High-temperature granulites and supercontinents

Touret, J.L.R., Santosh, M., and Huizenga, J.M. (2016) High-temperature granulites and supercontinents. Geoscience Frontiers, 7 (1). pp. 101-113.

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Abstract

The formation of continents involves a combination of magmatic and metamorphic processes. These processes become indistinguishable at the crust-mantle interface, where the pressure-temperature (P-T) conditions of (ultra) high-temperature granulites and magmatic rocks are similar. Continents grow laterally, bymagmatic activity above oceanic subduction zones (high-pressure metamorphic setting), and vertically by accumulation of mantle-derived magmas at the base of the crust (high-temperature metamorphic setting). Both events are separated from each other in time; the vertical accretion postdating lateral growth by several tens of millions of years. Fluid inclusion data indicate that during the high-temperature metamorphic episode the granulite lower crust is invaded by large amounts of low H₂O-activity fluids including high-density CO₂ and concentrated saline solutions (brines). These fluids are expelled from the lower crust to higher crustal levels at the end of the high-grade metamorphic event. The final amalgamation of supercontinents corresponds to episodes of ultra-high temperature metamorphism involving large-scale accumulation of these low-water activity fluids in the lower crust. This accumulation causes tectonic instability, which together with the heat input from the subcontinental lithospheric mantle, leads to the disruption of supercontinents. Thus, the fragmentation of a supercontinent is already programmed at the time of its amalgamation.

Item ID: 42121
Item Type: Article (Research - C1)
ISSN: 1674-9871
Keywords: continents; supercontinents; magmatism and metamorphism; fluids; tectonics
Additional Information:

© 2015, China University of Geosciences (Beijing) and Peking University. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NCND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Funders: James Cook University (JCU)
Date Deposited: 12 Feb 2016 05:20
FoR Codes: 04 EARTH SCIENCES > 0403 Geology > 040304 Igneous and Metamorphic Petrology @ 40%
04 EARTH SCIENCES > 0402 Geochemistry > 040299 Geochemistry not elsewhere classified @ 40%
04 EARTH SCIENCES > 0404 Geophysics > 040402 Geodynamics @ 20%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970104 Expanding Knowledge in the Earth Sciences @ 100%
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