Plate margin tectonics and metallogenyof the Delamerian Orogen: Discovering

what lies beneath the Murray Basin

Stacey CurtisGeological Survey of South Australia

Outline• Background on the Delamerian Orogen

• Rationale for the Delamerian NDI (National Drilling Initiative) Project

• Key questions we aim to answer

• Description of our work program

Taratap Granodiorite, ‘The Granites’, Coorong

Kennett et al. 2013

What is the Delamerian Orogen?

PrecambrianAustralia

PhanerozoicAustralia

Glen et al. 2005Foster & Gray 2000; Li & Powell 1993

Depth to the Lithosphere-Asthenosphere Boundary

Elements of the TasmanidesGondwana

Mt WrightVolcanicsc. 510 Ma

Loch Lily-Karsc. 495 Ma

Mount StavelyVolcanic Complex

510-500 Ma

Mt Reid Volcanics507-496 Ma

Eastern Delamerian

• continental volcanic arc and forearcsuccessions

Glenelg RiverComplex

Western Delamerian

• Inversion of continentalmargin successions

• bimodal magmatism

Adelaide Fold Belt

Stansbury Basin/Kanmantoo Trough

c. 522-520 Ma

Padthaway Ridge

CurnamonaProvince

Geoscience Australia 2.5M surface geology of Australia(post Ordovician units removed)Geoscience Australia Magnetics map of Australia 2015

Preserved elements of theDelamerian Orogen

Preserved elements of theDelamerian Orogen

Mt WrightArc

c. 510 Ma

Loch Lily-Karsc. 495 Ma

Mount StavelyVolcanic Complex

510-500 Ma

Mt Reid Volcanics507-496 Ma

Eastern Delamerian

• volcanic arc and forearc successions

Geoscience Australia 2.5M surface geology of Australia(post Ordovician units removed)Geoscience Australia Magnetics map of Australia 2015

Evolution of the DelamerianOrogen: a Victorian prespective

Cayley and Skladzien, 2018

525 Ma 510-505 Ma 505-503 Ma 503-490 Ma 435-415 Ma

Delamerian NDI (National Drilling Initiative) Area

Mt WrightVolcanicsc. 510 Ma

Loch Lily-Karsc. 495 Ma

Mount StavelyVolcanic Complex

510-500 Ma

Mt Reid Volcanics507-496 Ma

Eastern Delamerian

• volcanic arc and forearc successions

Glenelg RiverComplex

Western Delamerian

• Inversion of continentalmargin successions

• bimodal magmatism

Adelaide Fold Belt

Stansbury Basinc. 522-520 Ma

Padthaway Ridge

CurnamonaProvince

Geoscience Australia 2.5M surface geology of Australia(post Ordovician units removed)Geoscience Australia Magnetics map of Australia 2015

Delamerian NDI project aim

Murray BasinCover

Adelaide Fold Belt

DELAMERIANNDI AREA

To stimulate mineral exploration beneath cover of the Murray Basin by providing industry with new data and new constraints on the geological framework and mineral prospectivity in this greenfields region.

What do we already know about the Delamerian NDI area?

CODD1

WYN1

KTH2

SAW001 SHR25

PAD30

gabbro

granite

metasediments

rhyolite

basalt

mafic volcaniclastics

Metasedimentary rocksAdelaidean/Kanmantoo Group/Normanville Group equivalents?

Mafic to intermediate volcanics and volcaniclastic sediments, felsic volcanics, granites, diorites and gabbroic intrusivesExisting geochemical data (Foden et al. in prep) suggests a number of settings, including continental rift, back-arc, forearc and volcanic arc

Igneous rocks are commonly associated with sulphides (py-cpy-mo)

BD5 (Bendigo)

DDH2

py replacement in meta-granite

mo-py vein in granite

Manuum Quarry (A. Reid)

Py-cpy in mafic enclave

Key questions of the DelamerianNDI project

• What is the distribution of crystalline basement rocks beneath the Murray Basin?

• Can we map a volcanic arc – back-arc transition in South Australia? • How does the observed sedimentation, magmatism and deformation relate to the evolving plate

margin?

• What is the Delamerian deformational history? Is post-Delamerian deformation also recorded (Benambran and Bindian orogenies)?

• Which are the prospective mineral systems? e.g. Cu-(Mo-Au) porphyry, orogenic gold, VMS, magmatic Ni-Cu-PGE, SEDEX

• Are there key mineralising events relating to specific phases of magmatism and/or deformation?

The Delamerian NDI Project

• Geological Survey of South AustraliaStacey Curtis, Tom Wise, Wolfgang Preiss, Mark Pawley, Mario Werner, Adrian Fabris, Liz Jagodzinski, Liliana Stoian, Mark Griffiths, Kate Robertson, Stephan Thiel, Georgina Gordon, Alan Mauger, Carmen Krapf, Laz Katona, Phil Heath, Gary Reed

• MinEX CRC researchersWei Hong1, Lucy McGee1, Marnie Forster2, Naina2, Laura Morrissey3, Justin Payne3, Caroline Tiddy3, Stijn Glorie1, Martin Hand1, Alan Collins1, Juraj Farkas1, Andrew King4, Teagan Blaike4, Chris Kirkland5

1 2 3 4 5

Part of MinEX CRC National Drilling Initiative

Four year work program comprising:

• GSSA projects• MinEX CRC researcher

projects• a drilling program

The GSSA Delamerian NDI work program: data review

• Review of update of existing exploration data available in SARIG (drillholes, geochemistry, indexing)

• Lithostratigraphic logging of existing cored holes

• new geochemistry and geochronology data (with a focus on igneous lithologies)

• Hylogger scanning

The GSSA Delamerian NDI work program: structural mapping

• Field mapping along select traverses – SouthEast, Anabama region & Mount Lofty Ranges

• Interpretation of basement geology for the DelamerianNDI area from potential field data: inferences on rock, relationships, structural history and kinematics

• MT 2D profile/s, extending from AUSLAMP Delamerian model

TMI AGC and tilt + residual gravity

existing solid geologyrevised solid geology

Delamerian granite, Orphan Block Road, SouthEast

MinEx CRC researcher Delamerian projects

• Provenance and chemo-stratigraphy of metasediments under the Murray Basin, and correlations with the outcropping Kanmantoo Group/Normanville Group

• Constraining the Pressure-Temperature conditions and timing of deformation and uplift (U-Pbzircon and monazite, Ar-Ar and apatite thermochronology)

• Magmatic evolution and metal fertility of Delamerian igneous rocks

• Reviewing/characterising known Delamerian mineral deposits/prospects

• Isotopic constraints on Delamerian metal sources and ore-forming processes

• Cu-Mo porphyry potential and chemistry of alteration minerals as feritility indicators

• Potential field inversions (gravity, magnetics, EM) Anabama – Northern Murray Basin transect

The drilling program (2021/2022)

• Stratigraphic drilling program within to characterised poorly understood parts of the Delamerian basement to the Murray Basin

• Predominantly orientated diamond core (in basement), and may include a mineral systems component (fences or grid with CT rig)

• Drilling targets will be selected by June 2020. Some portion of Section 15 will be released at this time.

More InformationArticle in latest MESA Journalhttp://energymining.sa.gov.au/minerals/knowledge_centre/mesa_journal/news/minex_crc_targets_delamerian_orogen

Thank YouJustin Gum, John Foden, Peter Rolley, Caitlin Rowett, Eric Whittaker, Andy Burtt, Phil Gilmore, John Greenfield, Ross Cayley