Synchronism between development of Cenozoic volcanic arcs and back-arc basins: Reasons and consequences |
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| Authors: | O A Bogatikov E V Sharkov A V Vesselovskii V B Mescheryakova |
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| Institution: | (1) Dept. Geology, University of Rajasthan, 302004 Jaipur, India |
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| Abstract: | A geographic information system (GIS “Volcanic belts”) was used for analyzing the spatial and temporal relationship between
tectono-magmatic cycles in the Cenozoic that took place at the convergent plate boundaries, mostly in volcanic arc-back-arc
systems. The onset of back-arc basins and subaerial arc volcanism and their main evolutionary stages are shown to have occurred
about the same time. These processes are still ongoing, which is indicated by today’s active volcanoes, high heat flows, and
high deep-focus seismicity. The crust underlying both tectonic structures undergoes transformation, which results in a significant
thinning of the “granite” layer within the volcanic belts, whereas crust within the back-arc basins changes its properties
to the transitional (suboceanic) and oceanic type crusts. All processes that occur at the convergent plate boundaries can
be described within the arc-back-arc system, the principal dynamic components of which are the asthenospheric plume upwelling
above the continent edge and the oceanward-spreading plume head. This was accompanied by a gradual crustal thinning in the
back-arc region and the formation of areas with oceanic crust, as well as by involvement of crustal material, together with
rocks of the subducting slab, into subduction processes. As a result, the continental crust is removed from the tectonosphere
and stored in the “slab cemetery.” Only a minor portion of the crustal materials is returned to the surface as subduction-related
magmatism. |
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