Role of pre-orogenic heat flow in subsequent thermal regimes

• Published in: Thrustbelts pp. 261 - 269
• Main Authors: Nemcok, Michal, Schamel, Steven, Gayer, Rod
• Format: Book Chapter
• Language: English
• Published: Cambridge University Press 13.10.2005
• Subjects: Geology, Exploration & Drilling; Oil & Gas Engineering
• ISBN: 9780521110433; 9780521822947; 0521822947; 0521110432
• DOI: 10.1017/CBO9780511584244.013

The initial heat flow, present in an area prior to shortening, plays an important role in establishing the later thermal regime of the local thrust sheets. It sets the stage for the syn-orogenic thermal regime by determining its initial character, although its influence progressively diminishes during the subsequent development stages. The flexural study of the Aquitaine foreland basin on the French side of the Pyrenees (Desegaulx et al., 1991) serves as an example of the influence of the heat flow that existed prior to the onset of shortening. This foreland basin developed on thinned continental lithosphere, inherited from pre-orogenic extensional phases. The extension-induced transient thermal state of the lithosphere resulted in ongoing thermal subsidence and changes of the flexural rigidity through time. Numerical modelling shows that the inherited transient thermal state of the lithosphere contributed to the total basin depth and width, the post-compressional subsidence history and the forelandward sediment onlap pattern. The thermomechanical effects of pre-orogenic extension significantly reduced the magnitudes of the flexural rigidity (30–43%) and the topographic or thrust load (40%) required to form this basin.The variety of basins capable of being later incorporated in thrustbelts can be reviewed according to their tectonic setting or geothermal signatures (Fig. 12.1, Table 12.1; e.g., Allen and Allen, 1990; Platte River Associates, 1995).The coolest thermal regimes are present in regions formed by old continental shield or old oceanic crust (Figs. 12.1 and 12.2, Table 12.1).