Geologia e alteração hidrotermal nas rochas vulcânicas e plutônicas paleoproterozoicas na porção Sul da Província Mineral do Tapajós (PA).

Misas, Carlos Mario Echeverri; Juliani, Caetano

doi:10.11606/t.44.2015.tde-27082015-101343

Cited by 4 publications

(9 citation statements)

References 73 publications

(123 reference statements)

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“…A formação da sericita ocorre por instabilidade química dos feldspatos na presença de H + , OH -, K + , com formação de quartzo e micas brancas, além da lixiviação de Na, Mg, Ti, Fe e K (Misas, 2015). Os feldspatos alcalinos são extremamente susceptíveis a ação de soluções hidrotermais (Sial & McReath, 1984) e em zonas de hidrotermalismo é comum a substituição de feldspatos alcalinos por sericita (Tokashiki, Tabela 1.…”

Section: Geoquímicaunclassified

Geologia, petrografia e geoquímica das rochas metavulcânicas ácidas da Estrada Real, Rio de Contas (BA)

Santos

2019

PESQUI GEOCIENC

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Ao longo da Estrada Real, no município de Rio de Contas (BA), afloram rochas metavulcânicas ácidas representativas da Formação Novo Horizonte, Supergrupo Espinhaço, que se formaram na fase sin-rifte do Espinhaço. Estas rochas foram submetidas a intensos processos de deformação e metamorfismo, que modificaram as suas feições originais. Este trabalho visa compreender a gênese do magmatismo ácido sin-rifte do Espinhaço e os processos metamórficos e hidrotermais que afetaram a região, com base em dados de campo, petrográficos e geoquímicos de rocha total. As metavulcânicas ácidas possuem mineralogia constituída por blasto-pórfiros de quartzo, porfiroblastos de andaluzita e cianita, pseudomorfos de granada, feldspatos, biotita, muscovita, sericita, clorita, epidoto, monazita, zircão e minerais opacos imersos em uma matriz quartzo-feldspática. Os processos de sericitização e muscovitização estão presentes nas rochas e indicam a ocorrência de alterações hidrotermais. De acordo com as características petrográficas e geoquímicas, os protólitos das rochas metavulcânicas ácidas foram classificadas como riolitos. Os diagramas de Harker mostram valores dispersos dos elementos maiores Ca, Na e K e dos LILEs, indicando uma provável mobilidade desses elementos. No diagrama multielementar de elementos-traço e ETRs são visualizadas anomalias negativas de Nb-Ta, Sr, P e Eu, além de enriquecimento de ETRL em relação aos ETRP. A formação dessas rochas em um ambiente de rifte continental é sugerida, a partir de um processo de fusão crustal com a interação de um manto previamente modificado por zona de subducção (manto metassomatizado).

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Section: Geoquímicaunclassified

Geologia, petrografia e geoquímica das rochas metavulcânicas ácidas da Estrada Real, Rio de Contas (BA)

Santos

2019

PESQUI GEOCIENC

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“…Indeed, TD, IXD; and CJD, RMD share E‐W trending structures (Figure 9b), implicating that the Archean crust extends to the western limit of feature 6. This result is corroborated by Sm‐Nd T dm ages of 2.5–2.9 Ga and eNd dominantly negative (Echeverri‐Misas, 2015; Lamarão et al., 2005). Carneiro et al.…”

Section: Discussionmentioning

confidence: 65%

“…Indeed, TD, IXD; and CJD, RMD share E-W trending structures (Figure 9b), implicating that the Archean crust extends to the western limit of feature 6. This result is corroborated by Sm-Nd T dm ages of 2.5-2.9 Ga and eNd dominantly negative (Echeverri-Misas, 2015;Lamarão et al, 2005). Carneiro et al (2019) and Juliani et al (2021) argue the E-W structures are the result of the evolution of two continental magmatic arcs partially overlapped in TD.…”

Section: Comparison With Independent Datasets and Implications For Th...mentioning

confidence: 60%

Mapping the Thermal Structure of the Amazon Craton to Constrain the Tectonic Domains

et al. 2022

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Rheology of solids is primarily a function of temperature. Mapping depth to the bottom of the magnetic layer (DBML), which is assumed as a proxy for the depth to Curie temperature, can be used to constrain the thermal structure of the lithosphere. Heat flow data are commonly used to address the thermal structure of the lithosphere. However, these data are scarce for the Amazon Craton. Therefore, as an alternative, DBML was calculated using fractal magnetic source distribution. The Amazon craton is usually described in terms of geochronological provinces models. Nevertheless, geophysical data are poorly discussed in these models. We provide a DBML model that was integrated with the potential field, seismic tomography, and crustal thickness data to address this issue. Our model varies from 10 to 80 km, and almost 90% of the estimates are in the 20‐50 km range. The recurrence of long‐wavelength features on independent datasets supports the assessment that the model is robust and recovered real geophysical signals. Our model suggests that the limits between Carajás and Bacajás domains should be revisited as well as the limits between Tapajós and Iriri Xingú domains. Moreover, we also correlate the model with main mineral deposits. Further, the identified DBML anomaly suggests the mantle is serpentinized in the eastern Carajás domain. This feature is highly correlated with high p‐wave velocity indicating fertile mantle conditions, thus making this region favorable for world‐class mineral deposits.

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“…Neste período, estudos descreveram sistemas epitermais auríferos low-, intermediate-e highsulfidation (e.g. Echeverri-Misas, 2015;Guimarães et al, 2021;Juliani et al, 2000Juliani et al, , 2005Juliani et al, , 2021Tokashiki, 2015), sistemas hidrotermais do tipo pórfiro (e.g. Aguja-Bocanegra, 2013;Juliani et al, 2000Juliani et al, , 2002Juliani et al, , 2021Usero et al, 2009), ocorrências com afinidade com depósitos do tipo Intrusion-Related Gold System (e.g.…”

Section: Estudos Recentes Sugerem Extensão Da Crosta Arqueana Relacio...unclassified

“…Borges et al, 2009;. Esses estudos, juntamente de dezenas de outros efetuados na região, demonstram o alto potencial metalogenético da PMT para a existência de variados tipos de depósitos magmático-hidrotermais em rochas mais ou menos evoluídas petrogeneticamente (Echeverri-Misas, 2015).…”

Section: Estudos Recentes Sugerem Extensão Da Crosta Arqueana Relacio...unclassified

Integração de dados aerogeofísicos e mapeamento litológico preditivo com Self-Organizing Maps na Província Mineral do Tapajós, Cráton Amazônico

Cellier

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The Tapajós Mineral Province (TMP), located in the central-south region of Amazonian Craton, stands out for its gold production for over six decades and has demonstrated huge potential for occurrences of magmatic-hydrothermal polymetallic deposits, especially epithermal and porphyry types. However, even with all the efforts made in the last few decades, including the recent publication of the province geologic map, the geologic knowledge is uncomplete, a reality that disfavor the development of the mineral exploration in the region. This situation is aggravated by the natural difficulties that this region imposes, such as access difficulties, dense forest cover and thick weathering profile.The use of indirect mapping techniques in regions with similar difficulties is expanding in the last few years. In this context, predictive mapping based on Machine Learning techniques, using different datasets, has proved to be a useful tool to characterize and delimitate geological units, recognize compositional anomalies, geological structures and more.In this contribution, aerogeophysical data is processed and interpreted to investigate the geology of the eastern region of the TMP, in the light of the geologic map.The obtained data were utilized as parameters for the production of a predictive geologic map using Self-Organizing Maps (SOM), an unsupervised Machine Learning technique, which analyses and structure the data independently, clustering the samples according to their similarities, which is recognized by the algorithm itself.The results evidence the strong contribution from the aerogeophysical data in the production of the geologic map, with strong correlation between the contacts of both maps, attesting a successful outcome from the use of SOM in this study. However, in many regions of the geologic map, defined geological units and structures are not supported by the data obtained in this study, especially in regions with few or no-data from previous field surveys.The SOM technique was effective in the creation of a predictive geologic map and appears to be more efficient that the use of geophysical data alone to map previously described geological units and to infer units in not-studied regions. It also has potential to infer areas affected by hydrothermal activity, which can be useful in the elaboration of exploratory models and defining prospective areas for exploration.

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Geologia e alteração hidrotermal nas rochas vulcânicas e plutônicas paleoproterozoicas na porção Sul da Província Mineral do Tapajós (PA).

Cited by 4 publications

References 73 publications

Geologia, petrografia e geoquímica das rochas metavulcânicas ácidas da Estrada Real, Rio de Contas (BA)

Geologia, petrografia e geoquímica das rochas metavulcânicas ácidas da Estrada Real, Rio de Contas (BA)

Mapping the Thermal Structure of the Amazon Craton to Constrain the Tectonic Domains

Integração de dados aerogeofísicos e mapeamento litológico preditivo com Self-Organizing Maps na Província Mineral do Tapajós, Cráton Amazônico

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