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This book, "Submarine Mass Movements and Their Consequences IV", is dedicated to the memory of two colleagues whose wide-ranging field studies did so much to advance our understanding of deep-water sedimentation systems: Drs. Bill Normark and Bruno Savoye. I had the good fortune to count them among my closest professional and personal friends. Both were sea-going scientists par excellence, both were warm and supportive individuals, who always had time for students, and both were modest about their own accomplishments. Although many will remember Bill for his work on turbidites and submarine fans, he made important early contributions to our understanding of submarine mass movements. Large slides are a significant component of deep-water terrigenous basins and thus did not escape Bill's curiosity. In 1968, during his Ph.D. work, he acquired seabed imagery and sub-bottom profiles with the Scripps deeptow system over Ranger slide off Baja California. His 1974 and 1990 papers on this slide are classic Normark: meticulous use of multiple data sets and a clear mind as to what were the important issues. As Chief Scientist of the gloria cruise that mapped the seafloor around the Hawaiian islands, he was the first to appreciate the full extent of the flank-collapse debris avalanches, using the terms "prodigious" and "humongous" in the literature (and "giant" when reined in by editors).Likewise, Bruno is remembered by many for his work on turbidite systems, but he too worked on submarine slides, particularly earlier in his career. The first paper that he and I worked on together described a slide near the wreck of the Titanic, where his colleagues at ifremer had collected a magnificent survey with the next generation of deep-tow technology, the ifremer sar, but just missed the wreck. He is well known for his contributions on the 1979 Nice landslide, which triggered both a tsunami and a turbidity current. Bruno brought his enthusiasm and energy, together with his organisational and analytical skills as an engineer, to the science of turbidites and mass movements. He combined the technological expertise of ifremer, industry funding and his own instinct of what was necessary to make significant scientific advances at sea.Mass movements are an important part of the turbidite story. For Bill and Bruno, during much of their careers, mass movements were regarded as the predominant cause of turbidity currents. Both played an important role in challenging that dogma in recent years. Those who study mass movements from the comfort of the seismic work-station or by numerical modelling owe a lot to seagoing scientists like Bruno and Bill who laid the groundwork of where, why and how submarine mass-movements occur in the field.

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The Ashmore Platform–Timor Sea region of Australia’s North West Shelf is an area of significant petroleum exploration potential, with several large commercial oil fields present. Moreover, exploration activity seems likely to continue at current levels for the foreseeable future, and may also extend into deeper water, given high oil prices and improved drilling technologies. The area is also one of high conservation value, with both the Cartier Marine reserve and Ashmore Reef (a Category 1 marine park), as well as numerous other genetically-rich carbonate seed bank systems, closely associated spatially with exploration activities. Balancing the conservation and resource values in this area will present a key challenge into the future.The magnitude of this challenge has been highlighted by recent work undertaken by AGSO, which involved the acquisition and interpretation of assorted remote sensing data, such as high-resolution bathymetry (including sidescan sonar), satellite synthetic aperture radar (SAR), Landsat, water column geochemical sniffer, airborne laser fluorosensor, seismic data and seafloor sediment sampling. These studies have shown that, at both a regional and local scale, the development of these important carbonate systems appears to directly relate to the geological development of the area.At a regional scale, the collision between the Australian and Eurasian crustal plates in the Pliocene (At a local scale, new data also strongly suggest that the locations of the majority of reefs and carbonate banks and build-ups in the area are associated with active and palaeo-hydrocarbon seeps. These seeps are localised over either fault systems which tap the reservoir, along migration fairways, or at the pinch-out of the regional Cretaceous top seal. Our interpretations suggest that the reefs and the build-ups formed by a sequential process. Firstly, hydrocarbon seepage (induced by collisionrelated faulting) localised small seafloor (chemolithotrophic) biological carbonate communities, which ultimately formed topographically positive features. These higher relief features were subsequently preferentially colonised by an assortment of reef-building biota, whose rapid growth progressively kept up with rising sea-level (which was driven principally by collisionrelated subsidence). The most favourable conditions for initial reef colonisation probably occurred during periods of relatively low sea-level, when the areas around the reefs were located at much shallower water depths (Clearly, the fact that the genetically rich carbonate communities in this area are probably causally related to natural hydrocarbon seepage (and the attendant processes which drove that seepage) will present a series of almost unique exploration, development (especially engineering) and conservation challenges.

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