Duration of high-pressure metamorphism and cooling during the intraplate Petermann Orogeny

作者：Walsh A K^*; Raimondo T; Kelsey D E; Hand M; Pfitzner H L; Clark C

来源：Gondwana Research, 2013, 24(3-4): 969-983.

DOI：10.1016/j.gr.2012.09.006

• Central Australia
• Petermann
• Musgrave Province
• Intraplate
• SHRIMP U-Pb geochronology

The Ediacaran-Cambrian Petermann Orogeny, central Australia, is an exceptional example of intraplate orogenesis. It involved sub-eclogite facies metamorphism and extreme basin inversion during the exhumation of Musgrave Province basement from beneath the formerly contiguous Centralian Superbasin. Sensitive High Resolution Ion Microprobe (SHRIMP) U-Pb geochronology of zircon, titanite and rutile, along with Ti-in-zircon thermometry from meta-igneous samples, have been used to determine the timing and duration of high-pressure metamorphism and subsequent cooling associated with this orogenic event. Peak metamorphic temperatures of 720-760 degrees C were attained at 544 +/- 7 Ma (U-Pb zircon). Subsequent cooling to 600-660 degrees C by similar to 521 Ma occurred at a rate of similar to 2.6-7.0 degrees C Myr(-1), as recorded by the closure of Pb diffusion in titanite. Further cooling to 585-560 degrees C by 498-472 Ma occurred at a rate of 0.9-4.8 degrees C Myr(-1), as recorded by Pb closure in rutile. The duration of tectonism was long-lived (%26gt;40 Myr) across the central and western parts of the orogenic system, and deformation occurred in a comparatively warm and weak portion of crust, characterised by regional thermal gradients of 17-26 degrees C km(-1). This proposed duration of tectonism is much longer than that permitted by a shear heating mechanism, which requires an exceptionally short duration of tectonism, and additionally, an overall cold lithosphere characterised by geothermal gradients of similar to 9 degrees C km(-1).

• 出版日期2013-11