Late Triassic volcanic activity in South-East Asia: New stratigraphical, geochronological and paleontological evidence from the Luang Prabang Basin (Laos) - INSU - Institut national des sciences de l'Univers Access content directly
Journal Articles Journal of Southeast Asian earth sciences Year : 2013

Late Triassic volcanic activity in South-East Asia: New stratigraphical, geochronological and paleontological evidence from the Luang Prabang Basin (Laos)

Camille Rossignol
Sylvie Bourquin
Marie-Pierre Dabard
  • Function : Author
  • PersonId : 840697
Erwan Hallot
  • Function : Author
  • PersonId : 840703
Thierry Nalpas
  • Function : Author
  • PersonId : 894611
Marc Poujol
Et Al.
  • Function : Author

Abstract

In South-East Asia, sedimentary basins displaying continental Permian and Triassic deposits have been poorly studied. Among these, the Luang Prabang Basin (North Laos) represents a potential key target to constrain the stratigraphic and structural evolutions of South-East Asia. A combined approach involving sedimentology, palaeontology, geochronology and structural analysis, was thus implemented to study the basin. It resulted in a new geological map, in defining new formations, and in proposing a complete revision of the Late Permian to Triassic stratigraphic succession as well as of the structural organization of the basin. Radiometric ages are used to discuss the synchronism of volcanic activity and sedimentation. The Luang Prabang Basin consists of an asymmetric NE-SW syncline with NE-SW thrusts, located at the contact between Late Permian and Late Triassic deposits. The potential stratigraphic gap at the Permian- Triassic boundary is therefore masked by deformation in the basin. The Late Triassic volcaniclastic continental deposits are representative of alluvial plain and fluvial environments. The basin was fed by several sources, varying from volcanic, carbonated to silicic (non-volcanic). U-Pb dating of euhedral zircon grains provided maximum sedimentation ages. The stratigraphic vertical succession of these ages, from ca. 225, ca. 220 to ca. 216 Ma, indicates that a long lasting volcanism was active during sedimentation and illustrates significant variations in sediment preservation rates in continental environments (from 100 m/Ma to 3 m/Ma). Anhedral inherited zircon grains gave older ages. A large number of them, at ca. 1870 Ma, imply the reworking of a Proterozoic basement and/or of sediments containing fragments of such a basement. In addition, the Late Triassic (Carnian to Norian) sediments yielded to a new dicynodont skull, attributed to the Kannemeyeriiform group family, from layers dated in between 225 and 221 Ma (Carnian).

Dates and versions

insu-00822729 , version 1 (15-05-2013)

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Sébastien Blanchard, Camille Rossignol, Sylvie Bourquin, Marie-Pierre Dabard, Erwan Hallot, et al.. Late Triassic volcanic activity in South-East Asia: New stratigraphical, geochronological and paleontological evidence from the Luang Prabang Basin (Laos). Journal of Southeast Asian earth sciences, 2013, 70-71, pp.8-26. ⟨10.1016/j.jseaes.2013.02.024⟩. ⟨insu-00822729⟩
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