Preprints
https://doi.org/10.5194/egusphere-2025-390
https://doi.org/10.5194/egusphere-2025-390
11 Feb 2025
 | 11 Feb 2025

Characterizing some major Archean faults at depth in the Superior craton, North America

David B. Snyder, Jack M. Simmons, John A. Ayer, Mostafa Naghizadeh, Ademola Q. Adetunji, Taus R. C. Jørgensen, Graham J. Hill, Eric A. Roots, and Saeid Cheraghi

Abstract. The geometry of ancient faults at depth can only be mapped by high-resolution geophysical surveys such as seismic reflection profiling. Recent deep (35–48 km) reflection profiles acquired across the Archean southern Superior craton of North America provided such data with which to map in 3-D some major shear zones, many of which are associated with significant orogenic gold or VMS deposits. Most faults are (re)interpreted as thrusts; a few appear as sub-vertically aligned breaks in prominent reflectors. Sub-vertical faults possibly originated as syn-volcanic transform faults. Thrusting probably relates to the dominant phase of folding and horizontal shortening strain that occurred during the regional crustal deformation, mineralization and peak metamorphism at 2.72–2.66 Ga, associated with the Kenoran orogeny. Most deformation after this orogenic event resulted in modest lateral movement. Coincident magnetotelluric (MT) surveys indicate pervasive conductive minerals such as graphite/carbon and sulfides, exist within the mid-crust and in near-vertical channels within the more brittle and resistive upper (greenstone) crust. Many such channels, but not all, coincide with fault zones and mineral deposits. Palinspastic and paleomagnetic-based reconstructions suggest many faults had multiple periods of activity with changing vertical to horizontal offsets. Some faults appear paired, partitioning normal and oblique strains on vertical shear zones and dipping thrust zones, respectively.

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Journal article(s) based on this preprint

05 Sep 2025
Characterizing some major Archean faults at depth in the Superior craton, North America
David B. Snyder, Jack M. Simmons, John A. Ayer, Mostafa Naghizadeh, Ademola Q. Adetunji, Taus R. C. Jørgensen, Graham J. Hill, Eric A. Roots, and Saeid Cheraghi
Solid Earth, 16, 785–806, https://doi.org/10.5194/se-16-785-2025,https://doi.org/10.5194/se-16-785-2025, 2025
Short summary
David B. Snyder, Jack M. Simmons, John A. Ayer, Mostafa Naghizadeh, Ademola Q. Adetunji, Taus R. C. Jørgensen, Graham J. Hill, Eric A. Roots, and Saeid Cheraghi

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Report on “Characterizing some major Archean faults at depth in the Superior craton, North America” by David Snyder et al.', Anonymous Referee #1, 20 Mar 2025
    • AC1: 'Reply on RC1', David Snyder, 16 Apr 2025
  • RC2: 'Comment on egusphere-2025-390', Anonymous Referee #2, 24 Mar 2025
    • AC2: 'Reply on RC2', David Snyder, 16 Apr 2025
  • EC1: 'Comment on egusphere-2025-390', Christopher Juhlin, 27 Mar 2025
    • AC3: 'Reply on EC1', David Snyder, 16 Apr 2025

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Report on “Characterizing some major Archean faults at depth in the Superior craton, North America” by David Snyder et al.', Anonymous Referee #1, 20 Mar 2025
    • AC1: 'Reply on RC1', David Snyder, 16 Apr 2025
  • RC2: 'Comment on egusphere-2025-390', Anonymous Referee #2, 24 Mar 2025
    • AC2: 'Reply on RC2', David Snyder, 16 Apr 2025
  • EC1: 'Comment on egusphere-2025-390', Christopher Juhlin, 27 Mar 2025
    • AC3: 'Reply on EC1', David Snyder, 16 Apr 2025

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload
AR by David Snyder on behalf of the Authors (17 Apr 2025)  Author's response   Author's tracked changes   Manuscript 
ED: Referee Nomination & Report Request started (23 Apr 2025) by Christopher Juhlin
RR by Anonymous Referee #3 (06 May 2025)
RR by Anonymous Referee #1 (19 May 2025)
ED: Publish subject to minor revisions (review by editor) (21 May 2025) by Christopher Juhlin
AR by David Snyder on behalf of the Authors (04 Jun 2025)  Author's response   Author's tracked changes   Manuscript 
ED: Publish subject to technical corrections (08 Jun 2025) by Christopher Juhlin
ED: Publish subject to technical corrections (13 Jun 2025) by Michal Malinowski (Executive editor)
AR by David Snyder on behalf of the Authors (23 Jun 2025)  Manuscript 

Journal article(s) based on this preprint

05 Sep 2025
Characterizing some major Archean faults at depth in the Superior craton, North America
David B. Snyder, Jack M. Simmons, John A. Ayer, Mostafa Naghizadeh, Ademola Q. Adetunji, Taus R. C. Jørgensen, Graham J. Hill, Eric A. Roots, and Saeid Cheraghi
Solid Earth, 16, 785–806, https://doi.org/10.5194/se-16-785-2025,https://doi.org/10.5194/se-16-785-2025, 2025
Short summary
David B. Snyder, Jack M. Simmons, John A. Ayer, Mostafa Naghizadeh, Ademola Q. Adetunji, Taus R. C. Jørgensen, Graham J. Hill, Eric A. Roots, and Saeid Cheraghi
David B. Snyder, Jack M. Simmons, John A. Ayer, Mostafa Naghizadeh, Ademola Q. Adetunji, Taus R. C. Jørgensen, Graham J. Hill, Eric A. Roots, and Saeid Cheraghi

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Short summary
Sub-surface geometries of ancient faults must be mapped using high-resolution geophysical surveys using reflected seismic waves. Several such surveys in southern Canada map faults, many of which host significant gold or nickel deposits. Reflectors are considered upper crustal brittle, lava flows if folded or broken or mid-crustal if mostly parallel. Steep fault zones formed first in ocean settings when the lavas erupted. Folds and horizontal shortening occurred during later mountain building.
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