Evidence for multiphase deformation in the Archean basal Warrawoona Group in the Marble Bar area, East Pilbara, Western Australia

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doi: 10.1016/S0301-9268(97)00063-6
Authors:van Haaften, W. M.; White, S. H.
Author Affiliations:Primary:
University of Utrecht, Geodynamics Research Institute, Utrecht, Netherlands
CRA Exploration Pty., Box Hill, Victoria, Australia
Volume Title:tectonics and metallogenic evolution of the Pilbara Craton
Volume Authors:Barley, M. E., editor; Loader, S. E.
Source:The tectonics and metallogenic evolution of the Pilbara Craton, edited by M. E. Barley and S. E. Loader. Precambrian Research, 88(1-4), p.53-66. Publisher: Elsevier, Amsterdam, International. ISSN: 0301-9268
Publication Date:1998
Note:In English. 26 refs.Special issue; illus., incl. block diags., sects., 2 tables, geol. sketch maps
Summary:The results of a structural analysis of the Marble Bar Greenstone Belt in the McPhee Reward area of the eastern Pilbara Block in Western Australia indicate that the area has undergone a multiphase deformation on shears which approximately parallel the trace of stratigraphy (cf. primary igneous layering) around the Talga Talga Anticline. Early extensional movements were associated with the formation of the Warrawoona Group (chiefly the Duffer Formation) and indicate a WNW-ESE extensional direction similar to the syn-Warrawoona extension found in the area of the North Shaw Batholith. Extension was followed by thrusting with transport to the east. The Talga Talga anticline is a culmination which formed during this event by thrust stacking. A major shear in the area, the Duffada Shear, was reactivated during granodiorite emplacement with transport to the NE. In their present geometry, the shears have thrust movements on the south side of the Talga Talga anticline but normal movements on the north side. After the reactivation came a NW-SE shortening which was accompanied by conjugate shear activity on north-trending sinistral and west-trending dextral shears, and constrained to ∼2950 Ma in the North Shaw area. The final movements were associated with a N-S shortening which resulted in an E-W trending thrust, which cuts the northern flank of the Talga Talga anticline, and NW and NE trending conjugate faults. There is no evidence of radially oriented stretching lineations or slickensides which would be expected if the granitoid bodies which make up the Mount Edgar Batholith were emplaced by a solid-state diapiric process. The net result of deformation was tectonic disruption of the stratigraphic stacking within the type area of the Talga Talga Subgroup in the Warrawoona Group. This may offer an additional explanation for anomalously young dates of the Talga Talga Subgroup with respect to the Duffer Formation, and also indicates that the type section for the Talga Talga Subgroup is a lithotectonic sequence. Abstract Copyright (1998) Elsevier, B.V.
Subjects:Absolute age; Archean; Conjugate faults; Crustal shortening; Dates; Deformation; Diapirs; Extension tectonics; Faults; Folds; Kinematics; Lithostratigraphy; Nesosilicates; Orthosilicates; Polyphase processes; Precambrian; Reactivation; Shear; Shear zones; Silicates; Strike-slip faults; Tectonics; Thin sections; Thrust faults; Type sections; U/Pb; Warrawoona Group; Zircon; Zircon group; Australasia; Australia; Pilbara Craton; Western Australia; Duffada Shear; Duffer Formation; Marble Bar greenstone belt; McPhee Formation; McPhee Reward Mine; Mount Ada Basalt; Mount Edgar Batholith; North Star Basalt; Talga Talga Anticline; Talga Talga Subgroup
Abstract Numbers:98M/4238
Record ID:1998034865
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands
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