Authors / CoAuthors
Huston, D.L. | Cayley, R.A. | Champion, D.C.
Abstract
The period between 480 Ma and 410 Ma in the Lachlan Orogen of southeastern Australia is the most important metallogenically in eastern Australia, having contributed over half of the mineral wealth in the Tasman Element (or Orogen). The period of intense mineralisation is interpreted to be related to the development of the Lachlan Orocline at the very end of the Ordovician and into the Silurian. Formation of this orocline was triggered by the oblique accretion of the VanDieland crustal fragment, which includes the present day Melbourne Zone in Victoria and western Tasmania. Prior to this event, eastern Australia was characterised by a west-dipping convergent margin with associated small- to moderate-sized volcanic-hosted massive sulphide (VHMS: Girilambone, Mount Windsor and Balcooma) and calc-alkaline porphyry Cu-Au deposits (Copper Hill, Marsden) with ages of 480 Ma to 450 Ma. Orocline development was initiated by the accretion of the VanDieland at ~445 Ma, which was accompanied orogenic gold mineralisation in Victoria (Bendigo, Ballarat, etc). Importantly, because of the geometry of interaction, gold mineralisation did not extend into present-day New South Wales. As accretion of this block continued, the Tasman continental margin began to wrap around VanDieland to form the Lachlan Orocline. At this time, extension associated with orocline formation to the north initiated low degree partial melting and post-collisional alkaline magmatism. Alkaline porphyry Cu-Au deposits in the Macquarie volcanic province (Cadia and Northparkes) formed during this extension at ~435 Ma. Continued extension and the re-establishment of west-dipping subduction in the Silurian saw a second phase of VHMS mineralisation at 425-415 Ma, and granite-related Sn and Mo mineralisation at 430-410 Ma. The concept of the Lachlan Orocline can be used to identify new areas of mineral potential and the extension of known areas undercover.
Product Type
nonGeographicDataset
eCat Id
83936
Contact for the resource
Custodian
Point of contact
Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
Canberra
ACT
2601
Australia
Keywords
-
- External Publication
- Australian and New Zealand Standard Research Classification (ANZSRC)
-
- Earth Sciences
-
- Published_Internal
Publication Date
2015-01-01T00:00:00
Creation Date
Security Constraints
Legal Constraints
Status
Purpose
Maintenance Information
unknown
Topic Category
geoscientificInformation
Series Information
Lineage
Unknown
Parent Information
Extents
Reference System
Spatial Resolution
Service Information
Associations
Downloads and Links
Source Information
Source data not available.