Abstract In the 1960s, anticipating the award of concessions in the Gulf of Thailand, BP carried out reconnaissance geological mapping over all of Southern Thailand including its Gulf islands. The resulting eight geological maps at 1:250 000 scale provided a database that underpinned discussions of Thailand's place in global plate-tectonic reconstructions that were emerging at that time. In particular, new light was thrown on the Paleozoic succession, and important differences were found between the Upper Thai Peninsula and the Lower Peninsula (respectively, NW and SE of the prominent bend in the peninsula's outline). The Phuket Group of the Upper Peninsula is a very thick diamictite-bearing succession of possible Devonian to Early Permian age, apparently sourced in the west, a region now occupied by the Indian Ocean. That in turn suggested a possible Gondwana origin for SE Asia, a contentious concept at the time, but one that is now widely accepted. The emphasis of field mapping these days is on obtaining detailed data that necessarily means over areas of limited extent. But a very broad regional mapping project such as BP's in Thailand revealed stratigraphic and tectonic insights that could be revealed only from a wide-ranging regional study of this kind.

Abstract We describe a new elasmobranch fauna from the lower part of the Khlong Min Formation in Thailand. The fauna includes Hybodus sp., Asteracanthus sp., Lonchidion reesunderwoodi sp. nov., Belemnobatis aominensis sp. nov., and possibly a second species of Belemnobatis. This fauna supports a Bathonian–Callovian age for the Khlong Min Formation, and suggests a close taxonomic relationship between the Middle Jurassic elasmobranch faunas of Europe and Thailand. The presence of a monolayered enameloid in Belemnobatis aominensis sp. nov. and other primitive batoids is interpreted as the retention of a primitive character for neoselachians, which would suggest a divergence time between the batoids and the rest of the neoselachian sharks as early as the Carboniferous–Permian boundary.

ABSTRACT Texaco Exploration drilled the Mayura #1 well in the southern Pattani Basin of the Gulf of Thailand in the first half of 1994 with partners Fina and Ampolex. The well was drilled on the ramp side of a half-graben and had numerous oil shows in proximal, nonmarine reservoirs within the synrift section. One DST zone flowed oil but the permeability of the reservoir units was compromised by kaolinite in the pore system. High frequency, nonmarine sequence stratigraphy was applied to the wireline log data. Interpretation criteria are outlined suitable for application to proximal stratigraphic positions within alluvial fan to braided plain environments. A typical sequence is composed of stacked, fining-upward parasequence units that aggrade during times of relative base level rise. Each sequence shows the depositional response to factors that reorganize the drainage patterns and/or the delivery system of sediments to the basin. This response records an overall maturing-upward of depositional processes in each sequence through geologic time. Alluvial fan lithologies accumulated near the base of the sequence and braided plain to high energy fluvial sands aggraded in the middle to the top of each sequence. The resulting stratigraphic architecture formed two reservoir plumbing systems that affected the DST results in the Mayura well. Interpretation of seismic data shows that two large-scale movements on the border fault also affected the sediments in this basin. Tectonically-controlled sediment packages formed with rapid deposition into the accommodation created by slip on the border fault. Poorly organized depositional processes dominated at this time. As the accommodation filled, the fluvial plain broadened and a more mature, fluvial plain had time to develop and aggrade. Tectonic control on the sediments reduced and the influence of other factors, like base level, increased causing a stacked sequence architecture. Each rapid slip on the border fault created a low-order, shallowing-upward sediment package. It is also interpreted to be a ‘maturing-upward’ cycle of depositional processes. The low-order tectonic and higher-order sequence stratigraphy in graben settings show a hierarchy of depositional packages that can lead explorationists to greater predictability of reservoirs within nonmarine environments.

Abstract This paper describes the Ordovician stratigraphy of the Sibumasu Block, which formed part of equatorial peri-Gondwana during the early Paleozoic, and summarizes the palaeoenvironmental conditions that prevailed during that time. Upper Cambrian sequences are commonly dominated by coarse-grained clastic rocks of shallow-marine origin. The lithology of the Lower Ordovician varies from region to region, with fine-grained clastic rocks in the Shan Plateau, shallow-marine clastic rocks in northern to western Thailand and shallow-marine carbonate rocks in southern Thailand to northwestern Malaysia. Middle Ordovician strata consist entirely of shallow- to deeper-water carbonate rocks, with the exception of turbidites in midwestern Malaysia. Upper Ordovician rocks show an overall deeper environment, and the uppermost Ordovician consists of pelagic and deeper, fine-grained clastic rocks. On the basis of palaeobiogeographical data, the Sibumasu Block was adjacent to Western Australia throughout the early Paleozoic. Upper Cambrian rhyolitic rocks in the Shan Plateau and Lower–Middle Ordovician volcanics in midwestern Malaysia may have formed as a result of tectonomagmatism associated with the subduction of the Proto-Tethys Ocean plate into the northern Gondwanan margin. The close similarity of Late Ordovician fossil assemblages from Sibumasu and South China may be due to a sea-level rise during this time.

Abstract Among the thousands of people killed or reported missing in Thailand during the 2004 Indian Ocean Tsunami were villagers in small communities on the Andaman Coast. A combination of factors contributed to loss of life, including the lack of defined evacuation routes. This vulnerability to tsunami attacks has recently been addressed with the demarcation of evacuation routes, along both well-maintained arteries and native surface (unpaved) roads. However, poor location design and irregular maintenance will reduce the lifetime that the latter can provide safe egress from remote coastlines. In this work we identified 10 major gullies and 18 landslides along a critical 0.5 km section of a tsunami evacuation road accessing a remote beach of the Andaman Coast in southern Thailand. Erosion rates from landslides and gullies approached 9500 Mg ha −1 in less than a year following widening of the road. Importantly, the degradation features, landslides in particular, reduced the effectiveness of the road to serve as a safe passageway to escape future tsunamis or large storm surges. This study demonstrates that greater attention should be given to appropriate road location, design and maintenance in integrated programmes aimed at reducing tsunami vulnerability in remote coastal areas, not only on the Andaman Coast, but worldwide.