geological interpretations from the paterson aem …geological interpretations from the paterson aem...

Geological interpretations from the Paterson AEM survey


Ian C. Roach

With contributions from:A.J. Whitaker, M.T. Costelloe & N.C. Williams

Onshore Energy and Minerals Division, Geoscience AustraliaGPO Box 378, Canberra ACT 2601


Introduction

1. Surface geomorphology and geology:1. Topography-relief-palaeodrainage;2. Geological provinces, cover geology;3. Bedrock/cover relationship.

2. Airborne geophysics:1. Gravity;2. Aeromagnetics.

3. AEM data validation:1. Geological and Geophysical data compilation.

4. AEM: the big-picture:1. Surface conductivity;2. Depth slices;3. Detail of large objects – Anketell & Throssell shelfs, Rudall

Complex, palaeodrainage systems;4. Depth-to map.

5. Mineral Deposits.


BedrockBedrock--covercoverPrecambrian bedrock vs. Precambrian bedrock vs. Phanerozoic cover:Phanerozoic cover:

85% cover85% cover

Difficult to explore!Difficult to explore!

1m surface geologybedrock

cover


!(

!(

!(!(NIFTY

TELFER

KINTYRE

WOODIE WOODIE

0 10050 Kilometers

LakeLakeWaukarlycarlyWaukarlycarly

Percival LakesPercival Lakes

Total relief ca. 400 mTotal relief ca. 400 m

Easy area to fly AEMEasy area to fly AEM

TopographyTopography


!(

!(

!(!(NIFTY

TELFER

KINTYRE

WOODIE WOODIE

!( Major mines

Wallal Palaeovalley

van de Graaf

Fisher - Permian

Percival Palaeovalley

Oakover River

AEM interp

Beard

Commander

0 10050 Kilometers

PaleodrainagePaleodrainageMRVBF6 image, SRTM DEM

Surface relief hints atPalaeodrainage systems.Many interpretations with Similar themes


!(

!(

!(!(NIFTY

TELFER

KINTYRE

WOODIE WOODIE

Geological ProvincesPaleozoic-Mesozoic

Canning Basin

NeoproterozoicOfficer Basin

Yeneena Basin - Lamil Group

Yeneena Basin - Isdell Formation

Yeneena Basin

Yeneena Basin - Throssell Range Group

Granite

Paleo- MesoproterozoicRudall Complex - Connaughton Terane

Rudall Complex

Rudall Complex - Tabletop Terane

Rudall Complex - Talbot Terrane

ArcheanSylvania Dome

Fortescue Basin

Pilbara Craton

Collier Basin

Hamersley Basin

0 10050 Kilometers

Canning BasinCanning Basin

Officer BasinOfficer Basin

PilbaraPilbaraCratonCraton LamilLamil

GroupGroup

ThrossellThrossellRangeRangeGroupGroup

RudallRudallComplexComplex

Rudall RiverRudall RiverNational ParkNational Park

TalbotTalbot

ConnaughtonConnaughton TabletopTabletop

Geological ProvincesGeological Provinces


!(

!(

!(!(NIFTY

TELFER

KINTYRE

WOODIE WOODIE

Permian-Mesozoic solid geologyKslg - Lake George Formation

Ksbs - Broome Sandstone

Ksak - Anketell Sandstone

Ksfr - Frezier Sandstone

Kspa - Parda Formation

Kscr - Cronin Sandstone

Jksc - Callawa Formation

Pslt - Triwhite Sandstone

Psno - Noonkanbah Formation

Pspo - Poole Formation

Psp - Paterson Formation

Psg - Grant Group

0 10050 Kilometers

Paterson Paterson FormationFormation

AnketellAnketellSandstoneSandstone

Frezier SandstoneFrezier Sandstone

Callawa Callawa FormationFormation

PoolePooleFormationFormation

Triwhite Triwhite SandstoneSandstone

Compilation byCompilation byA.J. WhitakerA.J. Whitaker

Solid GeologySolid Geology

Interpreting AEMInterpreting AEMrequires morerequires moresophisticated knowledgesophisticated knowledgeof surface and nearof surface and near--surface geology like this surface geology like this new Permiannew Permian--MesozoicMesozoicsolid geology mapsolid geology map

Geological interpretations from the Paterson AEM survey0 10050 Kilometers

Cenozoic materialsCzik - Calcrete

Czk - Calcrete

Czl - Fe-duricrust

Czlra - Fe-duricrust/colluvium

!(

!(

!(!(NIFTY

TELFER

KINTYRE

WOODIE WOODIE

Indurated regolithIndurated regolith

Compilation byCompilation byA.J. WhitakerA.J. Whitaker

0 10050 Kilometers

Cenozoic materialsCzik - Calcrete

Czk - Calcrete

Czl - Fe-duricrust

Czlra - Fe-duricrust/colluvium

Interpreting AEMInterpreting AEMrequires morerequires moresophisticated knowledgesophisticated knowledgeof surface and nearof surface and near--surface geology like this surface geology like this new indurated regolith new indurated regolith mapmap


!(

!(

!(!(NIFTY

TELFER

KINTYRE

WOODIE WOODIE

Ternary RadiometricsRed: K

Green: Th

Blue: U

0 10050 Kilometers

Ternary radiometrics tells Ternary radiometrics tells us about what occurs at us about what occurs at the surface, and the surface, and serfuaceserfuaceprocess, but what lies process, but what lies underneath?underneath?


!(

!(

!(!(NIFTY

TELFER

KINTYRE

WOODIE WOODIE

0 10050 Kilometers

GravityGravity

Pilbara CratonPilbara Craton

WaukarlycarlyWaukarlycarlyEmbaymentEmbayment

Rudall ComplexRudall Complex


AnketellAnketellShelfShelf

Lamil GroupLamil GroupRudall ComplexRudall Complex

ThrossellThrossellRange GroupRange Group


Officer BasinOfficer Basin

Gravity can be used to Gravity can be used to interpret large scale interpret large scale density contrasts that density contrasts that may be related to different may be related to different rock typesrock types


!(

!(

!(!(NIFTY

TELFER

KINTYRE

WOODIE WOODIE

0 10050 Kilometers

1VD magnetics1VD magneticsWaukarlycarlyWaukarlycarlyEmbaymentEmbayment



AnketellAnketellShelfShelf

Lamil GroupLamil Group

ThrossellThrossellRangeRangeGroupGroup

Aeromagnetics can tell us Aeromagnetics can tell us the depth to magnetic the depth to magnetic basement and give us basement and give us another view of subanother view of sub--surface rock typessurface rock types


!(

!(

!(!(NIFTY

TELFER

KINTYRE

WOODIE WOODIE

0 10050 Kilometers

How do weHow do wevalidate this?validate this?

AEM can tell us about the AEM can tell us about the lateral continuation of lateral continuation of surface and subsurface and sub--surface surface materials and can be materials and can be interpreted for geology. interpreted for geology. How do we validate this?How do we validate this?


Geological validation

• Drill holes: a publicly-available drill hole compilation (Roach, 2009);

• Solid geology: a compilation by Czarnota et al.(2009);

• Surface geology: the 1:1 000 000 scale Surface Geology of Western Australia (Stewart, 2008);

• 1:250 000 and 1:100 000 geological maps;• Magnetics: GA Magnetic Map of Australia;• Gravity: GA Gravity map of Australia; • Radiometrics: GA Radiometric Map of Australia

(Minty et al., 2009);• Conductivity logs

All GA data are available onAll GA data are available on--line at: line at: www.ga.gov.auwww.ga.gov.au/minerals/minerals


• 4,300+ logged drill holes.

• Released as GA Record and database Roach (2009).

DrillingDrilling


Drill holes vs AEM conductivity sections

5 km

300300

200200

100100

0 m ASL0 m ASL

--100100

--200200


GA LEI section geological interpretation

• Line 30820, ca. 8 km north of Nifty Cu mine.

• Interpretation after Bagas (2002), Lamil 1:100,000 geology sheet.

W E


Large-scale geological interpretations

• Interpretations mostly from gridded data:– GA LEI Depth Slices:

• Created by draping gridded inversion conductivity values over an elevation model;

• Represent a conductivity ‘skin’ at a certain depth from topographic surface.

– GA LEI Elevation Slices:• Removes terrain;• Represent a conductivity ‘level’ from datum.

• Grids have data under the DOI removed.


Mapping palaeosurfaces-Conductivity anomaly contours

• Created using gridded GA LEI data and drill holes.

• Assumes conductivity anomaly follows broad sub-Permian unconformity – DOI permitting:

• Only drawn in areas where Permian and younger fill is conductive.

• Able to visualise large palaeotopographicfeatures and some unconformities.


Depth slices show Depth slices show subsurface conductivity subsurface conductivity features, Can these be features, Can these be used to map conductivity used to map conductivity surfaces?surfaces?GA LEI Depth slices


!(

!(

!(!(NIFTY

TELFER

KINTYRE

WOODIE WOODIE

0 10050 Kilometers

!(

!(

!(!(NIFTY

TELFER

KINTYRE

WOODIE WOODIE

Conductivity formlinesm ASL

-100

0

20

40

60

80

100

120

140

160

180

200

220

240

250

260

280

300

310

320

340

360

380

400

0 10050 Kilometers

!(

!(

!(!(NIFTY

TELFER

KINTYRE

WOODIE WOODIE

0 10050 Kilometers

!(

!(

!(!(NIFTY

TELFER

KINTYRE

WOODIE WOODIE

0 10050 Kilometers

Depth slice Depth slice information are used information are used here to develop a here to develop a model of the model of the PalaeozoicPalaeozoic--Proterozoic Proterozoic unconformity surface unconformity surface in the Paterson regionin the Paterson region


!(

!(

!(!(NIFTY

TELFER

KINTYRE

WOODIE WOODIE

0 10050 Kilometers

The PalaeozoicThe Palaeozoic--Proterozoic unconformity Proterozoic unconformity surface, shown here, is surface, shown here, is the prethe pre--Permian Permian palaeotopographypalaeotopography


!(

!(

!(!(NIFTY

TELFER

KINTYRE

WOODIE WOODIE

0 10050 Kilometers


CanningCanningBasinBasin

Anketell Shelf

Anketell Shelf

Waukarlycarly Em

bayment

Waukarlycarly Em

bayment


Throssell Shelf

Throssell Shelf

BroadhurstBroadhurstFormationFormation

DisappointmentDisappointmentPalaeovalleyPalaeovalley

CanningCanningPalaeovalleyPalaeovalley

PermianPermianpalaeovalleyspalaeovalleys

CoolbroCoolbroSandstoneSandstone

Fortescue/Fortescue/PilbaraPilbara

Depth slice with largeDepth slice with large--scale geological features scale geological features annotatedannotated


!(

!(

!(!(NIFTY

TELFER

KINTYRE

WOODIE WOODIE

0 10050 Kilometers



Anketell Shelf

Anketell Shelf

Waukarlycarly Em

bayment

Waukarlycarly Em

bayment


Throssell Shelf

Throssell Shelf

BroadhurstBroadhurstFormationFormation



PermianPermianpalaeovalleyspalaeovalleys

CoolbroCoolbroSandstoneSandstone

Fortescue/Fortescue/PilbaraPilbara

PalaeotopographicPalaeotopographic model model with largewith large--scale scale geological features geological features annotatedannotated


3D perspective views3D perspective views


PatersonPatersonSouthSouth

N

200 240160 280 320


systemsystem

Canning BasinCanning BasinMesozoic & PermianMesozoic & Permian

Sediments onSediments on--laplapRudall ComplexRudall Complex

Rudall ComplexRudall ComplexUnder coverUnder cover

RudallRudallComplexComplexoutcropoutcrop

m ASL


AEM interp

van de Graaf

Fisher - Permian

Percival Palaeovalley

Beard

0 2512.5 Kilometers

Disappointment PalaeovalleyDisappointment Palaeovalley

DisappointmentPalaeovalley

PreviouslyPreviouslyunmapped tributaryunmapped tributary

Flowdirection


PatersonPatersonNorthNorth

Anketell ShelfAnketell Shelf

Throssell Shelf

Throssell ShelfWaukarlycarly Embayment

Waukarlycarly Embayment

TelferTelferNiftyNifty Woodie Woodie

KintyreKintyre



N


!(TELFER

AEM interp

0 2010 Kilometers

Canning PalaeovalleyCanning Palaeovalley

TELFERTELFER

Flow directionFlow direction

??


!(

!(

!(!(NIFTY

TELFER

KINTYRE

WOODIE WOODIE

0 10050 Kilometers

InterpretedInterpretedPaleozoicPaleozoic--

ProterozoicProterozoicunconformityunconformity

Height of unconformityabove sea level


!(

!(

!(!(NIFTY

TELFER

KINTYRE

WOODIE WOODIEDepth to unconformitymetres

High : 292.081

Low : -31.3929

0 10050 Kilometers

Interpreted Interpreted cover thicknesscover thickness


!(

!(

!(!(WW

WW

WW

U

W

W

UU

Mn

FeFe

MnMn

MnMn

Fe

Fe

MnAu

Mn

Fe Fe

MnMn

MnMnFe

Fe

MnMn

MnMnMnMnMnMn

Fe

Fe

Au

FeFe

FeFe

Mn

MnMn

MnMn

MnMn

Mn

MnMn

Au

Cu

MnMn

Au

Mn

Li

AuAu

Mn

Mn

Mn

CuAuAuAu

AuAu

Au

AuAu

AuAu Pb

Au

HM

Cu

Ag

Au

Au

MnMn

MnCu

AuAuAu

Fe FeFe

FeFeFe

FeFe

Au

Fe

AuAuAuAu

Au

Au

Au

FlFlAu

Au

Au

AuAu

Au AuAu

Au

AuAu

AuAu

Au

Zn

CuCu

Au

Au

Au

Au

Au

Cu

Pb

Cu

Au

CuMn

CuMnCu

Mn

Cu

CuCu

Au

Cu

MnMnMn

MnMn

Mn

Cu

Cu

CuMn

Mn

Mn

MnMn Mn

CuAuAu

Au

Au

MnMnMn

Mn

AuMnMn

AuAuAu

Au

Cu

MnAu

Au

Au

AuAu

CuCu

AuAuAu

CuCuZn

Ni

Zn

CuCu

Mn

Mn

Mn

Mn

MnMn

MnAu AuAu

Cu

Cu

Au

Au

Au

Au

Au

Mn

Mn MnMn

Mn MnPb

ZnFl

FlFl

Cu

Fe

PbPb

AuGpMnMn

Mn

MnMnMn

Mn

MnPb

Au

CrCu

CuCu

Cu

Au

Pb

Gp

Gp

Gp

Gp

Au

Fe

Zn

FeFe

AuAu

FeFe

Fl

FeFe

Fe

Mn

CuCu

FeFe

Fe Fe

FeFe

Fe

FeFe

AuAu

Fe

Pb

Mn

Sn

CuCu

Cu

CuCu

Ta

Mn

Pb

AuAu

AuAu

Au

AuAu

Mn

Fe

Sd

FeFe

Mn

Mn

Mn

Fe

Mn

Mn

Au

Cor

Gvl

GvlGvl

Gvl

Gvl

GvlGvlGvl

Gvl

Brt

BrtPGEPGE

Brt

Cor

Brt

Brt

Dmd

BrlBrl

Clcp

Salt

Jasp

Cu, W

Shale

U, Cu

U, ZrU, Au

K2SO4

K2SO4Fe, Mn

Pb, ZnCu, PbAu, As

Au, Cu

Pb, Zn

Zn, Pb

Cu, Au

Cu, Au

Fe, MnMn, Fe

Cu, Pb

Pb, ZnCu, Zn

Zn, Cu

Pb, Cu

Au, Cu

Au, Cu

Au, Cu

Au, Cu

Fe, Mn

Cu, Co

Fe, Mn LnO, PbLnO, Pb

Cu, Au, V

U, Au, Pb

U, Cu, Pb

U, Pb, Cu

Au, Cu, As

Cu, Pb, Zn

Au, Cu, Co

Cu, Pb, As

Cu, Pb, Zn

Cu, Pb, Zn

Zn, Pb, Ag

Zn, Pb, Ag

Cu, Pb, ZnCu, Pb, Zn

Pb, Zn, Ag Au, Cu, Ag

K2SO4, Salt

Cu, U, Co, Mn

U, Pb, Zn, Cu

U, Au, Cu, Pb

Au, Cu, Zn, Pb

Cu, Zn, Pb, Au

Pb, Cu, Ce, LnOBrt, Sr, Mo, Ce

Cu, Au, Ni, PGE

U, Pb, Cu, Zn, Bi

Pb, Zn, Ag, Cu, U, Cd

Depth to unconformitymetres

High : 292.081

Low : -31.3929

0 10050 Kilometers

A large proportion of the A large proportion of the region remains underregion remains under--explored. AEM data can explored. AEM data can give more accurate depth give more accurate depth to target informationto target information


AEM Signatures of Mineral Deposits

• Finally, a quick look at how the AEM performed over some of the mineral deposits in the area.


Woodie Woodie plan & section

N


m ASL

m ASL

FL 30850

FL 30860

Woodie Woodie plan & sectionPermian PatersonFm and/or Tertiary Oakover Fm

Permian or Tertiary valley fill

Woodie Woodie Mn depositsPalaeokarst with Mn ore

Jeerinah Fm


Nifty plan & section

Permian (± Mesozoic)and Quaternary cover

Conductive Broadhurst FmBlack shale facies

Resistive Broadhurst Fmgreywacke facies

Resistive Broadhurst Fmgreywacke facies

Permian and Quaternary cover


Telfer plan & section

Conductive unit inTelfer Member Permian and Quaternary coverPermian and Quaternary cover


Conclusion

• Regional AEM data give us:– A better understanding of paleotopography;– A better information on under-cover extent of

mineralised rocks including 3-D disposition;– Reduced risk by providing more accurate

depth to target information;– Much more information on landscape

evolution for exploration models.

geological interpretations from the paterson aem …geological interpretations from the paterson aem...

Documents