Skip to main content
Article thumbnail
Location of Repository

Large NS convergence at the northern edge of the Tibetan plateau ? New Early Cretaceous paleomagnetic data from Hexi Corridor, NW China.

By Yan Chen, Hanning Wu, Vincent Courtillot and Stuart Gilder

Abstract

Nine Early Cretaceous paleomagnetic sites have been collected in the Yumen area of the Hexi Corridor (NW China). Magnetic directions isolated at lower temperatures fail the fold test, and lie close to the geocentric axial dipole field direction before tilt correction. High temperature components are carried by magnetite and/or hematite, all with normal polarity, and pass the fold test. The average paleomagnetic pole from the nine sites is at λ=75.5°N, small phi, Greek=169.9°E (A95=7.7°). These results are consistent with those from other areas of the North China block (NCB), but significantly different from those from the Qaidam Basin on the southern side of the Qilian Mountains. They suggest that: (1) the Yumen region behaved as a rigid part of the NCB since at least the Early Cretaceous; (2) 740±500 km of north-south directed convergence has taken place between the NCB and Qaidam, within the Qilian Mountains and (3) extrusion of Qaidam was accompanied by a 23±5° relative rotation with respect to North China. This is larger than implied by the maximum left lateral slip on the Altyn Tagh fault system. The same data imply some 1000±800 km of Cenozoic motion between the Tarim and NCB blocks, which were so far believed to have formed a rigid entity since at least the Jurassic. One interpretation could be that all Tarim and Qaidam Cretaceous paleomagnetic samples from red beds, but not those from Yumen and the NCB, suffered significant inclination shallowing, as observed in Cenozoic red beds from Central Asia. So far, we do not find support for this possibility. Possible tectonic interpretations include: (1) the existence of a large, as yet uncharted, tectonic discontinuity between Tarim and the NCB in the vicinity of the desert corridor near 95-100°E longitude; (2) the occurrence of significant deformation within southwestern Tarim, to the north of Yingjisha where paleomagnetic sites were obtained, or (3) persistent clockwise rotation of Tarim with respect to the NCB, for at least 20 Ma, at the rate found for current block kinematics

Topics: paleomagnetism, North China platform, Tarim Basin, plate convergence, Qilian Mountains, [SDU.STU.TE] Sciences of the Universe [physics]/Earth Sciences/Tectonics, [SDE.MCG] Environmental Sciences/Global Changes
Publisher: Elsevier
Year: 2002
DOI identifier: 10.1016/S0012-821X(02)00722-7
OAI identifier: oai:HAL:hal-00076857v1
Provided by: Hal-Diderot
Download PDF:
Sorry, we are unable to provide the full text but you may find it at the following location(s):
  • https://hal-insu.archives-ouve... (external link)
  • https://hal-insu.archives-ouve... (external link)
  • https://hal-insu.archives-ouve... (external link)
  • https://hal-insu.archives-ouve... (external link)
  • https://hal-insu.archives-ouve... (external link)
  • Suggested articles


    To submit an update or takedown request for this paper, please submit an Update/Correction/Removal Request.