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Kilometer‐scale refolded folds caused by strike‐slip reversal and intraplate shortening in the Beishan region, China
Author(s) -
Zhang Jin,
Cunningham Dickson
Publication year - 2012
Publication title -
tectonics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.465
H-Index - 134
eISSN - 1944-9194
pISSN - 0278-7407
DOI - 10.1029/2011tc003050
Subject(s) - geology , terrane , seismology , intraplate earthquake , echelon formation , shear zone , craton , fold (higher order function) , slip (aerodynamics) , fault (geology) , shear (geology) , paleontology , lineament , strike slip tectonics , clockwise , tectonics , mechanical engineering , physics , engineering , thermodynamics
Spectacular refolded folds clearly visible from space deform Permian turbidite successions in a 180 km 2 fault‐bounded compartment within the Beishan region of northwestern China. The folds formed after final terrane amalgamation of the Central Asian Orogenic Belt and record an important sequence of intraplate deformation events in central Asia during the Late Permian‐Jurassic. The fold interference patterns are dominantly Type 2 refolds with kilometer‐scale wavelengths. They are bounded to the north and south by regional E‐W faults with multiple displacement histories as revealed by crosscutting ductile and brittle fabrics and kinematic indicators indicating opposing senses of motion. The proximity of the refolded folds to the main bounding faults strongly suggests that the fold interference structures were caused by strike‐slip fault reactivation and shear related bending of F 1 folds combined with components of N‐S compression across the compartment. Faulting within the folded compartment is limited to an array of right‐lateral strike‐slip faults which appear to have helped accommodate room problems during the refolding event. The driving force for the deformation was likely to be distant—including regional block collision to the south, large‐scale rotations between the Siberian and North China Cratons and plate boundary convergence along the eastern Chinese margin. Our study demonstrates that continental interior regions characterized by terrane collages are susceptible to reactivation by distant plate margin effects and that polyphase reactivation of major strike‐slip and oblique‐slip faults can generate refolding within upper crustal basinal compartments. In addition, the fault‐bounded basin containing the refolded folds in the Beishan region is surrounded by older more complexly deformed crystalline basement. Therefore, the deformed basin sequence represents a unique compartmental archive of the Permian‐Triassic history of intraplate deformation north of Tibet.