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Geology and mineral resources of the Northern Territory: Musgrave Province



Geology and mineral resources of the Northern Territory: Musgrave Province


Close, D. F; Close, DF

Issued by

Northern Territory Geological Survey; Northern Territory Geological Survey


E-Publications; E-Books; PublicationNT; NTGS Special Publication


2013; 2013


Musgrave Province


Made available via the Publications (Legal Deposit) Act 2004 (NT); Available from GEMIS - Geoscience Exploration and Mining Information System; Made available via the Publications (Legal Deposit) Act 2004 (NT); The whole book can be downloaded here




Geology; Mineral resources; Musgrave Province

Publisher name

Northern Territory Government; Northern Territory Government

Place of publication



NTGS Special Publication


No. 5, Chapter 21

File type



Attribution International 4.0 (CC BY 4.0)

Copyright owner

Northern Territory Government; Northern Territory Government


https://creativecommons.org/licenses/by/4.0/; https://creativecommons.org/licenses/by/4.0/

Related links

https://geoscience.nt.gov.au/gemis/ntgsjspui/handle/1/81501 [GEMIS]; https:\\hdl.handle.net\10070\794443 [Whole book]; https://geoscience.nt.gov.au/gemis/ntgsjspui/handle/1/81501

Parent handle

https://hdl.handle.net/10070/794722; https://geoscience.nt.gov.au/gemis/ntgsjspui/handle/1/81501

Citation address


Page content

Musgrave Province 21:6 folds (Scrimgeour et al 1999). The homogeneous granitic composition of felsic gneiss in the Olia Chain indicates an intrusive igneous precursor. SHRIMP U-Pb zircon protolith ages are in the range 15911539 Ma and a metamorphic rim from a felsic gneiss in the Olia Chain has yielded an age of 1176 40 Ma (Scrimgeour et al 1999). The Opparinna Metamorphics (Young et al 2002) are a distinctive succession of dominantly metasedimentary rocks in the southwestern Kelly Hills, north of the Musgrave Ranges. The succession consists of up to 30 m of basal Mn-rich quartz-muscovite schist (Figure 21.6), containing porphyroblastic Mn-rich andalusite (viridine), overlain by 15 m of quartzite and approximately 50 m of meta-igneous amphibolite, which is partly interlayered with the quartzite. In the quartz-muscovite schist, viridine occurs as medium to coarse strongly poikilitic grains and relict bedding, is strongly foliated, and contains muscovite and accessory euhedral garnet and piemontite. Coarse granite and pegmatite dykes of the 1150 Ma Kulpitjata Suite intrude the Opparinna Metamorphics, providing a minimum age for the sedimentary rocks. The quartzite has yielded a single zircon population with a SHRIMP U-Pb age of 1603 36 Ma, which provides a maximum depositional age for the quartzite (Young et al 2002). Camacho (1997) suggested that these sedimentary rocks might be remnants of oceanic crust that predate 16001540 Ma magmatism. A small area of garnet-muscovite-biotite gneiss occurs near Mount Fraser in the Mulga Park area. It is by alternating migmatitic and biotite-rich layers. A SHRIMP U-Pb monazite age of 1177 6 Ma from these were metamorphosed during the Musgrave Orogeny. Numerous ridges of quartzite in the Mulga Park area have been informally named the Sentinel beds (Edgoose et al 1993) and have been interpreted to be sedimentary in origin. They are composed of foliated quartzite and quartz-muscovite schist containing minor garnet and/or biotite, and are locally intercalated with granite, pegmatite and amphibolite. Outcrops and ridges of crystalline quartzite also occur in the Olia Chain to the south of Foster Cliff (Scrimgeour et al 1999), although these may represent recrystallised vein quartz. MUSGRAVE OROGENY (12201150 Ma) The 12201150 Ma Musgrave Orogeny is recorded throughout the Musgrave Province, but evidence for the in areas that were not pervasively reworked during the 580530 Ma Petermann Orogeny. The Musgrave Orogeny involved amphibolite- to granulite-facies metamorphism and intense deformation, which is associated with voluminous and long-lived syn- to post-tectonic granitic magmatism of the 12201120 Ma Pitjantjatjara Supersuite. This volume of felsic magmatism provides evidence for protracted heating of the lower crust, which is associated with an elevated geotherm during the Musgrave Orogeny. In Western Australia, metamorphic assemblages associated with the Musgrave Orogeny are preserved and represent between 1220 and 1150 Ma (Howard et al 2011). The combination of a prolonged period of ultra-high temperature (UHT) metamorphism and large-volume, compositionally anhydrous magmatism has led to the interpretation of a long-lived intracratonic extensional tectonic setting for the Musgrave Orogeny (Smithies et al 2011). The best estimates for the timing of the Musgrave Orogeny in the region are from felsic granulite in the eastern Mann Ranges and amphibolite-facies pelitic gneiss from near Mulga Park. In the felsic granulite, metamorphic rims on zircons have given a date of 1170 10 Ma, whereas in the pelitic gneiss, crystallisation of metamorphic monazite has given a 207Pb/206Pb age of 1177 6 Ma, a 206Pb/238U age of 1155 7 Ma and a 208Pb/232Th age of 1169 16 Ma (Camacho 1997). These estimates are within error of less precise ages of 1176 40 Ma for zircon rims in amphibolite-facies gneiss in the Olia Chain, and 1190 35 Ma from metamorphic rims on inherited zircons within the Walal Granite in the Mann Ranges. Metamorphic rims on a sample of Allanah Gneiss yielded a SHRIMP U-Pb zircon age of approximately 1206 Ma (Young et al 2002), with no error quoted. In addition, a sample of Mantarurr Suite from the Olia Chain, with an intrusive zircon age of 1168 14 Ma, contains narrow metamorphic rims with ages indistinguishable from the intrusive age. Titanite from the same rock has given 1165 11 Ma. These data are consistent with extensive zircon and monazite data from gneiss in the Musgrave Ranges (Camacho 1997) and in Western Australia (Howard et al Orogeny occurred in the interval 12201150 Ma. Musgrave Orogeny in Fregon Domain Within the Northern Territory, the structural evolution during the Musgrave Orogeny is preserved in the eastern Musgrave Province, in areas that escaped reworking metamorphic grade during the Musgrave Orogeny was generally granulite facies, with the exception of the Umbeara area in the far east, where the grade is amphibolite facies. Pressure estimates of metamorphism generally increase towards the west. Around Kulgera, transitional granulite-facies rocks have a well-developed S1 gneissosity that is transposed Figure 21.6. Viridine-bearing schist in Opparinna Metamorphics of Musgravian gneiss from Kelly Hills area within Mulga Park frame is 20 cm. Geology and mineral resources of the Northern Territory Special publication 5

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