The flow of surface-derived fluids through Alice Springs age middle-crustal ductile shear zones, Reynolds Range, central Australia

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doi: 10.1046/j.1525-1314.1999.00205.x
Authors:Cartwright, Ian; Buick, Ian S.
Author Affiliations:Primary:
Monash University, Victorian Institute of Earth and Planetary Sciences, Department of Earth Sciences, Clayton, Victoria, Australia
Other:
LaTrobe University, Australia
Volume Title:Journal of Metamorphic Geology
Source:Journal of Metamorphic Geology, 17(4), p.397-414. Publisher: Blackwell, Oxford, United Kingdom. ISSN: 0263-4929
Publication Date:1999
Note:In English. 51 refs.; illus., incl. sects., 2 tables, geol. sketch maps
Summary:The SE Reynolds Range is cut by steep NW-trending Alice Springs age (∼ 334 m.y.) reverse-slip shear zones up to hundreds of metres wide and several kilometers long. Amphibolite-facies (550-600°C, 500-600 MPa) cut metagranites. The sheared rocks commonly underwent metasomatism implying that the shear zones were the pathways of significant fluid flow. Altered granites within greenschist-facies shear zones have gained Si and K but lost Ca and Na relative to their unsheared counterparts, suggesting that the fluid flowed down-T and, hence, probably upwards through the shear zones. Time-integrated fluid fluxes calculated from silica addition are ≤ 2.1 × 1010 mol/m2 (∼ 4.2 × 105 m3/m2). Similar time-integrated fluid fluxes are also estimated from changes in K and Na. The sheared granitic rocks locally have δ 18O values as low as 0 0/00 which is much lower than the δ 18O values of the adjacent unsheared granites (7 to 9 0/00), implying that the fluid which flowed through these shear zones was surface derived. For the estimated time-integrated fluid fluxes, the fluids would be able to retain their isotopic signature for many tens to hundreds of kilometres. The flow of surface-derived fluids into the ductile middle crust, with subsequent expulsion upwards through the shear zones, may have been driven by seismic activity accompanying deformation. [P.J.T.]
Sections:Geochemistry
Subsections:Metamorphic rocks
Subjects:Alice Springs Orogeny; Carboniferous; Chemical composition; Crust; Deformation; Ductile deformation; Electron probe data; Facies; Faults; Geochemistry; Greenschist facies; Isotope ratios; Isotopes; Lithofacies; Metamorphic rocks; Metasomatism; Meteoric water; Middle crust; O-18/O-16; Oxygen; P-T conditions; Paleozoic; Petrography; Shear zones; Spectra; Stable isotopes; X-ray fluorescence spectra; Australasia; Australia; Northern Territory Australia; Reynolds Range
Abstract Numbers:00M/1854
Record ID:1999057966
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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