Syn- and post-collisional heat flow in the Cenozoic Eastern Alps |
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| Authors: | Reinhard F Sachsenhofer |
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| Institution: | Montanuniversit?t Leoben, Institut fur Geowissenschaften, Peter Tunner-Stra?e 5, 8700 Leoben, Austria,
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| Abstract: | The heat flow evolution of a continental collisional zone is exemplified by the Eastern Alps. Heat flow maps for the syn-collision (Oligocene), syn-extrusion (Early/Middle Miocene), and post-extrusion (Late Miocene, Recent) stages are presented, and are discussed in relation to the orogenic evolution. Continental collision during Paleogene time was characterized by extremely low heat flow (<40 mW/m2) along the orogenetic front, and very high heat flow (>150 mW/m2) a few hundred kilometers south of it. The former was a result of crustal thickening and of thermal blanketing due to rapid sedimentation and nappe stacking. The latter was caused by slab break-off and magmatic activity. The Early/Middle Miocene syn-extrusion stage was characterized by rapid exhumation of metamorphic core complexes (Tauern and Rechnitz Windows), and by magmatic activity (Styrian Basin). Both mechanisms caused extremely high heat flow (>200 mW/m2). In contrast, the orogenetic front remained cold. Thereafter, magmatic activity ended and uplift rates decreased. Thus, Late Miocene heat flow is characterized by low to moderately high values. Heat flow values >75 mW/m2 were restricted to the transition zone of the Pannonian Basin characterized by thinned crust, and to the Tauern Window area. Recent temperature data indicate a subtle post-Miocene increase in heat flow. |
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