Petermann Orogeny

The Petermann Orogeny was an intracontinental event that affected basement rocks of the northern Musgrave Province and Ediacaran (Proterozoic) sediments of the (now) southern Amadeus Basin between ~550-535 Ma. The remains are seen today in the Petermann Ranges.

Prior to the Petermann Orogeny, which resulted in exhumation of the Musgrave Block, the Amadeus Basin was contiguous with the Officer Basin in South Australia.

The extent and effect of the Petermann Orogen appears to be relatively confined, occurring most pervasively within the central northern-Musgrave Block. Here, older Musgravian (~1200-1150 Ma) fabrics are partially to completely overprinted by sub-eclogite-facies mineral assemblages (11-12 kbar at 650 °C).

The Woodroofe Thrust, Davenport Shear Zone and Mann Fault accommodated much of the 30–40 km exhumation. Exhumation of the Musgrave Block (and overlying sediments) resulted in successive unroofing and deposition of rock types such as arkose and conglomerate in localised sedimentary basins that now outcrop as Uluru and Kata Tjuta respectively. Beyond this region of intense Petermann-aged activity, deformation related to the Petermann Orogen is less pervasive and ductile.

Sedimentation associated with the Petermann Orogeny is responsible for the deposition of the Georgina Basin, Officer Basin, Ngalia Basin and Amadeus Basin sediments in the Cambrian. Sediments are a mixture of fluvial conglomerates, sandstones, and siltstones.

Several pull-apart structural grabens formed at flexures in the orogenic belt, forming the Levenger and Moorilyanna Grabens.

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