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Glarus overthrust: A major pathway for the escape of fluids out of the Alpine orogen
Auteur(s)
Badertscher, Nicolas P.
Beaudoin, Georges
Therrien, René
Date de parution
2001
In
Geology, Geological Society of America, 2001/30/10/875-878
Résumé
Thrust-related fluid flow coupled with isotopic exchange between fluid and rock is simulated in a three-dimensional finite-element model of the Glarus nappe, eastern Swiss Alps. Numerical simulations are matched against well-established oxygen isotope gradients on the kilometer scale along the thrust. At internal southern locations, strongly channelized thrust-parallel fluid flow requires a high permeability contrast of >100:1 between the mylonite zone and country rocks and a high hydraulic head in the hinterland and footwall. In contrast, isotopic patterns ∼5–10 km farther north indicate a predominantly vertical, upward drainage of fluids. We propose a situation in which the Glarus thrust evolved northward across the boundary between the lithostatic and hydrostatic fluid- pressure regimes—the “impermeable cap.” A cyclic behavior of fluid-pressure buildup, fracturing, channelized fluid escape, and sealing explains structural and geochemical observations and the best-fit three-dimensional fluid-flow model parameters.
Identifiants
Type de publication
journal article
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