The Burdigalian Saumane-Venasque carbonate succession is located in the Rhodano-Provençal basin of southeastern France. These carbonates accumulated in a paleovalley that was flooded by marine waters. This marine embayment was filled by carbonates composed of twelve different facies. These sediments form two thick third-order sequences (S1 & S2) and several, thinner higher-order sequences (S1a, S1b, S1c). S1a is composed of quartzose grainstones with barnacles, echinoids, and bivalves derived from a rocky substrate paleocommunity in a high-energy, open-marine environment during the early phases of sea level rise. Compound dunes of S1a and S1b are composed of bryozoans and echinoids that are mixed with bioclasts from seagrass facies. Pervasive cross-bedded grainstones grade upward into low-energy mudstones and packstones of the S1 highstand. Bryozoan thickets populated sequence 2 during the second sea level cycle. Seven different phases of cement, including cloudy epitaxial, fibrous, isopachous columnar, isopachous equant, clear epitaxial, blocky, and pendant types, can be distinguished in these limestones. Marine hardgrounds are present throughout the area as steep, stepped margins in tidal channels. Marine cements are interpreted to have precipitated in the upper portion of subaqueous dunes with their location controlled by sedimentation rate and tidal pumping. Zoned epitaxial cements are interpreted to record shifts in the paleo-water table related to fluctuations in sea level throughout the Miocene in the Rhodano-Provençal basin. Shallow burial pressure dissolution features are present throughout the deposit. They are interpreted to result from extended exposure to fresh water, which produced grains that were particularly susceptible to compaction. The Saumane-Venasque temperate carbonates are different in that they were lithified without significant burial diagenesis, a situation that resulted from multiple sources of cement from marine and meteoric waters. / Thesis (Master, Geological Sciences & Geological Engineering) -- Queen's University, 2009-09-04 16:00:33.914

The Padthaway Ridge is overlain by a thin veneer (< 20 m) of Oligo-Miocene bioclastic carbonates representing the southern most extent of the Mannum Formation, Murray Supergroup, and Murray Basin limestones. The Mannum Formation is composed of warm-temperate carbonates rich in irregular echinoids, coralline algae, benthic foraminifers, and relict particles. The respective lithology are mostly structureless, burrow-mottled, and cross-cut by Thalassinoides burrows. These sediments are interpreted to have resulted from carbonate production along shallow, illuminated seafloors under high mesotrophic conditions. The composition and texture is similar to that of modern temperate seagrass accumulations with the exception of the abundant mobile infauna and bioturbation, which are more akin to associated intercalated and adjacent barren sands. The Mannum Formation is therefore interpreted as an amalgamation of these two environments. The ubiquitous relict grains and Fe-stained cements in the lithologies of the Mannum Formation are thought to be the product of Fe redox pumping within the subsurface of seagrass meadows, whereby consolidated sediments endured prolonged and repeated exposure to juxtaposed destructive and constructive diagenetic conditions at the redox boundary. Fluctuations in the organic carbon and oxygen influx to the subsurface are primarily a function of auto- and allogenic controls on seagrass density (i.e. turbidity, light, depth, hydrodynamics). The overlying Glenforslan Formation is interpreted as a seagrass-influenced deposit that accumulated under warm-temperate, low mesotrophic conditions and more rapid rates of sedimentation. Relict grains, however, are absent from the Glenforslan Formation. The subtle change in trophic resources is thought to have caused a significant shift in primary and secondary production, from organic carbon- to carbonate-dominated. Assessment of previously described temperate seagrass facies together with this research comprise reliable criteria for identification of temperate seagrass depositional settings. The signal of multigenerational accumulation, especially prominent in the Mannum Formation, represents an amalgamation of environments that would be difficult to assess in modern settings. The key attributes of temperate grass facies proposed herein allow for more accurate reevaluation of seagrass influenced, and relict rich lithologies in the rock record. / Thesis (Master, Geological Sciences & Geological Engineering) -- Queen's University, 2009-12-14 17:18:16.853