Igneous and Structural Features of Thailand
- Gordon A. Macdonald and
- Hisashi Kuno
Published Online: 21 MAR 2013
Copyright 1962 by the American Geophysical Union.
The Crust of the Pacific Basin
How to Cite
Klompé, T. H. F. (1962) Igneous and Structural Features of Thailand, in The Crust of the Pacific Basin (eds G. A. Macdonald and H. Kuno), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM006p0122
- Published Online: 21 MAR 2013
- Published Print: 1 JAN 1962
Book Series Editors:
- Waldo E. Smith
Print ISBN: 9780875900063
Online ISBN: 9781118669310
- Alpine folding;
- Geological time scale;
- Igneous and structural features of Thailand;
- Mesozoic orogenic cycle;
- Tertiary Alpine-Himalaya orogeny;
- Zonal development
This paper presents a survey of the igneous and structural features of Thailand and their possible ages of emplacement and development. Three groups of igneous rocks are distinguished. Oldest are mafic to ultramafic rocks in northern Thailand, intrusive in the Silurian—Lower Carboniferous Kanchanaburi Series; they may represent the result of an initial geosynclinal magmatic activity.
The Mesozoic granites are represented by an older, Upper Triassic, granite in the eastern, and a younger tin-bearing granite in the western part of the country. The age of this last granite is considered to be post-Triassic. Recent age determinations on granites from Billiton and Singkep have revealed that they were emplaced some 145–155 m y ago.
The youngest representatives are various kinds of effusives and some dioritic intrusions of Upper Tertiary and Pleistocene age; they are related to important faulting features.
Structurally, Thailand can be divided into a western and northern mountain belt, the Korat Plateau in the east, and the depression of the Gulf of Thailand in between. The first unit consists of a conformable Paleozoic sequence, locally conformably capped by Triassic deposits. The disconformities in the sequence are ascribed to epeirogenic movements at times that important orogenic movements were taking place in areas further east. The regularity of this sequence, the age of the granites and the unconformable contact between the folded layers and the overlying late Jurassic to early Cretaceous deposits in adjacent areas (Malaya, Borneo, Sumatra), favor an Upper Jurassic (young Cimmerian) phase of mountain building.
In the Korat Plateau the folded Paleozoic sequence is unconformably overlain by the almost horizontal Rhaetic-Liassic and younger members of the Korat Series. This unconformity and the age of the granites favor an Upper Triassic (old Cimmerian) phase of diastrophism for the basement in the eastern part of the country.
The depression of the Gulf of Thailand is the result of faulting. The northern part of this depression is being gradually filled with alluvial deposits and the coastline pushed southward approximately four to five meters per year. The structural features of Thailand and adjacent areas form an excellent example of zonal growth in this part of Asia.