and the εNd(t) values are from 3.73 to 4.17. The MMEs in the Nyemo intrusion have a limited range of SiO2 contents, are calc-alkaline with metaluminous affinity, and have relatively high contents of MgO (4.34–5.00 wt %) with Mg# (Mg2+/Mg2+ + Fe2+) values of 42.36–43.53, which is close to that of evolved basic magma. The contents of REEs vary from 108.87 to 120.59 ppm and show obvious Eu anomalies. The (87Sr/86Sr)i values of the MMEs range from 0.704680 to 0.704704, and the εNd(t) values are 0.35–3.74. The crystallization temperature of the hornblende in the diorite is 820 °C, the formation depth is 5.39 km, the oxygen fugacity is ΔNNO + 0.88 and the water content is 5.95 %. The crystallization temperature of the hornblende in the MMEs is 880 °C, the formation depth is 12.18 km, the oxygen fugacity is ΔNNO + 0.38 and the water content is 8.27 %. The Nyemo MMEs are formed by magma mingling, and originate from the partial melting of the depleted mantle, while the host diorite originates from partial melting of the juvenile crust with the addition of mantle material. The formation of the Gangdese magmatic belt is related to the Indo-Asian continental collision. The break-off of the subducted Neo-Tethyan oceanic plate triggered partial melting of the asthenosphere, which resulted in accumulation of the basaltic magma and then caused the partial melting of the juvenile crust with the addition of mantle material, thus forming a variety of granitic rocks and the large Gangdese magmatic belt.

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“…Hence, gamma spectrometric signature presents low to medium values of eTh (8-20 ppm) and eU (0.2-1.2 ppm), as well as medium values of K (2.3-3%). Medium values of K are either related to assimilation and magma mixing processes with granitoids of the SBCDS, or the K-enriched nature of the lithospheric mantle beneath the Borborema Province, which leads to the generation of K-rich mafic to intermediate rocks (Silva Filho et al 1993, Ferreira et al 1997, Neves and Mariano, 1997, Neves et al 2000, Mariano et al 2001, Hollanda et al 2003, Guimarães et al 2005. However, magma mixing processes between gabbro and leucogranites, as described by Silva et al (2016), should explain the medium K contents of Uruçu gabbros.…”

Section: Serra Branca: Coxixola Dike Swarmsmentioning

confidence: 99%

Using airborne gamma-ray spectrometry and geochemistry to characterize the late Neoproterozoic ferroan magmatism in the Transversal subprovince of the Borborema Province, NE-Brazil

et al. 2020

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Ferroan granites (585-530 Ma) in the Transversal subprovince of the Borborema Province (BP) comprise two groups: G1) slightly peraluminous to metaluminous, alkali-calcic rocks (Aroeiras Complex and Serra Branca-Coxixola dike swarms (SBCDS)); G2) metaluminous to slightly peraluminous, alkalic to alkali-calcic rocks (Queimadas and Prata intrusions). G1 are transitional from collision to transcurrence (ca. 585 Ma), or transcurrence to transtension (ca. 545 Ma). G2 represents the granitoids intruded during post-collisional crustal thinning (ca. 550 Ma), or coeval with deposition of intracratonic basins (ca. 530 Ma). The large-ion lithophile elements (LILE) and high field strength elements (HFSE) enriched geochemical signature of these granitoids are recognizable in gamma spectrometric maps of regional scale, highest values of K(%), eTh(ppm), and eU(ppm) contrast significantly with country rocks and magnesian granites. This study shows that gamma-ray spectrometric regional maps reflect the geochemical characteristics of the ferroan intrusions. Moreover, in the local maps for each intrusion, it is possible to identify internal heterogeneities in these plutons, which correlate to geological processes, geochemistry, and petrography. Diorites and gabbros show low to medium values of K (1-3%), eTh (5-20 ppm) and eU (0.2-2 ppm), contrasting with the high values of regions with a dominance of ferroan granitoids (K, 3-6%; eTh, 15-60 ppm; eU, 2-4 ppm).

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Paleoproterozoic subduction-related metasomatic signatures in the lithospheric mantle beneath NE Brazil: inferences from trace element and Sr–Nd–Pb isotopic compositions of Neoproterozoic high-K igneous rocks

Cited by 59 publications

References 38 publications

Geology, petrology and geochemistry of the Baishiquan Ni–Cu-bearing mafic–ultramafic intrusions in Xinjiang, NW China: Implications for tectonics and genesis of ores

Geology, petrology and geochemistry of the Baishiquan Ni–Cu-bearing mafic–ultramafic intrusions in Xinjiang, NW China: Implications for tectonics and genesis of ores

Geochemical characteristics of the Nyemo intrusion and crust–mantle interactions in southern Gangdese, Tibet

Using airborne gamma-ray spectrometry and geochemistry to characterize the late Neoproterozoic ferroan magmatism in the Transversal subprovince of the Borborema Province, NE-Brazil

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