|Paper No. 21-0|
|DEEP REFRIGERATION OF AN EVOLVING THRUST AND FOLD BELT BY ENHANCED PENETRATION OF METEORIC WATER: THE LEWIS THRUST SHEET, SOUTHERN CANADIAN ROCKY MOUNTAINS|
PRICE, Raymond A., Department of Geological Sciences and Geological Engineering, Queen's Univeristy, Kingston, ON K7L 3N6, Canada, firstname.lastname@example.org, OSADETZ, Kirk A., Geol Survey of Canada - Calgary, 3303 33rd St. N.W, Calgary, AB T2L 2A7, Canada, KOHN, Barry P., School of Earth Science, The Univeristy of Melbourne, Victoria, 3010, Australia, and FEINSTEIN, Shimon, Department of Geological and Environmental Sciences, Ben-Gurion Univ, Beer Sheva, 84105, Israel|
Refrigeration because of advective heat transport by deeply penetrating meteoric water is an integral part of the evolution of a foreland thrust and fold belt. Topographic relief generated during thrusting and folding drives large-scale deep penetration of cold meteoric water; and dilation due to the brittle deformation that accompanies thrusting and folding provides enhanced pervasive permeability. These considerations may resolve an apparent paradox in the thermal evolution of the Lewis thrust sheet and the rocks beneath it. The intuitively appealing notion that tectonic burial beneath a thick thrust sheet must lead to substantial heating of the rocks that are overridden is contradicted in the case of the Lewis thrust sheet in a region where it was > 8 km thick. Coalification levels in Upper Cretaceous rocks beneath the Lewis thrust sheet are low (0.74 % VR); and the thermal history of rocks both within and below the thrust sheet, as deduced from apatite and zircon fission track analysis, requires rapid cooling at the time of thrusting. The paradox may be ascribed to unwarranted assumptions about the relative roles of conductive and advective heat transport during and after thrusting. Meso-scale tectonic fabrics record brittle dilation and associated solution transport and precipitation during thrusting and thrust-related folding. "Penetrative" deformation was accomplished mainly by fracturing and by slip on joints, bedding, and small faults. Reconnaissance regional stable-isotope geochemistry of vein-filling minerals indicates that deep penetration of meteoric water was widespread in the southeastern Canadian Cordillera (Nesbitt and Muehlenbachs, GSAB, v. 107, 1033-1050, 1995; CJES, v. 32, 1699-1719, 1995). Diachronous, foreland-migrating, Upper Cretaceous chemical remagnetization of Devonian and Mississippian carbonate rocks in the Front Ranges of the southern Canadian Rocky Mountains provides evidence of hot pore fluids flowing through these rocks prior, probably just prior, to their incorporation into the evolving foreland thrust and fold belt (Enkin et al., GSAB, v. 112, 929-942, 2000). This "hot flush" evidently was driven ahead of the deeply penetrating cold meteoric water that refrigerated the developing thrust sheets and made them even more brittle.
GSA Annual Meeting, November 5-8, 2001
General Information for this Meeting
|Session No. 21|
Rheological Effects of Fluid-Rock Interactions at Depth: From Experimental Constraints to Interpretations of Field Observations
Hynes Convention Center: 200
8:00 AM-12:00 PM, Monday, November 5, 2001
© Copyright 2001 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.