Pop-Up Structures and the Fracture Pattern in the Balsam Lake Area
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Document generated on 09/24/2021 10:54 a.m. Géographie physique et Quaternaire Pop-Up Structures and the Fracture Pattern in the Balsam Lake Area, Southern Ontario Les structures de soulèvement (pop-ups) ef le réseau de fissures dans la région de Balsam Lake, au sud de l’Ontario Hebungsstrukturen und Bruchmuster im Gebiet des Balsam Lake, südliches Ontario Andrea L. Rutty and Alexander R. Cruden La néotectonique de la région des Grands Lacs Article abstract Neotectonics of the Great Lakes area An examination of topographic lineaments detectable in Landsat TM images Volume 47, Number 3, 1993 and measurement of joints in outcrop in the Balsam Lake area reveals a systematic bedrock fracture pattern with three principal sets oriented 091°, URI: https://id.erudit.org/iderudit/032965ar 027°, and 152°. The 027° trend is parallel to a major aeromagnetic anomaly, the DOI: https://doi.org/10.7202/032965ar Niagara-Pickering Linear Zone (NPLZ), which underlies the Balsam Lake area and is thought to mark the sub-Paleozoic continuation of the Proterozoic Central Metasedimentary Belt Boundary Zone (CMBBZ). Possible origins of the See table of contents main joint sets due to Acadian (091° set), Alleghanian (152° set) and St. Lawrence rift system tectonics (091° and 027° sets) are discussed. En-echelon pop-up structures have a mean principal trend of 118°. They displace Lake Publisher(s) Algonquin paleobeaches, suggesting formation less than 12,500 years ago. The orientation of the pop-up structures is subnormal to the current in situ Les Presses de l'Université de Montréal maximum horizontal stress direction, SHmax (020°), and is parallel to members of the 091° joint set, indicating possible nuclea-tion on favourably-oriented ISSN pre-existing joints. These pop-ups are the only features in the Balsam Lake area 0705-7199 (print) with strong evidence for a neotectonic age. 1492-143X (digital) Explore this journal Cite this article Rutty, A. L. & Cruden, A. R. (1993). Pop-Up Structures and the Fracture Pattern in the Balsam Lake Area, Southern Ontario. Géographie physique et Quaternaire, 47(3), 379–388. https://doi.org/10.7202/032965ar Tous droits réservés © Les Presses de l'Université de Montréal, 1993 This document is protected by copyright law. Use of the services of Érudit (including reproduction) is subject to its terms and conditions, which can be viewed online. https://apropos.erudit.org/en/users/policy-on-use/ This article is disseminated and preserved by Érudit. Érudit is a non-profit inter-university consortium of the Université de Montréal, Université Laval, and the Université du Québec à Montréal. Its mission is to promote and disseminate research. https://www.erudit.org/en/ Géographie physique et Quaternaire, 1993, vol. 47, n° 3, p. 379-388, 11 fig., 2 tabl. POP-UP STRUCTURES AND THE FRACTURE PATTERN IN THE BALSAM LAKE AREA, SOUTHERN ONTARIO Andrea L. RUTTY and Alexander R. CRUDEN1 Department of Geology, University of Toronto, Erindale Campus, Mississauga, Ontario L5L1C6. ABSTRACT An examination of topo RÉSUMÉ Les structures de soulèvement ZUSAMMENFASSUNG Hebungsstrukturen graphic lineaments detectable in Landsat (pop-ups) ef le réseau de fissures dans la und Bruchmuster im Gebiet des Balsam TM images and measurement of joints in région de Balsam Lake, au sud de l'Ontario. Lake, sùdliches Ontario. Eine Untersuchung outcrop in the Balsam Lake area reveals a L'examen des linéaments topographiques der topographischen Lineamente die in systematic bedrock fracture pattern with repérables sur les images Landsat (TM) et la Landsat TM-Bildern nachweisbar sind und three principal sets oriented 091°, 027°, and mesure des diaclases dans un affleurement Messungen der Fugen in den Aufschlùssen 152°. The 027° trend is parallel to a major de la région de Balsam Lake révèle la pré des Balsam Lake-Gebiets lassen ein syste- aeromagnetic anomaly, the Niagara- sence d'un réseau de fractures dont l'orien matisches Bruchmuster des anstehenden Pickering Linear Zone (NPLZ), which under tation des trois principaux ensembles est Gesteins erkennen mit drei nach 091°, 027° lies the Balsam Lake area and is thought to 091°, 027° et 152°. La direction 027° est und 152° ausgerichteten Haupteinheiten. mark the sub-Paleozoic continuation of the parallèle à une anomalie aéromagnétique Die Ausrichtung nach 027° ist parallel zu Proterozoic Central Metasedimentary Belt majeure, la zone linéaire Niagara-Pickering, einer wichtigen aeromagnetischen Ano Boundary Zone (CMBBZ). Possible origins présente sous la région de Balsam Lake; on malie, der linearen Zone von Niagara- of the main joint sets due to Acadian (091° croit qu'elle identifie le prolongement sub- Pickering, die unter dem Balsam Lake- set), Alleghanian (152° set) and St. paléozoïque de l'aire limite de la zone méta- Gebiet liegt; man halt sie fur eine Lawrence rift system tectonics (091° and sédimentaire centrale protérozoïque. On subpalàozoische Fortfùhrung des Grenz- 027° sets) are discussed. En-echelon traite des origines possibles des principaux bereichs der proterozoischen zentralen pop-up structures have a mean principal ensembles de fractures attribuables aux sys metasedimentàren Gùrtel-zone. Man dis- trend of 118°. They displace Lake Algonquin paleobeaches, suggesting formation less tèmes acadien (091°), alléghanien (152°) et kutiert môgliche Ursprùnge der Hauptfugen- than 12,500 years ago. The orientation of the du rift du Saint-Laurent (091 °et 027°). La systeme, die auf die akadische (091° pop-up structures is subnormal to the current direction des structures de soulèvement en System), alleghanische (152° System) und in situ maximum horizontal stress direction, échelon est de 118°. Elles ont déplacé des Sankt-Lorenz-Spaltensystem Tektonik (091° S„„„ (020°), and is parallel to members of paléo-plages du Lac Algonquin, indiquant und 027° System) zurùckgefùhrt werden. Die the 091° joint set, indicating possible nuclea- ainsi une formation postérieure à 12 500 ans. gestaffelten Hebungsstrukturen haben eine tion on favourably-oriented pre-existing L'orientation des structures de soulèvement durchschnittliche Hauptrichtung von 118°. joints. These pop-ups are the only features in est subnormale à la direction de la contrainte Sie haben Palào-Strànde vom Lake the Balsam Lake area with strong evidence horizontale maximale actuelle, SMm.% (020°), Algonquin versetzt, und weisen so auf eine for a neotectonic age. et est parallèle à des éléments de l'ensemble Bildung vor weniger als 12,500 Jahren. Die des fractures de direction 091°, montrant Orientierung der Hebungsstrukturen ist sub ainsi leur formation possible dans des frac normal zu der gegenwàrtigen maximalen tures existantes bien orientées. Ces struc horizontalen Stressrichtung, S„m„ (020°) und tures de soulèvement sont les seuls parallel zu Elementen des 091° Fugen- éléments de la région démontrant un âge systems, was auf ihre môgliche Bildung auf néotectonique. gùnstig orientierten schon vorhandenen Fugen weist. Dièse Hebungen sind die einzi- gen Strukturen im Balsm Lake-Gebiet, wel- che deutlich ein neotektonisches Alter belegen. Manuscrit révisé accepté le 2 août 1993 380 A.L RUTTY and A.R. CRUDEN INTRODUCTION dipping (15°-30°) seismic reflectors within the crystalline basement across the CMBBZ/NPLZ below Lake Ontario Historically, the interior of the North American craton has have been interpreted as ductile thrust faults (Milkereit et al., been viewed as stable, but evidence from Paleozoic and 1992). Brittle faulting in Precambrian rock and vertical dis Mesozoic strata, recent seismicity and studies of intracratonic placements of upper Middle Ordovician rocks along major basins suggests that the craton is not stable (Armstrong, NNE-oriented lineaments within the CMBBZ provide evi 1992) and current research has begun to focus on paleoseis- dence of post-upper Middle Ordovician reactivation of the mic studies and other geological studies for hazards mapping CMBBZ (Wallach and Mohajer, 1990a; Wallach, 1991; (Basham and Adams, 1989; Wallach and Mohajer, 1990b; Sanford, 1993). However, seismic data collected across the Wallach et al., in press). Linear zones of modern seismicity, NPLZ below Lake Ontario indicate that a shale-limestone such as occurs along the Clarendon-Linden fault zone in New marker is undisturbed at the data resolution scale and that York state (Fakundiny et al., 1978) and its possible extension this zone has been relatively stable since the Ordovician into Prince Edward County, Ontario (McFaII and Allam, period (Milkereit et al., 1992). 1991), provide evidence of post-Paleozoic reactivation of Precambrian basement faults (McFaII and Allam, 1991). Aeromagnetic data (Gupta, 1991) indicate that a similar The Balsam Lake area (Figs. 1 and 2) overlies the surface Precambrian basement structure, the Central projection of the CMBBZ/NPLZ and is located 15 to 20 km Metasedimentary Belt Boundary Zone (CMBBZ) exposed south of the Paleozoic/Precambrian unconformity. The area within the Grenville Province of southern Ontario (Fig. 1), continues southward beneath flat-lying Paleozoic cover 81" "80° i 79 78 sequences (Wallach and Mohajer, 1990b). Wallach and Mohajer (1990a) have suggested that this Precambrian struc ture may also have been reactivated. This paper presents remote sensing and field-based observations of the fracture (undifferentiated joints and faults) pattern and related pop-up structures within the Paleozoic bedrock of the Balsam Lake area which overlies the aero magnetic expression of the NNE-trending CMBBZ in