Continental Drift and Sea Floor Spreading, The Forerunners of Plate Tectonics

2013 ◽  
pp. 31-39
Keyword(s):  
Plate Tectonics ◽  
Continental Drift ◽  
Sea Floor ◽  
Sea Floor Spreading

scholarly journals A Geologist Reflects on a Long Career

2018 ◽  
Vol 46 (1) ◽  
pp. 1-20 ◽  
Author(s):  
Dan MKenzie
Keyword(s):  
Plate Tectonics ◽  
Continental Drift ◽  
Temperature Structure ◽  
Earth’S Gravity Field ◽  
Plate Motions ◽  
Sea Floor ◽  
Long Wavelength ◽  
Geological Processes ◽  
The Earth ◽  
Sea Floor Spreading

Fifty years ago Jason Morgan and I proposed what is now known as the theory of plate tectonics, which brought together the ideas of continental drift and sea floor spreading into what is probably their final form. I was twenty-five and had just finished my PhD. The success of the theory marked the beginning of a change of emphasis in the Earth sciences, which I have spent the rest of my career exploring. Previously geophysicists had principally been concerned with using ideas and techniques from physics to make measurements. But the success of plate tectonics showed that it could also be used to understand and model geological processes. This essay is concerned with a few such efforts in which I have been involved: determining the temperature structure and rheology of the oceanic and continental lithosphere, and with how mantle convection maintains the plate motions and the long-wavelength part of the Earth's gravity field. It is also concerned with how such research is supported.

scholarly journals Geological archive of the onset of plate tectonics

2018 ◽  
Vol 376 (2132) ◽  
pp. 20170405 ◽  
Author(s):  
Peter A. Cawood ◽  
Chris J. Hawkesworth ◽  
Sergei A. Pisarevsky ◽  
Bruno Dhuime ◽  
Fabio A. Capitanio ◽  
...  
Keyword(s):  
Plate Tectonics ◽  
Foreland Basin ◽  
Sea Floor ◽  
Palaeomagnetic Data ◽  
Peraluminous Granites ◽  
Lithospheric Plates ◽  
Crustal Reworking ◽  
Sea Floor Spreading ◽  
Back Arc ◽  
Earth Dynamics

Plate tectonics, involving a globally linked system of lateral motion of rigid surface plates, is a characteristic feature of our planet, but estimates of how long it has been the modus operandi of lithospheric formation and interactions range from the Hadean to the Neoproterozoic. In this paper, we review sedimentary, igneous and metamorphic proxies along with palaeomagnetic data to infer both the development of rigid lithospheric plates and their independent relative motion, and conclude that significant changes in Earth behaviour occurred in the mid- to late Archaean, between 3.2 Ga and 2.5 Ga. These data include: sedimentary rock associations inferred to have accumulated in passive continental margin settings, marking the onset of sea-floor spreading; the oldest foreland basin deposits associated with lithospheric convergence; a change from thin, new continental crust of mafic composition to thicker crust of intermediate composition, increased crustal reworking and the emplacement of potassic and peraluminous granites, indicating stabilization of the lithosphere; replacement of dome and keel structures in granite-greenstone terranes, which relate to vertical tectonics, by linear thrust imbricated belts; the commencement of temporally paired systems of intermediate and high dT/dP gradients, with the former interpreted to represent subduction to collisional settings and the latter representing possible hinterland back-arc settings or ocean plateau environments. Palaeomagnetic data from the Kaapvaal and Pilbara cratons for the interval 2780–2710 Ma and from the Superior, Kaapvaal and Kola-Karelia cratons for 2700–2440 Ma suggest significant relative movements. We consider these changes in the behaviour and character of the lithosphere to be consistent with a gestational transition from a non-plate tectonic mode, arguably with localized subduction, to the onset of sustained plate tectonics. This article is part of a discussion meeting issue ‘Earth dynamics and the development of plate tectonics'.

Introductory remarks

1980 ◽  
Vol 297 (1431) ◽  
pp. 137-138
Keyword(s):  
Mantle Convection ◽  
Plate Tectonics ◽  
Sharp Change ◽  
Indirect Approach ◽  
Sea Floor ◽  
Wave Velocities ◽  
The Earth ◽  
Magnesium Silicates ◽  
Sea Floor Spreading ◽  
Seismic Discontinuity

The substratum of the Earth, as Arthur Holmes originally described it, now generally known as the mantle , is the envelope, mainly of magnesium silicates, surrounding the fluid metallic core. It is separated from the continental and oceanic crusts which overlie it by the Mohorovicic seismic discontinuity, where there is a sharp change from earthquake wave velocities less than 7.2 km s -1 above to 7.8-8.1 km s -1 below. The thickness of the envelope is of the order of 2900 km, compared with about 4 km for ocean crust and 30 km for unthickened continental crust. Much attention has been devoted by geophysicists to the properties of the mantle, particularly in the course of the Geodynamics Project of I.U.G.G./I.U.G.S., during which important conclusions regarding sea floor spreading, plate tectonics and mantle convection have been reached. The fact that the overwhelming bulk of the mantle is not, and never will be, accessible for direct collection has perhaps resulted in less interest so far from the geochemical side. Accepting, however, that a partly indirect approach is inevitable, the time is now ripe for a thorough examination of the contribution that geochemical techniques can make.

Sea-floor spreading and plate tectonics

Eos ◽  
1971 ◽  
Vol 52 (5) ◽  
pp. IUGG 130
Author(s):  
W. C. Pitman
Keyword(s):  
Plate Tectonics ◽  
Sea Floor ◽  
Sea Floor Spreading

Tuzo Wilson and the acceptance of pre-Mesozoic continental drift

2014 ◽  
Vol 51 (3) ◽  
pp. 197-207 ◽  
Author(s):  
Paul F. Hoffman
Keyword(s):  
Continental Drift ◽  
Early Experience ◽  
Canadian Shield ◽  
Sea Floor ◽  
Geologic Time ◽  
Sea Floor Spreading ◽  
Continental Accretion

Tuzo Wilson’s well-known pre-1961 opposition to continental drift stemmed from his early experience as a geologist in the Appalachians and the Canadian Shield, which convinced him that orogenesis did not change drastically over geologic time. Conversely, Taylor (in 1910) and Wegener (in 1912) hypothesized that continental drift began in Cenozoic or Mesozoic time. Between 1949 and 1960, Tuzo Wilson with Adrian Scheidegger developed a quasi-uniformitarian model of progressive continental accretion around fixed Archean nuclei. Tuzo abruptly jettisoned this model in 1961 when, under pressure from paleomagnetic evidence for continental drift and a nascent concept of sea-floor spreading, he finally entertained the possibility of pre-Mesozoic as well as younger continental drift. He immediately found it a superior fit to Appalachian and Shield geology, while his uniformitarian conviction remained intact. Tuzo had blinded himself to the evidence for continental drift so long as he confined it to Taylor or Wegener’s conception. In continental drift operating continuously over geologic time, he found a theory he could eagerly accept.

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