What was the Paleogene latitude of the Lhasa terrane? A reassessment of the geochronology and paleomagnetism of Linzizong volcanic rocks (Linzhou basin, Tibet)

Wentao Huang, Guillaume Dupont-Nivet, Peter C. Lippert, Douwe J J Van Hinsbergen, Mark J. Dekkers, Ross Waldrip, Morgan Ganerød, Xiaochun Li, Zhaojie Guo, Paul A Kapp

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Abstract

The Paleogene latitude of the Lhasa terrane (southern Tibet) can constrain the age of the onset of the India-Asia collision. Estimates for this latitude, however, vary from 5°N to 30°N, and thus, here, we reassess the geochronology and paleomagnetism of Paleogene volcanic rocks from the Linzizong Group in the Linzhou basin. The lower and upper parts of the section previously yielded particularly conflicting ages and paleolatitudes. We report consistent <sup>40</sup>Ar/<sup>39</sup>Ar and U-Pb zircon dates of ∼52 Ma for the upper Linzizong, and <sup>40</sup>Ar/<sup>39</sup>Ar dates (∼51 Ma) from the lower Linzizong are significantly younger than U-Pb zircon dates (64-63 Ma), suggesting that the lower Linzizong was thermally and/or chemically reset. Paleomagnetic results from 24 sites in lower Linzizong confirm a low apparent paleolatitude of ∼5°N, compared to the upper part (∼20°N) and to underlying Cretaceous strata (∼20°N). Detailed rock magnetic analyses, end-member modeling of magnetic components, and petrography from the lower and upper Linzizong indicate widespread secondary hematite in the lower Linzizong, whereas hematite is rare in upper Linzizong. Volcanic rocks of the lower Linzizong have been hydrothermally chemically remagnetized, whereas the upper Linzizong retains a primary remanence. We suggest that remagnetization was induced by acquisition of chemical and thermoviscous remanent magnetizations such that the shallow inclinations are an artifact of a tilt correction applied to a secondary remanence in lower Linzizong. We estimate that the Paleogene latitude of Lhasa terrane was 20 ± 4°N, consistent with previous results suggesting that India-Asia collision likely took place by ∼52 Ma at ∼20°N.

Original languageEnglish (US)
Pages (from-to)594-622
Number of pages29
JournalTectonics
Volume34
Issue number3
DOIs
StatePublished - Mar 1 2015

Fingerprint

Geochronology
paleomagnetism
Volcanic rocks
geochronology
Tibet
Remanence
Paleogene
volcanology
terrane
volcanic rock
paleolatitude
rocks
Petrography
remanence
hematite
India
zircon
collision
basin
petrography

Keywords

  • geochronology
  • India-Asia collision
  • remagnetization
  • rock magnetism

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics

Cite this

What was the Paleogene latitude of the Lhasa terrane? A reassessment of the geochronology and paleomagnetism of Linzizong volcanic rocks (Linzhou basin, Tibet). / Huang, Wentao; Dupont-Nivet, Guillaume; Lippert, Peter C.; Van Hinsbergen, Douwe J J; Dekkers, Mark J.; Waldrip, Ross; Ganerød, Morgan; Li, Xiaochun; Guo, Zhaojie; Kapp, Paul A.

In: Tectonics, Vol. 34, No. 3, 01.03.2015, p. 594-622.

Research output: Contribution to journalArticle

Huang, W, Dupont-Nivet, G, Lippert, PC, Van Hinsbergen, DJJ, Dekkers, MJ, Waldrip, R, Ganerød, M, Li, X, Guo, Z & Kapp, PA 2015, 'What was the Paleogene latitude of the Lhasa terrane? A reassessment of the geochronology and paleomagnetism of Linzizong volcanic rocks (Linzhou basin, Tibet)', Tectonics, vol. 34, no. 3, pp. 594-622. https://doi.org/10.1002/2014TC003787
Huang, Wentao ; Dupont-Nivet, Guillaume ; Lippert, Peter C. ; Van Hinsbergen, Douwe J J ; Dekkers, Mark J. ; Waldrip, Ross ; Ganerød, Morgan ; Li, Xiaochun ; Guo, Zhaojie ; Kapp, Paul A. / What was the Paleogene latitude of the Lhasa terrane? A reassessment of the geochronology and paleomagnetism of Linzizong volcanic rocks (Linzhou basin, Tibet). In: Tectonics. 2015 ; Vol. 34, No. 3. pp. 594-622.
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AU - Lippert, Peter C.

AU - Van Hinsbergen, Douwe J J

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