The detailed morphologies, evolution and termination of Neogene tropical carbonate platforms in the Northern Carnarvon Basin (NCB) on the passive margin of the Northwest Shelf of Australia reveal information on the history of local oceanographic processes and changing climate. Cool-water carbonate deposition, dominant during the early-middle Miocene, was superseded by a siliciclastic influx, which prograded across the shelf beginning in the late-middle Miocene during a period of long-term global sea-level fall. The resulting prograding clinoform sets, interpreted as delta lobes, created relict topographic highs following Pliocene termination of the siliciclastic influx (Sanchez et al., 2012a; 2012b). These highs created a favorable shallow-water environment for subsequent photozoan carbonate production. A composite, commercial 3D seismic volume allows investigation of the temporal and spatial evolution of the resulting Pliocene-Pleistocene carbonate platforms. Initiation of carbonate development, in addition to being a response to cessation of siliciclastic influx and the existence of suitable shallow-water substrate, was also influenced by the development of the warm-water Leeuwin Current (LC), flowing southwestward along the margin. Four flat-topped platforms are mapped; each platform top is a sequence boundary defined by onlap above and truncation below the boundary. Successive platforms migrated southwestward, along-strike. Internally, platforms have progradational seismic geometries. The mapped platform tops are large (≥ 10 km wide). Evidence of karst (e.g., v-shaped troughs up to 50m deep and ~1 km wide and broader karst basins up to 20 km2 coverage area) on platform tops suggests episodic subaerial exposure that contributed to the demise of individual platforms. The most recent platform, platform 4, is unique in having interpreted reefs superimposed on the progradational platform base. The base of these reefs now lies at ~153 m and the reefs may therefore have developed post-LGM (~21 Ka). The reefs subsequently drowned, with drowning possibly aided by turbidity associated with formation of adjacent sediment drifts and weakening and strengthening LC during the late Pleistocene. The progressive drowning and termination of platforms from northeast to southwest along strike may result from differential compaction of the deltaic substrate or differential tectonic subsidence caused by the collision at the Banda Arc between the Australian and Pacific plates.

The Cenozoic carbonate systems of Australasia are the product of a diverse assortment of depositional and post-depositional processes, reflecting the interplay of eustasy, tectonics (both plate and local scale), climate, and evolutionary trends that influenced their initiation and development. These systems, which comprise both land-attached and isolated platforms, were initiated in a wide variety of tectonic settings (including rift, passive margin, and arc-related) and under warm and cool-water conditions where, locally, siliciclastic input affected their development. The lithofacies, biofacies, growth morphology, diagenesis, and hydrocarbon reservoir potential of these systems are products of these varying influences. The studies reported in this volume range from syntheses of tectonic and depositional factors influencing carbonate deposition and controls on reservoir formation and petroleum system development, to local studies from the South China Sea, Indonesia, Kalimantan, Malaysia, the Marion Plateau, the Philippines, Western Australia, and New Caledonia that incorporate outcrop and subsurface data, including 3-D seismic imaging of carbonate platforms and facies, to understand the interplay of factors affecting the development of these systems under widely differing circumstances. This volume will be of importance to geoscientists interested in the variability of Cenozoic carbonate systems and the factors that controlled their formation, and to those wanting to understand the range of potential hydrocarbon reservoirs discovered in these carbonates and the events that led to favorable reservoir and trap development.

This volume also discusses the computer modelling of carbonate cycles and sequence analysis. This will prove an invaluable text for senior undergraduate and postgraduate students in the earth sciences in general and will also be of value to the professional researcher. Carbonate platforms contains contributions from an international authorship and the volume has been edited by one of the most respected names in the earth sciences. Areas covered include; early rifting deposition; examples from carbonate sequences of Sardinia (Cambrian) and Tuscany (Triassic-Jurassic), Italy; geometry and evolution of platform-margin bioclastic shoals, late Dinantian (Mississippian), Derbyshire, UK; cyclic sedimentation in cabonate and mixed carbonate/clastic environments; four simulation programs for a desktop computer; middle Triassic carbonate ramp systems in the Catalan Basis, N.E. Spain; facies, cycles, depositional sequencies and controls; stages in the evolution of late Triassic and Jurassic platform carbonates; western margin of the Subalpine basin, Ardech, France. The formation and drowning of isolated carbonate platforms; tectonic and ecologic control of the Northern Apennines; controls on Upper Jurassic carbonate build up development in the Lusitanian Basin, Portugal; Hauterivian to Lower Aptian carbonate shelf sedimentation and sequence stratigraphy in the Jura and northern Subalpine chains (southeastern France and Swiss Jura); basement structural controls on Mesozoic carbonate facies in northeastern Mexico; the Aptian-Albian carbonate episode of the Basque-Cantabrian Basis (Northern Spain); general characteristics, controls and evolution; response of the Arabian carbonate platform margin slope to orogenic closing of an ocean basin, Cretaceous, Oman.

Isolated carbonate platforms can provide substantial hydrocarbon reservoirs because they develop significant depositional relief and are commonly buried by relatively impermeable basin-filling sediments. Consequently, there is ongoing interest in the mechanisms that control their morphology and facies distributions. Because the deposition of carbonate sediments is influenced by a complex interaction of environmental conditions that vary both temporally and spatially across depositional systems, the relative importance of controls on platform morphology is difficult to constrain. The key to developing a better understanding is to recognize causal links between changes in oceanographic conditions and variability in resulting geometries. Unfortunately, most studies of exposed carbonate platforms limit the ability to discern influences beyond fluctuations in relative sea level, because they are based on a single cross section of a platform and record deposition during periods of relative stasis in ocean chemistry and biotic evolution. In this study, however, I examined cross-sectional exposures from three geographic sectors of the Late Permian to Late Triassic Great Bank of Guizhou (GBG) in the Nanpanjiang Basin of south China. Deposition on the GBG spanned the tumultuous transition from Paleozoic to Mesozoic oceans, providing a rare opportunity to evaluate the influence of changes in carbonate factory type during a period of significant global change. In addition, I compared multiple exposures of the platform to determine the differential impact of basin-wide controls such as external sediment supply and antecedent topography on the evolution of platform geometries. The integrated analysis of satellite imagery, field mapping, chemostratigraphy, biostratigraphy and petrography shows that chemical and biological controls associated with end-Paleozoic extinction and environmental disturbance led to changes in carbonate factory type that contributed to significant temporal variability in the platform geometry. The GBG initiated with small patch reefs in the latest Permian, was dominated by microbial carbonates in the immediate aftermath of extinction, progressed to a low-relief bank with oolite shoal margins in the earliest Triassic when skeletal organisms were rare, developed a high-relief morphology with steep slopes when transport was limited by rapid cementation, and later established a reef-rimmed margin as environmental conditions allowed for the return of abundant skeletal organisms in benthic environments. In contrast, physical controls, including antecedent topography and external sediment supply, produced significant spatial variability in the GBG. In the northwestern sector, over-steepening led to the development of an erosional escarpment and bypass margin following an initial interval of Early Triassic progradation over a shallow basin floor. In the northeastern sector, a similar pattern was disrupted by Middle Triassic influx of siliciclastic sediments that raised the basin floor, reduced topographic relief, and provided a structural foundation for multiple episodes of progradation and the retention of an accretionary margin. In the southwestern sector, an adjacent deep basin established significant topographic relief, eliminating the structural support for progradation and leading to large-scale sector collapse of the platform margin. This study provides causal links between depositional environments and resulting geometries and shows that changes in carbonate factory type, differences in antecedent topography, and the pattern and timing of external sediment supply have a significant impact on the stratigraphic evolution of isolated carbonate platforms.

This volume covers many subjects relative to geology of carbonate platforms and adjoining slopes and basins. A preliminary section based on principles of deposition and computer modeling studies is followed by a group of a dozen papers devoted to examples of carbonate platforms on passive cratonal margins resuting from rifting.The volume also considers halos of carbonate developed as a fringe around the pericratonic Permian basin as well as some examples of isolated offshore platforms.

This book on geology and hydrogeology of carbonate islands is volume 54 in the Developments in Sedimentology series.