Tracing the thermal evolution of the Corsican lower crust during Tethyan rifting

Nikki M. Seymour, Daniel F. Stockli, Marco Beltrando, Andrew James Smye

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

Continental rifting requires thinning the continental lithosphere from ~120 km to <20 km by a series of processes which each impart a characteristic thermal signature to the extending lithosphere. Here high-resolution thermochronology is used to trace the synrift thermal evolution within a lower crustal section of an upper plate hyperextended margin sampled in Corsica. Novel zircon, rutile, and apatite 206Pb/238U depth profiling coupled with garnet trace element diffusion modeling provide compelling evidence for rift-related crustal reheating. A Jurassic thermal pulse is recorded in the footwall of the Belli Piani Shear Zone (BPSZ), where 200–180 Ma zircon 206Pb/238U overgrowth ages on Permian core populations and the preservation of stranded diffusion profiles in resorbed garnets implies the dominant footwall fabric formed as a result of high-temperature (T ~ 800°C) ductile thinning of the lower crust. Conductive reheating of middle crustal rocks in the immediate BPSZ hanging wall, demonstrated by Jurassic apatite 206Pb/238U ages, was likely achieved by synkinematic juxtaposition against the hot footwall and wholesale conductive steepening of geothermal gradients. Subsequent rapid cooling from 180 to 160 Ma, coeval with extensional unroofing of the footwall, underscores the importance of extreme ductile thinning during crustal hyperextension. The results of this study suggest that early lithospheric-scale depth-dependent thinning follows an early phase of diffuse rifting and tectonic subsidence and triggers crustal reheating during early hyperextension. Continued extension results in rapid exhumation and cooling of the lower crust, extreme crustal attenuation, and mantle exhumation followed by relaxation to a steady state thermal field coeval with the start of seafloor spreading.

Original languageEnglish (US)
Pages (from-to)2439-2466
Number of pages28
JournalTectonics
Volume35
Issue number10
DOIs
StatePublished - Oct 1 2016

Fingerprint

thermal evolution
footwall
tracing
lower crust
rifting
crusts
apatites
thinning
lithosphere
Apatites
garnets
heating
Garnets
exhumation
apatite
shear
shear zone
cooling
garnet
zircon

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Geochemistry and Petrology

Cite this

Seymour, Nikki M. ; Stockli, Daniel F. ; Beltrando, Marco ; Smye, Andrew James. / Tracing the thermal evolution of the Corsican lower crust during Tethyan rifting. In: Tectonics. 2016 ; Vol. 35, No. 10. pp. 2439-2466.
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Tracing the thermal evolution of the Corsican lower crust during Tethyan rifting. / Seymour, Nikki M.; Stockli, Daniel F.; Beltrando, Marco; Smye, Andrew James.

In: Tectonics, Vol. 35, No. 10, 01.10.2016, p. 2439-2466.

Research output: Contribution to journalArticle

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