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To mark A.R. Wallace's 200th birthday, we review the direct and indirect contributions he made to our understanding of the Indo‐Australian Archipelago's biogeography. He is widely known for his field research (1854–1862) and his 1863 boundary line separating the Oriental and Australasian faunal realms (between Bali and Lombok, Borneo and Sulawesi, and the Philippines and the Moluccas). Notably, though, he never accepted Huxley's 'Wallace Line' proposal (1868), whose northern part runs between the main Philippine islands and the Palawan Group to the west. Furthermore, in 1910, which was 3 years prior to his demise, he transferred Sulawesi's fauna to the Oriental realm. In 1924, Merrill introduced the 'Wallacea' transition zone. Although the label is today widely used to denote a sub‐region within the Indo‐Australian Archipelago between Wallace's 1863 line and Lydekker's 1896 line (first presented by Darlington in 1957), the western boundary was originally based on Huxley's line, and thus included the Philippine islands minus the Palawan group. Most biogeographers appear to be unaware of Merrill and his intention. Finally, recent attempts to define the faunal break have not led to a consensus view, despite the huge increase in primary data plus the application of modern analytical techniques. This reflects the complexities and diversity of the region's faunal distribution patterns, plus the differences in the ways that researchers choose to process their data. [ABSTRACT FROM AUTHOR]

The Middle Permian (c. 262 Ma) Emeishan Basalt Formation of SW China is a commonly cited example of a large igneous province (LIP) that formed as a result of a deep-mantle plume impinging on the base of the lithosphere and generating large regional-scale up-doming prior to volcanism. Recently, however, this assertion has been challenged on the grounds that some lava flows close to the centre of the LIP were erupted in a submarine setting. Here we analyse all the available biolithostratigraphical, petrological, geochemical and volcanological information and show that this supports the idea that the terrain was generated by a plume that originated in the mantle. Emeishan basalt magma melted from a hot mantle source with trace element contents that are similar to the source of Icelandic and intraplate ocean island basalts. However, the amount and lateral extent of uplift is significantly less than is predicted by conventional deep-mantle plume models. We conclude that large-scale doming is not a diagnostic feature of mantle plumes; surface topography can be greatly influenced by the type of lower mantle plume (thermal or thermochemical), how it passes through the transition zone, and how it interacts with the lithosphere. doi: 10.1144/0016-76492009-129.

The discovery of two Early Cretaceous (mid-Valanginian---mid-Aptian range) radiolarian faunal assemblages from ribbon-bedded cherts collected near Photoskar in northern Ladakh, NW India, provides the first robust biostratigraphic age constraints associated with the Spongtang massif. This klippe of relict Neotethyan suprasubduction-zone ophiolitic rocks and related arc volcanic rocks crops out 30 km south of the Indus suture in Ladakh. The radiolarian assemblages, the age assignment of which lies between published radiometric ages, provide new constraints on the evolution of this intra-oceanic island arc system. Critically, from them it can be inferred that the system was appreciably long-lived (Jurassic--Cretaceous) and more continuous than is commonly considered. doi: 10.1144/0016-76492009-099.

Madagascar hosts one of the world's most unusual, endemic, diverse and threatened concentrations of fauna (1). To explain its unique, imbalanced biological diversity, G. G. Simpson proposed the 'sweepstakes hypothesis', according to which the ancestors of Madagascar's present-day mammal stock rafted there from Africa (2). This is an important hypothesis in biogeography and evolutionary theory for how animals colonize new frontiers (1,3-5), but its validity is questioned (5-9). Studies suggest that currents were inconsistent with rafting to Madagascar (9) and that land bridges provided the migrants' passage (5-8). Here we show that currents could have transported the animals to the island and highlight evidence inconsistent with the land-bridge hypothesis. Using palaeogeographic reconstructions and palaeo-oceanographic modelling, we find that strong surface currents flowed from northeast Mozambique and Tanzania eastward towards Madagascar during the Palaeogene period, exactly as required by the 'sweepstakes process'. Subsequently, Madagascar advanced north towards the equatorial gyre and the regional current system evolved into its modern configuration with flows westward (10) from Madagascar to Africa. This may explain why no fully non-aquatic land mammals have colonized Madagascar since the arrival of the rodents and carnivorans during the early-Miocene epoch. One implication is that rafting may be the dominant means of overseas dispersal in the Cenozoic era when palaeocurrent directions are properly considered., Madagascar is home to one of the most intriguing inventories of flora and fauna anywhere on Earth (1). It is characterized by unusually high levels of mammalian endemism combined with [...]

[1] The northern termination of the Philippine archipelago is remarkably abrupt. The distinctive, almost rectangular, shape of northern Luzon is a consequence of the almost simultaneous disappearance near 18[degrees]N of the Central Cordillera, the much narrower Sierra Madre, and the broad floodplain of the Cagayan River. The floodplain is underlain by a deep sedimentary basin that is closed off just inland of the coast by an ENE-WSW structural high known as the Sicalao Ridge. Gravity surveys show that the ridge has steep flanks that are almost certainly defined by faulting. In the same region, there is also a dramatic change in the Luzon Arc, which is the volcanic expression of subduction of the South China Sea. The volcanic centers in the Central Cordillera (the North Luzon Segment of the arc) are all now inactive, but further north eruptions are frequent on the small eastern islands of the Bashi Segment. The differences between the North Luzon and Bashi segments suggest that they had very different geological histories until the late Neogene, but the evolution of northern Luzon is so poorly understood that it is not even known on which plate it originated. New paleomagnetic data and the existence of the Sicalao Ridge provide important constraints on reconstructions and, when combined with geological data, favor the possibility that in the Paleogene the Central Cordillera and Sierra Madre were combined as parts of an arc at the southern margin of the Philippine Sea. The Sicalao Ridge can be interpreted as a rift margin feature created during the detachment of Luzon from continental Sundaland. Citation: Milsom, J., J. R. Ali, and K. L. Queano (2006), Peculiar geometry of northern Luzon, Philippines: Implications for regional tectonics of new gravity and paleomagnetic data, Tectonics, 25, TC4017, doi:10.1029/2005TC001930.

'Greater India' is an 80-yr-old concept that has been used by geoscientists in plate tectonic models of the India-Asia collision system. Numerous authors working on the orogen and/or plate models of the broader region have added various sized chunks of continental lithosphere to the now northern edge of their reconstructed Indian plate. Prior to plate tectonic theory, Emile Argand (1924) [Argand, E., 1924. La tectonique de l' Asie. Proc. 13th Int. Geol. Cong. 7 (1924), 171-372.] and Arthur Holmes (1965) [Holmes, A., 1965. Principles of Physical Geology, Second Edition. The Ronald Press Company, New York, 1128.] thought that the Himalayan Mountains and Tibetan Plateau had been raised due to the northern edge of the Indian craton under-thrusting the entire region. Since the advent of plate tectonic theory, Greater India proposals have been based principally on three lines of logic. One group of workers has added various amounts of continental lithosphere to India as part of their Mesozoic Gondwana models. A second form of reconstruction is based on Himalayan crustal-shortening estimates. A third body of researchers has used India continent extensions as means of allowing initial contact between the block and the Eurasian backstop plate in southern Tibet to take place at various times between the Late Cretaceous and late Eocene in what we call 'fill-the-gap' solutions. The Indian craton and the southern edge of Eurasia were almost invariably some distance from one another when the collision was supposed to have started; extensions to the sub-continent were used to circumvent the problem. Occasionally, Greater India extensions have been based on a combination of fill-the-gap and shortening estimate arguments. In this paper, we exhume and re-examine the key Greater India proposals. From our analysis, it is clear that many proponents have ignored key information regarding the sub-continent's pre break-up position within Gondwana and the bathymetry of the Indian Ocean west of Australia, in particular the Wallaby-Zenith Plateau Ridge and the Wallaby-Zenith Fracture Zone. We suggest that the Indian continent probably extended no more than 950 km in the central portion of the Main Boundary Thrust, up to the Wallaby-Zenith Fracture Zone. At the Western Syntaxis, the extension was about 600 km. These estimates are broadly compatible with some of the geophysically-derived models depicting subducted Indian lithosphere beneath Tibet, as well as estimates of Himalayan shortening. Models requiring sub-continent extensions < 9[degrees] ahead of the craton are probably wrong. We also suggest that northern India did not have a thinned rifted passive margin due to the earlier rifting of blocks away from it when it formed part of Gondwana. Instead, the boundary developed as a transform fault and probably had a very narrow ocean-continent transition zone (5-10 km wide), similar to the Romanche Fracture Zone offshore of Ghana, West Africa. Keywords: Gondwana; Indian Ocean; Tethys; Wallaby Plateau; Palaeogeography

Petrological, geochemical, geochronological and palaeomagnetic data for rocks of the Northland ophiolite terrane of northern New Zealand suggest that it formed in a suprasubduction-zone setting between c. 29 and 26 Ma, at c. 35[degrees]S, close to its Late Oligocene obduction site. Cretaceous igneous rocks formerly considered to be part of the ophiolite probably represent the basement upon which the ophiolite was emplaced, and are probably part of the Mount Camel arc-related terrane. The ophiolite is believed to have been generated in the southeastern South Fiji Basin, close to a NW--SE-oriented transform fault located to the SW of the Vening Meinesz Fracture Zone, and was probably emplaced in response to the collision of the Hikurangi Plateau with eastern New Zealand at the end of the Oligocene. This collision would have involved a major adjustment on the transform fault, thereby allowing a portion of the upper-crustal section of the southern South Fiji Basin to be emplaced southwestward onto northern New Zealand as well as the coeval emplacement of the East Cape Allochthon to the south. Concomitant subduction of the lower crust mantle section led to the initiation of are volcanism that resulted in the Northland Lower Miocene volcanic--plutonic suite. Keywords: SW Pacific, Northland ophiolite, tectonics, palaeomagnetism, absolute age.

A magnetostratigraphic investigation of the Permian Emeishan LIP (large igneous province) was carried out on a composite section in Ebian County, close to the type area in Sichuan, SW China. The main succession of twelve flows (175 m thick) carries a normal polarity whilst the one reliable site from the overlying 30 m thick volcanic waning sequence is marked by a reverse polarity. The data enable a correlation to be proposed with an Emeishan Basalt sequence in western Guizhou, c. 400 km to the SE. From our knowledge of the geomagnetic field's reversal behaviour during the Permian, it suggests that the main lava pile along the eastern half of the Emeishan Basalt outcrop belt was erupted within a half to one million years. Using magnetobiostratigraphic data from the adjacent South China platform, the normal polarity magnetozone is correlated with the normal polarity chron associated with the upper part of the Maokou Limestones. Constrained by conodont data, the main Emei Basalts appear to be at least two biozones older (1-1.5 Ma) than the Mid-Late Permian boundary. It is possible, however, that the Emei Basalt waning zone sequence, which represents an explosive volcanic phase, might be coeval with the `end-Guadalupian' biotic crisis. Thus arguments implicating Emei Basalt volcanism as the causal mechanism behind this major global event have to accommodate the new relative-age constraints. Keywords: Sichuan; China; Permian, Guadalupian, magnetostratigraphy; extinction.

Using all available biostratigraphic information and our own extensive magnetostratigraphic database, we have attempted to assess the synchronicity of depositional cycles recorded in the Paleogene epicontinental deposits on both sides of the North Atlantic as stage two of a four-stage global assessment of the eustatic sea-level model. Our conclusion is that the depositional histories of the U.S. Gulf of Mexico-Atlantic coastal plain and the North Sea basin show many similarities, on a variety of time scales, over the interval 60-46 Ma. Considering the tectonic imprint of the northeast Atlantic opening on the North Sea basin sea-level record for part of this time, it must give some weight to the claim that eustasy is the dominant mechanism controlling deposition on passive continental margins.