eCite Digital Repository

Evolution of fluid chemistry and fluid-flow pathways during folding and faulting: an example from Taemas, NSW, Australia

Citation

Barker, SLL and Cox, SF, Evolution of fluid chemistry and fluid-flow pathways during folding and faulting: an example from Taemas, NSW, Australia, Geology of the Earthquake Source: A Volume in Honour of Rick Sibson, The Geological Society, A Fagereng, VG Toy, JV Rowland (ed), United Kingdom ISBN 9781862396074 (2011) [Research Book Chapter]


Preview
PDF
17Mb
  

Copyright Statement

Geology of the Earthquake Source http://dx.doi.org/10.1144/SP359.12 Copyright The Geological Society of London 2011

DOI: doi:10.1144/SP359.12

Abstract

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.

Vein δ18O compositions increase upwards through the Murrumbidgee Group in response to a progressive reaction of an externally derived, upwards-flowing low-δ18O fluid (of probable meteoric origin) with host limestones. Vein δ18O and 87Sr/86Sr 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.

Supplementary material:

Two appendices are available at http://www.geolsoc.org.uk/SUP18492.

Item Details

Item Type:Research Book Chapter
Keywords:Lachlan Fold Belt, structural geology, geochemistry, isotopes, fold, fault
Research Division:Earth Sciences
Research Group:Geology
Research Field:Structural Geology
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Earth Sciences
Author:Barker, SLL (Dr Shaun Barker)
ID Code:129313
Year Published:2011
Deposited By:CODES ARC
Deposited On:2018-11-22
Last Modified:2018-12-06
Downloads:0

Repository Staff Only: item control page