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Geochemistry and geochronology of Late Triassic volcanic rocks in the Chiang Khong region, northern Thailand
Citation
Srichan, W and Crawford, AJ and Berry, RF, Geochemistry and geochronology of Late Triassic volcanic rocks in the Chiang Khong region, northern Thailand, The Island Arc, 18, (1) pp. 32-51. ISSN 1038-4871 (2009) [Refereed Article]
DOI: doi:10.1111/j.1440-1738.2008.00660.x
Abstract
The Chiang Khong segment of the Chiang Khong-Lampang-Tak Volcanic Belt is composed of three broadly meridional sub-belts of mafic to felsic volcanic, volcaniclastic, and associated intrusive rocks. Associated sedimentary rocks are largely non-marine red beds and conglomerates. Three representative Chiang Khong lavas have Late Triassic (223-220 Ma) laser ablation inductively coupled mass-spectroscopy U-Pb zircon ages. Felsic-dominated sequences in the Chiang Khong Western and Central Sub-belts are high-K calc-alkaline rocks that range from basaltic to dominant felsic lavas with rare mafic dykes. The Western Sub-belt lavas have slightly lower high field strength element contents at all fractionation levels than equivalent rocks from the Central Sub-belt. In contrast, the Eastern Sub-belt is dominated by mafic lavas and dykes with compositions transitional between E-mid-oceanic ridge basalt and back-arc basin basalts. The Eastern Sub-belt rocks have higher FeO* and TiO2 and less light rare earth element enrichment than basalts in the high-K sequences. Basaltic and doleritic dykes in the Western and Central sub-belts match the composition of the Eastern Sub-belt lavas and dykes. A recent geochemical study of the Chiang Khong rocks concluded that they were erupted in a continental margin volcanic arc setting. However, based on the dominance of felsic lavas and the mainly non-marine associated sediments, we propose an alternative origin, in a post-collisional extensional setting. A major late Middle to early Late Triassic collisional orogenic event is well documented in northern Thailand and Yunnan. We believe that the paucity of radiometric dates for arc-like lavas in the Chiang Khong-Lampang-Tak Volcanic Belt that precede this orogenic event, coupled with the geochemistry of the Chiang Khong rocks, and strong compositional analogies with other post-collisional magmatic suites, are features that are more typical of volcanic belts formed in a rapidly evolving post-collisional, basin-and range-type extensional setting.
Item Details
Item Type: | Refereed Article |
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Keywords: | Thailand, geology, Chiang Kong-Lampang volcanic belt, Late Triassic volcanism, tectonics |
Research Division: | Earth Sciences |
Research Group: | Geology |
Research Field: | Structural geology and tectonics |
Objective Division: | Mineral Resources (Excl. Energy Resources) |
Objective Group: | Mineral exploration |
Objective Field: | Mineral exploration not elsewhere classified |
UTAS Author: | Srichan, W (Mr Weerapan Srichan) |
UTAS Author: | Crawford, AJ (Professor Anthony Crawford) |
UTAS Author: | Berry, RF (Associate Professor Ron Berry) |
ID Code: | 62079 |
Year Published: | 2009 |
Web of Science® Times Cited: | 35 |
Deposited By: | Centre for Ore Deposit Research - CODES CoE |
Deposited On: | 2010-03-09 |
Last Modified: | 2010-04-15 |
Downloads: | 0 |
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