Revised geochronology of magmatism in the western Capricorn Orogen at 1805–1785 Ma: diachroneity of the Pilbara–Yilgarn collision

Abstract

The June Hill Volcanics occupy a central stratigraphic position in the tectonic evolution of the Capricorn Orogeny that occurred along the southwestern margin of the Pilbara Craton in Palaeoproterozoic time. The volcanic rocks have been interpreted alternatively as due to continental rifting, foreland‐basin development, or backarc extension. Previous multigrain zircon U–Pb results from these rocks, as well as from an unnamed rhyolitic porphyry that is interstratified in turbidites of the overlying Ashburton Formation, are influenced by the combined effects of Pb loss and xenocrystic inheritance. We report new SHRIMP zircon ages of 1799 ± 8 and 1786 ± 11 Ma, respectively from the June Hill Volcanics and the unnamed porphyry, both of which have been deformed during the Capricorn Orogeny. Close similarity between these ages and results from various late‐stage Capricorn granitoids (including our new SHRIMP result of 1795 ± 8 Ma for the Minnie Creek granite) imply rapid development of the western Ashburton Trough, accumulating and deforming ∼10 km of turbiditic sediments in about 10 million years. Comparison of our new June Hill age with previous SHRIMP results from the central Ashburton Trough implies that foreland‐basin development of the Capricorn Orogeny was significantly diachronous, younging westward during oblique Pilbara–Yilgarn convergence.

Spatio-temporal evolution of the Satpura Mountain Belt of India: A comparison with the Capricorn Orogen of Western Australia and implication for evolution of the supercontinent Columbia

“…On the basis of these observations Sharma (2007) has questioned the proposition of Bhowmik et al (1999Bhowmik et al ( , 2000 and Acharyya (2001Acharyya ( , 2003 that the Satpura orogenic event I at 1500e1600 Ma is pre-Sausar in age. Tyler and Thorne, 1990;Evans et al, 2003;Occhipinti and Reddy, 2004;W-12: 3.2. The eastern continuation of the Satpura Orogen…”

Crustal architecture of the Capricorn Orogen, Western Australia and associated metallogeny

“…Although the Capricorn Orogeny had been widely interpreted to be the result of oblique collision between the Yilgarn and Pilbara Cratons (Myers 1990;Tyler & Thorne 1990;Krape z 1999;Evans et al 2003), most of those models were based largely on interpretations of poorly dated metasedimentary successions in the northern part of the orogen, or else did not take into account the ages, spatial distribution and composition of granitic magmatism in the Gascoyne Province. The recognition of pre-1950 Ma tectonometamorphic events associated with the assembly of the West Australian Craton also negates a Capricorn Orogeny-aged collision.…”

“…The upper part of the lower Wyloo Group is dominated by the $ 2 km thick, ca 2210 Ma Cheela Springs Basalt, and both the Turee Creek and lower Wyloo Groups are intruded by similar-aged dolerite sills and dykes (Martin The tectonic setting of the upper Wyloo Group is considered to be a retro-foreland basin associated with the onset of the 1820-1770 Ma Capricorn Orogeny (Tyler & Thorne 1990;Thorne & Seymour 1991;Evans et al 2003), although Blake & Barley (1992) and Martin & Morris (2010) suggest that the setting may have been extensional in its early stages.…”

“…Horwitz & Smith 1978;Gee 1979) favoured an intracratonic setting. These were followed by plate tectonic models in which the Proterozoic orogeny was driven by collision between the hitherto unrelated Pilbara and Yilgarn Cratons (Muhling 1988;Tyler & Thorne 1990;Blake & Barley 1992;Powell & Horwitz 1994;Evans et al 2003). More recent work, however, has highlighted the complexity of the Capricorn Orogen, which has now been shown to record at least seven major orogenic events (Figure 4; Figure 4, and a detailed geotectonic history of the orogen, in the vicinity of the seismic traverse, is provided below.…”

Oceanic plateau accretion onto the northwestern margin of the Yilgarn Craton, Western Australia

“…Simplified geology of the Bryah Basin; modified from . the other during the Capricorn Orogeny at $ 1.8 Ga (Tyler et al, 1998;Cawood and Tyler, 2004;Evans et al, 2003).…”