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9. Relics of ophiolite-bearing accretionary wedges in NE Brazil and NW Africa: Connecting threads of western Gondwana´s ocean during Neoproterozoic times

Author

Lauro Cézar M. de Lira Santos, Fabrício A. Caxito, Merlain H. Bouyo, Sonia Ouadahi, Kawther Araïbia, Geysson A. Lages, Glenda L. Santos, João Paulo A. Pitombeira, and Peter A. Cawood

Subjects
Ophiolites, Western Gondwana, Suture zones, Neoproterozoic orogenic belts, Physical geography, GB3-5030
Abstract

Neoproterozoic breakup of Rodinia resulted in the formation of several oceanic realms between dispersing cratons, which were later consumed during the assembly of Gondwana. In its western portion, the interior orogenic belts of Gondwana formed during the Brasiliano-Pan African Orogeny in the late Neoproterozoic-early Cambrian. Available geophysical, structural and petrological data suggest that the complex network of shear zones that once connected the Borborema province (NE Brazil), Tuareg shield (Hoggar) and Central African domain (NW Africa) likely represent ancient sutures that mark collisional episodes between Archean-Paleoproterozoic paleocontinents such as Amazonian-West African and São Francisco-Congo. Mafic, ultramafic and sedimentary sequences associated with this set of structures respresent dismembered ophiolite slices interpreted as oceanic remnants (sensu lato) that were emplaced during the late stages of the Gondwana assembly. For instance, the composite Transbrasiliano-Khandi-In-Tedeini-Silet shear system crosscuts rock assemblages preserving a complex history of oceanic-crust-transition development (Novo Oriente complex) in association with primitive to evolved magmatic arcs and UHP rocks both in the Borborema province and NW Africa. In the central Borborema province, preserved ophiolitic slices are strongly overprinted by ductile and brittle deformation events, but partially preserved MORB-like amphibolites are akin to subduction-related-types that crystallized in early- and late Neoproterozoic times docked via terrane accretion and dispersed by strike-slip shear zones. In the southern Borborema province, an example of a Neoproterozoic ophiolitic assemblage is the Monte Orebe complex, that encompasses T-MORB mafic rocks, ultramafic lenses, and exhalative sedimentary rocks akin to early to late stages of oceanic basin spreading, emplaced during convergent plate motions between the Pernambuco-Alagoas superterrane and the São Francisco craton. Correlative units are found in Cameroon, including the strongly hydrotermalized ultramafic rocks of the Lomié and Boumnyebel complexes, that are structurally controlled by top-to-the-south verging nappes found in the N-NW margin of the Congo craton. In all scenarios, the ophiolitic complexes are related to intra-oceanic and continental magmatic arcs as well as to geophysical signatures comparable to Phanerozoic suture zones. Although strongly dismembered, scrapped off Neoproterozoic oceanic crust partially preserved within the major belts of western Gondwana demonstrate the role of accretion-collisional orogenesis during its assembly.

Published
2023
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27. Relics of ophiolite-bearing accretionary wedges in NE Brazil and NW Africa: connecting threads of western Gondwana´s ocean during Neoproterozoic times

Author

de Lira Santos, Lauro Cézar M., primary, Caxito, Fabrício A., additional, Bouyo, Merlain H., additional, Ouadahi, Sonia, additional, Araïbia, Kawther, additional, Lages, Geysson A., additional, Santos, Glenda L., additional, Pitombeira, João Paulo A., additional, and Cawood, Peter A., additional

Published
2022
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41. Neoproterozoic pre-collisional events recorded in the Sergipano belt, Southern Borborema Province, West Gondwana.

Author

Passos, Luiz Henrique, A. Fuck, Reinhardt, Chemale Junior, Farid, Lenz, Cristine, Porcher, Carla Cristine, Pinto, Viter Magalhães, and de Lira Santos, Lauro Cézar M.

Subjects
GEOLOGICAL time scales, AMPHIBOLITES, QUARTZITE, NEOARCHAEAN, ZIRCON
Abstract

The Canindé Domain is crucial for understanding the pre-collisional events in Sergipano Belt, Borborema Province, especially during the Late Stenian/Early Tonian (740–680 Ma). We present thermobarometric, geochronology, and isotopic studies of the metavolcanosedimentary rocks of the Novo Gosto unit. The calculated metamorphic conditions resulted in a range of T: 600–740°C and P: 3.5–10.0 kbar for non-mylonitic amphibolites and values of T: 636–808°C and P: 7.0–12.0 kbar for mylonites, both of amphibolite facies. The minimum metamorphic conditions imprint in these rocks are T: 390°C and P: 2.5 kbar, indicating retrometamorphism in greenschist facies. The probable age of the peak metamorphic event was obtained in zircon rims from a quartzite at 692 ± 8.5 Ma. U-Pb detrital zircon and Nd model ages of the metasedimentary rocks point out Early Tonian as primary source rocks. Subordinate contributions of Mesoproterozoic, Paleoproterozoic, and Neoarchean sources were also recognized. These primary sources are related to Cariris Velhos event rocks, whereas the subordinate sources are from the Pernambuco-Alagoas superterrane. Early Tonian and Late Stenian ages were recognized for the first time in the Canindé Domain, with U-Pb zircon ages of 1005 ± 3 and 989 ± 6 Ma in amphibolites and mylonitized granites, mostly outcropping at the southwestern limit of the area. New ages were also obtained in the Novo Gosto surrounding intrusions: Canindé Layered Gabbroic Intrusion (~718 Ma), Garrote (~715 Ma) and Curralinho/Boa Esperança (~708 Ma) metagranites, and Gentileza metavolcanic rock (~700), which integrate the early pre-collisional magmatism of the Sergipano Belt (~740-680 Ma). Finally, U-Pb zircon ages were obtained in the Poço Redondo Domain, potential source area of the Novo Gosto metasedimentary rocks, resulting in ages of 957 ± 11 and 988 ± 15 Ma. The new data bring perspective to future correlations with adjacent belts and the understanding of the structuration of West Gondwana during the Brasiliano-Pan-African Orogeny. [ABSTRACT FROM AUTHOR]

Published
2023
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47. Enabling security in software-defined wireless sensor networks for internet of things

Author

Cézar M. G. de Toledo, Cintia Borges Margi, Doriedson A. G. Oliveira, and Marcos A. Simplicio

Subjects
Software, Computer science, business.industry, Internet of Things, business, Wireless sensor network, Computer network
Abstract

In Software-Defined Wireless Sensor Networks (SDWSN), a logically centralized controller manages data flows according to high level policies. As a result, it provides Wireless Sensor Networks (WSN) with further flexibility and control over its nodes’ behavior. One challenge in this scenario, though, is that SDWSN are mainly composed of resource-constrained devices, which hinders the application of traditional cryptographic protocols in such networks. In this article, we propose a secure framework for SDWSN that takes into account such constraints, enabling the establishment of end-to-end security among nodes and between nodes and the SDN controller. Besides showing how our proposal can enforce different security services in an SDWSN, we also simulate our framework and present a preliminary security cost of framework.

Published
2020
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49. Description and hierarchy of ductile deformation events in the Camalaú region, state of Paraíba, central portion of the Alto Moxotó Terrane, Borborema Province, Brazil

Author

Santos, Lauro Cézar M. de Lira, Pereira, Caio dos S., Lima, Haroldo M., Guedes, Pedro A., Medeiros, Roberta S. de, Silva, Jefferson W. Alves, Araújo Neto, José Ferreira de, Santos, Glenda L., and Paixão, Mariana S.

Subjects
Moxotó Terrane, Ductile deformation in Camalaú, Borborema Province
Abstract

The Borborema Province (NE Brazil) has a long history of deformation, magmatism and metamorphism during the Precambrian Eon. Thus, it represents a natural laboratory to investigate widely developed ductile-deformation markers, such as major fold belts and large-scale shear zones. This paper describes the structural evolution of a complex folded area of the Alto Moxotó Terrane, Central Borborema Province. In this region, para-derived rocks of the Sertânia Complex are intruded by orthogneisses and migmatitic orthogneisses. The Geophysical magnetometric expressions of the Borberma Province are characterized by strong aligned and folded magnetic lineaments and integrated structural analysis, allowed us to identify three ductile deformation episodes. Brittle tectonics is also present, but not described. D1 stage represents the basement structural framework restricted to local structural windows of ancient orthogneisses and migmatites that are not mappable at the work scale. D2 deformation is widespread throughout the Central Borborema Province, producing nappes that mark top-to-NW tectonic vergence.Foliation and lineation attitudes are compatible with progressive deformation from tangential to strike-slip tectonics (i.e. D2 to D3). The latter is associated with the NE-SW Xinxó and Congo-Cruzeiro do Nordeste sinistral strike-slip shear zones, producing refold patterns that resemble Type-3 interference geometry. Based on airborne magnetic geophysical imaging interpretations and mesoscopic observations, we suggest that progressive deformation strongly affected the region and overprinted at large-scale early formed rocks.

Published
2020

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