The conventional modeling of crustal temperatures is based on the steady-state approach, which is reliable in tectonically stable regions only. The present work focuses on the assessment of the influence of the transient effects on the thermal field at regions of ongoing continental collision. In the first part of this study, the thermal effects of most evident processes operating in collision zones (thickening and flaking of the crust, frictional heating on the surfaces of flakes, bulk replacement of mantle lithosphere by hotter rocks, and also uplift and erosion) are estimated on the basis of 1-D time-dependent synthetic models. The results show that surface heat flow caused by the most of investigated transient processes may differ from the steady-state one by quantities of the order of magnitude larger than the uncertainties of the heat flow measurements. These differences may exist over tens of millions of years. In the second part, three 2-D time-dependent temperature sections gradually including the above assessed effects have been calculated for the Central Alps. The results show that time-dependent models give better agreement of the calculated and measured heat flow patterns than previously developed for the same region steady-state model (Čermák et al., 1990). Best agreement is achieved when only the transient effects of thickening and flaking and increased heat inflow from the mantle are taken into account. A poorer coherence of the other versions with the measured heat flow is probably attributable to uncertain knowledge (and consequently great simplification) of spacing and time dependence of erosion and/or frictional heating.
ASJC Scopus subject areas
- Earth-Surface Processes