Range, Central Australia: the brain and
2004-2011 by Roberto Weinberg. All rights reserved. Unlimited
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I would very much appreciate an email stating how this material will be used: Roberto Weinberg, Monash University, Australia. Thanks, RW.
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|The brain (top half of
the image): a circular body in Central
(the Entia Dome, see Buick, I. 1988, Ph.D. Thesis,
Mawby, J., Ph.D. thesis, Adelaide University), comprised of
Palaeoproterozoic granite and sedimentary rocks showing an internal
flow geometry akin to the pattern of internal convection similar to
those in ascending spherical diapirs as Cruden, Schmeling and Weinberg
showed in the early 90s. Notice also the presence of a granitic tail in
the SW quadrant, and how the country rocks turn norhwards (upwards?) on
either side of the tail. Notice also how dark rocks (Ordovician
basalts) seem to wrap around the dome. Metamorphism reached amphibolite
facies (Arnold, J., Sandiford, M., Wetherly, S., 1995, Metamorphic
events in the Eastern Arunta Inlier, Part 1. Metamorphic petrology,
Precambrian Research, 71, 183-205). Scale: the dome is approximately 30
km wide on its widest E-W section.
Interpretation: this is a potential example of internal circulation in a diapiric body of granite+sediment, rising obliquely to the NE through a denser carapace of basalts, leaving its pathway behind. The age difference between the older granite and younger basalt carapace suggests that diapirism took place in the solid state. Rock dating can be found in Hand, Mawby, Kinny, Foden, J. 1999. SHRIMP evidence for multiple high-T Palaeozoic events in the Arunta Inlier, central Australia. Geological Society of London Journal, 156, 715-730.