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Cretaceous synfolding remagnetization components revealing tectonic rotation of the middle Yangtze fold belt
Zhang, H; Tan, XD; Han, YL; xdtan@scsio.ac.cn
2007
Source PublicationCHINESE SCIENCE BULLETIN
ISSN1001-6538
Volume52Issue:20Pages:2837-2846
AbstractTo reveal the deformation process of the middle Yangtze fold belt, we conducted a paleomagnetic study on Middle Triassic limestones and Middle to Late Jurassic sandstones from Wanzhou, Chongqing. Stepwise thermal and alternating field demagnetization were used to isolate the multi-component remanent magnetizations. The Jurassic samples were overprinted by recent geomagnetic field, while three magnetization components were isolated from the Middle Triassic samples. A low temperature component (LTC) was isolated at temperatures below 200 degrees C, an intermediate temperature component (ITC) at 200-360 degrees C and a high temperature component (HTC) at 400-460 degrees C. The LTC is distributed around the present-day Earth magnetic field, probably a viscous component. Stepwise unfolding indicates that the maximum precision parameters of ITC and HTC components are achieved at 33 +/- 8% and 50 +/- 27% (with 95% confidence) unfolding, respectively. The best-clustered ITC mean direction, Dec = 11.2 degrees, Inc = 45.2 degrees (alpha(95) = 4.5 degrees, N = 34), corresponding to a paleopole at 79.3 degrees N, 219.5 degrees E (d(p) = 3.6 degrees, d(m) = 5.7 degrees), is consistent with the Cretaceous reference direction of the South China Block (SCB). The best-clustered HTC mean direction (taking 70% unfolding), Dec = 24.2 degrees, Inc =49.0 degrees (alpha(95) = 3.6 degrees, N = 23), corresponding to a paleopole at 69.2 degrees N, 195.5 degrees E (d(p) =3.1 degrees, d(m) = 4.8 degrees), suggests a clockwise rotation of 12.8 degrees +/- 3.5 degrees. These synfolding remagnetization components clearly reveal that a clockwise rotation happened at the middle stage of folding, thus supporting that at least part of the variation in fold axis strikes is due to orocline rotation. Combined with published data, our analysis indicates that the Wanzhou-Xiangxi segment of the middle Yangtze fold belt experienced oroclinal bending. Furthermore, a published post-folding component isolated from the Middle Triassic Puqi Formation suggests a 27.5 degrees +/- 5.8 degrees clockwise rotation, confirming that at least 50% of the observed clockwise rotations in the eastern middle Yangtze fold belt can be attributed to oroclinal bending. The remagnetization data and geological evidence observed in the middle Yangtze fold belt suggest that collision between SCB and North China Block (NCB) probably lasted till the early period of Early Cretaceous.
DepartmentChinese Acad Sci, So China Sea Inst Oceanol, Key Lab Marginal Sea Geol, Guangzhou 510301, Peoples R China; Chinese Acad Sci, Grad Univ, Coll Earth Sci, Beijing 100049, Peoples R China
KeywordPaleomagnetism Remagnetization Mesozoic Orocline Yangtze Fold Belt South China Block
Subject AreaMultidisciplinary Sciences
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Indexed Bysci
Funding Project海洋地质
WOS IDWOS:000249986200015
Citation statistics
Cited Times:9[WOS]   [WOS Record]     [Related Records in WOS]
Document Type期刊论文
Identifierhttp://ir.scsio.ac.cn/handle/344004/4464
Collection中科院边缘海地质重点实验室
Corresponding Authorxdtan@scsio.ac.cn
Recommended Citation
GB/T 7714
Zhang, H,Tan, XD,Han, YL,et al. Cretaceous synfolding remagnetization components revealing tectonic rotation of the middle Yangtze fold belt[J]. CHINESE SCIENCE BULLETIN,2007,52(20):2837-2846.
APA Zhang, H,Tan, XD,Han, YL,&xdtan@scsio.ac.cn.(2007).Cretaceous synfolding remagnetization components revealing tectonic rotation of the middle Yangtze fold belt.CHINESE SCIENCE BULLETIN,52(20),2837-2846.
MLA Zhang, H,et al."Cretaceous synfolding remagnetization components revealing tectonic rotation of the middle Yangtze fold belt".CHINESE SCIENCE BULLETIN 52.20(2007):2837-2846.
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