Journal articles: 'Geology Tasmania, Northern'

1

Direen, N. G., and D. E. Leaman. "Geophysical Modelling of Structure and Tectonostratigraphic History of the Longford Basin, Northern Tasmania." Exploration Geophysics 28, no. 1-2 (March 1997): 29–33. http://dx.doi.org/10.1071/eg997029.

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Direen, N. G., and M. J. Roach. "Geophysical Indicators of Controls on Soil Salinisation and Implications, Longford Basin, Northern Tasmania." Exploration Geophysics 28, no. 1-2 (March 1997): 34–38. http://dx.doi.org/10.1071/eg997034.

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Van Moort, J. C., and D. W. Russell. "Electron spin resonance of auriferous and barren quartz at Beaconsfield, Northern Tasmania." Journal of Geochemical Exploration 27, no. 1-2 (October 1987): 227–37. http://dx.doi.org/10.1016/0375-6742(87)90021-5.

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Van Moort, J. C., and D. W. Russell. "Electron spin resonance of auriferous and barren quartz at beaconsfield, Northern Tasmania." Journal of Geochemical Exploration 27, no. 3 (December 1987): 227–37. http://dx.doi.org/10.1016/0375-6742(87)90153-1.

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Adams, C. J., J. D. Bradshaw, and T. R. Ireland. "Provenance connections between late Neoproterozoic and early Palaeozoic sedimentary basins of the Ross Sea region, Antarctica, south-east Australia and southern Zealandia." Antarctic Science 26, no. 2 (July 18, 2013): 173–82. http://dx.doi.org/10.1017/s0954102013000461.

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AbstractThick successions of turbidites are widespread in the Ross–Delamerian and Lachlan orogens and are now dispersed through Australia, Antarctica and New Zealand. U-Pb detrital zircon age patterns for latest Precambrian, Cambrian and Ordovician metagreywackes show a closely related provenance. The latest Neoproterozoic–early Palaeozoic sedimentary rocks have major components, at c. 525, 550, and 595 Ma, i.e. about 40–80 million years older than deposition. Zircons in these components increase from the Neoproterozoic to Ordovician. Late Mesoproterozoic age components, 1030 and 1070 Ma, probably originate from igneous/metamorphic rocks in the Gondwanaland hinterland whose exact locations are unknown. Although small, the youngest zircon age components are coincident with estimated depositional ages suggesting that they reflect contemporaneous and minor, volcanic sources. Overall, the detrital zircon provenance patterns reflect the development of plutonic/metamorphic complexes of the Ross–Delamerian Orogen in the Transantarctic Mountains and southern Australia that, upon exhumation, supplied sediment to regional scale basin(s) at the Gondwana margin. Tasmanian detrital zircon age patterns differ from those seen in intra-Ross Orogen sandstones of northern Victoria Land and from the oldest metasediments in the Transantarctic Mountains. A comparison with rocks from the latter supports an allochthonous western Tasmania model and amalgamation with Australia in late Cambrian time.

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Fitzsimons, Sean J., and Eric A. Colhoun. "Pleistocene glaciation of the King Valley, Western Tasmania, Australia." Quaternary Research 36, no. 2 (September 1991): 135–56. http://dx.doi.org/10.1016/0033-5894(91)90022-w.

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AbstractAnalysis of the geomorphology, geology, and palynology of deposits in the King Valley permits the identification of four glaciations and two interglaciations and has led to a revision of the Pleistocene stratigraphy of the West Coast Range. The oldest late-Cenozoic deposits in the valley appear to predate glaciation, contain extinct pollen types, and are probably of late-Tertiary age. Overlying deposits of the Linda Glaciation show intense chemical weathering and have a reversed detrital remanent magnetization indicating deposition before 730,000 yr B.P. The highly weathered tills are conformably overlain by organic deposits of the Regency Interglaciation which show a transition from montane scrub rainforest to lowland temperate rainforest. Deposits formed during the later Moore Glaciation record advances of the King Glacier and glaciers from the West Coast Range. A pollen-bearing fluvial deposit records an interstade during this glaciation. On the basis of weathering rinds, amino acid dating, and palaeomagnetism the deposits are estimated to have formed between 730,000 and 390,000 yr B.P. The Moore Glaciation deposits are overlain by sediments of the Henty Glaciation which are believed to predate 130,000 yr B.P. These deposits record multiple advances of the King Glacier and the development of a large lake during an interstade. Deposits of the subsequent Pieman Interglaciation consist of organic fine sands and silts that record a lowland scrub rainforest. Deposits of the last (Margaret) glaciation are restricted to small areas in the northern part of the valley. Although the most recent ice advance culminated after 19,000 yr B.P., evidence of older deposits of the Margaret Glaciation suggests that an early last-glaciation ice advance may have occurred. When combined with earlier studies, the recent work in the King Valley has provided one of the more complete records of Pleistocene glaciation in the Southern Hemisphere. Comparison of the deposits with the record of glaciation in southern South America and Westland, New Zealand, suggests some similarities exist between pre-last-glaciation events and indicates that glacial events in Southern Hemisphere middle latitude areas were synchronous during the last glaciation.

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Thiele, Deborah, and Peter C. Gill. "Cetacean observations during a winter voyage into Antarctic sea ice south of Australia." Antarctic Science 11, no. 1 (March 1999): 48–53. http://dx.doi.org/10.1017/s0954102099000073.

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Cetacean observations were made from a platform of opportunity (a winter sea ice and oceanography research voyage) in Antarctic sea ice south of Tasmania. Minke whales and killer whales were sighted well within the sea ice. Minkes were found between 180–350 km south of the ice edge, while killer whales were nearly 450 km south of the ice edge. Minkes were sparsely distributed throughout the seasonal sea ice, even in areas of apparent total ice cover. Killer whales (including calves) were found at the northern edge of a major coastal polynya system. The winter sea ice is a complex and dynamic environment in which lead and polynya systems may enable travel and foraging by some cetacean species. While biological productivity is known to be reduced from summer levels, large numbers of seals, penguins – and possibly small numbers of whales – may be supported by krill and other biota intimately associated with the sea ice habitat during winter.

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Parkinson, M. L., M. Pinnock, J. A. Wild, M. Lester, T. K. Yeoman, S. E. Milan, H. Ye, J. C. Devlin, H. U. Frey, and T. Kikuchi. "Interhemispheric asymmetries in the occurrence of magnetically conjugate sub-auroral polarisation streams." Annales Geophysicae 23, no. 4 (June 3, 2005): 1371–90. http://dx.doi.org/10.5194/angeo-23-1371-2005.

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Abstract. Earthward injections of energetic ions and electrons mark the onset of magnetospheric substorms. In the inner magnetosphere (L4), the energetic ions drift westward and the electrons eastward, thereby enhancing the equatorial ring current. Wave-particle interactions can accelerate these particles to radiation belt energies. The ions are injected slightly closer to Earth in the pre-midnight sector, leading to the formation of a radial polarisation field in the inner magnetosphere. This maps to a poleward electric field just equatorward of the auroral oval in the ionosphere. The poleward electric field is subsequently amplified by ionospheric feedback, thereby producing auroral westward flow channels (AWFCs). In terms of electric field strength, AWFCs are the strongest manifestation of substorms in the ionosphere. Because geomagnetic flux tubes are essentially equi-potentials, similar AWFC signatures should be observed simultaneously in the Northern and Southern Hemispheres. Here we present magnetically conjugate SuperDARN radar observations of AWFC activity observed in the pre-midnight sector during two substorm intervals including multiple onsets during the evening of 30 November 2002. The Northern Hemisphere observations were made with the Japanese radar located at King Salmon, Alaska (57, and the Southern Hemisphere observations with the Tasman International Geospace Environment Radar (TIGER) located at Bruny Island, Tasmania (55. LANL geosynchronous satellite observations of energetic ion and electron fluxes monitored the effects of substorms in the inner magnetosphere (L6). The radar-observed AWFC activity was coincident with activity observed at geosynchronous orbit, as well as westward current surges in the ionosphere observed using ground-based magnetometers. The location of AWFCs with respect to the auroral oval was inferred from FUV auroral images recorded on board the IMAGE spacecraft. DMSP SSIES ion drift measurements confirmed the presence of AWFCs equatorward of the auroral oval. Systematic asymmetries in the interhemispheric signatures of the AWFCs probably arose because the magnetic flux tubes were distorted at L shells passing close to the substorm dipolarisation region. Transient asymmetries were attributed to the development of nearby field-aligned potential drops and currents.

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Mendillo, M., and C. Narvaez. "Ionospheric storms at geophysically-equivalent sites – Part 1: Storm-time patterns for sub-auroral ionospheres." Annales Geophysicae 27, no. 4 (April 7, 2009): 1679–94. http://dx.doi.org/10.5194/angeo-27-1679-2009.

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Abstract. The systematic study of ionospheric storms has been conducted primarily with groundbased data from the Northern Hemisphere. Significant progress has been made in defining typical morphology patterns at all latitudes; mechanisms have been identified and tested via modeling. At higher mid-latitudes (sites that are typically sub-auroral during non-storm conditions), the processes that change significantly during storms can be of comparable magnitudes, but with different time constants. These include ionospheric plasma dynamics from the penetration of magnetospheric electric fields, enhancements to thermospheric winds due to auroral and Joule heating inputs, disturbance dynamo electrodynamics driven by such winds, and thermospheric composition changes due to the changed circulation patterns. The ~12° tilt of the geomagnetic field axis causes significant longitude effects in all of these processes in the Northern Hemisphere. A complementary series of longitude effects would be expected to occur in the Southern Hemisphere. In this paper we begin a series of studies to investigate the longitudinal-hemispheric similarities and differences in the response of the ionosphere's peak electron density to geomagnetic storms. The ionosonde stations at Wallops Island (VA) and Hobart (Tasmania) have comparable geographic and geomagnetic latitudes for sub-auroral locations, are situated at longitudes close to that of the dipole tilt, and thus serve as our candidate station-pair choice for studies of ionospheric storms at geophysically-comparable locations. They have an excellent record of observations of the ionospheric penetration frequency (foF2) spanning several solar cycles, and thus are suitable for long-term studies. During solar cycle #20 (1964–1976), 206 geomagnetic storms occurred that had Ap≥30 or Kp≥5 for at least one day of the storm. Our analysis of average storm-time perturbations (percent deviations from the monthly means) showed a remarkable agreement at both sites under a variety of conditions. Yet, small differences do appear, and in systematic ways. We attempt to relate these to stresses imposed over a few days of a storm that mimic longer term morphology patterns occurring over seasonal and solar cycle time spans. Storm effects versus season point to possible mechanisms having hemispheric differences (as opposed to simply seasonal differences) in how solar wind energy is transmitted through the magnetosphere into the thermosphere-ionosphere system. Storm effects versus the strength of a geomagnetic storm may, similarly, be related to patterns seen during years of maximum versus minimum solar activity.

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Seton, Maria, Simon Williams, Nick Mortimer, Sebastien Meffre, Steven Micklethwaite, and Sabin Zahirovic. "Magma production along the Lord Howe Seamount Chain, northern Zealandia." Geological Magazine 156, no. 9 (January 18, 2019): 1605–17. http://dx.doi.org/10.1017/s0016756818000912.

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AbstractOne of the world’s most notable intraplate volcanic regions lies on the eastern Australian plate and includes two age-progressive trails offshore (Tasmantid and Lord Howe seamount chains) and the world’s longest continental hotspot trail (Cosgrove Track). While most studies agree that these chains formed by the rapid northward motion of the Australian plate over a slowly moving mantle source, the volcanic output along these trails, their plate–mantle interactions and the source of the magmatism remain unconstrained. A geophysical mapping and dredging campaign on the RV Southern Surveyor (ss2012_v06) confirmed the prolongation of the Lord Howe Seamount Chain to the South Rennell Trough, ∼200 km further north than previously sampled. Radiometric dating of these new samples at 27–28 Ma, together with previously published results from the southern part of the chain, indicate straightforward northward motion of the Australian plate over a quasi-stationary hotspot as predicted by Indo-Atlantic and Pacific hotspot models. A peak in Lord Howe Seamount Chain magmatism in late Oligocene time, also seen in the Tasmantid and Cosgrove trails, matches a 27–23 Ma slowdown of Australian plate motion. The average magma flux of the Lord Howe hotspot is estimated at 0.4 m3 s−1, similar to rates of crustal production at the South Rennell Trough prior to cessation of spreading in middle Oligocene time, supporting a potential genetic relationship to this spreading system. In addition, plate tectonic modelling suggests that the seamounts and plateaus in the Coral Sea may host the earliest evidence of plume activity in the area.

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Hill, P. J. "Capricorn and Northern Tasman Basins: Structure and Depositional Systems." Exploration Geophysics 23, no. 1-2 (March 1992): 153–61. http://dx.doi.org/10.1071/eg992153.

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12

Henderson, R. A. "Geology of the Mt Windsor subprovince—a lower Palaeozoic volcano‐sedimentary terrane in the northern Tasman orogenic zone." Australian Journal of Earth Sciences 33, no. 3 (September 1986): 343–64. http://dx.doi.org/10.1080/08120098608729371.

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Vos, I. M. A., F. P. Bierlein, and D. Phillips. "The Palaeozoic tectono-metallogenic evolution of the northern Tasman Fold Belt System, Australia: Interplay of subduction rollback and accretion." Ore Geology Reviews 30, no. 3-4 (March 2007): 277–96. http://dx.doi.org/10.1016/j.oregeorev.2006.05.001.

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Seebeck, Hannu, Glenn Paul Thrasher, and Graham Paul Viskovic. "Inversion history of the northern Tasman Ridge, Taranaki Basin, New Zealand: implications for petroleum migration and accumulation." New Zealand Journal of Geology and Geophysics 63, no. 3 (December 1, 2019): 299–323. http://dx.doi.org/10.1080/00288306.2019.1695633.

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Zurli, Luca, Gianluca Cornamusini, Jusun Woo, Giovanni Pio Liberato, Seunghee Han, Yoonsup Kim, and Franco Maria Talarico. "Detrital zircons from Late Paleozoic Ice Age sequences in Victoria Land (Antarctica): New constraints on the glaciation of southern Gondwana." GSA Bulletin, April 27, 2021. http://dx.doi.org/10.1130/b35905.1.

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The Lower Permian tillites of the Beacon Supergroup, cropping out in Victoria Land (Antarctica), record climatic history during one of the Earth’s coldest periods: the Late Paleozoic Ice Age. Reconstruction of ice-extent and paleo-flow directions, as well as geochronological and petrographic data, are poorly constrained in this sector of Gondwana. Here, we provide the first detrital zircon U-Pb age analyses of both the Metschel Tillite in southern Victoria Land and some tillites correlatable with the Lanterman Formation in northern Victoria Land to identify the source regions of these glaciogenic deposits. Six-hundred detrital zircon grains from four diamictite samples were analyzed using laser ablation−inductively coupled plasma−mass spectrometry. Geochronological and petrographic compositional data of the Metschel Tillite indicate a widespread reworking of older Devonian Beacon Supergroup sedimentary strata, with minor contribution from Cambro-Ordovician granitoids and meta-sedimentary units as well as Neoproterozoic metamorphic rocks. Euhedral to subhedral Carboniferous−Devonian zircon grains match coeval magmatic units of northern Victoria Land and Marie Byrd Land. This implies, in accordance with published paleo-ice directions, a provenance from the east-southeast sectors. In contrast, the two samples from northern Victoria Land tillite reflect the local basement provenance; their geochronological age and petrographic composition indicates a restricted catchment area with multiple ice centers. This shows that numerous ice centers were present in southern Gondwana during the Late Paleozoic Ice Age. While northern Victoria Land hosted discrete glaciers closely linked with the northern Victoria Land-Tasmania ice cap, the west-northwestward flowing southern Victoria Land ice cap contributed most of the sediments comprising the Metschel Tillite.

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Böhm, Sigrid, Johannes Böhm, Jakob Gruber, Lisa Kern, Jamie McCallum, Lucia McCallum, Tiege McCarthy, Jonathan Quick, and Matthias Schartner. "Probing a southern hemisphere VLBI Intensive baseline configuration for UT1 determination." Earth, Planets and Space 74, no. 1 (July 28, 2022). http://dx.doi.org/10.1186/s40623-022-01671-w.

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AbstractThe deviation of Universal Time from atomic time, expressed as UT1−UTC, reflects the irregularities of the Earth rotation speed and is key to precise geodetic applications which depend on the transformation between celestial and terrestrial reference frames. A rapidly varying quantity such as UT1−UTC demands observation scenarios enabling fast delivery of good results. These criteria are currently met only by the Very Long Baseline Interferometry (VLBI) Intensive sessions. Due to stringent requirements of a fast UT1−UTC turnaround, the observations are limited to a few baselines and a duration of one hour. Hence, the estimation of UT1−UTC from Intensives is liable to constraints and prone to errors introduced by inaccurate a priori information. One aspect in this context is that the regularly operated Intensive VLBI sessions organised by the International VLBI Service for Geodesy and Astrometry solely use stations in the northern hemisphere. Any potential systematic errors due to this northern hemisphere dominated geometry are so far unknown. Besides the general need for stimulating global geodetic measurements with southern observatories, this served as a powerful motivation to launch the SI (Southern Intensive) program in 2020. The SI sessions are observed using three VLBI antennas in the southern hemisphere: Ht (South Africa), Hb (Tasmania) and Yg (Western Australia). On the basis of UT1−UTC results from 53 sessions observed throughout 2020 and 2021, we demonstrate the competitiveness of the SI with routinely operated Intensive sessions in terms of operations and UT1−UTC accuracy. The UT1−UTC values of the SI reach an average agreement of 32 µs in terms of weighted standard deviation when compared with the conventional Intensives results of five independent analysis centers and of 27 µs compared with the 14C04 series. The mean scatter of all solutions of the considered northern hemisphere Intensives with respect to C04 is at a comparable level of 29 µs. The quality of the results is only slightly degraded if just the baseline HtHb is evaluated. In combination with the e-transfer capabilities from Ht to Hb, this facilitates continuation of the SI by ensuring rapid service UT1−UTC provision. Graphical Abstract

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Craddock, John P., Timothy Paulsen, Renata de Silva Schmitt, Stephen T. Johnston, Paul M. Myrow, and Nigel C. Hughes. "Amalgamation of Gondwana: Calcite Twinning and Finite Strains from the early to late Paleozoic Buzios, Ross, Kurgiakh, and Gondwanide Orogens." Geological Society, London, Special Publications 531, no. 1 (November 3, 2022). http://dx.doi.org/10.1144/sp531-2022-165.

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Abstract Oriented carbonate (calcite twinning strains; n=78 with 2414 twin measurements) and quartzites (finite strains, n=15) were collected around Gondwana to study the deformational history associated with the amalgamation of the supercontinent. The Buzios orogen (545-500 Ma), within interior Gondwana, records the high-grade collisional orogen between São Francisco craton (Brazil) and Congo-Angola craton (Angola-Namibia) and twinning strains in calcsilicates record a SE-NW shortening fabric parallel to thrust transport. Along Gondwana's southern margin, the Saldanian-Ross-Delamerian orogen (590-480 Ma) is marked by a regional unconformity that cuts into deformed Neoproterozoic-Ordovician sedimentary rocks and associated intrusions. Cambrian carbonate is preserved in the central part of the southern Gondwana margin, namely in the Kango inlier of the Cape fold belt and the Ellsworth, Pensacola and Transantarctic Mountains. Paleozoic carbonate is not preserved in the Ventana Mountains, Argentina; Islas Malvinas/Falkland Islands or Tasmania. Twinning strains in these Cambrian carbonate strata and synorogenic veins record a complex, overprinted deformation history with no stable foreland strain reference. The Kurgiakh orogen (490 Ma) along Gondwana's northern margin is also defined by a regional Ordovician unconformity throughout the Himalaya; these rocks record a mix of layer-parallel and layer-normal twinning strains with a likely Himalayan (40 Ma) strain overprint and no autochthonous foreland strain site. Conversely, the Gondwanide orogen (250 Ma) along Gondwana's southern margin has three foreland (autochthonous) sites for comparison with 59 allochthonous thrust belt strain analyses. From west to east: finite strains from Devonian quartzite preserve a layer-parallel shortening (LPS) strain rotated clockwise in the Ventana Mountains, Argentina; the frontal (calcite twins) and internal (quartzite strains) samples in the Cape belt preserve a LPS fabric that is rotated clockwise from the autochthonous N-S horizontal shortening in the foreland strain site; Falkland Devonian quartzite shows the same clockwise rotation of the LPS fabric; Permian limestone and veins in Tasmania record a thrust transport-parallel LPS fabric. Early amalgamation of Gondwana (Ordovician) is preserved by local layer-parallel and layer-normal strain without evidence of far-field deformation whereas the Gondwanide orogen (Permian) is dominated by layer-parallel shortening, locally rotated by dextral shear along the margin, that propagated across the supercontinent.

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Bahr, André, Stefanie Kaboth-Bahr, and Cyrus Karas. "The opening and closure of oceanic seaways during the Cenozoic: pacemaker of global climate change?" Geological Society, London, Special Publications, December 9, 2021, SP523–2021–54. http://dx.doi.org/10.1144/sp523-2021-54.

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AbstractThe opening and constriction of oceanic gateways played an essential role in shaping the global climate throughout Earth's history. In this review, we provide an overview of the best-documented feedbacks between gateway dynamics and climate change throughout the Cenozoic. The discussed tectonically induced events comprise: (i) the opening of the Tasmanian Gateway and the glaciation of Antarctica during the Eocene–Oligocene; (ii) the water-mass exchange between the Atlantic and the Mediterranean via the Strait of Gibraltar that has occurred since the Miocene; and (iii) the closure of the American Seaway and (iv) the constriction of the Indonesian Throughflow, both argued to have been instrumental in the intensification of Northern Hemisphere Glaciation during the late Pliocene and early Pleistocene. Lastly, we look at (v) the climatic impact of the flooding and submergence of the Bering Strait during the Plio-Pleistocene and its influence on the Atlantic Meridional Overturning Circulation. While different in their underlying mechanisms, geographical scale and temporal evolution, these case studies demonstrate that even seemingly small-scale changes in the configuration of ocean seaways fundamentally altered the global climate system via their impact on oceanic currents, global heat transfer and carbon storage.

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Journal articles on the topic 'Geology Tasmania, Northern'

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