A Review of the Thermal-Mechanical Structures at Convergent Plate Boundaries and their Implications for Crust/Mantle Recycling
Oceanic plates are derived from the mantle at mid-ocean ridges. They migrate away until they reach convergent zones where they subduct into the mantle and in time they will be assimilated through heating. This represents the large scale crust/mantle recycling process. There are other processes that contribute to recycling at smaller scales. Island arc volcanism and back-arc spreading at convergent plate boundaries are some of the examples. Dynamic motions responsible for recycling are driven largely through thermal mechanisms. In this paper we review the thermal mechanical processes at zones of plate convergence and their implications to geological recycling processes. From a thermal point of view, plate subduction represents the cooling of the mantle since “cold” lithospheric plates are being returned to the “hot” interior. However, surface geological observations do not support the notion that extensive cooling has occurred within the mantle surrounding a descending slab, although the slab itself remains relatively cool. Active island arc volcanism and the high heat flows observed in back arc regions suggest the existence of a hot mantle above the subducting slab, produced by induced motions or secondary processes, that play an important role in influencing local geological evolution.
KeywordsMantle Wedge Recycling Process High Heat Flow Plate sUbduction Convergent Plate Boundary
Unable to display preview. Download preview PDF.
- Toksöz, M.N., W.R. Buck and A.T. Hsui, ′Crustal evolution and thermal state of Tibet′, in D.S. Liu (ed.), Geological and Ecological Studies of Qinqhai-Xizang Plateau, Gordon and Breach, New York, NY 847–857, 1981.Google Scholar
- Toksöz, M.N., N.H. Sleep and A.T. Smith, ′Evolution of the downgoing lithosphere and the mechanisms of deep focus earthquakes.′ Geophys. J.R. Astr. Soc., 35, 285–310, 1973.Google Scholar