Orogenic fold-belts and a hypothesis of earth evolution

Dearnley, R.

doi:10.1016/0079-1946(66)90002-4

Cited by 27 publications

(4 citation statements)

References 225 publications

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“…One of the problems common to ideas concerning both Archaean tectonics and crustal accre tion is how efficient tectonic reworking might be at disguising the existence of older crust. Because the surviving remnants of Archean crust are of deformed rocks which were obviously more extensive in the past it has been assumed that both the Archaean crust and Archaean tectonic processes were considerably more extensive (Sutton 1967) or even world wide (Dearnley 1966). It will be assumed for this model that there was never very much more Archaean crust than is still obvious.…”

Section: The Formation O F Sialic Crustmentioning

confidence: 99%

A Discussion on the evolution of the Precambrian crust - A plate tectonic model for the Archaean crust

Talbot

1973

Phil. Trans. R. Soc. Lond. A

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The characteristics of Archaean greenstone belt terrains are briefly summarized together with some of the models which have been used to account for their genesis. Crystalline sialic crust is interpreted as having increased with time by separation from the mantle. Many of the problems posed by Archaean greenstone belt terrains may be eased if the first sialic crust is assumed to have consisted of small masses concentrated by plate tectonic processes similar to those still in operation. Even if Archaean plates were of similar size, and were formed and lost at rates similar to those since the Mesozoic, there would be differences in the manner in which the sialic crust was concentrated because so little had separated from the mantle during Archaean times. The original formation of the rocks now forming the earliest tonalite gneisses and migmatites is attributed to very early Archaean times when no large sialic concentrations are likely to have existed on subduced lithospheric plates and the only form of orogeny was of the Island Arc type. Even after sialic concentrations did become incorporated in subduced plates they may for a long time have been too small for significant areas to survive extensive remobilization and addition of magmas from below whenever they were associated with plate boundary zones. Sets of greenstone belts are interpreted as vestiges of former oceans. By the end of Archaean times the sialic crustal concentrations, despite possible fragmentation and periods of independent development, became sufficiently extensive for large areas to survive ocean closure without significant remobilization. This model implies that there is no need for orogeny to have been any more extensive in Archaean times than now; it could merely have been more extensive compared to the area of the sialic crust in existence at the time. Plate tectonic models of Archaean tectonics are distinguished from the alternatives by their implication that large relative motions occurred between the oldest parts of the granitoid masses now on either side of the greenstone belts. Palaeomagnetism may be able to distinguish the relative usefulness of the models if any such relative motions can be recognized through the effects of remobilization of most, if not all, the sialic crust in Archaean times. Other tests are possible but the most useful might be the necessity for any model of the formation of the greenstone belts being adaptable enough to account for the relationships emerging from studies of the Archaean crustal remnants characterized by granulite facies metamorphism and anorthosites.

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Section: The Formation O F Sialic Crustmentioning

confidence: 99%

A Discussion on the evolution of the Precambrian crust - A plate tectonic model for the Archaean crust

Talbot

1973

Phil. Trans. R. Soc. Lond. A

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“…A periodicidade dos fenômenos, mesmo antes da Tectônica de Placas, já fora mencionada no início deste artigo. De Umbgrove (1947) até Dearnly (1966), com especial ênfase nas contribuições meritórias de Sutton (1963). Setenta anos após Wegener, 40 anos após Umbrove, a periodicidade característica dos processos foi praticamente equacionada por Worsley et al (1982Worsley et al ( , 1984Worsley et al ( , 1985.…”

Section: Ciclo Dos Supercontinentesunclassified

A Teoria dos Supercontinentes: discussão e crítica construtiva

Neves

2022

Geol. USP. Sér. Cient.

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A Teoria dos Supercontinentes teve como seu instaurador principal Alfred Wegener, nos seus clássicos trabalhos nas primeiras décadas do século XX. Deve ser destacada a frente de contestação que lhe foi imposta de geocientistas dos dois mundos (então, todos “geossinclinalistas”). A retomada (e o crédito) só veio com Harry Hess, em 1962, quando este mostrou que os grandes empecilhos (fatores desconhecidos da deriva continental, não explicados devidamente), inibidores da teoria, passaram a ser cientificamente demonstráveis. Isso com suas pesquisas, com o conceito de convecção mantélica e mais ainda com proveito do ímpeto do surgimento da Tectônica de Placas (e o combate ao fixismo sensu lato). Seguindo Hess, alguns trabalhos foram acrescentados, com novas proposições, adendos, revisões, principalmente entre 1992 e 2005. Desde então, instalou-se fase notável de contribuições, publicações, livros e capítulos, todos com novos dados científicos. Temos que admitir que esse ramo das geociências ainda está em estágio de fluxo. A aplicação desses conceitos e conhecimentos, merecedora de um projeto internacional específico, foi estendida do Arqueano (no caso mais problemático de todos erátemas) até o fim do Mesoproterozoico (e.g. projetos “Gondwana”, “Rodínia” etc.). Concomitantemente a esses trabalhos e dados, já surgiram várias questões pendentes, para todos os casos de supercontinentes. Catalogamos uma série de problemas que queremos expor e as soluções que são demandadas. O conclusivo hoje é que o supercontinente Pangea, pelos seus dados geológicos gerais, geocronológicos e paleomagnéticos, é o único que pode ser colocado no status de fato científico. Todas as demais configurações propostas anteriores à Pangea são boas hipóteses de trabalho, a serem investigadas/exploradas de forma multidisciplinar.

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“…20 to use such oscillations for establishing tectonic periods in the Earth's history, which naturally divides itself into epochs of high and low intensities of tectono-magmatic processes measured by the quantity of volcanic and metamorphic rocks of the corresponding age in the Earth's continental crust. The histogram constructed by Dearnley (21) to show the ages of such rocks (Fig. 4) reveals four maxima with the ages of 2.6, 1.9, 1.0, and 0.4-0.25 billion years.…”

Section: Tectono-magmatic Processesmentioning

confidence: 99%

“…The historic sequence of the forms of convection in the Earth's mantle could be the following. It reached intensity sufficient for breaking the protogenic lithosphere cooled by heat emission to the outside to form the first rifts and plate subduction zones and make a start for magmatic outflows, mantle (21)]. Tectono-magmatic activity is given in terms of relative amounts of volcanic and metamorphic rocks in the Earth's continental crust.…”

Section: Tectono-magmatic Processesmentioning

confidence: 99%

On some global problems of geophysical fluid dynamics (A Review)

Monin

1978

Proc. Natl. Acad. Sci. U.S.A.

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Orogenic fold-belts and a hypothesis of earth evolution

Cited by 27 publications

References 225 publications

A Discussion on the evolution of the Precambrian crust - A plate tectonic model for the Archaean crust

A Discussion on the evolution of the Precambrian crust - A plate tectonic model for the Archaean crust

A Teoria dos Supercontinentes: discussão e crítica construtiva

On some global problems of geophysical fluid dynamics (A Review)

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