An alternative interpretation for the map expression of 鈥渁brupt鈥?changes in lateral stratigraphic level near transverse zones in fold-thrust belts

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• 作者：Sanghoon Kwon^a ; ^{skwon@yonsei.ac.kr} ; ^{earthstructure@gmail.com} ; Gautam Mitra^b
• 关键词：Lateral stratigraphic changes ; Fold-thrust belt ; Transverse zone ; Frontal r Lateral r Displacement gradient
• 刊名：Geoscience Frontiers
• 出版年：2012
• 期刊代码：pc98_16749871
• 类别：ear
• 出版时间：July, 2012
• 卷：3
• 期：4
• 页码：401-406
• 文件大小：924 K

摘要

The map expression of 鈥渁brupt鈥?changes in lateral stratigraphic level of a thrust fault has been traditionally interpreted to be a result of the presence of (1) a lateral (or oblique) thrust-ramp, or (2) a frontal ramp with displacement gradient, and/or (3) a combination of these geometries. These geometries have been used to interpret the structures near transverse zones in fold-thrust belts (FTB). This contribution outlines an alternative explanation that can result in the same map pattern by lateral variations in stratigraphy along the strike of a low angle thrust fault. We describe the natural example of the Leamington transverse zone, which marks the southern margin of the Pennsylvanian-Permian Oquirrh basin with genetically related lateral stratigraphic variations in the North American Sevier FTB. Thus, the observed map pattern at this zone is closely related to lateral stratigraphic variations along the strike of a horizontal fault. Even though the present-day erosional level shows the map pattern that could be interpreted as a lateral ramp, the observed structures along the Leamington zone most likely share the effects of the presence of a lateral (or oblique) ramp, lateral stratigraphic variations along the fault trace, and the displacement gradient.