Ian Metcalfe | University of New England - Australia (original) (raw)

Papers by Ian Metcalfe

Journal of Asian Earth Sciences, 2009

Measured lithostratigraphic sections of the classic Permian-Triassic non-marine transitional sequ... more Measured lithostratigraphic sections of the classic Permian-Triassic non-marine transitional sequences covering the upper Quanzijie, Wutonggou, Guodikeng and lower Jiucaiyuan Formations at Dalongkou and Lucaogou, Xinjiang Province, China are presented. These measured sections form the framework and reference sections for a range of multi-disciplinary studies of the P-T transition in this large ancient lake basin, including palynostratigraphy, vertebrate biostratigraphy, chemostratigraphy and magnetostratigraphy. The 121 m thick Wutonggou Formation at Dalongkou includes 12 sandstone units ranging in thickness from 0.5 to 10.5 m that represent cyclical coarse terrigenous input to the lake basin during the Late Permian. The rhythmically-bedded, mudstone-dominated Guodikeng Formation is 197 m and 209 m thick on the north and south limbs of the Dalongkou anticline, respectively, and 129 m thick at Lucaogou. Based on limited palynological data, the Permian-Triassic boundary was previously placed approximately 50 m below the top of this formation at Dalongkou. This boundary does not coincide with any mappable lithologic unit, such as the basal sandstones of the overlying Jiucaiyuan Formation, assigned to the Early Triassic. The presence of multiple organic d 13 C-isotope excursions, mutant pollen, and multiple algal and conchostracan blooms in this formation, together with Late Permian palynomorphs, suggests that the Guodikeng Formation records multiple climatic perturbation signals representing environmental stress during the late Permian mass extinction interval. The overlap between the vertebrates Dicynodon and Lystrosaurus in the upper part of this formation, and the occurrence of late Permian spores and the latest Permian to earliest Triassic megaspore Otynisporites eotriassicus is consistent with a latest Permian age for at least part of the Guodikeng Formation. Palynostratigrahic placement of the Permian-Triassic boundary in the Junggar Basin remains problematic because key miospore taxa, such as Aratrisporites spp. are not present. Palynomorphs from the Guodikeng are assigned to two assemblages; the youngest, from the upper 100 m of the formation (and the overlying Jiucaiyuan Formation), contains both typical Permian elements and distinctive taxa that elsewhere are known from the Early Triassic of Canada, Greenland, Norway, and Russia. The latter include spores assigned to Pechorosporites disertus, Lundbladispora foveota, Naumovaspora striata, Decussatisporites mulstrigatus and Leptolepidites jonkerii. While the presence of Devonian and Carboniferous spores and Early Permian pollen demonstrate reworking is occurring in the Guodikeng assemblages, the sometimes common occurrence of Scutasporites sp. cf. Scutasporites unicus, and other pollen, suggests that the Late Permian elements are in place, and that the upper assemblage derives from a genuine transitional flora of Early Triassic aspect. In the Junggar Basin, biostratigraphic data and magnetostratigraphic data indicate that the Permian-Triassic boundary (GSSP Level) is in the middle to upper Guodikeng Formation and perhaps as high as the formational contact with the overlying Jiucaiyuan Formation.

Present-day East and Southeast Asia comprises a heterogeneous collage of continental blocks deriv... more Present-day East and Southeast Asia comprises a heterogeneous collage of continental blocks derived from the Indian-west Australian margin of eastern Gondwana, and subduction related volcanic arcs assembled by the closure of multiple Tethyan and back-arc ocean basins. Now destroyed ocean basins are represented by suture zones containing ophiolites, accretionary complexes and remnants of ocean islands .

Lanchang IN DOCH I NA Semanggol Semantan Foredeep VolcaniclasUc Acidic Volcanics SIBUMASU 0 50 km... more Lanchang IN DOCH I NA Semanggol Semantan Foredeep VolcaniclasUc Acidic Volcanics SIBUMASU 0 50 km 0 250 km (approx.)

The Tethys in East Asia is represented by three successive ocean basins, the Palaeo-Tethys, Meso-... more The Tethys in East Asia is represented by three successive ocean basins, the Palaeo-Tethys, Meso-Tethys and Ceno-Tethys. The Palaeo-Tethys ranges in age from late Early Devonian to Middle Triassic , the Meso-Tethys from late Early Permian to Late Cretaceous, and the Ceno-Tethys from Late Triassic (west)/Late Jurassic (east) to Cenozoic. These ocean basins had a range of water depths comparable to modem ocean basins and the concept of a shallow Tethys should only be applied to the shallow regions of these oceans. All three Tethyan ocean basins, based on palaeogeographic reconstructions , had maximum widths between 2,000 and 3,000 kilometers in their eastern parts at their maximum development.

The Phanerozoic tectonic evolution of Southeast Asia has involved the dispersion of continental t... more The Phanerozoic tectonic evolution of Southeast Asia has involved the dispersion of continental terranes from the margin of Gondwanaland, their northwards drift and amalgamation/accretion to form present-day East and Southeast Asia. The continental terranes of mainland Southeast Asia include the South China (which may be composite), Indochina, Qamdo-Simao (possibly an extension of Indochina), Sibumasu (including the Baoshan and Tenchong blocks of Yunnan), South West Borneo, Semitau, West Burma, Sikuleh, Natal, Bengkulu and Hainan Island terranes. These terranes rifted and separated from Gondwanaland during three episodes; in the Devonian (South China, Indochina, Qamdo-Simao, Hainan); late Early Permian (Sibumasu); and Late Triassic-Late Jurassic (West Burma, Sikuleh and Natal). During the separation of the three collages of terranes from Gondwanaland, three Tethyan ocean basins opened, the Palaeo-Tethys, Meso-Tethys and Ceno-Tethys. The Southeast Asian terranes were assembled during Carboniferous to Cretaceous times, ftrst with the amalgamation of South China and Indochina in the Lower Carboniferous, followed by the amalgamation of this superterrane with Sibumasu in the Triassic and then the accretion of the other smaller Southeast Asian terranes in the Mesozoic. The various terranes of Southeast Asia are bounded by suture zones that represent the remnants of the various Tethyan ocean basins, or by major strike-slip faults. The main Palaeo-Tethys ocean basin, which separates Late Palaeozoic Gondwanaland terranes to the west from Late Palaeozoic Cathaysian terranes to the east, is represented by the Lancangjian and Changning-Menglian sutures of SW China, the Nan-Uttaradit and Sra Kaeo sutures of Thailand, and the Bentong-Raub suture zone of Peninsular Malaysia. Other subsidiary branches of the Palaeo-Tethys are represented by the Ailaoshan suture in Yunnan, the Song Ma suture in Vietnam and other possible suture segments in North Thailand and southern Guangxi, South China. Radiolarian biostratigraphic and geochemical studies of ribbon-bedded cherts of the main Palaeo-Tethys, together with other constraining data, suggest that the Palaeo-Tethys opened in the Mid-Late Devonian and closed in the Triassic.

The proliferation of technological tools such as satellite digital image processing and Geographi... more The proliferation of technological tools such as satellite digital image processing and Geographic Information Systems (GIS) has increased the flexibility in the analysis of geological data. An integrated GIS approach has been accepted as the best way of using these new methods for handling spatially referenced geological data sets and performing statistical and spatial analysis for exploration. Analytical methods, such as spatial modelling of GIS databases for the generation of mineral prospectivity maps, and statistical methods for the analysis and interpretation of geological structures within the GIS environment are described. These methods assist in understanding the structural style and pattern within various geological units and structural/tectonic blocks and the relationship between these and economic mineral deposits. Advances in GIS research, in terms of real time modelling and 3D query as an on the spot decision making tool are also described.

The Bentong-Raub suture zone of Peninsular Malaysia represents a segment of the former ocean - Pa... more The Bentong-Raub suture zone of Peninsular Malaysia represents a segment of the former ocean - Palaeo-Tethys that once separated two terranes , Sibumasu and Indochina/East Malaya. Melange of the Bentong-Raub suture zone contains coherent blocks of bedded chert, siliceous and tuffaceous argillite, chert clasts and lenses, rare conglomerate clasts, limestone, sandstone and serpentinite, set within a matrix of sheared argillite. The ages of the fault-bounded packages of marine siliceous sediments includes Late Devonian (Famennian), Early Carboniferous (Tornaisian and Visaan), and Early Permian (Wolfcampian and Leonardian). These ages are represented by eight radiolarian zones from ten localities along the suture zone. The well preserved radiolarians represent eight radiolarian zones. These are ; Holoeciscus 2-3 Assemblage Zones, Albaillella paradoxa Zone, Albaillella deflandrei Zone, Albaillella cartalla Zone, Pseudoalbaillella lomentaria Zone, Pseudoalbaillella scalprata m. rhombothoracata Zone, Albaillella sinuata Zone and Pseudoalbaillella longtanensis Zone. The lower Chert Member of the Semanggol Formation of northwest Peninsular Malaysia has revealed latest Lower Permian or early Upper Permian , Upper Permian (Guadalupian) and Middle Triassic (Anisian and /or Ladinian) radiolarian assemblages. Five radiolarian biostrat igraphic zones are represented. These are the ? Pseudoalbaillella longtanens is Zone, Follicucullus monacanthus Zone, Follicucuilus scholasticus Zone, N. ornithoformis Zone and the Triassocampe deweveri Zone. The range of ages of the radiolarians recovered from rocks within the Bentong-Raub suture zone (sensu stricto) suggests that an ocean existed between the Sibumasu and Indochina/ East Malaya terranes from at least Late Devonian to late Early Permian time. If the cherts previously considered the lower part of the Semanggol Formation, are in fact part of the accretionary complex of the Bentong-Raub suture zone. then the age of this zone can be extended to Middle Triassic and the accretionary complex is much wider than previously suggested.

Diamictites occurring in the Raub area, Pahang are interpreted as an olisthostrome associated wit... more Diamictites occurring in the Raub area, Pahang are interpreted as an olisthostrome associated with normal faults which were active along the western margin of the developing central graben of Peninsular Malaysia. Conodonts fran clasts in the diamictite and fron bedded limestone matrix sugest a late Farly Triassic age for these deposits and penecontanporaneous erosion and redeposition of Permian and early Triassic sediments. The early Triassic conodonts fran Raub belong to the Tethys Province and suggest that Malaya was unlikely to have been marginal to Gondwana in the early Triassic.

Southeast Asia comprises a complex assembly of continental fragments (ter­ranes), bounded by sutu... more Southeast Asia comprises a complex assembly of continental fragments (ter­ranes), bounded by suture zones that represent former ocean basins. ln the Early Palaeozoic (545-410 Ma), all the principal Southeast Asian continental terranes were located on the Hima­layan-Australian Gondwanaland margin, where they formed part of a "Greater Gondwanaland". Multidisciplinary studies suggest that the Asian te1nnes rifted and separated from NW Austra­lian Gondwanaland as three continental slivers around 350, 270, and 200-140 Ma. During the separation of these continental slivers, three ocean basins, the Palaeo-Tethys, Meso-Tethys and Ceno-Tethys, opened between each successive sliver and Gondwanaland. The first sliver, inter­preted to have separated at 350 Ma, included North China, South China, Tarim, and Indochina. By 325 Ma, these terranes had no Gondwanaland faunas and floras, and palaeomagnetic data indicate that they were separated from the parent craton. Clockwise rotation of Gondwanaland around 320-300 Ma sent Australia into high southern latitudes, and glaciation affected much of Gondwanaland from 320 to 270 Ma. During this time, glacial ice reached the marine environ­ment and glacial-marine sediments were deposited on the Sibumasu, Qiangtang, and Lhasa ter­ranes now located in South and Southeast Asia. Gondwanaland cold-climate faunas and floras and cold water oxygen isotopic signatures are also found in Lower Permian rocks of these ter­ranes. Rifting, starting at about 300 Ma, led to separation of the Sibumasu and Qiangtang ter­ranes from Gondwanaland at approximately 270 Ma. These Cinunerian terranes drifted rapidly northwards between 270 and 250 Ma and significant changes in both brachiopod and fusulinid biogeographic provinces on these between 300 and 250 Ma are interpreted as being primarily due to the separation and northwards drift of the Cimmerian continental terranes, coupled with climatic amelioration following retreat of the Gondwanaland glaciation. Rifting and separation of a third continental sliver from Gondwanaland began 230 million years ago with the separa­tion of the Lhasa block and progressed eastwards with separation of West Burma and possibly the small Sikuleh terrane of SW Sumatra and other small microcontinental fragments now lo­cated in Borneo and West Sulawesi around 160 Ma. Amalgamation and accretion of Gond­wanaland-derived Asian terranes occurred progressively between the Late Devonian and Creta­ceous.

Conodont faunas of the allochthonous East Asian terranes demonstrate bio­geographic affinities wi... more Conodont faunas of the allochthonous East Asian terranes demonstrate bio­geographic affinities with Australasia during the Cambrian to Permian and suggest close prox­imity or attachment to Australian Gondwanaland in the Palaeozoic over a time frame of about 250 My, from about 500 Ma in the Late Cambrian to the end of the Permian at about 253 Ma. Lower Palaeozoic conodonts that define an East Asia-Australasia province include the Late Cambrian genus Eodentatus and Ordovician taxa such as Serratognathus spp., Aurilobodus spp., Plectodina onychodonta and Tasmanognathus. The distinctive Lower to Middle Silurian conodont genera Tuberocostadontus and Nericodus are also restricted to East Asia and Austral­asia. Devonian conodont faunas appear to be more cosmopolitan, which may be related to global oceanic current distribution patterns. At the same time endemic forms are common, but species restricted to East Asia - Australasia have not been widely recognised. Lower Carbonif­erous conodont faunas of the Asian terranes and Western Australia are generally cosmopolitan. However, the distribution of Mestognathus beckmanni appears restricted to Gondwanaland (in­cluding the Siburnasu terrane), and Laurentia (including the allochthonous terranes ofN. Amer­ica). Eastern Australian conodont faunas are highly endemic during the Visean and are domi­nated by the genus Montognathus, which has also recently been discovered on the Sibumasu terrane. Conodonts appear to be absent from the Permian of eastern Australia due to the cold conditions present there as a result of high latitudinal position and Carbo-Permian glaciation. Conodonts were also thought, until recently, to be absent from Western Australia due to cold climatic conditions. However, scarce low diversity conodont faunas are now !mown from West­ern Australia and these are characterized and dominated by the cold-water tolerant genus Vjalo­vognathus which invaded the shallow continental margin seas of Gondwanaland during periods of climatic amelioration. Vjalovognathus is also recorded from Timor and the Pamirs and de­fines a Tethyan-Gondwanaland conodont province during the Permian.

Pre-Quaternary connections between SE Asia and Australia go back more than 1000 million years. Si... more Pre-Quaternary connections between SE Asia and Australia go back more than 1000 million years. Since plate-tectonics began operating back in the early Pre-Cambrian, continents created in the Archaean have collided, split, wandered around the earth and re-collided several times over. The continents are carried by constantly moving lithospheric plates that are created at mid-ocean ridges and destroyed by subduction at convergent plate boundaries. The present-day configuration of East and SE Asia is the result of these long drift histories, and of lost oceans now preserved as narrow remnant suture zones where 'worlds' have collided. Changing continent-ocean and land-sea configurations caused by plate tectonic movements, by continental collisions, volcanism and global eustatic sea-level changes have influenced the evolution and dispersal of faunas and floras, the environment and climate and ultimately the cultural history of the Sourtheast Asian-Australian region. The modern distribution of fauna and flora in SE Asia and Australia has its roots in the geological and tectonic history of the region. In this paper, I will provide an overview of the tectonic history of the region, beginning 1000 million years ago and ending just prior to the arrival of Homo erectus to the region, and will present palaeogeographic maps depicting the waxing and waning SE Asia-Australia connections and changing continentocean and land-sea configurations that have affected past climates.

Journal of Asian Earth Sciences, 2009

Measured lithostratigraphic sections of the classic Permian-Triassic non-marine transitional sequ... more Measured lithostratigraphic sections of the classic Permian-Triassic non-marine transitional sequences covering the upper Quanzijie, Wutonggou, Guodikeng and lower Jiucaiyuan Formations at Dalongkou and Lucaogou, Xinjiang Province, China are presented. These measured sections form the framework and reference sections for a range of multi-disciplinary studies of the P-T transition in this large ancient lake basin, including palynostratigraphy, vertebrate biostratigraphy, chemostratigraphy and magnetostratigraphy. The 121 m thick Wutonggou Formation at Dalongkou includes 12 sandstone units ranging in thickness from 0.5 to 10.5 m that represent cyclical coarse terrigenous input to the lake basin during the Late Permian. The rhythmically-bedded, mudstone-dominated Guodikeng Formation is 197 m and 209 m thick on the north and south limbs of the Dalongkou anticline, respectively, and 129 m thick at Lucaogou. Based on limited palynological data, the Permian-Triassic boundary was previously placed approximately 50 m below the top of this formation at Dalongkou. This boundary does not coincide with any mappable lithologic unit, such as the basal sandstones of the overlying Jiucaiyuan Formation, assigned to the Early Triassic. The presence of multiple organic d 13 C-isotope excursions, mutant pollen, and multiple algal and conchostracan blooms in this formation, together with Late Permian palynomorphs, suggests that the Guodikeng Formation records multiple climatic perturbation signals representing environmental stress during the late Permian mass extinction interval. The overlap between the vertebrates Dicynodon and Lystrosaurus in the upper part of this formation, and the occurrence of late Permian spores and the latest Permian to earliest Triassic megaspore Otynisporites eotriassicus is consistent with a latest Permian age for at least part of the Guodikeng Formation. Palynostratigrahic placement of the Permian-Triassic boundary in the Junggar Basin remains problematic because key miospore taxa, such as Aratrisporites spp. are not present. Palynomorphs from the Guodikeng are assigned to two assemblages; the youngest, from the upper 100 m of the formation (and the overlying Jiucaiyuan Formation), contains both typical Permian elements and distinctive taxa that elsewhere are known from the Early Triassic of Canada, Greenland, Norway, and Russia. The latter include spores assigned to Pechorosporites disertus, Lundbladispora foveota, Naumovaspora striata, Decussatisporites mulstrigatus and Leptolepidites jonkerii. While the presence of Devonian and Carboniferous spores and Early Permian pollen demonstrate reworking is occurring in the Guodikeng assemblages, the sometimes common occurrence of Scutasporites sp. cf. Scutasporites unicus, and other pollen, suggests that the Late Permian elements are in place, and that the upper assemblage derives from a genuine transitional flora of Early Triassic aspect. In the Junggar Basin, biostratigraphic data and magnetostratigraphic data indicate that the Permian-Triassic boundary (GSSP Level) is in the middle to upper Guodikeng Formation and perhaps as high as the formational contact with the overlying Jiucaiyuan Formation.

Present-day East and Southeast Asia comprises a heterogeneous collage of continental blocks deriv... more Present-day East and Southeast Asia comprises a heterogeneous collage of continental blocks derived from the Indian-west Australian margin of eastern Gondwana, and subduction related volcanic arcs assembled by the closure of multiple Tethyan and back-arc ocean basins. Now destroyed ocean basins are represented by suture zones containing ophiolites, accretionary complexes and remnants of ocean islands .

Lanchang IN DOCH I NA Semanggol Semantan Foredeep VolcaniclasUc Acidic Volcanics SIBUMASU 0 50 km... more Lanchang IN DOCH I NA Semanggol Semantan Foredeep VolcaniclasUc Acidic Volcanics SIBUMASU 0 50 km 0 250 km (approx.)

The Tethys in East Asia is represented by three successive ocean basins, the Palaeo-Tethys, Meso-... more The Tethys in East Asia is represented by three successive ocean basins, the Palaeo-Tethys, Meso-Tethys and Ceno-Tethys. The Palaeo-Tethys ranges in age from late Early Devonian to Middle Triassic , the Meso-Tethys from late Early Permian to Late Cretaceous, and the Ceno-Tethys from Late Triassic (west)/Late Jurassic (east) to Cenozoic. These ocean basins had a range of water depths comparable to modem ocean basins and the concept of a shallow Tethys should only be applied to the shallow regions of these oceans. All three Tethyan ocean basins, based on palaeogeographic reconstructions , had maximum widths between 2,000 and 3,000 kilometers in their eastern parts at their maximum development.

The Phanerozoic tectonic evolution of Southeast Asia has involved the dispersion of continental t... more The Phanerozoic tectonic evolution of Southeast Asia has involved the dispersion of continental terranes from the margin of Gondwanaland, their northwards drift and amalgamation/accretion to form present-day East and Southeast Asia. The continental terranes of mainland Southeast Asia include the South China (which may be composite), Indochina, Qamdo-Simao (possibly an extension of Indochina), Sibumasu (including the Baoshan and Tenchong blocks of Yunnan), South West Borneo, Semitau, West Burma, Sikuleh, Natal, Bengkulu and Hainan Island terranes. These terranes rifted and separated from Gondwanaland during three episodes; in the Devonian (South China, Indochina, Qamdo-Simao, Hainan); late Early Permian (Sibumasu); and Late Triassic-Late Jurassic (West Burma, Sikuleh and Natal). During the separation of the three collages of terranes from Gondwanaland, three Tethyan ocean basins opened, the Palaeo-Tethys, Meso-Tethys and Ceno-Tethys. The Southeast Asian terranes were assembled during Carboniferous to Cretaceous times, ftrst with the amalgamation of South China and Indochina in the Lower Carboniferous, followed by the amalgamation of this superterrane with Sibumasu in the Triassic and then the accretion of the other smaller Southeast Asian terranes in the Mesozoic. The various terranes of Southeast Asia are bounded by suture zones that represent the remnants of the various Tethyan ocean basins, or by major strike-slip faults. The main Palaeo-Tethys ocean basin, which separates Late Palaeozoic Gondwanaland terranes to the west from Late Palaeozoic Cathaysian terranes to the east, is represented by the Lancangjian and Changning-Menglian sutures of SW China, the Nan-Uttaradit and Sra Kaeo sutures of Thailand, and the Bentong-Raub suture zone of Peninsular Malaysia. Other subsidiary branches of the Palaeo-Tethys are represented by the Ailaoshan suture in Yunnan, the Song Ma suture in Vietnam and other possible suture segments in North Thailand and southern Guangxi, South China. Radiolarian biostratigraphic and geochemical studies of ribbon-bedded cherts of the main Palaeo-Tethys, together with other constraining data, suggest that the Palaeo-Tethys opened in the Mid-Late Devonian and closed in the Triassic.

The proliferation of technological tools such as satellite digital image processing and Geographi... more The proliferation of technological tools such as satellite digital image processing and Geographic Information Systems (GIS) has increased the flexibility in the analysis of geological data. An integrated GIS approach has been accepted as the best way of using these new methods for handling spatially referenced geological data sets and performing statistical and spatial analysis for exploration. Analytical methods, such as spatial modelling of GIS databases for the generation of mineral prospectivity maps, and statistical methods for the analysis and interpretation of geological structures within the GIS environment are described. These methods assist in understanding the structural style and pattern within various geological units and structural/tectonic blocks and the relationship between these and economic mineral deposits. Advances in GIS research, in terms of real time modelling and 3D query as an on the spot decision making tool are also described.

The Bentong-Raub suture zone of Peninsular Malaysia represents a segment of the former ocean - Pa... more The Bentong-Raub suture zone of Peninsular Malaysia represents a segment of the former ocean - Palaeo-Tethys that once separated two terranes , Sibumasu and Indochina/East Malaya. Melange of the Bentong-Raub suture zone contains coherent blocks of bedded chert, siliceous and tuffaceous argillite, chert clasts and lenses, rare conglomerate clasts, limestone, sandstone and serpentinite, set within a matrix of sheared argillite. The ages of the fault-bounded packages of marine siliceous sediments includes Late Devonian (Famennian), Early Carboniferous (Tornaisian and Visaan), and Early Permian (Wolfcampian and Leonardian). These ages are represented by eight radiolarian zones from ten localities along the suture zone. The well preserved radiolarians represent eight radiolarian zones. These are ; Holoeciscus 2-3 Assemblage Zones, Albaillella paradoxa Zone, Albaillella deflandrei Zone, Albaillella cartalla Zone, Pseudoalbaillella lomentaria Zone, Pseudoalbaillella scalprata m. rhombothoracata Zone, Albaillella sinuata Zone and Pseudoalbaillella longtanensis Zone. The lower Chert Member of the Semanggol Formation of northwest Peninsular Malaysia has revealed latest Lower Permian or early Upper Permian , Upper Permian (Guadalupian) and Middle Triassic (Anisian and /or Ladinian) radiolarian assemblages. Five radiolarian biostrat igraphic zones are represented. These are the ? Pseudoalbaillella longtanens is Zone, Follicucullus monacanthus Zone, Follicucuilus scholasticus Zone, N. ornithoformis Zone and the Triassocampe deweveri Zone. The range of ages of the radiolarians recovered from rocks within the Bentong-Raub suture zone (sensu stricto) suggests that an ocean existed between the Sibumasu and Indochina/ East Malaya terranes from at least Late Devonian to late Early Permian time. If the cherts previously considered the lower part of the Semanggol Formation, are in fact part of the accretionary complex of the Bentong-Raub suture zone. then the age of this zone can be extended to Middle Triassic and the accretionary complex is much wider than previously suggested.

Diamictites occurring in the Raub area, Pahang are interpreted as an olisthostrome associated wit... more Diamictites occurring in the Raub area, Pahang are interpreted as an olisthostrome associated with normal faults which were active along the western margin of the developing central graben of Peninsular Malaysia. Conodonts fran clasts in the diamictite and fron bedded limestone matrix sugest a late Farly Triassic age for these deposits and penecontanporaneous erosion and redeposition of Permian and early Triassic sediments. The early Triassic conodonts fran Raub belong to the Tethys Province and suggest that Malaya was unlikely to have been marginal to Gondwana in the early Triassic.

Southeast Asia comprises a complex assembly of continental fragments (ter­ranes), bounded by sutu... more Southeast Asia comprises a complex assembly of continental fragments (ter­ranes), bounded by suture zones that represent former ocean basins. ln the Early Palaeozoic (545-410 Ma), all the principal Southeast Asian continental terranes were located on the Hima­layan-Australian Gondwanaland margin, where they formed part of a "Greater Gondwanaland". Multidisciplinary studies suggest that the Asian te1nnes rifted and separated from NW Austra­lian Gondwanaland as three continental slivers around 350, 270, and 200-140 Ma. During the separation of these continental slivers, three ocean basins, the Palaeo-Tethys, Meso-Tethys and Ceno-Tethys, opened between each successive sliver and Gondwanaland. The first sliver, inter­preted to have separated at 350 Ma, included North China, South China, Tarim, and Indochina. By 325 Ma, these terranes had no Gondwanaland faunas and floras, and palaeomagnetic data indicate that they were separated from the parent craton. Clockwise rotation of Gondwanaland around 320-300 Ma sent Australia into high southern latitudes, and glaciation affected much of Gondwanaland from 320 to 270 Ma. During this time, glacial ice reached the marine environ­ment and glacial-marine sediments were deposited on the Sibumasu, Qiangtang, and Lhasa ter­ranes now located in South and Southeast Asia. Gondwanaland cold-climate faunas and floras and cold water oxygen isotopic signatures are also found in Lower Permian rocks of these ter­ranes. Rifting, starting at about 300 Ma, led to separation of the Sibumasu and Qiangtang ter­ranes from Gondwanaland at approximately 270 Ma. These Cinunerian terranes drifted rapidly northwards between 270 and 250 Ma and significant changes in both brachiopod and fusulinid biogeographic provinces on these between 300 and 250 Ma are interpreted as being primarily due to the separation and northwards drift of the Cimmerian continental terranes, coupled with climatic amelioration following retreat of the Gondwanaland glaciation. Rifting and separation of a third continental sliver from Gondwanaland began 230 million years ago with the separa­tion of the Lhasa block and progressed eastwards with separation of West Burma and possibly the small Sikuleh terrane of SW Sumatra and other small microcontinental fragments now lo­cated in Borneo and West Sulawesi around 160 Ma. Amalgamation and accretion of Gond­wanaland-derived Asian terranes occurred progressively between the Late Devonian and Creta­ceous.

Conodont faunas of the allochthonous East Asian terranes demonstrate bio­geographic affinities wi... more Conodont faunas of the allochthonous East Asian terranes demonstrate bio­geographic affinities with Australasia during the Cambrian to Permian and suggest close prox­imity or attachment to Australian Gondwanaland in the Palaeozoic over a time frame of about 250 My, from about 500 Ma in the Late Cambrian to the end of the Permian at about 253 Ma. Lower Palaeozoic conodonts that define an East Asia-Australasia province include the Late Cambrian genus Eodentatus and Ordovician taxa such as Serratognathus spp., Aurilobodus spp., Plectodina onychodonta and Tasmanognathus. The distinctive Lower to Middle Silurian conodont genera Tuberocostadontus and Nericodus are also restricted to East Asia and Austral­asia. Devonian conodont faunas appear to be more cosmopolitan, which may be related to global oceanic current distribution patterns. At the same time endemic forms are common, but species restricted to East Asia - Australasia have not been widely recognised. Lower Carbonif­erous conodont faunas of the Asian terranes and Western Australia are generally cosmopolitan. However, the distribution of Mestognathus beckmanni appears restricted to Gondwanaland (in­cluding the Siburnasu terrane), and Laurentia (including the allochthonous terranes ofN. Amer­ica). Eastern Australian conodont faunas are highly endemic during the Visean and are domi­nated by the genus Montognathus, which has also recently been discovered on the Sibumasu terrane. Conodonts appear to be absent from the Permian of eastern Australia due to the cold conditions present there as a result of high latitudinal position and Carbo-Permian glaciation. Conodonts were also thought, until recently, to be absent from Western Australia due to cold climatic conditions. However, scarce low diversity conodont faunas are now !mown from West­ern Australia and these are characterized and dominated by the cold-water tolerant genus Vjalo­vognathus which invaded the shallow continental margin seas of Gondwanaland during periods of climatic amelioration. Vjalovognathus is also recorded from Timor and the Pamirs and de­fines a Tethyan-Gondwanaland conodont province during the Permian.

Pre-Quaternary connections between SE Asia and Australia go back more than 1000 million years. Si... more Pre-Quaternary connections between SE Asia and Australia go back more than 1000 million years. Since plate-tectonics began operating back in the early Pre-Cambrian, continents created in the Archaean have collided, split, wandered around the earth and re-collided several times over. The continents are carried by constantly moving lithospheric plates that are created at mid-ocean ridges and destroyed by subduction at convergent plate boundaries. The present-day configuration of East and SE Asia is the result of these long drift histories, and of lost oceans now preserved as narrow remnant suture zones where 'worlds' have collided. Changing continent-ocean and land-sea configurations caused by plate tectonic movements, by continental collisions, volcanism and global eustatic sea-level changes have influenced the evolution and dispersal of faunas and floras, the environment and climate and ultimately the cultural history of the Sourtheast Asian-Australian region. The modern distribution of fauna and flora in SE Asia and Australia has its roots in the geological and tectonic history of the region. In this paper, I will provide an overview of the tectonic history of the region, beginning 1000 million years ago and ending just prior to the arrival of Homo erectus to the region, and will present palaeogeographic maps depicting the waxing and waning SE Asia-Australia connections and changing continentocean and land-sea configurations that have affected past climates.