Abstract: The storm-dominated, high-energy, cool-water Lincoln Shelf occupies the central part of the southern Australian continental margin. Carbonate sediments on this modern distally-steepened ramp were produced by slow deposition during the Terminal Quaternary Sea-level Cycle (0 75 Ka), a high-amplitude, asymmetric cycle of sea-level change. The 50 to 150-mwd (meters water depth), 120-170 km-wide surface is a rocky substrate covered by a patchy, m-scale, palimpsest sediment veneer composed mostly of bryozoans, molluscs, foraminifers and coralline algae. Facies of the condensed Terminal Quaternary Sequence are interpreted to reflect accumulation during different parts of the Terminal Quaternary Sea-level Cycle that are now variably mixed. Accumulation during early stages of the Terminal Quaternary Regression, Isotope Stage-3/4 (IS-3/4), when sea level fluctuated between 30- and at least 60-mwd, took place in a series of shallow marine to paludal environments. Small-scale, 5th-order sea-level fluctuations resulted in recurring deposition, surf-zone reworking and exposure. Such conditions generating Relict Particles, brown- colored, abraded grains filled with carbonate precipitates, that are now concentrated on the middle to inner shelf (< 100-mwd). The Terminal Quaternary Lowstand (early IS-2) at 120-mwd resulted in deposition on the outermost shelf and exposure of the middle and inner shelf. This was a period of mesotrophic conditions and overall upwelling, leading to prolific bryozoan growth and the formation of a bryozoan biostrome at the shelf edge. These conditions continued during the early Terminal Quaternary Transgression (late IS-2) resulting in shelf facies rich in articulated coralline algal particles and rhodolites. Rapid sea-level rise, coupled with a change to more oligotrophic conditions during the late Terminal Quaternary Transgression (early IS-1), drowned these environments and resulted in belts of Stranded Particles on the middle to outer shelf. The modern setting, during the present Terminal Quaternary Highstand, reflects a complex oceanography. Waters are mildly oligotrophic, with yearly incursion of warm, oligotrophic waters from the west, seasonal upwelling of mesotrophic waters and annual outflow of cold, saline bottomwaters from the large shallow embayment of Spencer Gulf. Recent Particles are diverse: bivalves dominate inner-middle shelf sediments; bryozoans are most abundant on the outer shelf; shelf sediments opposite Spencer Gulf saline outflows are rich in benthic foraminifers; and corallines are most abundant inshore. The moribund biostrome is now populated by a rich and diverse suite of deeper water bryozoans and ahermatypic corals. Sediments on the western part of the shelf, with scattered large foraminifers, illustrate the sporadic influence of warmer waters.

Abstract: There are three depositional scenarios for Miocene reef development within the Pelagian Region as follows: Carbonate ramps provide an important setting for coral patch reefs, with the additional important development of coralline algal (often rhodolitic) biostromes immediately basinward of the lime-mud dominated patch reefs. Delta tops and chaannels, in total contrast to the clear water carbonates of gently sloping ramps, are the tectonically active zones associated with areas immediately to the south of the Sicilian Alpine fold belt. Here, in association with delta top channels and small offshore culminations above thrust-generated sea floor ridges, localised reefs developed whenever turbidity and siliciclastic sedimentation was reduced. Generally this was coincidental with marine onlap events of relatively short duration. Finally, carbonate shelf slope breaks, there are the monogeneric coral curtain reefs which developed under clear water conditions at basin-facing breaks in slope such as the submarine fault scarps bordering on to the central Mediterranean graben systems. From a palaeoecological viewpoint, the limited range of coral genera present may most conveniently be catalogued on the basis of their respective growth form strategy. These range from slender rods in excess of 1 m long in the coral curtains, to vermiform and ramose bushy growths in the areas of highest siliciclastic sedimentation. Additionally, dome headed corals dominate upper fore-reef and reef crest locations; whereas, undulose growth forms typify lagoonal and ramp patch reefs. Each peculiar reef type is the product of a variable range of parameters including substrate stability, eustatic fluctuations, tectonism and sedimentation rates. These are all considered before proposing several sedimentological models common to the central Mediterranean region and possibly of value elsewhere within Tertiary "Tethyan realm."

Abstract The Guayanilla superhighway outcrop section of southwestern Puerto Rico offers an unusual chance to examine the development and diagenesis of an Oligocene fringing reef and carbonate platform. The stratigraphic section embodies a complex sequence of three cycles of reef development. Reef cycle 2, some 48 m (150 ft) thick, comprises the development of a major fringing or barrier reef at this locality. Reef growth in cycle 2 was inhibited by intermittent ecological stress, perhaps by upwelling colder waters, so that rhodolite-paved ramps replaced shelf margin framework. Tectonic downwarp drowned the reef tract, replacing it by deep open shelf conditions, but a shallowing cycle due to uplift led to establishment of a third cycle of reef growth. Despite the substantial thickness of reef framework, reservoir quality porosity and permeability are low, primarily due to pervasive lime mud matrix. The paleoecological and sedimento-logical models derived from a study of the Guayanilla reef sequence will serve as a standard of comparison for other Tertiary reefs, both in the subsurface and surface.