Researchers build model that may explain how plate tectonics got its start

Researchers build model that may explain how plate tectonics got its start

center_img PausePlay% buffered00:0000:00UnmuteMuteDisable captionsEnable captionsSettingsCaptionsDisabledQuality0SpeedNormalCaptionsGo back to previous menuQualityGo back to previous menuSpeedGo back to previous menu0.5×0.75×Normal1.25×1.5×1.75×2×Exit fullscreenEnter fullscreen More information: Plate tectonics, damage and inheritance, Nature (2014) DOI: 10.1038/nature13072AbstractThe initiation of plate tectonics on Earth is a critical event in our planet’s history. The time lag between the first proto-subduction (about 4 billion years ago) and global tectonics (approximately 3 billion years ago) suggests that plates and plate boundaries became widespread over a period of 1 billion years. The reason for this time lag is unknown but fundamental to understanding the origin of plate tectonics. Here we suggest that when sufficient lithospheric damage (which promotes shear localization and long-lived weak zones) combines with transient mantle flow and migrating proto-subduction, it leads to the accumulation of weak plate boundaries and eventually to fully formed tectonic plates driven by subduction alone. We simulate this process using a grain evolution and damage mechanism with a composite rheology (which is compatible with field and laboratory observations of polycrystalline rocks1, 2), coupled to an idealized model of pressure-driven lithospheric flow in which a low-pressure zone is equivalent to the suction of convective downwellings. In the simplest case, for Earth-like conditions, a few successive rotations of the driving pressure field yield relic damaged weak zones that are inherited by the lithospheric flow to form a nearly perfect plate, with passive spreading and strike-slip margins that persist and localize further, even though flow is driven only by subduction. But for hotter surface conditions, such as those on Venus, accumulation and inheritance of damage is negligible; hence only subduction zones survive and plate tectonics does not spread, which corresponds to observations. After plates have developed, continued changes in driving forces, combined with inherited damage and weak zones, promote increased tectonic complexity, such as oblique subduction, strike-slip boundaries that are subparallel to plate motion, and spalling of minor plates. An idealized simulation showing how plate-tectonic boundaries (including complex ones) emerge because of inherited damage following a shift in plate-tectonic driving forces; in this case the shift is similar to that which caused the Emperor-Hawaiian Bend in the Pacific. Credit: David Bercovici Citation: Researchers build model that may explain how plate tectonics got its start (2014, April 7) retrieved 18 August 2019 from https://phys.org/news/2014-04-plate-tectonics.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. An idealized simulation showing how plate-tectonic boundaries (including complex ones) emerge because of inherited damage following a shift in plate-tectonic driving forces; in this case the shift is similar to that which caused the Emperor-Hawaiian Bend in the Pacific. Credit: David Bercovicilast_img

Leave a Reply

Your email address will not be published. Required fields are marked *

Recent Comments