Sanqingshan
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Structure


  Sanqingshan Geopark is located at the zone of conjunct the Yangtze and Cathaysia paleoplates, the northwest edge of Huaiyu Terrain and the southeast side of Qin-Hang paleoplate. Since the Mesozoic Era, Sanqingshan has been located in the southeast part of the Eurasian plate and the western Pacific continental margin active zone. It successively underwent the Caledonian Orogeny and Indosinian-Hercynian Orogeny, the Yanshan Movement and Himalayan Movement as characterized by block-faulting tectonics since the Mesozic Era.

  (i) Folds

  The Geopark is located at the core of Huaiyushan Anticlinorium, the northwest part of Jiangxi Province. The multifolds in the rock layers are developed. The main folds are as follows.

  Huangtuling Anticlinorium: This is located at Huangtuling area in the northwest of the Geopark and is a part of the larger Huangtuling-Kaihua Anticlinorium. The main fold axis trends northeast, as do the plunging subsidiary folds, each extending approximately 5 km. The axial plane of the fold is nearly vertical with the northwest flank dipping at 30°-350°∠30°-75°, and the relative gentle southeast flank at 120°-150°∠30°-60°. The core is made up of Nanhua strata, and its flanks are composed of the Sinian-Ordovician strata. The south flank is well exposed, forming some secondary anticlines and synclines.

  Huameishan Syncline: This is located in the northeast of the Geopark and has a fold axis trending NE-SW. Its southwest end was uplifted against the side of Huaiyushan granite body, while the northeast end extends in a direction of 67° through Yuantou. The northwest flank dips at 40°~60°, while the southeast flank dips at 30°~50°. The core is made up of the early Ordovician Yinzhubu Formation strata, while the flanks are composed of late Cambrian strata.

  There are rich and various secondary folds, which are common in the Lower Paleozoic and Neoproterozoic strata. Folds of differnt shapes and sizes are visible on both the outcrop and the specimen scale, and they have an educational and tourism value.

  (ii) Faults

  Faults are well developed within the Geopark (Table B-4). They mainly have a NE, NNE and NW trend. The NE trending faults formed earliest, followed by the NNE trending faults and the NW trending faults. Most of the faults are normal and thrust faults.

  The Fenglin-Zihu Fracture Belt, the Xiaoken-Bajiaowu Fault, and the Egongling-Xiaxiken Fault are all normal faults. Sanqingshan was cut by them and the main part formed a typical “triangle fault-block mountain” with the dips of 50°~80°. Speaking of the “triangle fault-block mountain” , the rocks or strata inside of the “triangle fault-block mountain” are upthrown walls, while those outside are downthrown walls. During the late period of Yanshan Movement, the magma was subjected to intrusion, condensation and crystallization, forming granites. About 20~30 million years ago, the Himalayan Orogeny, that is, neotectonic movement occurred, as a result the mountain was uplifted. The Sanqingshan area as a whole was also uplifted. During this period, the faults underwent intense movements, Fenglin-Zihu Fracture Belt, Xiaoken-Bajiaowu Fault, and Egongling-Xiaxiken Fault in particular were very active. The “triangle fault-block mountain” centered Yujing Peak was uplifted once again, then Yujing Peak became the highest peak in this area.


The features of main fractures of Sanqingshan Geopark


Strike

Name

Location

Extended scale

Attitude

Feature description

Property

Active period

Dip

Dip angle

NE

Changpeng Fault

Changpeng

8km

NW

500

As it cut Sinian and Cambrian strata, some strata are lacking and became narrower. Along the fault there is a crushed zone, 2-6meters wide, consisting of squeeze lenticle, fracture rocks, structural brecciaand fault clay.

reverse fault

Caledonian

epoch

NE

Lengshuikeng-Xujia Village Fault  

Lengshuikeng, Xujia Village

2km

SE

600

~700

As it cut SE-oriated section, the NE end of the syncline composed of Paleozoic strata is lacking due to the lack of the strata of the SE flank. Along the fault there are silicification, striation and fault clay.

reverse fault

Indo-Chinese epoch

NE

Fenglin-Zihu Town Fracture Belt

Fenglin, Zihu Town

6km

SE

500

~600

It is composed of a couple of NE faults with 50°-60° and the large ones are Fenglin-Dalongkou Fault and Xiabuling-Zihu Town Fault. The individual strike extends 12 km and the Fracture Belt cut the SE flank of Huangtuling Anticlinorium. The NW block is an upthrown block and the SE block isa downthrown block. Along the fault there are crushed zones (10-40m wide), cleavage zone, schistositized zone, crumple, flexure, etc. It is a multi-phase active fracture.

Mainly normal fault

Caledonian epoch- Himalaya

epoch

NNE

Xiaokeng-Bajiaowu Fault

Xiaokeng, Bajiaowu

Length10km, Width:20~40

NWW

600~

800

It cut not only the cap rock of the Indo-Chinese fold and Sanqingshan granite rock body, but the NE fault whose SEE block is an upthrown block and NWW block is a downthrown block. There are crushed zones (20-40m wide, ), striations and crumples.

normal fault

Yanshan epoch- Himalaya epoch

NW

E’Gongling- Xiaxikeng Fault

E’Gongling, Xiaxikeng

13km

NE

700

It cut the core and SE flank of Huangtuling Anticlinorium and Lengshuikeng-Xujia Village NE-oriented fault, and horizontal displacement occured. The SW block is an upthrown block and NE block is a downthrown block. It contains structural breccia, silicified rock and cataclasite.

normal fault

Yanshan epoch- Himalaya epoch

NE

Wujia- Tucheng Fault

Wujia, Tucheng

10km

SE

500

~600

It cut Ordovician strata and the SE flank of Huangtuling Anticlinorium. Along the fold there are a fault crushed zone, cleavage zone and schistositized zone where the rocks are broken with crumples and flexure.

reverse fault

Caledonian

epoch,

Indo-Chinese epoch, Yanshan epoch 


  (iii) Joints

  Joints occur in all kinds of geological bodies, especially in granite body in the Geopark. Within the core zone there are two sets of vertical joints, NE-NNE trending and NW trending, which together form a chess- board structure. These structural features control most of the peak forests. The NE-NNE trending joints tend to converge in the southwest and diverge towards the northeast, occurring in abundance and forming a fan-shaped arrangement. These joints have controlled the formation of the peak walls in the west (West Sea Peak Wall, Screen to Firmament) and gorges in the south (Fushou Gate, A Gleam of Sky, etc.). The NW trending joints gradually increase in number from north to south, outcropping in groups. These are the main controlling structures of the peak pillars in the central part of the Geopark, and the peak walls as well as gorges in the southeast. In addition, there are a set of sub-horizontal joints which mainly control the formation of odd-shape stones. More specifically, these provide definition to the peak walls and peak pillars, which have been further shaped to form unusual figures by weathering and scouring.


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