HR: 1340h
AN: T53C-1452    [Abstracts]
TI: Chemical Evidence for Episodic Growth of a Fibrous Antitaxial Calcite Vein From Externally Derived Fluid
AU: * Barker, S L
EM: shaun.barker@anu.edu.au
AF: Research School of Earth Sciences, The Australian National University, Canberra, ACT 0200 Australia
AU: Cox, S F
EM: stephen.cox@anu.edu.au
AF: Research School of Earth Sciences, The Australian National University, Canberra, ACT 0200 Australia
AU: Cox, S F
EM: stephen.cox@anu.edu.au
AF: Department of Earth and Marine Sciences, The Australian National University, Canberra, ACT 0200 Australia
AU: Eggins, S M
EM: stephen.eggins@anu.edu.au
AF: Research School of Earth Sciences, The Australian National University, Canberra, ACT 0200 Australia
AU: Gagan, M K
EM: michael.gagan@anu.edu.au
AF: Research School of Earth Sciences, The Australian National University, Canberra, ACT 0200 Australia
AB: Fibrous, massive and crustiform textured quartz and calcite veins occur within a deformed limestone-shale sequence at Taemas, in the Lachlan Fold Belt, eastern New South Wales, Australia. Stable isotope analyses of veins and host rock indicate that these veins formed from upwardly migrating, externally derived fluids. High spatial resolution (100 μm) analyses reveal per mil scale variations of stable C and O isotope ratios, and radiogenic Sr isotope ratios in a 1.5 cm thick, fibrous, antitaxial-growth calcite vein. LA-ICP-MS analyses (30 μm resolution) demonstrate significant variations in Fe, Mn, Sr, REE and Eu/Eu* parallel to the long axes of fibres. Stable and radiogenic isotopic ratio variations, and trace and REE concentration changes correlate with different cathodoluminesence zones, and slight changes in fibre orientation and thickness. The covariance of calcite textures and chemistry indicate that this fibrous vein grew episodically. Moreover, calcite in this vein was precipitated from externally derived fluid, which underwent variable fluid-rock interaction, and had a fluctuating oxidation state. This fibrous, antitaxial growth vein likely formed from fluid that migrated along fracture-controlled flow pathways.
DE: 1040 Radiogenic isotope geochemistry
DE: 1041 Stable isotope geochemistry (0454, 4870)
DE: 1065 Major and trace element geochemistry
DE: 8010 Fractures and faults
DE: 8045 Role of fluids
SC: Tectonophysics [T]
MN: Fall Meeting 2005