Middle–Late Paleozoic Australia–Asia convergence and tectonic extrusion of Australia

Abstract

Recent and new paleomagnetic data from ignimbrite-rich Carboniferous successions of the western Tamworth Belt, Southern New England Orogen, eastern Australia, show a northward excursion over~30°. Paleozoic data from the Australian craton and Tasman Orogenic System (TOS) suggest an Early Devonian start. At the middle-late Visean peak, the central New Guinean promontory of the Australian craton reached 30°-40°N, within the latitude range of the western Central Asian Orogenic Belt (CAOB). Devonian-Carboniferous convergence of Australia/northeastern Gondwana with the CAOB, across the Paleoasian-Rheic Ocean, is proposed as a major driver for contemporaneous tectonism throughout Australia and the CAOB. This implies a substantial Variscan, Pangea-forming, influence on Australian Devonian-Carboniferous tectonics-Alice Springs Orogeny (ASO) and Quilpie and Kanimblan Orogenies. Convergence-related compressional deformation of Australia is largely confined to a "compression box", extending southward from the New Guinean promontory and bounded westward by the Lasseter Shear Zone and eastward by the East Australian Rift System. Comparable characteristics of Paleozoic Australia-Asia and Cenozoic India-Asia convergencenorth-south compression, weak and heated crust (Larapintine Graben and TOS/Tibetan Plateau), eastern "free oceanic boundary" (Paleopacific/Pacific)do link Paleozoic Australia-Asia convergence to Cenozoic tectonic extrusion of Tibet. Tectonic extrusion of ductile lower crust from the Larapintine Graben led to eastward displacement of the Thomson and Northern New England Orogens, with upper crustal displacement bounded northward by Arunta Block shear zones, the Diamantina River Lineament, the Clarke River Fault Zone and the Townsville Trough, and southward by the Darling River/Cobar-Inglewood Lineaments and Cato Fracture Zone with the Lake Blanche-Olepoloko Fault Zones and Lachlan Transverse Zone as a subsidiary. Recognition of ASO-related tectonic extrusion opens novel, provocative, insights into puzzling aspects of Australian Middle-Late Paleozoic evolution.

Intracontinental Orogeny Enhanced by Far‐Field Extension and Local Weak Crust

“…Model M4b, and to a lesser extent Model M2 (Figures b–b), shows higher values for vorticity in the Harts Range area compared with all remaining models (Table ). These vorticity values can be explained by the west directed protrusion and flow of crustal material inside the weak wedge (Figures b and b), similar to the channel flow extrusion documented in the Himalaya‐Tibetan Plateau (Beaumont et al, ; Bird, ; Godin et al, ) and hypothesized by Klootwijk () for the intraplate Australian continent. This movement of material inside the wedge would imply both sinistral and dextral strike‐slip kinematics along the northern and southern boundaries of the wedge, respectively (Figure b–b and ).…”

“…Thus, the westward tectonic stress influences on central Australia orogenesis have largely been ignored. Studies by Roberts and Houseman (2001), Klootwijk (2013), and Kröner et al (2016) correlate intraplate reactivation of central Australia with the mainly N-S convergence between Gondwana and Laurasia, forming the Qinling Orogen in the north (Figure 3a). Using numerical models, Roberts and Houseman (2001) showed that rotation of the north Australian block induced simultaneous extension of the Canning Basin in NW Australia and N-S convergence within an area of lithospheric weakness in central Australia.…”

“…Tectonics The localization of higher crustal thickening is not randomly distributed in the Arunta Region (Figure 1b). As proposed by a number of authors (e.g., Cunningham, 2013;Klootwijk, 2013;Molnar & Dayem, 2010;Raimondo et al, 2014;Roberts & Houseman, 2001;Sandiford & Hand, 1998;Shaw et al, 1991), crustal thickening in intracontinental orogens is usually preferentially located in regions of weakened rheology, leading to enhanced strain accumulation in structures at a low angle relative to the principal stress component and in regions adjacent to crustal strength heterogeneities. In our case, the central sector of the low-viscosity band and the eastern weak wedge (Figures 6-9) model such localization.…”

Orogen-perpendicular structures in the central Tasmanides and implications for the Paleozoic tectonic evolution of eastern Australia

“…1b, c). The origin of these (~E-W) structural features is controversial (Burton, 2010;Glen et al, 2013;Klootwijk, 2013;Burton and Trigg, 2014;Glen et al, 2014), partly because of the very limited exposure of the Thomson Orogen in central Queensland and northwestern New South Wales (Fig. 1a).…”

Early Palaeozoic continental growth in the Tasmanides of northeast Gondwana and its implications for Rodinia assembly and rifting

“…Exceptions to this approach include linking intraplate deformation in central Australia in the late Paleozoic Alice Springs Orogeny to megakinking in the Lachlan Orogen (Powell, 1984b) and tectonic extrusion in eastern Australia linked to Australian-Asian collision (Klootwijk, 2013). Paleomagnetic data suggest that there has been a 40° anticlockwise rotation between the North Australian Craton and an amalgam of the West and South Australian cratons along the southern margin of the Musgrave Block in central Australia in the interval 650 to 550 Ma (Li and Evans, 2011).…”