Determination of controls on Holocene barrier progradation through application of OSL dating: The Ilha Comprida Barrier example, Southeastern Brazil

Barrier development during the Holocene is studied using the example of the Ilha Comprida, Southeastern Brazil. Aerial photos, facies analysis, and optically stimulated luminescence dating are used to define the barrier emergence and evolution. Optically stimulated luminescence ages and facies successions indicate that the Ilha Comprida probably began as a Holocene transgressive barrier island 6000 years ago, just before the last relative sea-level maximum. Since then the barrier has progradated through the addition of curved beach ridges. Based on beach ridge alignments, six units of growth are identified with two growth directions, transverse and longitudinal. Rates of progradation with transverse growth vary from 0.13 to 4.6 m/year. Rates of longitudinal growth to NE range from 5.2 to 30 m/year. Variation in coastal progradation rates and sediment retention during the last 6000 years is compared with climate, physiography and relative sea-level changes. The physiography, represented by pre-Cenozoic hills, is the major control on sediment retention and alternation between longitudinal and transverse growth. Climate variations, such as the Little Ice Age event, apparently control the formation of ridges types: beach ridges, foredunes, and blowouts. These results allow the use of the Ilha Comprida Barrier as an example to analyze the major controls on barriers progradation. (C) 2011 Elsevier B.V. All rights reserved.

The development of blowouts and foredunes in the Ilha Comprida barrier (Southeastern Brazil): the influence of Late Holocene climate changes on coastal sedimentation

Middle to Late Holocene barriers are conspicuous landforms in southeastern and southern Brazilian regions. The barriers in the coastal zones of northern Santa Catarina, Parana and Sao Paulo states (27 degrees 19`-24 degrees 00`S) are formed mainly by beach ridge alignments and many barriers present foredune and blowout alignments in their seaward portion. The development of these eolian landforms appears to record a regional shift in coastal dynamics and barrier building. In this context, the Ilha Comprida barrier stands out for its well-developed and well-preserved foredunes and blowouts. Based on the presence or not and type of eolian landforms, the Ilha Comprida barrier can be divided seaward into inner, middle and outer units. The inner unit is formed entirely by beach ridges. The middle unit comprises a narrow belt of blowouts (up to 15 m high) aligned alongshore. Blowout lobes pointing NNW are indicative of their generation by southern winds. The outer unit is represented by low (<= 1 m high) active or stabilized foredunes and a small transgressive dunefield (similar to 1 km(2)). Twenty-seven luminescence ages (SAR protocol) obtained for the beach ridges, foredunes, and blowouts of these three units allow definition of a precise chronology of these landforms and calculation of rates of coastal progradation. The inner unit presents ages greater than 1004 +/- 88 years. The blowouts of the middle unit show ages from 575 +/- 47 to 172 +/- 18 years. The ages of the outer unit are less than 108 +/- 10 years. Rates of coastal progradation for the inner and outer units are 0.71-0.82 m/year and 0.86-2.23 m/year, respectively. The main phase of blowout development correlates well with the Little Ice Age (LIA) climatic event. These results indicate that southern winds in subtropical Brazil became increasingly more intense and/or frequent during the LIA. These conditions persist to the present and are responsible for the development of the eolian landforms in the outer unit. Thus, barrier geomorphology can record global climatic events. The sensitivity of barrier systems in subtropical Brazil to Late Holocene climate changes was favored by the relative sea level stillstand during this time. Luminescence dating makes it possible to analyze barrier geomorphology during Late Holocene climate changes operating on timescales of a hundred to thousand years. These results improve our knowledge of barrier building and will help in the evaluation of the impact of future climate changes on coastal settings. (C) 2008 Elsevier Ltd. All rights reserved.

First record of contourites from Lower Devonian Liptrap Formation in southeast Australia

Typical contourite deposits associated with submarine turbidite fan deposits are recognized for the first time from the Lower Devonian Liptrap Formation at Cape Liatrap, Victoria in southeast Australia. The contourites are well integrated within the turbidite fan deposits and are characterized by thin (5–8 cm), lenticular, well-sorted coarse-grained siltstones to fine-grained sandstones with current-ripples and cross beddings. The palaeocurrent directions of the turbidite fan and contourites are perpendicular to each other, with the former directed generally westward while the latter varying from 165° to 190° southward. In view of the facies types and architecture, we suggest that the turbidite fan was developed at the base of a westward inclined palaeo-slope, at the front of which the contourites were deposited as a result of southward flowing deep-sea contour (geostrophic) currents. The depositional setting interpreted for the Liptrap Formation thus may provide a provisional model for the Lower Devonian continental slope and abyssal basin environment in the southeastern part of the Melbourne Trough.

Palaeontological aspects of the Permian Broughton Formation, Sydney Basin, Australia

An abundant, low diversity cool-water macroinvertebrate fauna from the Middle Permian Broughton Formation in the Sydney Basin, eastern Australia, was investigated. The fauna was described and identified, which assisted in regional and global correlation of the Broughton Formation, as well as palaeogeographical and palaeontological research.

Importance of riparian vegetation to terrestrial avifauna along the Murray River, south-eastern Australia

Bird life occurring along the Murray River was distinctly different from surrounding much drier vegetation. It was found that the presence of the Murray River, with it's associated moist Red Gum forests, provide a corridor whereby birds typically of cool climates can expand their range and occur in an arid landscape.

Reproduction in five sympatric batoid species (family urolophidae) from south-eastern Australia

This PhD determines the reproductive biology of five stingaree species caught as bycatch from south-eastern Australian commercial fisheries for fisheries stock assessments, ecological risk assessments, and species extinction risk evaluations.

Provenance of Holocene Calcareous Aeolianites, Eastern South Australia

The southeastern coast of South Australia contains a spectacular and world-renown suite of Quaternary calcareous aeolianites. This study is focused on the provenance of components in the Holocene sector of this carbonate breach-dune succession. Research was carried out along seven transects from ~30 meters water depth offshore across the beach and into the dunes. Offshore sediments were acquired via grab sampling and SCUBA. Results indicate that dunes of the southern Lacepede and Otway coasts in particular are mostly composed of modern invertebrate and calcareous algal allochems. The most numerous grains are from molluscs, benthic foraminifera, coralline algae, echinoids, and bryozoans. These particles originate in carbonate factories such as macroalgal forests, rocky reefs, seagrass meadows, and low-relief seafloor rockgrounds. The incorporation of carbonate skeletons into coastal dunes, however, depends on a combination of; 1) the infauna within intertidal and nearshore environments, 2) the physical characteristics of different allochems and their ability to withstand fragmentation and abrasion, 3) the wave and swell climate, and 4) the nature of aeolian transport. Most aeolian dune sediment is derived from nearshore and intertidal carbonate factories. This is particularly well illustrated by the abundance of robust infaunal bivalves that inhabit the nearshore sands and virtual absence of bryozoans that are common as sediment particles in water depths > 10mwd. Thus, the calcareous aeolianites in this cool-water carbonate region are not a reflection of the offshore marine shelf factories, but more a product of shallow nearshore-intertidal biomes.