The regression which commenced in the Triassic continued through the Jurassic, with marine sediments confined to the western side of Northern, Western and Peninsular Thailand, while continental red-beds were deposited in Northern and Northeast Thailand. The marine facies are predominantly sandstone, conglomerate, mud-stone and limestone, and contain a fauna which includes bivalves, gastropods, corals, ammonites, brachiopods and foraminifera which indicate that the succession is of Toarcian to Aalenian or possibly Early Bajocian age.
With caveats discussed below, non-marine Jurassic rocks are widespread in NE Thailand where they are more than 1000 m thick and form part of the Khorat Group of the Khorat Plateau. They also occur, but are less widespread, in Northern and Peninsu lar Thailand. Age determinations are based mainly on vertebrates, bivalves and palynomorphs, although the position of the Jurassic-Cretaceous boundary remains under discussion.
After the widespread volcanic activity of the Triassic, the Jurassic was a period of apparent volcanic quiescence and there are no confirmed occurrences of volcanic rocks of this age.
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The Geology of Thailand
This is the first volume in the English language to cover the entire range of the geology of Thailand since the joint Thai—US account by Brown et al. exactly 60 years ago. Over this period there has been a phenomenal growth in interest in this core area of SE Asia. This has been led by geologists in Thailand, but with important and highly significant input from geologists based elsewhere in Asia and in Europe, Australasia and North America. Some of that research was prompted by commercial considerations, since Thailand has important energy and mineral resources, while other research has sought to understand better the stratigraphic and structural history, including the plate-tectonic story which Thailand's rocks reveal. This new volume seeks to bring together all of this knowledge into a single accessible book; it is the work of an international team drawn from Thailand, Japan, Australia, USA, Canada, Germany and the UK.