10.6084/m9.figshare.3452957.v1
Shaun L. L. Barker
Shaun
L. L. Barker
Stephen F. Cox
Stephen F.
Cox
Evolution of fluid chemistry and fluid-flow pathways during folding and faulting: an example from Taemas, NSW, Australia
Geological Society of London
2016
fluid
Vein δ 18 O
subhorizontal extension fractures
vein swarm
fault
mineral precipitation events
New South Wales
REE
Vein δ 18 O compositions increase
pathway
NSW
Geology
2016-06-21 11:00:51
Dataset
https://geolsoc.figshare.com/articles/dataset/Evolution_of_fluid_chemistry_and_fluid-flow_pathways_during_folding_and_faulting_an_example_from_Taemas_NSW_Australia/3452957
<p>In the Taemas area, New South Wales, Australia, a swarm of hydrothermal calcite and quartz veins is hosted in upright, open
to close folded limestones and shales. Overprinting relationships and vein geometries demonstrate that the vein swarm formed
progressively during fold growth and associated reverse faulting. Textures preserved in veins reveal that veins formed via
hundreds to thousands of individual dilation and mineral precipitation events. Bedding-parallel flexural slip during fold
growth was associated with laminated vein development, and limb-parallel stretching during fold growth was associated with
the formation of bedding-orthogonal extension veins. The presence of subhorizontal extension fractures and severely misoriented
reverse faults imply that fluid pressures exceeded lithostatic levels, at least transiently, during the development of the
vein swarm.
</p> <p>Vein δ<sup>18</sup>O compositions increase upwards through the Murrumbidgee Group in response to a progressive reaction of an externally derived,
upwards-flowing low-δ<sup>18</sup>O fluid (of probable meteoric origin) with host limestones. Vein δ<sup>18</sup>O and <sup>87</sup>Sr/<sup>86</sup>Sr compositions vary spatially and temporally within the same outcrop, and within individual veins. These variations are inferred
to be caused by the ascent of packages of fluid along constantly changing flow pathways caused by multiple permeability creation–destruction
cycles associated with fault slip and fault sealing. Vein trace and rare earth element (REE) concentrations are more variable,
probably reflecting rapid rock buffering along fluid pathways on length scales of less than 10 m. Our results indicate that
fluid-flow pathways change dynamically during crustal shortening, with pathways switching between states of low and high permeability
during episodic fault slip and associated fracture development.
</p>