A Pliocene foraminiferid fauna from Flinders Island, Bass Strait

A foraminiferid fauna from the Cameron Inlet Formation, Flinders Island, Tasmania is probably Late Pliocene in age. The benthic foraminiferid fauna has a strong Kalimnan aspect but the formation is probably a little younger than the stratotype Kalimnan

Miocene and Pliocene sediments dredged from the sea-floor off St Helens, northeastern Tasmania

Calcarenites dredged from 807 and 960m, 50km southeast of St Helens, Tasmania, have yielded Early Miocene and mid-Pliocene foraminiferid faunas. The Miocene fauna is a deeper water continental shelf type of the same age (N4j 5) as other sediments well known from the northern coast of Tasmania. It contains a higher percentage of planktic forms than known in coeval sediments elsewhere in Tasmania. The mid-Pliocene (approximately N20) including a significant planktic component, is the first such fauna documented from Tasmania

A Middle Cambrian Xiphosuran(?) from Western Tasmania

An arthropod from the Que River Beds of western Tasmania is tentatively referred to the Order AGLASPlDA Walcott, of the Sub-class XIPHOSURA Latreille

Extreme events in the sub-Antarctic

Extreme physical events, excluding meteorological events, can be divided into two broad categories — endogenous and exogenous. Endogenous phenomena include earthquakes, landslides, tsunami, volcanic or gas hydrate eruptions that occur within the region but may have both local and distant impacts; the 2011 Puyehue-Cordon Caulle volcanic eruption, and the frequent major earthquakes along the Chile margin or near Macquarie Island are examples. Exogenous events are those originating outside the area but influencing it. These include the terminal Cretaceous asteroid impact, asteroid/meteorite impacts, such as the major Eltanin Asteroid impact 2.5 million years ago, and extraterrestrial-sourced radiation from extreme solar/galactic or extra-galactic events in which the effect is not confined to the sub-Antarctic but is global

Origin and evolution of the sub-Antarctic islands: the foundation

Sub-Antarctic islands have a diversity of origins in detail but most are volcanic and very young suggesting that they are short-lived and that the distribution would have been very different a few million years ago. They contrast with the common tourist brochure concept of oceanic islands. As the Antarctic Plate is virtually static, the islands seldom show signs of association with long-lived linear island chains and most thus stand alone. Longer-lived islands are either on submarine plateaux or are continental remnants of the dispersion of Gondwana. The islands are classified in relation to raised sea-floor, transform fault, triple junction, subduction zone, submarine plateau, submerged continent or continental. Many are difficult of access and poorly known geologically. Their geological history controls their many other roles such as sites as observatories, or for study of colonisation, evolution and speciation rates

The Pliocene environment of Antarctica

Debate continues about the environment of Antarctica during intervals in the Pliocene (5.2-1.8 Ma), particularly during the Late Pliocene (3.5-1.8 Ma). Two schools of thought - dynamic versus stable ice sheet - have developed. One hypothesis calls for the Antarctic ice sheet to vary dramatically, for Antarctica at times to be vegetated and for circum-antarctic waters to be significandywarmer than at present. The other calls for a stable ice sheet, no vegetation and water temperatures much less varied. During 1995, the two sides converged by recognising that the change to conditions suitable for vegetation may not have been as marked as originally thought, and that oxygen isotope data may contain scope for more flexibility in interpretation than the stabilist view has supported. New data and new participants have emerged, but there is a long way to go in resolving the issue. The key issue remains the age of the Sirius Group in the Transantarctic Mountains and the source of its contained diatoms. Diatoms of Pliocene age have been recovered from the Sirius Group but also from modern ice, and this raises the question of whether the Sirius Group diatoms are actually in situ. New data and re-evaluation of existing data are necessary. Ocean Drilling Program activity, particularly in the Prydz Bay region, and analysis of samples from the Prince Charles Mountains can be expected to contribute significantly to a solution, by providing more information on past temperatures and evidence of possible terrestrial vegetation

The Biostratigraphy of the Tasmanian Marine Tertiary

Tertiary marine rocks occur in small scattered outcrops around Tasmania's north and west coasts, on some islands in Bass Strait, and below sea level in Mussel Roe Bay. All occurrences except those in Mussel Roe Bay and on Preservation Island have been recorded previously. From 64 samples, about 300 categories (form, subspecies, species, genus etc,) of foraminifera have been identified. Planktonic species are generally poorly preserved, but good faunas have been identified from Fossil Bluff, Brittons Swamp and Marrawah, the latter in company with Lepidocyclina howchini Chapman and Crespin and Amphistegina lessonii d'Orbigny. All rocks are of Early and Middle Miocene age (Longfordian Batesfordian, Carter's Faunal Units 6, 8 and 9) with the possible exception of one sample from Mussel Roe Bay which may be Late Oligocene (Janjukian, Faunal Unit 5). All sediments are of shallow water origin, deposited in depths of less than 20, usually less than 10, fathoms. Water temperatures were those of the Warm Temperate to Subtropical Zones in Faunal Unit 6 time, Subtropical during Faunal Unit 8 time and Tropical during Faunal Unit 9 time. Waters may have been slightly warmer in the north-east than in the north-west during Faunal Unit 6 time. Sediments at about 100 feet below sea level in Mussel Roe Bay, and at less than 150 feet above sea level at Wynyard, King Island, Cape Grim, Mt Cameron West, Marrawah, Daisy Creek and Granville Harbour formed during a marine transgression throughout Faunal Units 5 and 6, There seems to be a Faunal Unit 7 hiatus which may represent regression. Higher level sediments (above sea level on Cape Barren and Preservation Islands) and at 170-310 feet above sea level at Brittons Swamp, Redpa, and Marrawah formed during another, more extensive transgression in the time of Faunal Units 8 and 9. Comments are made on the age of some basalts in the north-west of the State; on the relation of these outcropping sediments to those of the Bass Basin; on the common occurrence of large and planktonic foraminifera in a single sample from Marrawah; and a palaeogeographic map is presented

Early Miocene silicified limestone from Temma, northwestern Tasmania: further evidence of substantial post-Early Miocene uplift or tilting of Tasmania

Silicified shallow-water Early Miocene (Longfordian) marine limestone occurs in altitudes to over 160m, 12km east of Temma in northwestern Tasmania, the highest elevation known to date for rocks of this age and environment of deposition. Age and environmental data are provided by Foraminifera, calcareous algae and poorly preserved macrofauna. Mode of silicification of Foraminifera varies systematically between suborders - miliolids and agglutinated species as internal moulds, nodosariids, rotaliids and cibicidids as vohune-for-volume replacements. Foraminifera are benthic only. Miliolids dominate but preservation is too poor to allow statistically valid analysis. The locality provides only the second occurrence of Tenisonina tasmaniae Quilty, and, for the first time, it occurs with Sherbornina atkinsoni Chapman

Heard Island and the McDonald Islands: a window into the Kerguelen Plateau

The modern phase of volcanism on Heard Island probably is younger than one million years and is responsible for building Big Ben, the bulk of the island. The nearby McDonald Islands are less than 100 000 years old and are volcanically active. Big Ben sits on the Drygalski Formation, a Late Miocene-Early Pliocene volcanic/marine sediment with glacial influence, which occurs as a generally flat-lying, cliff forming unit over most of Heard Island. The "basement" of Palaeogene limestone crops out mainly on Laurens Peninsula but also sporadically beneath Big Ben and occurs as clasts in volcanics. Historical eruptions of Heard Island, most recently from 1985 to at least 1992 and probably later, have occurred from Mawson Peak, the summit cone built upon Big Ben, but young lavas and ash cones are widespread around the island. Recent volcanic activity is summarised. Heard Island and the McDonald Islands, with the Kerguelen Islands, are exposed parts of the Kerguelen Plateau, possibly the largest submarine plateau on earth, and provide geochemical and isotopic insights into the formation of oceanic plateaux, mantle plume development and the separation of Australia, India and Africa from Antarctica. The Plateau has a complex history that commenced with subaerial basaltic volcanism at 115 Ma, about 10 million years after India and Antarctica separated. It sank below sea level in the mid-Cretaceous, and subsided to its present setting as Broken Ridge and Kerguelen Plateau separated at 43 Ma when the Southeast Indian Ridge came between Australia and Antarctica. It is likely that, during its entire existence, some part of the plateau has been volcanically active, yielding a long-term geochemical record of large-scale crust-mantle evolution

Marine Neogene Samples from around Tasmania: an extension to the Miocene/Pliocene marine record in Tasmania

New Miocene and Quaternary foraminiferid faunas have been recovered from previously unrecorded localities onshore near Penguin and Strahan, and at nine offshore localities off northwestern, northeastern and southeastern Tasmania. Most Miocene benthic forms found in these samples are well known from other Tasmanian Tertiary sections but a few previously unreported taxa are recorded in Tasmania for the first time. Two samples from off northeastern Tasmania are Miocene. The sample from southeastern Tasmania is Early Miocene with Quaternary overlying it. Pebbles from Ocean Beach, north of Strahan, contain earliest Middle Miocene faunas. Other samples from off northeastern and northwestern Tasmania contain Quaternary faunas which probably reflect both periods of lower sea level and cool water and also periods of higher sea level and warmer water. These samples extend the range of Miocene calcareous sediments much farther south on both west and east coasts of Tasmania. They also reinforce the pattern of Tasmanian Neogene sedimentation cycles (earliest Early Miocene, latest Early-earliest Middle Miocene, midLate Pliocene) identified previously