Chapter 6. Underthrusting of the Lithosphere and Plate Tectonics

This page uses JavaScript to progressively load the article content as a user scrolls. Screen reader users, click the load entire article button to bypass dynamically loaded article content. JavaScript is disabled on your browser. Please enable JavaScript to use all the features on this page. This page uses JavaScript to progressively load the article content as a user scrolls. Click the View full text link to bypass dynamically loaded article content. This chapter discusses the underthrusting of the lithosphere and plate tectonics. Excellent seismic evidence tells us that the lithosphere is absorbed by underthrusting mostly at deep oceanic trenches to compensate its widening at the ridges. “Subduction,” as this consumption process is called, and spreading of the lithosphere are united in the theory of plate tectonics magnetic evidence, for the consumption of the lithosphere at oceanic trenches, consists of the disappearance of the lineated magnetic anomalies where the latter reach the trench. Bathymetric and magnetic surveys have shown that the expanding oceanic ridges consist of straight sections nearly parallel to each other that are connected by faults at right angles to them. Each section of the ridge terminates abruptly at these “transform faults.” The relative motions of the plates at the present instant of geologic time can be represented by angular velocity vectors through their poles of rotation. Two or more known vectors can be added around a circuit to give the direction and magnitude of a vector that has not been directly measured. However, this analysis is valid only for infinitesimal rotations. Copyright © 2016 Elsevier B.V. or its licensors or contributors. ScienceDirect® is a registered trademark of Elsevier B.V. Source.


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