Supplementary Information for: Giant Kiruna-type deposits form by. efficient flotation of magmatic magnetite suspensions

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1 GSA DATA REPOSITORY Supplementary Information for: Giant Kiruna-type deposits form by efficient flotation of magmatic magnetite suspensions 3 4 Jaayke L. Knipping, Laura D. Bilenker, Adam C. Simon, Martin Reich, Fernando Barra, Artur P. Deditius, Craig Lundstrom, Ilya Bindeman, Rodrigo Munizaga 5 Item DR1: Fe and O Isotope Data 6 Stable isotope data are reported in the conventional delta notation, following the equations: 7 56 Fe sample ( ) = [( 56 Fe/ 54 Fe) measured / ( 56 Fe/ 54 Fe) IRMM-14 1] * 1000 (equation 1) 8 18 O sample ( ) = [( 18 O/ 16 O) measured / ( 18 O/ 16 O) SMOW 1] * 1000 (equation 2) Iron isotope values were obtained by using a Multi-Collector Inductively Coupled Plasma Mass Spectrometer (MC-ICP-MS) at the University of Illinois, Urbana-Champaign by following the double-spike method of Millet et al. (2012) by using dry plasma and pseudo high resolution analysis. Oxygen isotope values were measured by using a laser fluorination line and Thermo- Finnigan MAT 253 gas isotope ratio mass spectrometer in dual inlet mode at the University of Oregon. For all measurements, only magnetite separates were analyzed. Since LC magnetite grains contain inclusions, sample would respond to exposure of the laser by jumping out of the sample well. Therefore, we employed a careful approach during the laser fluorination process in which the laser power was increased percentage-wise once the entire sample was exposed evenly to the current strength. Smaller grain size fractions were optimal for this method to insure homogeneous and quicker heating of individual grains The data reported in Table DR1 below include stable Fe and O isotope pairs for 13 LC samples, as well as two additional deposits for comparison: one from the Fe oxide deposit at

2 Mineville, NY, USA, and one from the Paleoproterozoic Kiruna deposit, Sweden. The deposit at Mineville is speculated to have formed by secondary hydrothermal processes (Valley et al. 2012), which explains its significantly lighter signature in both Fe and O stable isotopes. By contrast, the Kiruna deposits are believed to be of an origin similar to that of Los Colorados and the CIB IOAs, as reflected by their similar isotopic signature although the lighter 18 O-values of Kiruna ore may be due to the fact that Kiruna is much older, with reported isotopic age constraints ranging from ~1882 to ~1887 Ma (Westhues et al., 2014). Thus, Kiruna has likely suffered greater post-formation alteration Table DR1: 56 Fe- and 18 O-values with twice standard deviation for each indicated sample from drill core LC-05 and LC-04. Standard deviations were calculated based on the entire population of analyses, which ranged from 2-4 data points for each sample. The following numbers refer to sample depth (m) in each drill core. Location Sample 56 Fe ( ) 2sd ( ) 18 O ( ) 2sd ( ) Los Colorados, Core LC Los Colorados, Core LC Mineville, NY Mineville Kiruna, Sweden K

3 35 Item DR2: Methodology for EPMA Analyses of Magnetite The EMP analysis of the magnetite was a combined study using the Cameca SX-100 (EMAL) at the University of Michigan and the JEOL 8530F (Centre of Microscopy) at the University of Western Australia to resolve zonation from high-ti magnetite to the surrounding magnetite matrix (Fig. S1). In both cases, operating conditions employed an accelerating voltage of 20 kv and a focused beam to avoid measuring inclusions or exsolutions in the magnetite. The beam current was set to 30 na at the University of Michigan and to 50 na at the University of Western Australia. The standards and analytical conditions used are summarized for each institution in Table DR Figure DR1: BSE image showing massive magnetite with high-ti (dark grey) magnetite microlites (~100 µm) surrounded by massive low-ti magnetite (bright grey). Red arrows point to some microlites (Sample LC ). As discussed in the text, the chemical signature of the high-ti zones is consistent with magnetite that grows from a silicate melt and the chemical signature of the low-ti zones is consistent with magnetite that grows from a magmatichydrothermal aqueous fluid. 51

4 A total of 551 spot electron probe microanalyses (EPMA) were conducted on magnetite from two different drill cores including 10 samples from drill core LC-05 with 1-3 grains per sample (10-40 analyses per grain) and 7 samples from drill core LC-04 with 1-3 grains per sample (11-40 analyses per grain). Energy dispersive X-ray (EDX) maps were generated using the Hitachi S-3200N scanning electron microscope (SEM) at the University of Michigan, while wavelength dispersive X-ray (WDX) maps were collected at the University of Western Australia using an accelerating voltage of 20 kv, a beam current of 150 na and a counting time of ms/step. Table DR3 below includes all results of every single measurement of magnetite from drill core LC-05 and LC-04. Relative errors are on average 4% (Ti+V) and 8% (Al+Mn). The samples in each drill core are listed from shallow to deep levels and the results from each grain (indicated with lowercase letters) are listed from core to rim. Oxygen values are calculated based on the assumption that all Fe is present as Fe 3 O 4 with a stoichiometric magnetite composition. Thus, large deviations from 100 % total may indicate non-stoichiometric compositions. Figures DR1a and DR1b include elemental maps of additional grains showing core (magmatic) to rim (magmatichydrothermal) zonation

5 73 74 Table DR2: Probe conditions of wavelength dispersive (WDS) X-ray spectrometers for each institute. MDL: mean detection limit University of Michigan: Cameca SX kv, 30 na, focused Element/Line Crystal Standard Counting time [s] MDL [wt%] Mg/K TAP geikielite Al/K TAP zoisite Si/K LTAP wollastonite Ca/K PET wollastonite Ti /K PET ilmenite V /K LLIF V 2 O Mn/K LLIF rhodondite Fe/K LLIF magnetite Murdoch University: Jeol JXA kv, 30 na, focused Element/Line Crystal Standard Counting time [s] MDL [wt%] Mg/K TAP pyrope Al/K TAP spessartine Si/K TAP spessartine Ca/K PETJ wollastonite Ti /Kv PETJ rutile V /K LIFH V-metal Mn/K LIFH spessartine Fe/K LIF magnetite

6 76 77 Figure DR2a: caption below

7 Figure DR2a and b: WDX maps of two different grains of magnetite from sample LC Upper left: BSE image, followed by Fe, Mg, Si, Ti and V individual WDX maps. Strong zonation is observed, and the three magnetite types (1, 2 and 3) are labeled in Fig. S2a and b. Scale bar in top left panel of Figure S2a is 100 microns. Scale bar in all other panels of Figure S2a are 500 microns.

8 Table DR3: All EMP analysis ordered by depth within drill cores LC-05 and LC-04. Lowercase letters indicate different grains from the same sample depth. Analyses are ordered from core to rim in grains, which were analyzed at UMich. Empty boxes indicated that the concentration was below the limit of detection for the element. sample Mg Al Si Ca Ti V Mn Fe O Total Point# Ti+V Al+Mn Institute [wt%] [wt%] [wt%] [wt%] [wt%] [wt%] [wt%] [wt%] [wt%] [wt%] [wt%] [wt%] LC-05-32d UMIch LC-05-32d UMIch LC-05-32d UMIch LC-05-32d UMIch LC-05-32d UMIch LC-05-32d UMIch LC-05-32d UMIch LC-05-32d UMIch LC-05-32d UMIch LC-05-32d UMIch LC-05-32d UMIch LC-05-32d UMIch LC-05-32d UMIch LC-05-32d UMIch LC-05-32d UMIch LC-05-32d UMIch LC-05-51b b UWAustralia LC-05-51b b UWAustralia LC-05-51b b UWAustralia LC-05-51b b UWAustralia LC-05-51b b UWAustralia LC-05-51b b UWAustralia LC-05-51b b UWAustralia LC-05-51b b UWAustralia LC-05-51b b UWAustralia LC-05-51b b UWAustralia LC-05-51b b UWAustralia LC-05-51b b UWAustralia LC-05-51b b UWAustralia LC-05-51b b UWAustralia LC-05-51b b UWAustralia LC-05-51b b UWAustralia LC-05-51b b UWAustralia LC-05-51b b UWAustralia LC-05-51b b UWAustralia LC-05-51b b UWAustralia LC-05-51b b UWAustralia LC-05-51b b UWAustralia

9 LC-05-51b b UWAustralia LC-05-51b b UWAustralia LC-05-51b b UWAustralia LC-05-51b b UWAustralia LC-05-51b b UWAustralia LC-05-51b b UWAustralia LC-05-51b b UWAustralia LC-05-51b b UWAustralia LC-05-51b b UWAustralia LC-05-51b b UWAustralia LC-05-51b b UWAustralia LC-05-51b b UWAustralia LC-05-51b b UWAustralia LC-05-51b b UWAustralia LC-05-51b b UWAustralia LC-05-51b b UWAustralia LC-05-51b b UWAustralia LC-05-51d d UWAustralia LC-05-51d d UWAustralia LC-05-51d d UWAustralia LC-05-51d d UWAustralia LC-05-51d d UWAustralia LC-05-51d d UWAustralia LC-05-51d d UWAustralia LC-05-51d d UWAustralia LC-05-51d d UWAustralia LC-05-51d d UWAustralia LC-05-52c UMich LC-05-52c UMich LC-05-52c UMich LC-05-52c UMich LC-05-52c UMich LC-05-52c UMich LC-05-52c UMich LC-05-52c UMich LC-05-52c UMich LC-05-52c UMich LC-05-52c UMich LC-05-52c UMich LC-05-52e UMich LC-05-52e UMich LC-05-52e UMich LC-05-52e UMich LC-05-52e UMich LC-05-52e UMich LC-05-52e UMich LC-05-52e UMich LC-05-52e UMich LC-05-52e UMich LC-05-52e UMich

10 LC-05-63a a UWAustralia LC-05-63a a UWAustralia LC-05-63a a UWAustralia LC-05-63a a UWAustralia LC-05-63a a UWAustralia LC-05-63a a UWAustralia LC-05-63a a UWAustralia LC-05-63a a UWAustralia LC-05-63a a UWAustralia LC-05-63a a UWAustralia LC-05-63a a UWAustralia LC-05-63a a UWAustralia LC-05-63a a UWAustralia LC-05-63a a UWAustralia LC-05-63a a UWAustralia LC-05-63a a UWAustralia LC-05-63a a UWAustralia LC-05-63a a UWAustralia LC-05-63a a UWAustralia LC-05-63a a UWAustralia LC-05-63a a UWAustralia LC-05-63a a UWAustralia LC-05-63a a UWAustralia LC-05-63a a UWAustralia LC-05-63a a UWAustralia LC-05-63a a UWAustralia LC-05-63a a UWAustralia LC-05-63a a UWAustralia LC-05-63a a UWAustralia LC-05-63a a UWAustralia LC-05-63a a UWAustralia LC-05-63a a UWAustralia LC-05-63a a UWAustralia LC-05-63a a UWAustralia LC-05-63a a UWAustralia LC-05-63a a UWAustralia LC a Umich LC a Umich LC a Umich LC a Umich LC a Umich LC a Umich LC a Umich LC a Umich LC a Umich LC a Umich LC a Umich LC a Umich LC a Umich LC a Umich

11 LC a Umich LC a Umich LC a Umich LC a Umich LC a Umich LC a Umich LC a Umich LC d Umich LC d Umich LC d Umich LC d Umich LC d Umich LC d Umich LC d Umich LC d Umich LC d Umich LC d Umich LC d Umich LC d Umich LC d Umich LC d Umich LC d Umich LC d Umich LC d Umich LC b b UWAustralia LC b b UWAustralia LC b b UWAustralia LC b b UWAustralia LC b b UWAustralia LC b b UWAustralia LC b b UWAustralia LC b b UWAustralia LC b b UWAustralia LC b b UWAustralia LC b b UWAustralia LC b b UWAustralia LC b b UWAustralia LC b b UWAustralia LC b b UWAustralia LC b b UWAustralia LC b b UWAustralia LC b b UWAustralia LC b b UWAustralia LC b b UWAustralia LC b b UWAustralia LC b b UWAustralia LC b b UWAustralia LC b b UWAustralia LC b b UWAustralia LC b b UWAustralia

12 LC b b UWAustralia LC b b UWAustralia LC b b UWAustralia LC b b UWAustralia LC b d UWAustralia LC b d UWAustralia LC b d UWAustralia LC b d UWAustralia LC b d UWAustralia LC b d UWAustralia LC b d UWAustralia LC b d UWAustralia LC b d UWAustralia LC b d UWAustralia LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich LC e UMich LC e UMich LC e UMich

13 LC e UMich LC e UMich LC e UMich LC e UMich LC e UMich LC e UMich LC e UMich LC e UMich LC e UMich LC e UMich LC e UMich LC e UMich LC e UMich LC e UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich LC a a UWAustralia

14 LC a a UWAustralia LC a a UWAustralia LC a a UWAustralia LC a a UWAustralia LC a a UWAustralia LC a a UWAustralia LC a a UWAustralia LC a a UWAustralia LC a a UWAustralia LC a a UWAustralia LC a a UWAustralia LC a a UWAustralia LC a a UWAustralia LC a a UWAustralia LC a a UWAustralia LC a a UWAustralia LC a a UWAustralia LC a a UWAustralia LC a a UWAustralia LC a a UWAustralia LC a a UWAustralia LC a a UWAustralia LC a a UWAustralia LC a a UWAustralia LC a a UWAustralia LC a a UWAustralia LC a a UWAustralia LC a a UWAustralia LC a a UWAustralia LC a a UWAustralia LC a a UWAustralia LC a a UWAustralia LC a a UWAustralia LC a a UWAustralia LC a a UWAustralia LC a a UWAustralia LC a a UWAustralia LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich

15 LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich LC d UMich LC e UMich LC e UMich LC e UMich LC e UMich LC e UMich LC e UMich LC e UMich LC e UMich LC e UMich LC e UMich LC e UMich LC e UMich LC e UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC b UMich LC b UMich LC b UMich LC b UMich LC b UMich LC b UMich LC b UMich LC b UMich LC b UMich

16 LC b UMich LC b UMich LC b UMich LC b UMich LC b UMich LC b UMich LC b UMich LC b UMich LC b UMich LC b UMich LC b UMich LC b UMich LC b UMich LC b UMich LC b UMich LC b UMich LC b UMich LC b UMich LC b UMich LC b UMich LC b UMich LC b UMich LC b UMich LC b UMich LC b UMich LC b UMich LC b UMich LC b UMich LC b UMich LC b UMich LC b UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich

17 LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMich LC c UMIch LC c UMIch LC c UMIch LC c UMIch LC c UMIch LC c UMIch LC c UMIch LC c UMIch LC c UMIch LC c UMIch LC c UMIch LC c UMIch LC c UMIch LC c UMIch LC c UMIch LC c UMIch LC c UMIch LC d UMIch LC d UMIch LC d UMIch LC d UMIch LC d UMIch LC d UMIch LC d UMIch LC d UMIch LC d UMIch LC d UMIch LC d UMIch LC d UMIch LC d UMIch LC d UMIch LC d UMIch LC d UMIch LC d UMIch LC d UMIch

18 LC e UMIch LC e UMIch LC e UMIch LC e UMIch LC e UMIch LC e UMIch LC e UMIch LC e UMIch LC e UMIch LC e UMIch LC e UMIch LC e UMIch LC e UMIch LC e UMIch LC e UMIch LC e UMIch LC e UMIch LC e UMIch LC e UMIch LC e UMIch LC e UMIch LC e UMIch LC e UMIch LC e UMIch LC e UMIch LC e UMIch LC e UMIch LC e UMIch LC e UMIch LC e UMIch LC e UMIch LC e UMIch LC e UMIch LC e UMIch LC e UMIch LC a UMIch LC a UMIch LC a UMIch LC a UMIch LC a UMIch LC a UMIch LC a UMIch LC a UMIch LC a UMIch LC a UMIch LC a UMIch LC a UMIch LC a UMIch LC a UMIch LC a UMIch

19 LC a UMIch LC a UMIch LC a UMIch LC a UMIch LC a UMIch LC a UMIch LC a UMIch LC a UMIch LC a UMIch LC a UMIch LC a UMIch LC a UMIch LC a UMIch 86

20 87 Item DR3: Model calculation Figure DR3: Portion of primary magnetite in aqueous fluid suspension vs. FeO leached from magma vs. magma chamber size. The percentages indicate degassing portions of a hydrous andesitic magma (6 wt% H 2 O) with a density of 2.27 g/cm 3 (calculated by using the model of Ochs & Lange (1999) for 1000 C and 2 kbar). A magnetite-bubble-suspension will not ascend when primary magnetite makes up > 65 wt% (> 37 vol%) of the suspension (F Buoyancy <0). The deposition of 343 Mt Fe at Los Colorados exclusively from conventional orthomagmatic fluids would require a large degassing proportion or a large magma chamber size to exsolve sufficient

21 fluid (white star, A=92 km 3, when assuming 20% degassing). In contrast, the addition of 8 wt% primary (type 1) magnetite microlites to this suspension would decrease the required magma chamber significantly to magma chamber sizes reasonable (white star, B=50 km 3 ) for the caldera sizes measured at the extrusive IOA deposit of El Laco (~6 km caldera diameter), assuming a similar magma chamber size as for Crater Lake (6.5 km caldera diameter, 55 km 3 total erupted volume, Bacon, 1983; Lipmann, 1997). In this case, the total amount of FeO leached from the parental magma chamber to deposit 343 Mt Fe (including magmatic and magmatic-hydrothermal magnetite) would be 0.4 wt% FeO. 104