The tectono-metamorphic evolution of the Balcooma Metamorphic Group, north-eastern Australia: a multidisciplinary approach

Ali, A. (2010) The tectono-metamorphic evolution of the Balcooma Metamorphic Group, north-eastern Australia: a multidisciplinary approach. Journal of Metamorphic Geology, 28 (4). pp. 397-422.

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Abstract

The sequential growth of biotite, garnet, staurolite, kyanite, andalusite, cordierite and fibrolitic sillimanite, their microstructural relationships, foliation intersection axes preserved in porphyroblasts (FIAs), geochronology, P–T pseudosection (MnNCKFMASH system) modelling and geothermobarometry provide evidence for a P–T–t–D path that changes from clockwise to anticlockwise with time for the Balcooma Metamorphic Group. Growth of garnet at ∼530 °C and 4.6 kbar during the N–S-shortening event that formed FIA 1 was followed by staurolite, plagioclase and kyanite growth. The inclusions of garnet in staurolite porphyroblasts that formed during the development of FIAs 2 and 3 plus kyanite growth during FIA 3 reflect continuous crustal thickening from c. 443 to 425 Ma during an Early Silurian Benambran Orogenic event. The temperature and pressure increased during this time from ∼530 °C and 4.6 kbar to ∼630 °C and 6.2 kbar. The overprinting of garnet-, staurolite- and kyanite-bearing mineral assemblages by low-pressure andalusite and cordierite assemblages implies ∼4-kbar decompression during Early Devonian exhumation of the Greenvale Province.

Item ID: 16582
Item Type: Article (Refereed Research - C1)
Keywords: foliation intersection/inflection axes; geochronology; geothermobarometry; MnNCKFMASH; pseudosections
ISSN: 1525-1314
Date Deposited: 05 May 2011 09:32
FoR Codes: 04 EARTH SCIENCES > 0403 Geology > 040312 Structural Geology @ 100%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970104 Expanding Knowledge in the Earth Sciences @ 100%
Citation Count from Web of Science Web of Science 15
Downloads: Total: 2
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