Lower Permian glacially influenced deposits in Phuket and adjacent islands, peninsular Thailand
Article first published online: 17 FEB 2009
© 2009 The Authors. Journal compilation © 2009 Blackwell Publishing Asia Pty Ltd
Volume 18, Issue 1, pages 52–68, March 2009
How to Cite
Ampaiwan, T., Hisada, K.-I. and Charusiri, P. (2009), Lower Permian glacially influenced deposits in Phuket and adjacent islands, peninsular Thailand. Island Arc, 18: 52–68. doi: 10.1111/j.1440-1738.2008.00653.x
- Issue published online: 17 FEB 2009
- Article first published online: 17 FEB 2009
- Received 5 June 2007; accepted for publication 21 August 2008.
- dropstone structure;
- dump structure;
- Early Permian;
- Sibumasu block
It has previously been proposed that the Sibumasu block of Southeast Asia, which contains glaciomarine deposits, became detached from the Gondwana margin during the Early Permian. A combination of facies analysis and the identification of dropstones and dump structures from a Lower Permian diamictite-bearing sequence at Phuket, Thailand, and adjacent islands suggests that the sediments originated as glaciomarine and debris-flow deposits. The Lower Permian diamictite-bearing sequence in the study area corresponds to the Ko Sire and Ko He Formations, both of which consist of three principal lithofacies: diamictite, sandstone, and fine-grained facies. The low-lying Ko Sire Formation is up to 400 m thick and is characterized by laminated mudstone; the presence of dropstones and dump structures associated with Cruziana ichnofacies indicates ice-rafted sedimentation in a glacially influenced offshore area. The Ko Sire Formation is overlain by a diamictite sequence of the Ko He Formation (up to 400 m thick). Poorly and well-stratified diamictites with tabular and lensoidal geometries, in combination with resedimentation textures, indicate that the diamictites within the Ko He Formation are debris-flow deposits. The similar lithology of clasts in the diamictites and dropstones possibly suggests that the debris-flow diamictite was presumably remobilized from pre-existing glacial deposits. The evidence of a glacially influenced offshore environment supports a previously proposed paleogeographic interpretation in which the Sibumasu block was most likely located at the Northwest Australian margin of Gondwana.