Open Access Repository

Blind orogen: Integrated appraisal of multiple episodes of Mesoproterozoic deformation and reworking in the Fowler Domain, western Gawler Craton, Australia


Downloads per month over past year

Thomas, JL, Direen, NG and Hand, M 2008 , 'Blind orogen: Integrated appraisal of multiple episodes of Mesoproterozoic deformation and reworking in the Fowler Domain, western Gawler Craton, Australia' , Precambrian Research, vol. 166, no. 1-4 , pp. 263-282 , doi: 10.1016/j.precamres.2007.05.006.

[img] PDF
THOMAS~1.PDF | Request a copy
Full text restricted
Available under University of Tasmania Standard License.


The Fowler Domain in the western Gawler Craton in southern Australia is a poorly exposed region that
can only presented be explored using a combination of information from drilling and potential field
geophysics. Regional maps of the Total Magnetic Intensity (TMI) field of the Fowler Domain highlight an
anastomosing systemof terrain-scale shear zones that bound four crustal-scale tectonic blocks: fromwest
to east, the Colona, Barton, Central and Nundroo blocks.
Integrated thermobarometry and electron microprobe chemical dating ofmetamorphic monazites from
drillholes in the Fowler Domain suggest that the Colona Block in the west underwent two mid-crustal
amphibolite grade metamorphic events at ca. 1643 and 1600 Ma. The younger age corresponds to the
timing of regional high-grade metamorphism in the Barton Block. Together, the age data suggest that the
western Fowler Domain underwent a major tectonothermal event at ca. 1600 Ma.
In contrast, regional lower crustalmetamorphism in theNundroo Block, which forms the eastern Fowler
Domain, occurred at ca. 1545 Ma. In both the Barton and Nundroo Blocks, petrological relationships, mineral
zoning, and pressure–temperature (P–T) modelling suggest the terrains cooled in the mid- to lower
crust, rather than undergoing exhumation immediately following peak metamorphism. Age data fromthe
geophysically defined shear zone systems that bound the blocks suggest that exhumation of these lower
crustal domains occurred between ca. 1470 and 1450Ma and was associated with transpressional reactivation
of the terrain during the Coorabie Orogeny. A key finding of this study is that the tectonic evolution
of the crustal blocks in the Fowler Domain was not in concert until at least 1500 Ma. Thus, the evolution
of the individual blocks is unlikely to be related to the macroscopic character of the terrain defined by
the regional-scale shear zone systems, which are one of the youngest tectonic imprints on the Fowler
Domain. Coincident gravity and magnetic forward modelling of significant bounding faults suggests the
shear zones form a steeply dipping transpressional array, consistent with the observed metamorphic field
character of the different blocks. This study provides a demonstration of the integration of geophysical and
petrological approaches to investigate the time-integrated tectonic evolution of poorly exposed basement

Item Type: Article
Authors/Creators:Thomas, JL and Direen, NG and Hand, M
Keywords: Fowler Domain Gawler Craton Gravity Magnetics Monazite Proterozoic Rodinia Transpression
Journal or Publication Title: Precambrian Research
ISSN: 0301-9268
DOI / ID Number: 10.1016/j.precamres.2007.05.006
Additional Information:

The definitive version is available at

Item Statistics: View statistics for this item

Actions (login required)

Item Control Page Item Control Page