The role of mechanical stratigraphy in the lateral variations of thrust development along the central Alberta Foothills, Canada

Hyunjung Lee, Yirang Jang, Sanghoon Kwon, Myong Ho Park, Gautam Mitra

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

Fold-thrust belts generally exhibit significant variations in structural styles such as differences in thrust geometries and frequencies in imbrication. A natural laboratory of this pattern is preserved in the central Alberta Foothills of the Canadian Rockies, where differences in thrust geometries are represented by the existence vs. non-existence of triangle zones. To seek the factors that make this difference in these regions in terms of structural geometry, stratigraphic thickness variations and mechanical stratigraphy of the sedimentary layers, structural interpretation is conducted based on admissible cross-sections and well log interpretations. In northern region, a backthrust is detached from an incompetent layer (viz. Nomad Unit of the Wapiabi Formation), which gets thinner from the Foothills to the Plains, indicating that it is developed where the shale layers are pinched out where triangle zone is developed. Backthrust is also developed in the southern region, where mechanical strengths of strata (viz. Bearpaw Formation) increase toward the foreland. In the central region, however, only forethrusts are developed along the weak continuous decollement layers (viz. Turner Valley and Brazeau formations), forming an imbricate fan without development of the triangle zone. Incompetent layers such as the top Wapiabi (Nomad), Brazeau (Bearpaw), Coalspur and Paskapoo formations are also pinched out laterally, forming fault glide horizons in different stratigraphic levels in each region. These results indicate that, along the transport direction, triangle zone is developed in relation to the stratigraphic pinch out of the Nomad Unit in the northern region, and is formed associated with the variations in strengths of the layers constituting the Bearpaw Formation in the southern region. It is notable that all the glide horizons are developed along incompetent layers. However, triangle zones are not developed in the areas of continuous stratigraphy of the Nomad Unit, which does not serve as a glide horizon in the central region. This suggests that factors such as stratigraphic thickness changes of incompetent layers and mechanical stratigraphy of the sedimentary layers play an important role in the development of lateral variations in thrust system evolution in terms of triangle zone vs. imbricate fan in the central Alberta Foothills.

Original languageEnglish
Pages (from-to)1451-1464
Number of pages14
JournalGeoscience Frontiers
Volume9
Issue number5
DOIs
Publication statusPublished - 2018 Sep

Bibliographical note

Funding Information:
This research was supported by the Korea Institute of Geoscience and Mineral Resources research project (2015-11-1637; Development of IOR/EOR technologies and field verification for carbonate reservoir in UAE), funded by the Ministry of Science and ICT (Information, Communication and Technology ), Korea to S. Kwon. SK also appreciate the support by the 2017R1A6A1A07015374 (Multidisciplinary study for assessment of large earthquake potentials in the Korean Peninsula) through the National Research Foundation of Korea funded by the Ministry of Science and ICT, Korea. Part of this research is also supported by the 20162010201980 ( Demonstration-scale Offshore CO 2 Storage Project in Pohang Basin, Korea ) funded by the Ministry of Science and ICT (Information, Communication and Technology), Korea to M. Park. YJ appreciate the support by a Basic Research Project ( GP2017-021 ; Development of integrated geological information based on digital mapping) of the Korea Institute of Geoscience and Mineral Resources (KIGAM), funded by the Ministry of Science and ICT (Information, Communication and Technology) after she joined to KIGAM during the preparation of the revised manuscript. This work represents part of H. Lee's M.S. Research performed at Yonsei University. H. Lee, Y. Jang and S. Kwon equally contribute to the final manuscript.

Funding Information:
This research was supported by the Korea Institute of Geoscience and Mineral Resources research project (2015-11-1637; Development of IOR/EOR technologies and field verification for carbonate reservoir in UAE), funded by the Ministry of Science and ICT (Information, Communication and Technology), Korea to S. Kwon. SK also appreciate the support by the 2017R1A6A1A07015374 (Multidisciplinary study for assessment of large earthquake potentials in the Korean Peninsula) through the National Research Foundation of Korea funded by the Ministry of Science and ICT, Korea. Part of this research is also supported by the 20162010201980 (Demonstration-scale Offshore CO2 Storage Project in Pohang Basin, Korea) funded by the Ministry of Science and ICT (Information, Communication and Technology), Korea to M. Park. YJ appreciate the support by a Basic Research Project (GP2017-021; Development of integrated geological information based on digital mapping) of the Korea Institute of Geoscience and Mineral Resources (KIGAM), funded by the Ministry of Science and ICT (Information, Communication and Technology) after she joined to KIGAM during the preparation of the revised manuscript. This work represents part of H. Lee's M.S. Research performed at Yonsei University. H. Lee, Y. Jang and S. Kwon equally contribute to the final manuscript.

All Science Journal Classification (ASJC) codes

  • Earth and Planetary Sciences(all)

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