The 3D thermal field across the Alpine orogen and its forelands and the relation to seismicity

https://doi.org/10.1016/j.gloplacha.2020.103288Get rights and content
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Highlights

  • Bulk lithology asserts a primary control on maximum temperature of seismicity.

  • The thermal effect of alpine topography is present to lower crustal depths (20 km).

  • The Adriatic crust is more mafic than the European crust.

Abstract

Temperature exerts a first order control on rock strength, principally via thermally activated creep deformation and on the distribution at depth of the brittle-ductile transition zone. The latter can be regarded as the lower bound to the seismogenic zone, thereby controlling the spatial distribution of seismicity within a lithospheric plate. As such, models of the crustal thermal field are important to understand the localisation of seismicity. Here we relate results from 3D simulations of the steady state thermal field of the Alpine orogen and its forelands to the distribution of seismicity in this seismically active area of Central Europe. The model takes into account how the crustal heterogeneity of the region effects thermal properties and is validated with a dataset of wellbore temperatures. We find that the Adriatic crust appears more mafic, through its radiogenic heat values (1.30E-06 W/m3) and maximum temperature of seismicity (600 °C), than the European crust (1.3–2.6E-06 W/m3 and 450 °C). We also show that at depths of <10 km the thermal field is largely controlled by sedimentary blanketing or topographic effects, whilst the deeper temperature field is primarily controlled by the LAB topology and the distribution and parameterization of radiogenic heat sources within the upper crust.

Keywords

Steady-state
Thermal-field
Europe
Alps
Adria
Seismicity

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