- Title
- High-pressure metamorphism in the southern New England Orogen: implications for long-lived accretionary orogenesis in eastern Australia
- Creator
- Phillips, G.; Offler, R.; Rubatto, D.; Phillips, D.
- Relation
- Tectonics Vol. 34, Issue 9, p. 1979-2010
- Publisher Link
- http://dx.doi.org/10.1002/2015TC003920
- Publisher
- Wiley-Blackwell
- Resource Type
- journal article
- Date
- 2015
- Description
- New geochemical, metamorphic, and isotopic data are presented from high-pressure metamorphic rocks in the southern New England Orogen (eastern Australia). Conventional and optimal thermobarometry are augmented by U-Pb zircon and 40Ar/39Ar phengite dating to define pressure-temperature-time (P-T-t) histories for the rocks. The P-T-t histories are compared with competing geodynamic models for the Tasmanides, which can be summarized as (i) a retreating orogen model, the Tasmanides formed above a continuous, west dipping, and eastward retreating subduction zone, and (ii) a punctuated orogen model, the Tasmanides formed by several arc accretion, subduction flip, and/or transference events. Whereas both scenarios are potentially supported by the new data, an overlap between the timing of metamorphic recrystallization and key stages of Tasmanides evolution favors a relationship between a single, long-lived subduction zone and the formation, exhumation, and exposure of the high-pressure rocks. By comparison with the retreating orogen model, the following links with the P-T-t histories emerge: (i) exhumation and underplating of oceanic eclogite during the Delamerian Orogeny, (ii) recrystallization of underplated and exhuming high-pressure rocks at amphibolite facies conditions coeval with a period of rollback, and (iii) selective recrystallization of high-pressure rocks at blueschist facies conditions, reflecting metamorphism in a cooled subduction zone. The retreating orogen model can also account for the anomalous location of the Cambrian-Ordovician high-pressure rocks in the Devonian-Carboniferous New England Orogen, where sequential rollback cycles detached and translated parts of the leading edge of the overriding plate to the next, younger orogenic cycle.
- Subject
- high-pressure metamorphic rocks; southern New England Orogen; eastern Australia; accretionary orogenesis
- Identifier
- http://hdl.handle.net/1959.13/1329890
- Identifier
- uon:26266
- Identifier
- ISSN:0278-7407
- Language
- eng
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