Lower crustal rheological expression in inverted basins
Mike Sandiford
David L. Hansen
Sandra N. McLaren
10.6084/m9.figshare.3454328.v1
https://geolsoc.figshare.com/articles/dataset/Lower_crustal_rheological_expression_in_inverted_basins/3454328
<p>Although lithospheric modelling has provided extraordinary insights into the processes that shape the continental crust, considerable
uncertainty surrounds the basic rheology that governs behaviour at geological timescales. In part, this is because it has
proved difficult to identify the geological observations that might discriminate, or unify, models of lithospheric rheology.
In particular, the relative strength of lower crust and upper mantle remains a contentious aspect of continental lithospheric
rheology. We show that various models for lower crustal rheology may produce distinct patterns of inversion in extensional
sedimentary basins, consistent with some of the observed natural variability of inversion styles. Inversion of basin interiors,
as is common in European Mesozoic basins, is favoured by a lithospheric rheology more sensitive to lateral thermal structure
than to changes in the depth of the Moho, consistent with there being little strength contrast between the lower crust and
upper mantle in these settings. In contrast, inversion of basin margins, particularly involving basinward verging structures,
is consistent with a rheological sensitivity to the depth of Moho as would apply for a lower crust much weaker than the upper
mantle. We use an example from central Australia to demonstrate this latter response, together with thermochronologic data
that suggests that a relatively weak lower crust in this setting may reflect abnormally high geothermal gradients.
</p>
2016-06-21 12:03:22
mantle
basinward verging structures
strength
lithospheric rheology
contrast
European Mesozoic basins
crustal rheological expression
inversion
depth
model
Moho
Geology