Tectonic overview of the West Gondwana margin

Vaughan, Alan P. M.; Pankhurst, R. J.

doi:10.1016/j.gr.2007.07.004

Cited by 158 publications

(64 citation statements)

References 101 publications

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“…Paleogeographic reconstructions and dynamic interpretations of the proto-Andean margin of Gondwana in the Mesoproterozoic to Ordovician time span have been strongly stimulated over the past 15 years by the hypothesis of allochthonei ty of the Precordillera terrane (e.g., Vaughan and Pankhurst, 2008). According to most supporters of the hypothesis, this terrane consists of a Grenville age basement that crops out in the Western Sierras Pampeanas and a non-metamorphic Early Cambrian to Middle Ordovician passive margin cover sequence, i.e., the Argentine Precordillera ( Fig.…”

Section: Geological and Paleogeographical Settingmentioning

confidence: 99%

A deformed alkaline igneous rock–carbonatite complex from the Western Sierras Pampeanas, Argentina: Evidence for late Neoproterozoic opening of the Clymene Ocean?

Casquet

Pankhurst

Galindo

et al. 2008

Precambrian Research

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A deformed ca. 570 Ma syenite-carbonatite body is reported from a Crenville-age (1.0-1.2 Ca) terrane in the Sierra de Maz, one of the Western Sierras Pampeanas of Argentina. This is the first recognition of such a rock assemblage in the basement of the Central Andes. The two main lithologies are coarse-grained syen ite (often nepheline-bearing) and enclave-rich fine-grained foliated biotite-calcite carbonatite. Samples of carbonatite and syenite yield an imprecise whole rock Rb-Sr isochron age of 582 ± 60 Ma (MSWD = 1.8; Sri = 0.7029); SHRIMP U-Pb spot analysis of syenite zircons shows a total range of2 0 6Pb_238U ages between 433 and 612 Ma, with a prominent peak at 560-580 Ma defined by homogeneous zircon areas. Te xtural interpretation of the zircon data, combined with the constraint of the Rb-Sr data suggest that the car bonatite complex formed at ca. 570 Ma. Further disturbance of the U-Pb system took place at 525 ± 7 Ma (Pampean orogeny) and at ca. 430-440 Ma (Famatinian orogeny) and it is concluded that the Western Sierras Pampeanas basement was joined to Condwana during both events. Highly unradiogenic values in calcites (0.70275-0.70305) provide a close estimate for the initial Sr isotope composition of the carbonatite magma. Sm-Nd data yield BNds7 0 values of +3.3 to +4.8. The complex was probably formed during early opening of the Clymene Ocean from depleted mantle with a component from MesojNeo proterozoic lower continental crust.

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Section: Geological and Paleogeographical Settingmentioning

confidence: 99%

A deformed alkaline igneous rock–carbonatite complex from the Western Sierras Pampeanas, Argentina: Evidence for late Neoproterozoic opening of the Clymene Ocean?

Casquet

Pankhurst

Galindo

et al. 2008

Precambrian Research

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“…In the Ediacaran, after the Tonian extensional phase, with deposition of the Itaiacoca Sequence, the region was transformed into an unstable active margin, with the predominance of magmatic arcs (Três Córregos, Cunhaporanga and Agudos Grandes) and restricted sedimentation (Abapã, Antinha and Iporanga Sequences). This was process related to the assembly of a collage of early Precambrian continental blocks by the consumption of the oceanic domains between them and the formation of Western Gondwana (Cordani, Brito Neves, D'Agrella, 2003;Schmitt et al, 2008;Vaughan and Pankhurst, 2008;Valladares et al, 2008;Heilbron et al, 2008;Santosh, 2002, 2009). …”

Section: Resultsmentioning

confidence: 99%

Extensional and colisional magmatic records in the Apiaí Terrane, south-southeastern Brazil: integration of geochronological U-PB Zircon ages

Siga

Basei

Nutman

et al. 2011

Geol. USP, Sér. cient.

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“…Thus, the tectonics of western Gondwana appears as a controversial topic and a matter of contention, both in old and recent studies (e.g. Paulsen et al, 2007;Tucker et al, 2007;Goscombe & Gray, 2008;Vaughan & Pankhurst, 2008;Casquet et al, 2008). Indeed, despite the existence of good petrologic and isotopic data and a relatively clear definition of the regional geochrono-stratigraphy in the Pan-African domain of Cameroon and northwestern regions, the lack of detailed structural studies has generated controversial tectonic models.…”

Section: Introductionmentioning

confidence: 99%

Plates Amalgamation and Plate Destruction, the Western Gondwana History

Ngako¹,

Njonfang²

2011

Tectonics

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Tectonics 4This study involves modern structural analysis and concepts (phase chronology, strain analysis, deformation and kinematics), petrology (metamorphic parageneses and phase equilibrium, relation with deformation, geothermobarometry), geochemistry (major and trace elements) and geochronology. Data from regional literature including geophysical data are also abundantly used for synthesis and re-interpretation. The most important achievements include: 1. A new tectonic model for the Pan-African/Brasiliano belts; this model includes many original aspects and developments with regards to the collisional setting, tectonics, metamorphic and magmatic processes. In particular, a three-plate model is proposed, and the role of the asthenosphere on crustal melting and reactivation during collision is emphasized. 2. Evidence of a tectonic indent in the central Nigeria-Cameroon domain, inferred from the regional strain field; indentation in central-west Africa strongly suggests that the East Saharan Block (ESB) evolved originally as a rigid prong prior to crustal melting, batholiths emplacement and subsequent dismantling of the prong during the late PanAfrican evolution. 3. Clear distinction between Pan-African and Post Pan-African tectonic and magmatic processes which raises the question on the relevance of integrating Phanerozoic lithospheric structures inferred from geophysical data (gravity, seismic tomography, etc.) in the interpretation and reconstruction of the Pan-African tectonic evolution. Future research would be focused on the Central Cameroon Shear Zone (CCSZ) kinematics and the characterization of vestiges of the dismantled SFCC/ESB cratons and hypothetic pre-tectonic boundaries.

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Tectonic overview of the West Gondwana margin

Cited by 158 publications

References 101 publications

A deformed alkaline igneous rock–carbonatite complex from the Western Sierras Pampeanas, Argentina: Evidence for late Neoproterozoic opening of the Clymene Ocean?

A deformed alkaline igneous rock–carbonatite complex from the Western Sierras Pampeanas, Argentina: Evidence for late Neoproterozoic opening of the Clymene Ocean?

Extensional and colisional magmatic records in the Apiaí Terrane, south-southeastern Brazil: integration of geochronological U-PB Zircon ages

Plates Amalgamation and Plate Destruction, the Western Gondwana History

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