Intra-continental Dabashan orocline, southwestern Qinling, Central China

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• 作者：Wei Shi^a ; ^b ; ^c ; ^{weishinmg@hotmail.com} ; Yueqiao Zhang^a ; ^b ; Shuwen Dong^d ; Jianmin Hu^a ; Maria Wiesinger^c ; ^e ; Lothar Ratschbacher^c ; Raymond Jonckheere^c ; Jianhua Li^a ; Mi Tian^a ; Hong Chen^a ; Guoli Wu^a ; Licheng Ma^a ; Hailong Li^a
• 关键词：Dabashan belt ; Paleostress fields ; Arc-shape fold belt ; Superposed deformation ; Intra-continental orogeny
• 刊名：Journal of Asian Earth Sciences
• 出版年：2012
• 出版时间：2 March 2012
• 年：2012
• 卷：46
• 期：Complete
• 页码：20-38
• 全文大小：6616 K

文摘

Using field investigation, structural analysis, and ⁴⁰Ar-³⁹Ar and fission-track geochronology, we synthesize the structural architecture, stress fields, and tectonic evolution of the Dabashan orocline, southwestern Qinling. Three paleostress fields govern deformation: The first (Late Triassic to Early Jurassic, T₃-J₁) reflects ¡«N-S to NNE-SSW shortening in the foreland of the Qinling-Dabie orogen and is the result of the collision of the North China and Yangtze blocks; the principal structures in the Dabashan belt are ¡«E-trending folds. The second event (Late Jurassic to Early Cretaceous, J₃-K₁) shows NE-SW shortening; a fold-thrust belt formed with ?50 km shortening above a detachment layer at 10-12 km depth. During this event, the Dabashan foreland acquired its convex-to-southwest oroclinal shape. The third event (Late Cretaceous to Paleogene, K₂-E) reflects ENE-WSW or NE-SW extension coeval with the formation of local basins. The Dabashan orocline formed due to pinning of the Qinling-Dabie thrust front at two basement culminations within the subducting Yangtze craton; foreland progradation was made possible by the activation of a Lower-Middle Triassic gypsum-salt detachment of the Sichuan-basin sedimentary pile. During expansion, movements were radially along the orocline. This study gives an example of intra-continental orogeny when terminal deformation is governed by foreland heterogeneities.