Crustal-Scale Fluid Pathways and Source Rocks in the Victorian Gold Province, Australia: Insights from Deep Seismic Reflection Profiles

• DOI: 10.2113/econgeo.105.5.895
• Publication Date: 2013-05-07T16:58:56Z
• Authors: C. E. Willman; R. J. Korsch; D. H. Moore; R. A. Cayley; V. A. Lisitsin; T. J. Rawling; V. J. Morand; P. J. O'Shea
• Keywords: Reflection

Deep seismic reflection data collected across the western Lachlan orogen of southeast Australia have provided important insights into crustal-scale fluid pathways and possible source rocks in one richest orogenic gold provinces world. The profiles span three most productive structural zones Victoria: Stawell, Bendigo, Melbourne zones. zone-scale variations age style deposits correspond with differences crustal structure composition. bilateral distribution production Stawell Bendigo is related to V-shaped geometry two cross section. Major first-order faults, like east-dipping Moyston fault a set west-dipping listric faults within zone, were probably major conduits lower middle crust during mineralization. First-order appear accommodated large-scale thickening down crust. converge region beneath zone where thick section mafic volcanic lesser sedimentary are identified as likely common gold-bearing that was largely generated by Late Ordovician Early Silurian metamorphism.

The areas greatest endowment lie above regions preserved thickest succession “fertile” igneous up about 25 km thick. They also thin or absent Precambrian lithosphere. Mafic far partly consumed Cambrian subduction. Similar rest lay outside influence subduction-accretion deformed later, beginning Ordovician-Early Benambran orogeny imbrication. This imbrication much form crust.

First-order interpreted controls on locations goldfields, even though they unmineralized near present surface. shallow-dipping segments favorably oriented for reactivation at time mineralization acted In contrast, upper steeply dipping unfavorably poor conduits.

The show transition from predominantly shallow- occurs boundary between imbricated metavolcanic immediately below 6 15 folded metasedimentary rocks. may coincided escape aided transfer permeability away overlying fold-dominated turbidites. enhanced growth subvertical, fold-related fracture meshes upper-crustal consisted bedding-parallel limb thrusts, tension vein arrays developed along fold hinges. individual hinges regional culminations flow. Fluid flow syndeformational but overlapped immediate postdeformational period orogeny. Later Devonian again led further, although less important, mineralizing events fluids exploited preexisting architecture.

Deeply penetrating, north-dipping rich cut inferred Proterozoic basement been event.