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AGU: Journal of Geophysical Research, Solid Earth

 

Keywords

  • South China Block
  • Late Cretaceous
  • Paleogene
  • paleomagnetism
  • tectonic evolution

Index Terms

  • Geomagnetism and Paleomagnetism: Paleomagnetism applied to tectonics: regional, global
  • Geomagnetism and Paleomagnetism: Magnetic fabrics and anisotropy
  • Tectonophysics: Continental tectonics: compressional
  • Geographic Location: Asia
  • Information Related to Geologic Time: Paleogene
Abstract
Cited By (7)
 

Abstract

JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 111, B03101, 19 PP., 2006
doi:10.1029/2004JB003455

New Late Cretaceous and Paleogene paleomagnetic results from south China and their geodynamic implications

Zhiming Sun

Laboratory of Paleomagnetism, Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing, China

Zhenyu Yang

Department of Earth Sciences, Nanjing University, Nanjing, China

Tienshui Yang

Institute of Tibetan Plateau Research, Chinese Academy of Science, Beijing, China

Junling Pei

Laboratory of Paleomagnetism, Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing, China

Qinfan Yu

Department of Geophysics and Geoinformation Systems, China University of Geosciences, Beijing, China

To better understand the tectonic evolution of South China Block (SCB) in response to the India-Asia collision, we present new paleomagnetic results from Late Cretaceous and Paleogene red bed formations of the Hengyang basin of Hunan province, in the interior part of the SCB. Stepwise thermal demagnetization of the rocks isolated a high-temperature component. The tilt-corrected mean direction from the Late Cretaceous rocks is D = 15.6°, I = 29.9° with a 95 = 5.7°, N = 26 sites, corresponding to a paleopole at 71.9°N, 236.3°E with A95 = 4.7°, which passes reversal tests. The tilt-corrected mean direction (D = 358.9°, I = 35.4° with a 95 = 5.0°, N = 22 sites) from the Paleogene rock, which passes the reversal test, gives a pole at 82.6°N, 300.6°E with A95 = 4.4°. The low-field anisotropy of magnetic susceptibility results suggest that the red beds have not experienced significant strain due to compaction or tectonic stress, while the anisotropy of isothermal remanence results suggest that postdepositional compaction in these red beds produced no more than 3°–4° of inclination shallowing. These paleomagnetic and rock magnetic tests imply that the remanence is primary. On the basis of paleomagnetic results obtained from coeval basalts in Mongolia and Siberia, we suggest that no significant latitudinal motion has taken place between the SCB and Siberia since the Late Cretaceous. The significant latitudinal discrepancy between the SCB and European block could be due to nonrigid behavior of the Eurasian plate since the Late Cretaceous. A 16.7 ± 5.0° clockwise rotation of the SCB during the Late Cretaceous to the Paleogene could be related to the collision of India and Asia in the west and the subduction of the circum-Pacific plate to eastern Asia in the east.

Received 28 September 2004; accepted 22 November 2005; published 4 March 2006.

Citation: Sun, Z., Z. Yang, T. Yang, J. Pei, and Q. Yu (2006), New Late Cretaceous and Paleogene paleomagnetic results from south China and their geodynamic implications, J. Geophys. Res., 111, B03101, doi:10.1029/2004JB003455.

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