Basin scale evolution of zebra textures in fault-controlled, hydrothermal dolomite bodies: insights from the Western Canadian Sedimentary Basin

McCormick, C. A., Corlett, H., Clog, M. , Boyce, A. J. , Tartèse, R., Steele‐MacInnis, M. and Hollis, C. (2023) Basin scale evolution of zebra textures in fault-controlled, hydrothermal dolomite bodies: insights from the Western Canadian Sedimentary Basin. Basin Research, 35(5), pp. 2010-2039. (doi: 10.1111/bre.12789)

Abstract

Structurally controlled dolomitization typically involves the interaction of high-pressure (P), high-temperature (T) fluids with the surrounding host rock. Such reactions are often accompanied by cementation and recrystallization, with the resulting hydrothermal dolomite (HTD) bodies including several ‘diagnostic’ rock textures. Zebra textures, associated with boxwork textures and dolomite breccias, are widely considered to reflect these elevated P/T conditions. Although a range of conceptual models have been proposed to explain the genesis of these rock textures, the processes that control their spatial and temporal evolution are still poorly understood. Through the detailed petrographical and geochemical analysis of HTD bodies, hosted in the Middle Cambrian strata in the Western Canadian Sedimentary Basin, this study demonstrates that a single genetic model cannot be applied to all the characteristics of these rock textures. Instead, a wide array of sedimentological, tectonic and metasomatic processes contribute to their formation; each of which is spatially and temporally variable at the basin scale. Distal to the fluid source, dolomitization is largely stratabound, comprising replacement dolomite, bedding-parallel zebra textures and rare dolomite breccias (non-stratabound, located only proximal to faults). Dolomitization is increasingly non-stratabound with proximity to the fluid source, comprising bedding-inclined zebra textures, boxwork textures and dolomite breccias that have been affected by recrystallization. Petrographical and geochemical evidence suggests that these rock textures were initiated due to dilatational fracturing, brecciation and precipitation of saddle dolomite as a cement, but significant recrystallization occurred during the later stages of dolomitization. These rock textures are closely associated with faults and carbonate-hosted ore deposits (e.g. magnesite, rare earth element and Mississippi Valley–type mineralization), thus providing invaluable information regarding fluid flux and carbonate metasomatism under elevated P/T conditions.

• Item Type: Articles
• Additional Information: This work was conducted as part of C. A. McCormick's doctoral research, funded by the President's Doctoral Scholar Award (The University of Manchester). We are grateful to Parks Canada and Alberta Tourism, Parks and Recreation for the research and collection permits.δ13C, δ18O and Δ47analyses were made possible by a National Environmental Isotope Facility grant from the Natural Environment Research Council (NERC). The authors acknowledge The University of Manchester and the Science and Technology Facilities Council (#ST/S002170/1) for funding the LA ICP- MS facility and the NERC- funded Nanoscale Imaging and Analysis Facility for Environmental Materials in the Williamson Research Centre for Molecular Environmental Science (NERCCC042). Additional support to C.A. McCormick came from the Society for Sedimentary Geology Foundation(Student Research Grant), the International Association of Sedimentologists (Postgraduate Research Grant),the British Sedimentological Research Group (Trevor Elliot Memorial Grant) and the American Association of Petroleum Geologists Foundation (Classen Family Named Grant).
• Keywords: Rare earth element analysis, zebra texture, saddle dolomite, recrystallization, fault‐controlled dolomitization, clumped isotope thermometry.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Boyce, Professor Adrian and Clog, Dr Matthieu
• Authors: McCormick, C. A., Corlett, H., Clog, M., Boyce, A. J., Tartèse, R., Steele‐MacInnis, M., and Hollis, C.
• College/School: College of Science and Engineering > Scottish Universities Environmental Research Centre
• Journal Name: Basin Research
• Publisher: Wiley
• ISSN: 0950-091X
• ISSN (Online): 1365-2117
• Published Online: 23 June 2023
• Copyright Holders: Copyright © 2023 The Authors
• First Published: First published in Basin Research 35(5):2010-2039
• Publisher Policy: Reproduced under a Creative Commons license