Exploring for the Future- Whole rock geochemistry data ... · batches. No levelling between the two batches has been undertaken. Full results are provided in Appendix A (batch number

Record 2020/02 | eCat 134710

Exploring for the Future- Whole rock geochemistry data release of sedimentaryand igneous rocks from the South Nicholson region, Northern Territory and Queensland

APPLYING GEOSCIENCE TO AUSTRALIA’S MOST IMPORTANT CHALLENGES www.ga.gov.au

C.J. Carson, A. J. M. Jarrett, J.R. Anderson, D.C. Champion, and P.A. Henson

Exploring for the Future – Whole-rock geochemistry data release of sedimentary and igneous rocks from the South Nicholson region, Northern Territory and Queensland GEOSCIENCE AUSTRALIA RECORD 2020/02

C.J. Carson, A.J.M. Jarrett, J.R. Anderson, D.C. Champion and P.A. Henson

Department of Industry, Science, Energy and Resources Minister for Resources, Water and Northern Australia: The Hon Keith Pitt MP

Secretary: Mr David Fredericks PSM

Geoscience Australia Chief Executive Officer: Dr James Johnson This paper is published with the permission of the CEO, Geoscience Australia

Geoscience Australia acknowledges the traditional custodians of the country where this work was undertaken. We also acknowledge the support provided by individuals and communities to access the country, especially in remote and rural Australia.

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ISSN 2201-702X (PDF) ISBN 978-1-925848-65-6 (PDF) eCat 134710

Bibliographic reference: Carson, C.J., Jarrett, A.J.M, Anderson, J.R., Champion, D.C., Henson, P.A. 2020. Exploring for the Future – Whole-rock geochemistry data release of sedimentary and igneous rocks from the South Nicholson region, Northern Territory and Queensland. Record 2020/02. Geoscience Australia, Canberra. http://dx.doi.org/10.11636/Record.2020.002

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http://dx.doi.org/10.11636/Record.2020.0

EFTF Geochemistry Data Release 1

Contents

Executive Summary ............................................................................................................. 2

1 Introduction....................................................................................................................... 3 2 Sampling strategy and details ............................................................................................ 4 3 Sample preparation ........................................................................................................... 7

3.1 Sample preparation ...................................................................................................... 7 3.2 Geochemical Analysis .................................................................................................. 7

3.2.1 X-Ray Fluorescence (XRF) ...................................................................................... 7 3.2.2 Loss on ignition (LOI) .............................................................................................. 7 3.2.3 Inductively coupled plasma mass spectrometry (ICP-MS) .......................................... 8 3.2.4 Iron Titration (FeO) ................................................................................................10 3.2.5 X-Ray Diffraction (XRD) .........................................................................................10 3.2.6 Total organic carbon (TOC) and Rock-Eval pyrolysis................................................10

4 Results ............................................................................................................................12

5 Acknowledgements ..........................................................................................................13 6 References ......................................................................................................................14 Appendix A Geochemical Results - May 2017 .......................................................................16

Appendix B Geochemical Results - May 2018 .......................................................................17

2 EFTF Geochemistry Data Release

Executive Summary

The Exploring for the Future Program (EFTF) is a $100.5 million four year, federally funded initiative to better characterise the mineral, energy and groundwater potential of northern Australia. As part of this initiative, this record presents new outcrop whole-rock geochemistry data, from 53 samples of sedimentary and volcanic rocks (and underlying metamorphic basement) collected from across the South Nicholson region, encompassing north-eastern Northern Territory and north-western Queensland. This work complements other components of the EFTF program, including the South Nicholson Basin seismic survey, a comprehensive geochronology program and hydrocarbon prospectivity studies to better understand the geological evolution and basin architecture of the region, and facilitate identification of areas of unrecognised resource potential and prospectivity.

The South Nicholson region, straddling north-eastern Northern Territory and north-western Queensland, arguably represents one of the least geologically understood regions of Proterozoic northern Australia. The South Nicholson region is situated between two highly prospective provinces, the greater McArthur Basin in the Northern Territory, the Lawn Hill Platform and the Mount Isa Province in Queensland, both with demonstrated hydrocarbon and base metal potential. These new geochemical data provide baseline understanding of regional resource prospectivity of sedimentary and volcanic rocks in the South Nicholson region.

During May 2017, 18 outcrop samples were collected, with an additional 35 outcrop samples collected in May 2018. This data release contains the results of elemental analyses on these samples, which include X-Ray Fluorescence (XRF), Loss-On-Ignition (LOI), Inductively Coupled Plasma-Mass Spectrometry (ICP-MS), iron titration (FeO), and Rock-Eval pyrolysis.

These data were generated at the Geochemistry Laboratories at Geoscience Australia as part of the Exploring for the Future program. All data was quality controlled based on Certified Reference Material standards (CRMs) and duplicate samples analysed with each batch of samples.


1 Introduction

The Exploring for the Future (EFTF) program is a four year $100.5 million initiative undertaken by the Australian Government to boost investment in resource exploration and development in northern Australia. The energy and mineral system components of the EFTF program focus on providing precompetitive data and baseline knowledge of the geology, and petroleum and minerals systems of northern Australia. The Paleoproterozoic and Mesoproterozoic rocks of the McArthur Basin, South Nicholson Basin and the Mount Isa Province, situated in the Northern Territory and Queensland, (Figure 1) have the potential to host both conventional and unconventional petroleum systems (e.g. Gorton and Troup, 2018; Jarrett et al., 2018). The South Nicholson region also contains a number of world class and smaller basin-hosted base metal deposits, for example, HYC, Century and Lady Loretta Pb-Zn±Ag deposits and the Walford Creek Zn-Pb-Cu-Ag deposit (e.g. Rohrlach et al., 1998; Huston et al., 2006; Hutton et al., 2012; Southgate et al., 2013).

Previous geochemical studies have focused on the mines, or regions in close proximity of deposits (e.g. Large et al., 1998a,b and many others). An improved understanding of the regional distribution and baseline composition of sedimentary rocks is required to characterise the resource potential of this region. This study aims to characterise the whole-rock geochemistry of Paleoproterozoic and Mesoproterozoic outcrop samples collected during EFTF ground fieldwork in 2017 and 2018 (Figure 1) and complements a number of other regional EFTF data acquisition programs including the South Nicholson reflection seismic survey (e.g. Carr et al., 2019), and geochronology and geochemistry investigations (e.g. Jarrett et al., 2018, 2019a,b; Anderson et al., 2019; Kositcin and Carson, 2019).

Samples were collected from the late Paleoproterozoic Carrara Range Group, Benmara Group, McNamara Group, Tawallah Group (and Tawallah Group equivalent units from CALVERT HILLS 250K map sheet; Ahmad and Wygralak, 2014), the Mesoproterozoic South Nicholson Group and several units for which the stratigraphic affinity is unclear. Analysed samples were predominately quartz sandstones although three volcanic units (Buddycurrawa Volcanics, Peters Creek Volcanics and the Top Rocky Rhyolite), two samples of low-grade metamorphic basement from the Murphy Province and hematitic and manganiferous rich gossanous units were also analysed.

This report contains the geochemical data (inorganic and organic), density and porosity determinations and associated sample metadata for samples collected within the South Nicholson region (Figure 1) in the Northern Territory and Queensland. The full list of samples, analyses and metadata are documented in Appendices A and B and summarised in Table 1.


2 Sampling strategy and details

In this study, a total of 53 surface outcrop samples were analysed (Table 1). The samples were collected during two EFTF field seasons conducted in May 2017 (18 samples, GA job number 33004) and May 2018 (35 samples, GA job number 33228). The full list of samples, location (latitude and longitude), stratigraphic units sampled and all geochemistry data are provided in Appendix A and B respectively. Sample locations are shown in Figure 1. Identified stratigraphic unit names (Table 1) follow existing stratigraphic names according to the relevant 250K mapsheets and accompanying explanatory notes. The stratigraphic affinity of several samples within the MOUNT DRUMMOND mapsheet are uncertain (Rawlings et al., 2008) and these units are noted and annotated in the Appendices. We note that recent U-Pb SHRIMP geochronology conducted in the region (Anderson et al., 2019; Kositcin and Carson, 2019) will necessitate a revision of the currently accepted stratigraphic position of some Mesoproterozoic and late Paleoproterozoic units, but this is not addressed here.

Figure 1 Location map of the South Nicholson region, encompassing the McArthur and South Nicholson basins, the Mt Isa Province and the Murphy Province, showing outcrop sample locations for whole-rock geochemistry analysis, presented in this study. Mesoproterozoic and Paleoproterozoic outcrop geology also shown (from Stewart, 2018). Province and basin outlines from Stewart et al. (2013). Red circles = outcrop sample locations from May 2017 fieldwork; Blue circles = outcrop sample locations from May 2018 fieldwork.


Table 1 Summary of samples analysed. See Figure 1 for general outcrop locations (see Appendix A and B for location details). Existing stratigraphic assignment as per Rawlings et al. (2008).

Basin or Province Group Stratigraphic unit Number of samples Comments

Carpentaria Basin Mullaman beds 1

Georgina Basin

Barkly Group Silicified breccia

(Wonarah Formation?)

1 At basal unconformity

Kiana Group

Camooweal Dolostone 1

Bukalara Sandstone 1

South Nicholson Basin South Nicholson Group

Mittiebah Sandstone 3 Mullera Sandstone 1

Top Lily Sandstone Member 2

No Mans Sandstone Member 1

Wangalinji Member 1

Burangoo Sandstone Member 1

Bowgan Sandstone 1 Subject to stratigraphic revision

Crow Formation 4 Subject to stratigraphic revision

Mount Isa Province

McNamara Group

Drummond Formation 2 Plain Creek Formation 2 One sample of

possible Mn ‘gossan’ Termite Range

Formation 1

Riversleigh Siltstone 1 Brumby Formation 4

Widdallion Sandstone Member 1

Bullrush Conglomerate 1

Shady Bore Quartzite 3

Benmara Group Buddycurrawa Volcanics 3

One sample of possible ‘white

smokers’

Carrara Range Group

Top Rocky Rhyolite 2 Gator Sandstone 1

Tawallah Group (and equivalents)

Sly Creek Sandstone 3 McDermott Formation 1

Peters Creek Volcanics 2

Wire Creek Sandstone 1

Metamorphic basement Murphy Metamorphics 2 One sample

elevated Cu


Basin or Province Group Stratigraphic unit Number of samples Comments

unassigned

unassigned Caulfield beds 2

unassigned Surprise Creek Formation 2

unassigned unit uncertain 1


3 Sample preparation

3.1 Sample preparation Raw samples were washed to remove surficial contaminants (e.g. weathering rinds etc) prior to milling and analyses.

Samples were milled to a powder using a Herzog HP-MS auto mill with a tungsten carbide mill head assembly. The automill was run for 30 seconds for shales and quartz blanks, and for 45 seconds for carbonates and sandstones. The automill was self-cleaned between samples using a cycle of pre-combusted (650°C, 9 hours) quartz sand, distilled water and ethanol.

At the beginning of each mill sequence, an analytical quartz blank was milled to establish a machine baseline. Quartz blanks were then run every 10 samples to track potential cross-contamination from the machine.

During the sample preparation process splits were taken of ~10% of samples for Quality Assurance/Quality Control QA-QC purposes. Results for these samples are reported in each Appendix.

3.2 Geochemical Analysis Sample analysis on all samples were undertaken at Geoscience Australia in 2018 as two separate batches. No levelling between the two batches has been undertaken. Full results are provided in Appendix A (batch number 33004) and B (batch number 33228) for samples collected during May 2017 and May 2018 fieldwork respectively. Details on the techniques and detection limits are provided below by method.

3.2.1 X-Ray Fluorescence (XRF)

Major and minor (in wt%; SiO2, TiO2, Al2O3, Fe2O3 Tot (= total Fe as Fe2O3), MnO, MgO, CaO, Na2O, K2O, P2O5, SO3) and selected trace elements (in ppm; Sc, V, Cr, Ni, Cu, Zn, As, Rb, Sr, Y, Zr, Nb, Ba, La, Ce, Nd, Pb) were analysed by wavelength-dispersive X-ray fluorescence (XRF) using a Bruker S8 Tiger™ spectrometer with methods similar to those of Norrish & Hutton (1969) and Norrish et al., 1977. Elements were analysed using 30 mm diameter fused beads prepared from a 1:6 sample/flux (lithium tetraborate + lithium metaborate) mixture from calcined powder. Limits of quantification are listed in Table 2. Certified Reference Material standards (CRMs) were analysed with each XRF batch analysed. CRMs include the Woodstock basalt WG-1 for all batches, and shale standards SBC-1 (33004 batch) and GSB-2 (33228 batch). Individual results for all CRMs are listed in each Appendix under the raw data.

3.2.2 Loss on ignition (LOI)

Loss on ignition (LOI) was measured by gravimetry after combustion at 1100° C. Reported LOI values have not been corrected for oxidation of FeO and S. Quality Assurance and duplicate samples were regularly run, as were CRMs. CRMS include WG-1 and a GA Internal Standard.. The limit of


quantification for LOI is 0.1 wt%. Loss on Ignition is reported under the ‘XRF’ tab in the datasets in Appendix A and B.

3.2.3 Inductively coupled plasma mass spectrometry (ICP-MS)

Trace elements analyses were undertaken via quadrupole inductively coupled plasma mass spectrometry (ICP-MS) using an Agilent 7500 series machine with a reaction cell. The method used is similar to those of Eggins et al. (1997), but on solutions obtained by dissolution of fused glass disks (Pyke, 2000). Trace elements analysed include Be, Sc, V, Cr, Co, Ni, Cu, Zn, Ga, Ge, As, Rb, Sr, Y, Zr, Nb, Mo, Ag, Cd, Sn, Sb, Cs, Ba, La, Ce, Pr, Nd, Sm, Eu, Tb, Gd, Dy, Ho, Er, Yb, Lu, Hf, Ta, Pb, Bi, Th, U. Limits of quantification are listed in Table 2.

CRMs were analysed with each ICP-MS batch analysed. CRMs include WG-1 for all batches, SBC-1 and the Sietronic VHG calibration check standard for the 2017 batch and the GSP-2 standard for the 2018 batch. Individual results for all CRMs are listed in each Appendix under the raw data.

Table 2 Analytical methods, units of measure (UOM) and limit of quantification (LOQ) - the lowest concentration of an analyte in a sample that can be determined with acceptable precision and accuracy and/or the detection limit (DL) for analytes analysed at Geoscience Australia, the relative standard deviation (RSD% = standard deviation*100 / sample mean) for the WG-1 certified reference material data.

Analyte UOM Method LOQ WG-1 RSD% May 2017

WG-1 RSD% May 2018

Duplicates Average RSD% May 2017


SiO2 % XRF fused disk 0.10 0.1% 0.0% 0.4% 0.3%

TiO2 % XRF fused disk 0.01 0.0% 0.0% 4.0% 1.1%

Al2O3 % XRF fused disk 0.20 0.5% 0.0% 0.9% 0.9%

Fe2O3tot % XRF fused disk 0.04 0.1% 0.1% 0.0% 3.4%

FeO % Titration 0.10 3.5% 0.4% 5.37% 14.6%

MnO % XRF fused disk 0.01 0.0% 0.0% NA 2.6%

MgO % XRF fused disk 0.05 0.0% 0.0% 4.2% 0.0%

CaO % XRF fused disk 0.01 0.2% 0.1% 3.1% 0.0%

Na2O % XRF fused disk 0.05 0.2% 0.0% 2.9% 1.2%

K2O % XRF fused disk 0.05 0.0% 0.0% 2.1% 0.3%

P2O5 % XRF fused disk 0.01 0.0% 0.0% 0.0% 5.6%

SO3 % XRF fused disk 0.10 NA NA NA NA

LOI % Gravimetry 0.10 0.0% 0.0% 22.4% 4.3%

Be ppm ICP-MS solution 2.0 NA NA NA 9.6%

Sc ppm ICP-MS solution 0.5 2.3% 1.3% 2.5% 2.6%

V ppm ICP-MS solution 1.0 1.2% 0.6% 3.4% 2.3%

Cr ppm ICP-MS solution 3.5 0.9% 0.4% 5.5% 6.3%

Co ppm ICP-MS solution 0.5 0.8% 01.0% 2.1% 6.7%

Ni ppm ICP-MS solution 8.0 0.8% 2.6% 11.9% 2.8%

Cu ppm ICP-MS solution 1.5 0.8% 0.6% 6.4% 17.0%


Analyte UOM Method LOQ WG-1 RSD% May 2017

WG-1 RSD% May 2018



Zn ppm ICP-MS solution 4.0 1.1% 0.7% 34.2% 0.1%

Ga ppm ICP-MS solution 0.3 3.8% 1.6% 12.7% 3.8%

Ge ppm ICP-MS solution 0.3 5.5% 5.1% 5.4% 3.1%

As ppm ICP-MS solution 0.6 14.2% 6.6% 10.2 7.2%

Rb ppm ICP-MS solution 1.0 0.6% 2.1% 4.8 2.6%

Sr ppm ICP-MS solution 1.0 0.6% 0.9% 2.6 2.3%

Y ppm ICP-MS solution 0.2 1.9% 1.82% 4.0% 3.9%

Zr ppm ICP-MS solution 0.5 0.6% 0.40% 1.8% 1.7%

Nb ppm ICP-MS solution 0.2 2.4% 1.82% 3.4% 3.9%

Mo ppm ICP-MS solution 0.9 12.0% 9.60% NA 1.4%

Ag ppm ICP-MS solution 1.0 NA NA NA NA

Cd ppm ICP-MS solution 0.5 NA NA NA NA

Sn ppm ICP-MS solution 0.5 2.8% 6.08% 7.6% 8.3%

Sb ppm ICP-MS solution 0.9 NA NA NA 5.8%

Cs ppm ICP-MS solution 0.2 3.4% 2.45% 9.3% 1.5%

Ba ppm ICP-MS solution 1.4 0.9% 1.58% 6.2% 1.6%

La ppm ICP-MS solution 0.2 1.2% 1.14% 4.5% 2.6%

Ce ppm ICP-MS solution 0.1 1.4% 1.48% 1.6% 1.7%

Pr ppm ICP-MS solution 0.1 0.9% 1.08% 4.4% 3.2%

Nd ppm ICP-MS solution 0.2 1.6% 0.67% 5.2% 3.0%

Sm ppm ICP-MS solution 1.0 3.4% 3.42% 10.1% 2.5%

Eu ppm ICP-MS solution 0.1 1.9% 2.5% 5.0% 3.6%

Tb ppm ICP-MS solution 0.1 1.7% 1.7% 2.9% 2.6%

Gd ppm ICP-MS solution 0.1 0.6% 1.0% 2.5% 3.0%

Dy ppm ICP-MS solution 0.5 1.8% 2.6% 2.0% 3.0%

Ho ppm ICP-MS solution 0.1 0.0% 1.7% 4.2% 2.6%

Er ppm ICP-MS solution 0.1 2.0% 1.8% 3.3% 2.9%

Yb ppm ICP-MS solution 0.2 1.8% 1.8% 5.0% 3.5%

Lu ppm ICP-MS solution 1.0/0.3 NA NA NA NA

Hf ppm ICP-MS solution 0.2 2.1% 2.1% 4.4% 2.1%

Ta ppm ICP-MS solution 0.1 1.1% 1.0% 3.4% 3.5%

Pb ppm ICP-MS solution 0.5 1.5% 0.8% 12.2% 2.3%

Bi ppm ICP-MS solution 0.2 NA NA NA 2.3%

Th ppm ICP-MS solution 0.1 3.9% 1.6% 1.8% 1.6%

U ppm ICP-MS solution 0.1 2.1% 1.5% 1.6% 2.3%

TOC wt% Powder 0.1 0.9% 0.8% NA 0.0%


3.2.4 Iron Titration (FeO)

Ferrous iron oxide (FeO) was determined by redox titrimetry using a Metrohm automatic titrator following a modified methodology based on Shapiro & Brannock (1962). Samples were first digested in a boiling mixture of hydrofluoric (HF) and sulphuric (H2SO4) acids, then diluted in an aqueous solution of orthophosphoric acid and boric acid before being analysed by the auto titrator. FeO was determined automatically using the Metrohm Tiamo software.

Quality Assurance (QA) and duplicate samples were run every 10 samples, along with the WG-1 CRM and GA internal standard 84162015. Individual results for all CRMs are listed in each Appendix under the raw data. Limits of quantification are listed in Table 2.

3.2.5 X-Ray Diffraction (XRD)

X-Ray Diffraction (XRD) was conducted on randomly oriented powder mounts using a Bruker D4™ Endeavour X-ray diffractometer with a Cu anode X-Ray tube. Whole-rock scans were analysed in the range 2 to 70° (2ϴ) in 0.020° steps at one second per step. Identification of the multiphase mixtures was undertaken qualitatively using the Bruker DIFFRAC EVA™ software suite according to peak best-fit. The minerals were subsequently quantified using the Bruker TOPAS v 3.0 software suite (see Jarrett et al., 2019b for detailed methodology). Quality Assurance and Quality Control (QA/QC) measures included analysis of a Bruker AXS Corundum standard to ensure the machine was operating effectively. Additionally, every tenth sample was treated as a repeat with a separate milling and analysis. These replicates provide an assessment of sample preparation precision and homogeneity of the samples. After analyses the data was checked and reviewed by a second laboratory technician.

3.2.6 Total organic carbon (TOC) and Rock-Eval pyrolysis

Total Organic Carbon (TOC) and Rock-Eval pyrolysis was measured using a Rock-Eval 6 Turbo™ (Vinci Technologies, France). Approximately 60 mg of powdered whole-rock was placed into pre-combusted crucibles (600°C; 9 hours) and heated under inert nitrogen in both the pyrolysis and oxidation ovens. The pyrolysis oven was first held at 300°C for 5 minutes and then increased at 25°C per minute to 650°C. The oxidation oven was held at 400°C for 3 minutes, and then increased at 20°C per minute to 850°C and held isothermal at 850°C for 5 minutes. The results were processed with Optkin 3.0.0 software (Beicip, France). See Jarrett et al. (2018) for detailed explanation of Rock-Eval pyrolysis and methodology. Table 3 summarises the Rock-Eval pyrolysis parameters presented in Appendices A and B (under tab ‘Rock-Eval pyrolysis’).


Table 3 Definitions of Rock-Eval pyrolysis parameters used in Appendices A and B.

Parameter Name (units) Definition

S1 mg extractable hydrocarbons (HCs) / g rock

Measure of the amount of free hydrocarbons (HCs) present in the rock. The free HCs are those thermally desorbed at 300°C for 3 mins.

S2 mg HCs (kerogen pyrolysate) / g rock

Measure of HCs formed by cracking of kerogen, resins and asphaltenes. The pyrolysate is measured from 300°C to 650°C at 25°C/min

S3 mg CO2 (organic) / g rock Measure of CO2 generated from oxygenated functional groups in kerogen. The CO2 is collected from 300°C to 390°C at 25°C/min

Tmax Maximum height of the S2 peak in the temperature program (°C)

The temperature corresponding to the maximum rate of HC generation from the cracking of kerogen (S2)

TOC Total Organic Carbon (wt %) Measure of the rock's organic richness. TOC = PC (pyrolysable carbon, wt %) + RC (Residual carbon, wt %)

PC Pyrolysable carbon (wt %) The amount of TOC represented by S1 and S2. PC = 0.83 * (S1 + S2)

RC (S4) mg C / g rock Measure of the residual carbon (RC) in a rock. Also termed S4.

PI Production Index The extent to which kerogen has been transformed into oil and gas. PI = [S1 /(S1 + S2)]

HI Hydrogen Index Amount of HCs released on pyrolysis (S2) normalised to

TOC. [mg hydrocarbons (S2) /g TOC] HI = 100 * S2 / TOC

OI Oxygen Index Amount of carbon dioxide released on pyrolysis (S3)

normalised to TOC. [mg CO2 (S3) /g TOC] OI = 100 * S3 / TOC

MINC Mineral Carbon (wt %) The amount of carbon (C) contained in mineral phases e.g. carbonates. Also termed total inorganic carbon (TIC)


4 Results

To assess the suitability of analytes for subsequent statistical analysis, several quality assurance and control measures were applied, including:

• Checking internal quartz blanks for potential cross-contamination

• Assessing the variability of internal standards and certified reference materials to check for machine drift, accuracy and precision and

• Checking laboratory duplicates for variability.

The results of this Quality Assurance and Quality Control (QA/QC) are provided in each of the relative appendices for XRF, LOI and ICP-MS (Appendix A and B). The majority of samples passed QA/QC with some exceptions described below, and highlighted in bold text in Table 2.

All laboratory blanks used for XRF, ICP-MS and FeO did not identify any potential cross-contamination. Minor contamination was reported in some of the blanks analysed in succession with Rock-Eval pyrolysis. These results are at the detection limits (TOC and S1 ~0.01 wt%) and were not considered.

Using a relative standard deviation of <15% as the cut-off, the results demonstrate most trace elements are suitable for further imputation, statistics and interpretations (Table 2). This approach is similar to previous recent EFTF geochemistry outputs (Bastrakov et al., 2018; Main et al., 2019). Exceptions include elements that were below detection limits in the CRM and include Be, Ag, Cd, Sb, Lu and Bi and SO3 (Table 2). The data from these elements should be used with caution as this study was not able to ensure their precision and accuracy.

Analysis of duplicates revealed low RSDs (< 15%) demonstrating good sample homogeneity and laboratory procedures. Exceptions include Cu in the May 2018 batch (Appendix A) with a RSD of 17% and still within the error and Zn for the May 2017 batch (Appendix B) with a RSD of 34.2% (Table 2). Inspection of the data reveals that four samples had identical repeat analysis while one sample (2678607) had a large difference in absolute values with a 62% decrease in Zn ppm in the repeat sample. This may be due to homogenisation issues with a large sample with variable composition.

All results are provided as separate digital spreadsheets for samples collected during the 2017 fieldwork (Appendix A) and the 2018 fieldwork (Appendix B) with individual tabs for XRF (including LOI), ICP-MS, XRD, and Rock-Eval pyrolysis.

Geochemistry data has been incorporated into Geoscience Australia’s national databases including OZCHEM (inorganic geochemistry) and ORGCHEM (organic geochemistry) and is also available on Geoscience Australia’s EFTF portal for online data delivery (https://portal.ga.gov.au/persona/eft f).

https://portal.ga.gov.au/persona/eftf


5 Acknowledgements

This report is a product of the Australian Governments four year, $100.5 million Exploring for the Future initiative. Geoscience Australia laboratory staff Jess Byass, David DiBugnara, Stewart Gilmore, Ziqing Hong, Neel Jinadasa, Ian Long, Tara Webster and Simon Webber, are thanked for their efforts, assistance, attention to detail in the provision of the data presented here. Landholders of Benmara, Mittiebah and Mount Drummond Stations, and the traditional owners of the Waanyi-Garawa Aboriginal Land Trust are thanked for land access. Peter Campbell (Northern Territory Government) is especially acknowledged for efforts in effectively and efficiently negotiating access, and permission for sampling, in key locations within Waanyi-Garawa Aboriginal Lands. Anthony Schofield and Evgeniy Bastrakov (Geoscience Australia) provided valuable and constructive reviews that improved the final version. This Record is published with the permission of the CEO, Geoscience Australia. eCat 134710.


6 References

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Geochemical Results - May 2017

Geochemical data for all analysed outcrop samples collected in May 2017 (total samples analysed = 18) are provided in the associated file:

Appendix_A_33004_South_Nicholson_Geochemistry_May 2017.xlsx

Five tabs are present in the attached data file, labelled XRF, ICP-MS, FeO, XRD and Rock-Eval pyrolysis. The first three tabs (XRF, ICP-MS and FeO) tabs contain the certified reference materials run, and repeat samples, with each analytical batch, including accepted values. The fourth tab contains the XRD data with analytical parameters and conditions. The Rock-Eval pyrolysis tab contains organic geochemistry data, including blanks and standards.

Units of measurement for each analyte is provided in the heading, e.g. SiO2 [wt%] = SiO2 analysis in weight percent. Sample metadata (e.g. location [Latitude and Longitude], stratigraphic unit name, etc) is provided with each sample. Explanations for all metadata and analyte fields are also included in the data file.


Geochemical Results - May 2018

Geochemical data for all analysed outcrop samples collected in May 2018 (total samples analysed = 35) are provided in the associated file:

Appendix_B_33228_South_Nicholson_Geochemistry_May 2018.xlsx.

Five tabs are present in the attached data file, labelled XRF, ICP-MS, FeO, XRD and Rock-Eval pyrolysis. The first three tabs (XRF, ICP-MS and FeO) tabs contain the certified reference materials run, and repeat samples, with each analytical batch, including accepted values. The fourth tab contains the XRD data with analytical parameters and conditions. The Rock-Eval pyrolysis tab contains organic geochemistry data, including blanks and standards.

Units of measurement for each analyte is provided in the heading, e.g. SiO2 [wt%] = SiO2 analysis in weight percent. Sample metadata (e.g. location [Latitude and Longitude], stratigraphic unit name, etc) is provided with each sample. Explanations for all metadata and analyte fields are also included in the data file.

Only sedimentary units were analysed in this batch for Rock-Eval pyrolysis (tab five), igneous samples were not analysed. Number of samples analysed for organics = 27 (including two repeats for QA/QC). Four samples were analysed for XRD.

Documents

Exploring for the Future- Whole rock geochemistry data ... · batches. No levelling between the two batches has been undertaken. Full results are provided in Appendix A (batch number