返回6
Waged Thrust Block(楔冲体) Hengyang, Hunan, China
(From Zeng et al., 2008)
Folding related to thrust and Detachment(滑脱)
断弯褶皱作用
断展褶皱作用
滑脱褶皱作用
11
FAULT – BEND FOLD
Examples
West Qinling and Songpan Ganze Composite Orogenic Belt Appalachians Orogenic Belt Canadian Rockies Orogenic Belt Taiwan accretionary prism(增生棱柱体) Alps
Branch faults分支断层
Main thrust fault主逆冲断层
Imbricate thrust fault system or, thrust imbricate fan(叠瓦扇)
(Zeng et al.,2008)
Back Thrust Fault System背冲式逆冲断层系
Lecture 4 Thrust Fault System 第四讲 逆冲断层系统
Thrust Fault System
Terms related to thrust fault system Structures of thrust zones Style(样式) of thrust fault system Folding related to thrust and decollement 与滑脱逆冲有关的褶皱作用 Model(模式) of formation of thrust system Shortening resulted from thrust
Map of Lewis thrust near Canada-United States border
Different ramps
(from Twiss & Moores, 2007)
Frontal ramp前断坡, side-wall ramp侧断坡 oblique ramp斜断坡 Map of the Pine Mountain thrust in the southern Appalachian Valley and Ridge province
(Harris and Bayer, 1979)
Canadian Cordillera fold and thrust belt
(from Twiss & Morres, 2007)
Cross section of fold and thrust belts
A. Southern Appalachians (Davis et al., 1983) B. Canadian Cordillera (Davis et al., 1983, after Bally et al., 1966)
Terms Related toThrust Fault Systems
Fault system 断裂系统 Flat and Ramp 断坪与断坡 Klippe and window飞来峰与构造窗 Thrust sheet 逆冲席, or, nappe推覆体or allochothon外来系统 Autochthon原地系统
(from Twiss & Moores, 2007)
Taiwan accretionary prism
(Liou et al.,1977)
Three principal thrust complexes in Alpine region, Europe
(after Twiss & Moores, 2007, modified from Emst 1973)
Fault system : A set of faults of the same age, generated in the same tectonic process.
同一构造作用，同期形成的断层组合称为断层系统
A Small Scale Thrust Fault: Ramp & Flat
(Zeng et al., 2008)
Ang’ren
Dingri
Jumurangma
Wudabuerbao
Wedged thrust structure楔冲式: High Himalaya Extrusion Tectonics and Numerical Modeling
(Zeng et al., 2001)
Transfer faults 调节断层 (from Twiss & Moores, 2007)
Transfer fault bound the frontal ramp at either end
Style of thrust fault system
Imbricate (叠瓦式) thrust fault system Back (背冲式)thrust fault system Wedged(楔冲式) thrust fault system
Hanging Wall上盘
Flat断坪 断坪 Ramp断坡 断坡 Foot Wall下盘
(From Bruhn, 2001)
Allochthon
Klippe
Autochthon Window
Thrust fault
Minimum fault displacement Teeth on the hanging wall side
(Zuoxun Zeng et al., 2005)
Appalachians fold and thrust belt Foreland - A stable part of a continent bordering an orogenic or mobile belt Hinterland – The moving block on the back of a folded mountain chain
C – Piggyback(背驮式，前展式) thrust sequence new thrusts develop in the footwall D – Overstep(超覆式，后展式) thrust sequence new thrusts develop in the hangingwall E – Structure of duplex双重构造: imbricate（叠瓦） thrust slices are contained between a floor(底板） thrust and a roof （顶板）thrust
(from Twiss and Moores,2007)
Keystone Thrust in Southern Nevada
Elder strata
Klippe
Thrust fault Younger strata
Structures of Thrust Zones
A - Ramps and flats B – Hangingwall ramp and footwall ramp
1111 1
Xinjie新街 新街
Heling荷岭 荷岭
Duplex Structures
(From Zeng et al.,2008)
(From Bruhn, 2001)
Physical modeling of piggyback thrusts (from Bruhn, 2001)
1
2
3 4 5
Decollement thrust fold (Decollement followed by Thrust)
Thrust fault propagation fold (Thrust associated with Fold)
Ductile thrust fault (Thrust resulted from Folding) (from Twiss & Moores, 2007)
Klippe飞来峰 and Window构造窗 飞来峰 构造窗
A thrust sheet逆冲席 or a nappe, 推覆体 Allochthon外来系统, Paleozoic, moved 20 km Trace of the low-angle thrust fault, which dips gently to the west Autochthon原地系统, Jurassic sandstones
(Park,1997)
Problems for review
★ What is a duplex? ★ How do you distinguish between a ramp and a flat? ★ How does a pop up be formed? ★ How do you distinguish between a frontal ramp, a side wall ramp, an oblique ramp and a back thrust? ★ How do you distinguish between a piggyback thrust sequence and an overstep thrust sequence? ★ How do you distinguish between fault bending folding, fault propagation folding and decollement folding? ★ How does a wedged thrust structure formed?
Lanzhou
Xi’an
Chengdu
Tectonic Map of Songpan-Ganze Area