Evidence for shear heating, Musgrave Block, central Australia

Date

2001

Authors

Camacho, A
McDougall, Ian
Armstrong, Richard
Braun, Jean

Journal Title

Journal ISSN

Volume Title

Publisher

Pergamon-Elsevier Ltd

Abstract

The phenomenon of shear-heating is generally difficult to recognise from petrologic evidence alone. Establishing that shear zones attain higher temperatures than the surrounding country rocks requires independent evidence for temperature gradients. In the Musgrave Block, central Australia, there is a clear spatial association between shear zones and interpreted elevated temperatures. Eclogite facies shear zones that formed at ~ 550 Ma record temperatures of ~650-700°C. Outside the high-pressure shear zones, minerals with low closure temperatures such as biotite (~450°C in the 40Ar-39Ar and Rb-Sr systems), preserve ages >800 Ma, suggesting that these rocks did not experience temperatures greater than about 450°C at ~550 Ma for any extended period. Thus, the shear zones record temperatures that are ~200°C higher than the surrounding country rocks. Simple calculations show that the combination of relatively high shear stresses (~100 MPa) and high strain rates (~10-11 s-1) for short durations (<1 Ma) can account for the observed apparent temperature variations. The evidence indicates that shear heating is the dominant mechanism for localised temperature increases in the shear zones, while the country rock remained at relatively lower temperatures.

Description

Keywords

Keywords: Shear heating; High pressure effects; Petrology; Rocks; Shear stress; Structural geology; heat flow; heat source; isotopic analysis; petrology; Proterozoic; shear zone; Australia

Citation

Source

Journal of Structural Geology

Type

Journal article

Book Title

Entity type

Access Statement

License Rights

Restricted until

2037-12-31
Back to topicon-arrow-up-solid
 
APRU
IARU
 
edX
Group of Eight Member

Acknowledgement of Country

The Australian National University acknowledges, celebrates and pays our respects to the Ngunnawal and Ngambri people of the Canberra region and to all First Nations Australians on whose traditional lands we meet and work, and whose cultures are among the oldest continuing cultures in human history.


Contact ANUCopyrightDisclaimerPrivacyFreedom of Information

+61 2 6125 5111 The Australian National University, Canberra

TEQSA Provider ID: PRV12002 (Australian University) CRICOS Provider Code: 00120C ABN: 52 234 063 906