1,721,558 research outputs found
Australo-Antarctica in the supercontinent cycle
No full textThe large-scale continental domains that make up East Antarctica are important to global plate reconstructions. A key piece in this continental jigsaw puzzle is the AustraloAntarctic domain that formed part of the Gondwana‚-Pangea (0.5‚-0.3 Ga), Rodinia (1.0 Ga), and Nuna (1.7 Ga) supercontinents. Its vast underexplored bedrock can inform tectonic and paleogeographic reconstructions through deep time. The central aim of this thesis is to constrain the poorly-known continental evolution of Australo-Antarctica in the context of supercontinent cycles. This aim is addressed by examining the geological record of frontier regions of Australo-Antarctica and the conjugate southern Australian region using a combination of regional geophysical data and rock- and sediment-based geological analysis in a plate reconstruction framework. The first research chapter explores the poorly known age, composition and tectonic affinity of Precambrian basement and sedimentary cover of interior Wilkes Land. Zircon U‚-Pb‚-Hf isotopic data from isolated coastal outcrops are combined with regional aeromagnetic data to map Mesoproterozoic (c. 1600‚-1300 Ma) basement provinces across southern Australia and East Antarctica. This new analysis provides a revised basement architecture shaped through orogenic cycles associated with the Nuna and Rodinia supercontinents. Into the interior, the enigmatic subglacial Sabrina Basin mapped previously from geophysics, is here sampled for the first time via sandstone erratics deposited at the coast. Coupled in situ authigenic monazite and detrital zircon isotopic data reveal that these sandstones were deposited during the Neoproterozoic (before c. 633 Ma). Similarities in age and provenance between these Sabrina Basin samples and other Neoproterozoic strata in the Transantarctic Mountains (Beardmore Group) and southern Australia (Officer Basin) suggest that Neoproterozoic sedimentary rocks likely covered a large sector of the Australo-Antarctic domain, forming an extensive platform basin on the proto-Pacific rifting margin of Rodinia. The second research chapter of this thesis examines the Phanerozoic tectonic history of Australo-Antarctica, with a focus on the age and tectonic origin of onshore sedimentary basins. (U‚-Th)/He thermochronology data from basement rocks in the Bunger Hills region is used to investigate the timing of extensional tectonism of the inaccessible Knox Rift. Inverse modelling of thermochronology data support ~2‚-4 km of exhumation of local basement in the Late Paleozoic‚-Triassic during extension in the Knox Rift. These new results are combined with existing low-temperature (<300¬∫C) thermochronology constraints from East Antarctic basement rocks to propose widespread basement exhumation in the Late Paleozoic‚-Triassic driven by intraplate extension during the earliest stages of Pangea rifting. This phase of tectonic activity is responsible for the formation of large basins across Pangea including the Knox Rift as well as the Aurora, Vincennes and Wilkes subglacial basins further east across Australo-Antarctica. Paleozoic‚-Mesozoic km-scale exhumation of East Antarctic basement generated a significant volume of clastic material that filled basins across East Gondwana. The third research chapter focuses on refining sediment dispersal patterns using International Ocean Discovery Program (IODP) cores from Mesozoic strata in the frontier Mentelle Basin of southwestern Australia. Provenance of these sedimentary rocks is explored using detrital zircon and monazite isotopic data and is compared with the provenance record of other Antarctic and Australian Paleozoic‚-Mesozoic strata. The results provide the first record of a transcontinental sediment pathway connecting basement regions within the Gondwanaforming Kuunga Orogen (0.7‚-0.5 Ga) with the Tethys Ocean via a series of intraGondwanan rift basins. Together with other proposed large-scale sediment pathways, this was one of the principal modes of siliciclastic sediment delivery to Paleozoic‚-Mesozoic sedimentary basins in East Antarctica and Australia. The results presented in this thesis reveal plate-scale processes in Australo-Antarctica in unprecedented detail, and in doing so more clearly frame its continental evolution into current plate tectonic models. This body of work will inform both future regional studies and global tectonic reconstructions
COVID-X PPT template
No full text<p>This template will be used for all COVID-X presentations. </p>
The Australo-Antarctic Columbia to Gondwana transition
No full textFrom the Mesoproterozoic to Cambrian, Australo-Antarctica was characterised by tectonic reconfiguration as part of the supercontinents Columbia, Rodinia and Gondwana. New tectonic knowledge of the Wilkes Land region of Antarctica allows Australo-Antarctic tectonic linkages to be resolved through reconstruction into ca. 160 Ma Gondwana. We also resolve 330 ± 30 km of sinistral strike-slip offset on the > 3000 km long Mundrabilla-Frost Shear Zone and 260 ± 20 km of dextral offset on the > 1000 km long Aurora Fault to reconstruct the ca. 1150 Ma geometry of Australo-Antarctica. Using this revised geometry, we derive the first model of the Columbia to Gondwana reconfiguration process that is geometrically constrained to ~ 100 km scale. In this model, early Mesoproterozoic tectonics is driven by two opposing subduction systems. A dominantly west-dipping subduction zone existed at the eastern margin of Australo-Antarctica until ca. 1.55–1.50 Ga. A predominantly east-dipping subduction zone operated at the western margin of the Mawson Craton from ca. 1.70 Ga to ca. 1.42 Ga. The latter caused gradual westwards motion and clockwise rotation of the Mawson Craton relative to the West and North Australian Craton and the accretion of a series of continental ribbons now preserved in the Musgrave Province and its southern extensions. A mid-Mesoproterozoic switch to predominantly west-dipping subduction beneath the West Australian Craton brought about the final closure of the Mawson Craton with the North and West Australian Craton along the Rodona-Totten Shear Zone. Convergence was achieved prior to 1.31 Ga, but final collision may not have occurred until ca. 1.29 Ga. Post-1.29 Ga intraplate activity involved prolonged high-temperature orogenesis from 1.22 to 1.12 Ga, and significant movement on the Mundrabilla-Frost Shear Zone between 1.13 and 1.09 Ga, perhaps in response to the assembly of Rodinia at ca. 1.1 Ga. The Australo-Antarctic Craton was amalgamated with Indo-Antarctica along the Indo-Australo-Antarctic Suture (IAAS) and Kuunga Orogeny, probably in the latest Neoproterozoic to early Cambrian
Ischnura aurora (Brauer 1865) (Zygoptera: Coenagrionidae), an Australo-Pacific species
No full textThere is some confusion over the identity of small forms of Ischnura occurring in South and East Asia and the Australo-Pacific region. Here, characters are given that separate Ischnura aurora (Brauer 1865) of the Australo-Pacific region from animals from the Asian mainland and nearby islands. Difficulties in attaching a name, or names, to Asian forms are considered
Cryptic diversity and evolutionary relationships among Australian closed-forest Melomys (Rodentia: Muridae) and related Australo-Papuan mosaic-tailed rats
No full textThis thesis investigates patterns of evolution in a group of native Australo-Papuan rodents. Past climatic change and associated sea level fluctuations, and fragmentation of wet forests in eastern Australia has facilitated rapid radiation, diversification and speciation in this group. This study adds to our understanding of the evolution of Australia’s rainforest fauna and describes the evolutionary relationships of a new genus of Australian rodent
Differences of Lateral Cephalometry Values between Australo-Melanesian and Deutero-Malay Races
No full text 72 1024x768 Cephalometric is extensively used to study the facial morphology that supports orthodontic diagnosis and treatment planning. Correct cephalometric analyses need reference values obtained from the same ethnic, gender and age population of orthodontic patients. Objective: To compare the difference of lateral cephalometric values between Australo-Melanesian and Deutero-Malay race in 16 to 20 years of age subjects with normal occlusion. Methods: An observational with cross-sectional design study on 200 subjects (100 males and 100 females) from Australo-Melanesian and Deutero-Malay race was performed. Lateral cephalometric radiographs were taken, traced and analyzed. Results: Mann Whitney U test showed significant differences on SNA angle with median 84° for Australo-Melanesian race and 83° for Deutero-Malay race. Lower lip distance to aesthetic line 3mm for Australo-Melanesian race and 1mm for Deutero-Malay race also showed significant difference. Independent t-test showed significant differences in FM angle with mean 27.45±4.49° for Australo-Melanesian race and 28.14±5.36° for Deutero-Malay race, and upper I to APg angle 36.28±4.72°for Australo-Melanesian race and 32.69±6.24° for Deutero-Malay race. Conclusion: The Australo-Melanesian race had more protruded maxilla to cranial base, more flat mandibular plane, more proclined upper incisors, and more frontal lower lip to aesthetic line compared to Deutero-Malay race.DOI: 10.14693/jdi.v20i1.127</p
Differences of Lateral Cephalometry Values between Australo-Melanesian and Deutero-Malay Races
Full text linkCephalometric is extensively used to study the facial morphology that supports orthodontic diagnosis and treatment planning. Correct cephalometric analyses need reference values obtained from the same ethnic, gender and age population of orthodontic patients. Objective: To compare the difference of lateral cephalometric values between Australo-Melanesian and Deutero-Malay race in 16 to 20 years of age subjects with normal occlusion. Methods: An observational with cross-sectional design study on 200 subjects (100 males and 100 females) from Australo-Melanesian and Deutero-Malay race was performed. Lateral cephalometric radiographs were taken, traced and analyzed. Results: Mann Whitney U test showed significant differences on SNA angle with median 84° for Australo-Melanesian race and 83° for Deutero-Malay race. Lower lip distance to aesthetic line 3mm for Australo-Melanesian race and 1mm for Deutero-Malay race also showed significant difference. Independent t-test showed significant differences in FM angle with mean 27.45±4.49° for Australo-Melanesian race and 28.14±5.36° for Deutero-Malay race, and upper I to APg angle 36.28±4.72°for Australo-Melanesian race and 32.69±6.24° for Deutero-Malay race. Conclusion: The Australo-Melanesian race had more protruded maxilla to cranial base, more flat mandibular plane, more proclined upper incisors, and more frontal lower lip to aesthetic line compared to Deutero-Malay race.DOI: 10.14693/jdi.v20i1.12
SPATIAL podcast 3rd episode - The accountability of Artificial Intelligence-based systems
No full text<p>Thank you for tuning in to the SPATIAL podcast, where we explore the cutting-edge advancements and crucial discussions surrounding Artificial Intelligence. Today's episode, presented by Blanca Arregui, from AUSTRALO, is particularly special as we delve into the critical topic of the accountability of AI-based systems, aligning with the SPATIAL project's mission to prioritize trustworthy AI in Europe. Our esteemed guests today bring a wealth of knowledge and expertise to the table. First up is Prachi Bagave, a PhD candidate specializing in Accountable AI for Healthcare Systems at TU Delft, one of the world's leading engineering universities. Joining us from Fraunhofer FOKUS in Berlin, Germany, are Helene Knof and Michell Boerger. Both are actively engaged in applied research related to machine learning, with a specific focus on accountability and security. Fraunhofer FOKUS, being a renowned research institute, plays a pivotal role in advancing the field of AI, ensuring its responsible and secure integration into various domains. Throughout this episode, we'll gain insights and examples from these experts on the challenges and opportunities in ensuring accountability within AI systems. #SPATIALpodcasts</p>
- …
