Please use this identifier to cite or link to this item:
Type: Website
Title: Regional high-grade metamorphism during rift basin development: implications for burial mechanisms to lower crustal depths
Author: Tucker, N. M.
Issue Date: 2013
School/Discipline: School of Physical Sciences
Abstract: Crustal-scale exhumation during the intraplate Alice Springs Orogeny (c. 450–300 Ma) in central Australia has exposed the medium-pressure, high-grade metasedimentary and metabasaltic rocks of the Harts Range Group (HRG). Similarities in the detrital zircon age spectra and Lu–Hf-isotopic composition between the HRG and surrounding unmetamorphosed late Neoproterozoic–Cambrian Amadeus and Georgina basin sequences indicate the HRG is a highly metamorphosed equivalent to these basin successions. Calculated phase equilibria modelling and thermobarometry constrain peak metamorphic conditions to ~880ºC and 10.5 kbar and ~670ºC and 7 kbar in the structurally lowest and highest parts of the HRG, respectively. Peak metamorphic assemblages are associated with extensive mafic magmatism, a coarse layer-parallel fabric and NE-side-down kinematics, the combination of which points to an extensional setting. Metamorphic conditions indicate a high geothermal gradient regime also existed during burial, manifested by the prograde development of andausite-bearing metapelite mineral assemblages. Monazite within prograde-zoned garnet and the enclosing fabric yield a U–Pb age of c. 442 Ma which is interpreted to record the timing of high-grade metamorphism of the upper HRG during continuation of the late Ordovician Larapinta Event (c. 480–460 Ma). Burial and metamorphism was synchronous with Centralian Superbasin sedimentation in central Australia and accordingly the deep burial, metamorphism and deformation of the HRG to mid-lower crustal depths must be justified in the context of the broader intraplate basin evolution. The HRG seems consistent with burial by sediment loading and associated high-grade metamorphism driven by elevated heat flows in a super-deep rift. This suggests that regional medium-pressure, high-grade metamorphic terranes may be generated in deep intraplate rift basins during extension and therefore are not necessarily reflective of compressional thickening of the crust
Dissertation Note: Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2013
Where: Arunta Block, Central Australia
Keywords: Honours; Geology; deep-rift basin; intraplate deformation; regional high-grade metamorphism; zircon provenance; geochronology; Lu–Hf; pseudosection; Harts Range; Ordovician
Description: This item is only available electronically.
Provenance: This electronic version is made publicly available by the University of Adelaide in accordance with its open access policy for student theses. Copyright in this thesis remains with the author. This thesis may incorporate third party material which has been used by the author pursuant to Fair Dealing exceptions. If you are the author of this thesis and do not wish it to be made publicly available, or you are the owner of any included third party copyright material you wish to be removed from this electronic version, please complete the take down form located at:
Appears in Collections:School of Physical Sciences

Files in This Item:
File Description SizeFormat 
01frontGeoHon.pdf478.66 kBAdobe PDFView/Open
02wholeGeoHon.pdf8.48 MBAdobe PDFView/Open

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.