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Petroleum Geological Survey
Published in Muhammad Abdul Quddus, Petroleum Science and Technology, 2021
Ocean and continental crusts are not in static conditions, both are dynamic (very slow movement). The movement of oceanic crust is termed ‘ocean floor spreading’ and the motion of land crust is known as ‘continental drifting’. The ocean bottom crust is spreading from the mid-ocean ridges. Similarly the continental crust is drifting from its position slowly. Continental drifting and ocean floor spreading are due to underground geological processes. All geological processes originate from the movement of hot magma in the earth's mantle. The upwelling molten magma affects the ocean and continental crusts. These geological processes are also responsible for sea floor spreading (formation of new crust), and continental drifting for the creation of mid-ocean ridges, oceanic trenches, the collision of crusts, rock subduction, etc. Important geological processes are volcanic activities, earthquakes and plate tectonic.
Bathymetry: Features and Hypsography
Published in Yeqiao Wang, Coastal and Marine Environments, 2020
Heidi M. Dierssen, Albert E. Theberge
Comprehension of the significance and inter-relationships of the primary and secondary features of the seafloor has come about only since the formulation of the theory of plate tectonics. Plate tectonics describes the surface of the Earth in terms of numerous plates that either move away from each other at divergent plate boundaries, collide at convergent plate boundaries, or slide past each other along great faults known as transform faults. The median valleys of mid-oceanic ridges are the primary location of divergent boundaries, also known as seafloor spreading centers, where new seafloor is being produced from upwelling magma. Sites where plates collide with one plate being thrust under another consuming the seafloor, known as subduction zones, are marked by the great oceanic trenches, while colliding plates with no subduction form the great terrestrial mountain ranges of the world such as the Alpine- Himalayan belt of Europe and Asia. Sites where plates slide past one another are marked primarily by the numerous offsets on the mid-oceanic ridge system and are known as transform faults or fracture zones.
Magmatism and Magmatic Rocks
Published in Aurèle Parriaux, Geology, 2018
This is the basis of the second main principle of plate tectonics: the theory of seafloor spreading, which also introduces a new idea, that of the perpetual recycling of the crust. The ocean floor created at the ridges progresses to subduction zones where it sinks into the mantle. The continents also move but their lighter density prevents them from sinking into the mantle.
Scientific ocean drilling in the Australasian region: a review
Published in Australian Journal of Earth Sciences, 2022
The fundamental process of continental extension and breakup leading to amagmatic or magmatic seafloor spreading has been the object of intensive study (e.g. Lister et al., 1991), not least by the various incarnations of scientific ocean drilling programs. It has become clear from combinations of geophysical, petrologic, tectonic and modelling studies that non-rigid behaviour of the lithosphere is involved during these processes. Kusznir and Karner (2007) noted that depth-dependent continental lithosphere thinning is common at many rifted margins. For example, Kington and Goodliffe (2008) stated “extension during continental rifting is inferred to occur primarily in the mantle lithosphere while the upper crust extends at a much slower rate, with the difference accommodated by shear in the mid or lower crust”. West of the actively propagating tip of the Woodlark Ridge, extension of the continental crust has resulted in the generation of metamorphic core complexes and markedly rapid uplift of high-pressure metamorphic rocks from the lower crust and upper mantle (e.g. Abers et al., 2002; Baldwin et al., 2008; Little et al., 2007).