Resolving the routine presence of kyanite, andalusite and sillimanite across a region using foliation intersection/inflection axes preserved in porphyroblasts, petrographic observations and thermobarometry

Ali, Asghar (2012) Resolving the routine presence of kyanite, andalusite and sillimanite across a region using foliation intersection/inflection axes preserved in porphyroblasts, petrographic observations and thermobarometry. Acta Geologica Sinica, 86 (5). pp. 1241-1250.

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Abstract

Constraints from P-T pseudosections (MnNCKFMASH system), foliation intersection/inflection axes preserved in porphyroblasts (FIAs), mineral assemblages and textural relationships for rocks containing all three Al2SiO5 polymorphs indicate a kyanite→ andalusite→ sillimanite sequential formation at different times rather than stable coexistence at the Al2SiO5 triple point. All three Al2SiO5 polymorphs grew in the Chl, Bt, Ms, Grt, St, Pl and Crd bearing Ordovician Clayhole Schist in Balcooma, northeastern Australia separately along a looped P-T-t-D path that swaps from clockwise to anticlockwise in the tectono-metamorphic history of the region. Kyanite grew during crustal thickening in an Early Silurian Orogenic event followed by decompression/heating, andalusite and fibrolitic sillimanite growth during Early Devonian exhumation.

Item ID: 23849
Item Type: Article (Refereed Research - C1)
Keywords: Al2SiO5 triple point, microtextures, foliation intersection/inflection axes, Barrovian sequence, episodic porphyroblast growth
ISSN: 1755-6724
Date Deposited: 09 Nov 2012 01:26
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 2
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