Contribuição ao estudo do magmatismo Paleo e Mesoproterozóico do SW do Craton Amazônico através da aplicação de isótopos estáveis de O, H e S

Geraldes, Mauro César; Teixeira, Wilson; Valladares, Claudia Sayão

doi:10.1590/s0044-59672008000200012

Cited by 2 publications

(1 citation statement)

References 29 publications

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“…Another relevant aspect is that despite of these granites being defined as intraplate or no orogenic, some authors relate the rapakivi magmatism in Rondônia and other regions on world, like the Baltic Shield (Åhäll and Gower 1997), with the synchronous orogenic events that occurred in the region (Geraldes et al 2001;Matos et al 2004;Geraldes et al 2008;Ruiz et al 2004); Bettencourt et al (1999) believe that the youngest granites of Rondônia Tin Province (including Santa Clara and Rondônia Intrusive Suites) represent an inboard magmatism during a younger episode of reworking in the Rio Negro Juruena Province, during the final stages of the collisional Sunsás-Aguapeí orogeny (1.1 to 0.95 Ga). , comparing the idea proposed by Åhäll and Gower (1997) for the Baltic Shield case with the Amazonian Craton also suggested that an inboard bimodal rapakivi magmatism in Rondônia Tin Province could be related with the orogenic events that occurred in the southwest border of the Amazonian Craton.…”

Section: Discussionmentioning

confidence: 99%

Contribution to the understanding of the Rondonia Tin Province granites (SW Amazonian Craton) origin using U-Pb and Lu-Hf in zircon by LA-ICPMS: implications to A-type granite genesis

Debowski¹,

Alves²,

Santos³

et al. 2019

JGSB

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The study of granite rocks is important in order to understand chemical evolution of the continental crust. Their isotopic composition provides information on their magmatic sources, whether being mantle, crust or a mixture of both. In the SW border of the Amazonian Craton, suites of rapakivi granites related with tin-polymetallic mineralization are emplaced within heterogeneous Proterozoic crust. Zircons from eleven rocks from three granite intrusions, Massangana, São Carlos and Caritianas, representative of the Younger Granites of Rondônia have been studied by using laser ablation inductively coupled plasma source mass spectrometry (LA-ICP-MS) in order to obtain U-Pb ages and Hf isotopic compositions. The samples from Massangana massif, show greater range in age (between 1026 -993 Ma) and initial 176 Hf/ 177 Hf = 0.2817-0.2823. The ԐHf values are both negative and positive (-6.2 to +3.4) in some samples, and only negative in others (-14.1 to -1.6) which reflects the heterogeneity of sources. The TDM age varying between 2.40 to 1.61 Ga also indicates that different sources were involved in the formation of these rocks. The samples from São Carlos massif show U-Pb ages between 996 to 974 ± 10 Ma and initial ԐHf between -15 and +11, corresponding to a TDM age range between 2.65 and 1.08 Ga. The samples from Caritianas massif with U-Pb ages of 1001 and 999 Ma, show more initial ԐHf positive values (13 zircon grains) than negative (6 zircon grains), different from the other massifs. The range of initial ԐHf of the Caritianas massif is -1.5 to +8.2, and residence crustal ages between 1.76 and 1.25 Ga. The great variation in the ԐHf values indicates heterogeneity of sources; the Massangana and São Carlos massifs represent mainly crustal melts with a subordinate mantle contribution. The Caritianas massif, which shows more positive values of the ԐHf parameter, seems to have had more mantle contribution than the other massifs studied here. The characterization of the sources of the rapakivi rocks may play an important role in the genesis of cassiterite ore and could represent an important tool for mineral exploration.

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Section: Discussionmentioning

confidence: 99%

Contribution to the understanding of the Rondonia Tin Province granites (SW Amazonian Craton) origin using U-Pb and Lu-Hf in zircon by LA-ICPMS: implications to A-type granite genesis

Debowski¹,

Alves²,

Santos³

et al. 2019

JGSB

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Age and Origin of the Massangana Intrusive Suite and Associated Mineralizations, in the Rondônia Tin Province: Petrography, U-Pb, and Lu-Hf Isotopes Zircons

et al. 2022

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Rondônia intrusive suites represent the youngest A-type magmatism that occurred in the SW of the Amazon craton, with mineralizations in Sn, Nb, Ta, W, and topaz. Petrological and isotopic studies (U-Pb and Lu-Hf by LA-ICP-MS) allowed the Massangana granite to be subdivided into São Domingos facies (medium to fine biotite-granite), Bom Jardim facies (fine granite), Massangana facies (pyterlites and coarse granites) and Taboca facies (fine granites). The crystallization ages obtained were between 995.7 ± 9.5 Ma to 1026 ± 16 Ma, and the εHf values vary significantly between positive and negative, showing predominantly crustal sources for forming these rocks. Petrographic studies on ore samples indicate the action of co-magmatic hydrothermal fluids enriched in CO2, H2O, and F. These ores are characterized by endogreisens, exogreisens, pegmatites, and quartz veins that are explored in the São Domingos facies area. The endogreisens and exogreisens are formed by topaz-granites and zinnwaldite-granites; the pegmatites are formed by topaz-zinnwaldite-cassiterite-granites; and the veins by cassiterite-sulfides and quartz. The geometries of the mineralized bodies indicate a dome-shaped contact with the host rocks in the magma chamber and can be attributed to residual accumulation. In this sense, the origin of these ores is related to the evolution of intrusive granitic bodies where the terminal phases of the fluid-enriched magma are lodged in the apical portions, and the origin of the mineralized bodies present a biotite-granite, albite-granite, and endogreisens evolution (potassium series), or biotite-granite, alkali-granite and endogreisens (sodic series) and these rocks present TDM ages that indicate a concerning relation to the non-mineralized rocks of Massangana granite.

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Contribuição ao estudo do magmatismo Paleo e Mesoproterozóico do SW do Craton Amazônico através da aplicação de isótopos estáveis de O, H e S

Cited by 2 publications

References 29 publications

Contribution to the understanding of the Rondonia Tin Province granites (SW Amazonian Craton) origin using U-Pb and Lu-Hf in zircon by LA-ICPMS: implications to A-type granite genesis

Contribution to the understanding of the Rondonia Tin Province granites (SW Amazonian Craton) origin using U-Pb and Lu-Hf in zircon by LA-ICPMS: implications to A-type granite genesis

Age and Origin of the Massangana Intrusive Suite and Associated Mineralizations, in the Rondônia Tin Province: Petrography, U-Pb, and Lu-Hf Isotopes Zircons

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