Appendix 1
Drill cores stored at the Geological Survey of Sweden (SGU) in Malå or at the Boliden Mineral core
archive in Boliden (Sweden) were sampled as follows: (i) 57 samples from the Upper Sandstone and
Lower Sandstone orebodies at Laisvall (including 4 samples with steeply-dipping galena-sphaleritecalcite veinlets); (ii) eight samples from the sandstone orebody at Vassbo, (iii) one sample of shale
with pyrite at the base of the Grammajukku Formation at the contact with the underlying Upper
Sandstone at Laisvall, and (iv) one sample of pyrite-rich grey shale in the Alum Shale Formation at
Vassbo. At Laisvall, the samples were selected in profiles at proximal and distal positions relative to
the Nadok fault and Central Malm fault systems, which have been interpreted as feeder systems for
mineralization (Saintilan et al. 2015a). After petrographic investigations, aliquots of these samples
were utilized for determination of the sulfur isotope composition of sulfides and barite, and strontium
isotope composition of barite. An additional separate of phosphorite pellets in the phosphorite
conglomerate at Laisvall (Fig. 2a) was obtained from drill core samples using a microdrill and
processed for strontium isotope analyses.
In addition, thirteen drill core samples and one outcrop sample were taken from the stratigraphy at
Laisvall for organic geochemistry analyses: (i) Eleven shale samples from the Grammajukku and
Alum Shale Formations; (ii) two mineralized sandstone samples from the Upper and Lower
Sandstones; and (iii) one barren Lower Sandstone sample from outcrops located ~ 5 km to the
southeast of the mined area. The shale samples are representative of the stratigraphy upward from the
base of the Grammajukku Formation to the uppermost autochthonous part of the Alum Shale
Formation at Laisvall. The uppermost sample of black organic-rich shale (ASF 11) was sampled at the
top of a few centimeter-thick limestone horizon within the Alum Shale Formation (cf. Thickpenny
1984). Shale sample ASF4 was split in three subsamples (ASF4-0, ASF4-1 and ASF4-2). These
samples correspond to the first meter of organic-rich shale in the autochthonous part of the Alum
Shale Formation at Laisvall, above the contact with the Grammajukku Formation. Hydrocarbons were
extracted from ASF4-1 and ASF4-2, and from the three sandstone samples.
Thin sections of all samples were studied using transmitted and reflected light microscopy and a
Cl8200 MK5-optical cathodoluminescence microscope with a cold cathode that was mounted on a
petrographical microscope. The beam conditions were set at 15 kV and 50 to 60 mA with an
unfocused beam of approximately 1 cm in an observation chamber with a residual pressure of 80
mTorr. Samples were not coated. Twenty representative thin sections were mounted on an aluminum
stub with double-sided conductive carbon tape. A c. 25 nm thin coating of carbon was deposited on
the samples by low vacuum sputter prior to imaging with a Jeol JSM 7001F Scanning Electron
Microscope (SEM, Section of Earth and Environmental Sciences, University of Geneva, Switzerland).
Investigation of solid black inclusions in barite, calcite and fluorite, and dark fluid inclusions in
sphalerite in three samples from Laisvall was carried out by Raman spectrometry at the University of
Geneva using a LABRAM confocal Raman microspectrometer with a 532.8-nm He-Ne laser coupled
to a B40 Olympus microscope with a 50× objective. Barite and sphalerite fragments from these
samples were then mounted on an aluminum stub and coated with gold (c. 10 nm) before investigation
using SEM on back-scattered electron mode (BSE) and energy-dispersive X-ray analysis (EDX).
Three representative thin sections were selected for QEMSCAN® imagery and analysis: (i) a
sample from the Upper Sandstone orebody in which phosphorous- and/or REE-bearing minerals were
investigated in detail; and (ii) two samples from the Lower Sandstone orebody at Laisvall and the
sandstone orebody at Vassbo in which the distribution of the cementing phases (quartz, calcite, barite,
Pb-Zn sulfides) and their relationships were studied. Automated bulk-rock mineral analysis and
textural imaging of the studied samples were performed using an FEI QEMSCAN® Quanta 650F
facility at the Section of Earth and Environmental Sciences, University of Geneva, Switzerland. The
system is equipped with two Bruker QUANTAX light-element energy dispersive X-ray spectrometers.
Analyses were conducted at high vacuum, accelerating voltage of 25 kV, and probe current of 10 nA
on carbon-coated samples. FieldImage operating mode (Pirrie et al. 2004) was used for analyses. Xray spectra acquisition time was 10 ms per pixel, using a point-spacing of 5 µm. Up to 285 individual
fields were measured in each sample, with 1500 pixels per field. Data processing was performed using
the iDiscover software package. The final products consist of high-quality spatially resolved and fully
quantified mineralogical maps enabling basic image analysis, including particle size and shape
distribution, mineral assemblages and mineral proportion definitions.
For sulfur isotope studies, all samples were crushed using a hydraulic press and sieved. Following
heavy liquid separation of the 315 to 125 µm size fractions, the heavy mineral fractions were
handpicked under a binocular microscope to obtain sulfide (galena, sphalerite and pyrite) and barite
aliquots. All aliquots (n = 163 and 25 duplicates) were subsequently powdered using an agate mortar
and pestle, and analyzed for the stable sulfur isotope composition by elemental analysis and isotope
ratio mass spectrometry (EA-IRMS) at the Institute of Earth Surface Dynamics, University of
Lausanne, Switzerland. The EA-IRMS analyses were done using a Carlo Erba 1108 elemental
analyzer connected to a Thermo Fisher Delta V stable isotope ratio mass spectrometer that was
operated in the continuous He flow mode. The stable isotope composition of sulfur is reported in the
delta (δ) notation as the per mil (‰) deviation of the isotope ratio (34S/32S) relative to the VCDT
standard. The precision of the EA-IRMS analyses, evaluated by replicate measurements of laboratory
standards (barite, sphalerite, and pyrite) and international reference materials (sphalerite, silver
sulfide) is better than ± 0.2‰ (1σ).
For strontium isotope studies, barite and phosporite pellet aliquots were digested with HCl 6M
in screw-sealed Teflon vials on a hot plate at 140°C for several hours. The solutions were centrifuged
and the supernatant was recovered and transferred to Teflon vials, where it was dried down on a hot
plate. The residue was re-dissolved in a few drops of 14 M HNO3 and dried down again, before Sr
separation from the matrix using a Sr-Spec resin. The Sr separate was re-dissolved in 5 ml of ~2%
HNO3 solutions and ratios were measured using a Thermo Neptune PLUS Multi-Collector ICP-MS in
static mode. The 88Sr/86Sr (8.375209) ratio was used to monitor internal fractionation during the run.
Interferences at masses 84 (84Kr), 86 (86Kr) and 87 (87Rb) were also corrected in-run by monitoring
83
Kr and 85Rb. The SRM987 standard was used to check external reproducibility, which on the long-
term (more than 100 measurements during one year) was ± 10 ppm. The internally corrected 87Sr/86Sr
values were further corrected for external fractionation. A 87Sr/86Sr ratio of 0.721269 ± 1.4x10-5 is
reported as 0.721269 ± 14.
The samples for organic geochemical analyses were prepared and analyzed in the Stable Isotope
and Organic Geochemistry Laboratories at the University of Lausanne (Switzerland) using procedures
described previously (Spangenberg and Herlec 2006; Spangenberg et al. 2014). To remove the
weathered material and any contamination from packing and handling, the rocks were cut in slabs with
a water-cooled saw. The slabs were cleaned with deionized water (>18MΩ resistance), analytical
grade acetone and dried at 50°C for 24 hours. The cleaned slabs were crushed in a thoroughly cleaned
hydraulic press and powdered to <125 µm by short grinding periods in an agate ring grinder mill. The
powders were stored in pre-annealed (at 450°C for four hours) aluminum disposable canisters and
aluminum foil sheets prior to organic geochemical analyses. Total bitumen (extractable organic matter,
EOM) was obtained from an aliquot (100 to 200 g) of the powdered samples by refluxing with
dichloromethane (DCM) for six days, with a change of solvent after the first two days. The DCM
fractions were combined, gently evaporated to 1 mL, and passed through an activated copper column
to remove elemental sulfur. The solvent was passively evaporated to near dryness, and extracts with
0.5 mL DCM stored in 2 mL vials at +4 °C until required for analyses. The extracts were separated
into two fractions (aliphatic and aromatic hydrocarbons) using silica/alumina gel liquid
chromatography.
Chemical characterization of the aliphatic hydrocarbons was performed by gas
chromatography‒mass spectrometry (GC‒MS), using an Agilent Technologies gas chromatograph HP
6890 coupled to a HP 5973 quadrupole mass selective detector (MSD) with HP-5MS fused-silica
capillary column (60 m length, 0.25 mm internal diameter, coated with 0.10 μm 5%-diphenyl–95%
dimethyl-polysiloxane as stationary phase) and helium as carrier gas. An aliquot normalized to the
extracted aliquot size was introduced in a splitless injector at 280 °C. After an initial period of 7 min at
70 °C, the column was heated to 280 °C at 5 °C/min followed by an isothermal period of 20 min. The
MSD was operated in the electron impact mode at 70 eV, with a source temperature of 250 °C, an
emission current of 1 mA, multiple-ion detection with a mass range from 50 to 700 a.m.u, and a scan
rate of 1.5 scans/sec (resolution of 6.15 scans/a.m.u.). Compound identifications were made by
comparison with synthetic standards, GC retention times, interpretation of mass spectrometric
fragmentation patterns and literature mass spectra. The absence of measurable recovered bitumen in
two procedure blanks indicates that no detectable laboratory contaminations were introduced into the
samples.
Carbon and nitrogen stable isotope analyses of the total organic carbon were performed on the
eleven shale samples. The powdered samples were acidified (1M HCl) for removal of inorganic
carbon, rinsed thoroughly with deionized water, filtered, dried overnight, and stored in pre-annealed
beakers. The solid residues were mostly kerogen with some residual silicate fraction, and aliquots
were submitted to carbon and nitrogen isotope analyses by EA-IRMS. The C and N isotope
compositions are reported in the delta (δ) notation as the per mil (‰) deviation of the (13C/12C) and
(15N/14N) isotope ratios relative to the VPDB and N2 in AIR standards, respectively. The
reproducibility of the EA-IRMS measurements for C and N is better than ± 0.1‰ and ± 0.3‰ (1σ),
respectively. The TOC (wt.% C) and total organic nitrogen (TON, wt.% N) of each sample was
determined by integration of the corresponding EA-IRMS measurement of the carbon and nitrogen
isotope composition.