influence of contamination on banded iron formations in the isua supracrustal belt west greenland reevaluation of the eoarchean seawater compositions

Accepted Manuscript Influence of contamination on banded iron formations in the Isua supracrustal belt, West Greenland: Reevaluation of the Eoarchean seawater compositions Shogo Aoki, Chiho Morinaga, Yasuhiro Kato, Takafumi Hirata, Tsuyoshi Komiya PII: S1674-9871(17)30002-6 DOI: 10.1016/j.gsf.2016.11.016 Reference: GSF 524 To appear in: Geoscience Frontiers Received Date: April 2016 Revised Date: 11 November 2016 Accepted Date: 25 November 2016 Please cite this article as: Aoki, S., Morinaga, C., Kato, Y., Hirata, T., Komiya, T., Influence of contamination on banded iron formations in the Isua supracrustal belt, West Greenland: Reevaluation of the Eoarchean seawater compositions, Geoscience Frontiers (2017), doi: 10.1016/j.gsf.2016.11.016 This is a PDF file of an unedited manuscript that has been accepted for publication As a service to our customers we are providing this early version of the manuscript The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain 200 100 15 10 Age (Ga) 0 Age (Ga) Co(ppm) Co(ppm) Co contents in BIFs 0.2 300 200 100 U contents in BIFs 0.1 Age (Ga) 0 Age (Ga) 1 300 200 100 3 Age (Ga) Age (Ga) 1 0 Previous estimate AC C EP TE D This study Age (Ga) M AN U V Zn 0 SC U(ppm) V and Zn contents in BIFs RI PT 350 U(ppm) Ni contents in BIFs V, Zn(ppm) Ni(ppm) 30 Ni(ppm) ACCEPTED MANUSCRIPT Aoki et al Graphical Abstract ACCEPTED MANUSCRIPT Influence of contamination on banded iron formations in the RI PT Isua supracrustal belt, West Greenland: Reevaluation of the SC Eoarchean seawater compositions a M AN U Shogo Aokia,*, Chiho Morinagab, Yasuhiro Katob, Takafumi Hiratac, Tsuyoshi Komiyaa Department of Earth Science and Astronomy, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan b Department of Systems Innovation, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, c TE D Tokyo 113-8656, Japan Division of Earth and Planetary Sciences, KyotoUniversity, Kitashirakawa EP Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan AC C *Corresponding author e-mail address: shogo@ea.c.u-tokyo.ac.jp ACCEPTED MANUSCRIPT Abstract Banded Iron Formations (BIFs) are chemical sediments, ubiquitously distributed in the Precambrian supracrustal belts; thus their trace element compositions are helpful for deciphering geochemical evolution on the earth through time However, it is necessary to elucidate factors controlling the whole-rock compositions in order to decode the ancient seawater compositions because their compositions are highly variable.We analyzed major and trace element contents of the BIFs in the 3.8–3.7 Ga Isua supracrustal belt (ISB), southern West Greenland The BIFs are petrographically classified into four types: Black-, Gray-, Green- and White-types, respectively The 10 Green-type BIFs contain more amphiboles, and are significantly enriched in Co, Ni, Cu, 11 Zn, Y, heavy rare earth element (HREE) and U contents However, their bulk 12 compositions are not suitable for estimate of seawater composition because the 13 enrichment was caused by secondary mobility of metamorphic Mg, Ca and Si-rich fluid, 14 involvement of carbonate minerals and silicate minerals of olivine and pyroxene and/or 15 later silicification or contamination of volcanic and clastic materials The White-type 16 BIFs are predominant in quartz, and have lower transition element and REE contents 17 The Gray-type BIFs contain both quartz and magnetite The Black-type BIFs are 18 dominated by magnetite, and contain moderate to high transition element and REE 19 contents But, positive correlations of V, Ni, Zn and U contents with Zr contents suggest 20 that involvement of detrital, volcanic and exhalative materials influences on their 21 contents The evidence for significant influence of the materials on the transition 22 element contents such as Ni in the BIFs indicates the transition element contents in the 23 Archean ocean were much lower than previously estimated.We reconstructed secular 24 variations of V, Co, Zn and U contents of BIFs through time, which show Ni and Co 25 contents decreased whereas V, Zn and U contents increased through time Especially, 26 the Ni and Co contents drastically decreased in the Mesoarchean rather than around the 27 Great Oxidation Event On the other hand, the V, Zn and U contents progressively 28 increased from the Mesoarchean to the Proterozoic Stratigraphical trends of the BIFs 29 show increase in Y/Ho ratios and decrease in positive Eu anomaly upwards, respectively 30 The stratigraphic changes indicate that a ratio of hydrothermal fluid to seawater 31 component gradually decrease through the deposition, and support the Eoarchean plate AC C EP TE D M AN U SC RI PT 2 ACCEPTED MANUSCRIPT 32 tectonics, analogous to the their stratigraphic variations of seafloor metalliferous 33 sediments at present and in the Mesoarchean 34 36 37 Keywords Banded iron formations, Eoarchean, Isua supracrustal belt, bioessential elements, RI PT 35 seawater compositions 38 39 Introduction Coevolution of the surface environment and life through time is one of the most 41 significant features of the earth Decoding of ocean chemistry in the early Earth is a key 42 issue to understand the origin and evolution of life, but it is difficult to directly estimate 43 the composition because ancient seawater cannot be preserved The geochemistry of 44 banded iron formations (BIFs) provides one of the powerful proxies to estimate the 45 ancient seawater because they ubiquitously occur in the Archean, and contain high 46 abundances of transitional metals and rare earth elements (REEs).Their REE + Y 47 patterns and trace element compositions (e.g Ni, Cr, Co and U) are considered to be 48 related with contemporaneous ocean chemistry (e.g Bau and Dulski, 1996; Bau and 49 Dulski, 1999; Bjerrum and Canfield, 2002; Bolhar et al., 2004; Konhauser et al., 2009; 50 Konhauser et al., 2011; Partin et al., 2013; Swanner et al., 2014) Konhauser and his 51 colleagues showed that the Archean BIFs have higher Ni/Fe ratios than post-Archean 52 BIFs and iron-oxide deposits, and suggested that the Archean seawater was more 53 enriched in Ni contents due to higher hydrothermal Ni influx from komatiites to ocean, 54 resulting in prosperity of methanogens because Ni is an essential element to form 55 Cofactor F430 (Konhauser et al., 2009; Pecoits et al., 2009; Mloszewska et al., 2012; 56 Mloszewska et al., 2013), which act as the enzyme catalyzing the release of methane in 57 the final step of methanogenesis However, the estimate is still controversial because the 58 compiled Ni/Fe ratios of the BIFs are highly variable even in a single BIF sequence and 59 because their chemical compositions are dependent on not only seawater composition 60 but also various factors such as sedimentary rates (Kato et al., 1998; Kato et al., 2002), 61 involvement of clastic and volcanic materials (Bau, 1993; Manikyamba et al., 1993;Frei 62 and Polat, 2007;Pecoits et al., 2009; Viehmann et al., 2015a, b), secondary movement AC C EP TE D M AN U SC 40 ACCEPTED MANUSCRIPT 63 accompanied with metamorphism (Bau, 1993; Viehmann et al., 2015a, b) and kinetic of 64 adsorption rates of the elements on the iron oxyhydroxides (Kato et al., 1998; Kato et al., 65 2002), other interference elements (Konhauser et al., 2009), and so on In general, the BIFs contain not only iron oxides (hematite and magnetite) and 67 silica minerals (quartz), which are transformed from amorphous ferrihydrite and silica 68 precipitated from seawater, but also carbonate and silicate minerals (Klein, 2005) The 69 carbonate minerals are precipitated minerals from seawater or diagenetic minerals, and 70 silicate minerals possibly originate from carbonate minerals precipitated from seawater, 71 secondary minerals formed during diagenesis, metamorphism and alteration, and clastic 72 and volcanic material As a result, the whole-rock trace element compositions are 73 dependent on not only compositions of the iron oxides and quartz but also those of other 74 minerals The most predominant minerals of the other silicate minerals are Mg- and 75 Ca-bearing minerals such as amphibole and carbonate minerals (Dymek and Klein, 76 1988; Mloszewska et al., 2012; Mloszewska et al., 2013) They have high REE and 77 transition element contents but the effects of the involvement of the Mg- and Ca-bearing 78 minerals on the whole rock compositions have not been fully evaluated yet M AN U SC RI PT 66 The second component is derived from clastic and volcanic materials They 80 consist of clastic minerals such as detrital minerals of zircon, aluminosilicate minerals 81 and quartz, aeolian dusts, and volcanic exhalative materials of tiny insoluble grains or 82 colloidal particles Some previous studies tried eliminating contamination of the clastic 83 materials based on arbitrarily determined threshold values of some detritus-loving 84 elements such as Al, Ti, Sc, Rb, Y, Zr, Hf and Th (e.g Konhauser et al., 2009; Partin et 85 al., 2013) However, even insignificant contaminations of clastic materials resulted in 86 significant influence on the REE and transitional element compositions of the BIFs 87 because they are much more abundant in clastic and exhalative materials relative to pure 88 chemical sediments (Bolhar et al., 2004; Viehmann et al., 2015a, b), and are more 89 abundant than the index elements of Zr, Y and Hf in most clastic and volcanic materials 90 except for zircon Therefore, it is necessary to more strictly eliminate the 91 contaminations AC C EP TE D 79 92 The 3.8–3.7 Ga Isua supracrustal belt (ISB) in southern West Greenland contains 93 one of the oldest sedimentary rocks including BIFs and cherts, and have a potential to 94 estimate the Eoarchean surface environments (Fig 1) Thus, since early 1980s (Appel, ACCEPTED MANUSCRIPT 1980), many geochemical studies for the BIFs have been performed for their trace 96 element compositions (Dymek and Klein, 1988; Bolhar et al., 2004), stable isotope 97 ratios of S (Mojzsis et al., 2003; Whitehouse et al., 2005), Si (André et al., 2006) and Fe 98 (Dauphas et al., 2004; Dauphas et al., 2007; Whitehouse and Fedo, 2007; Yoshiya et al., 99 2015), Pb isotope systematics (Moorbath et al., 1973; Frei et al., 1999; Frei and Polat, 100 2007) and Sm–Nd isotope systematics (Shimizu et al., 1990; Frei et al., 1999; Frei and 101 Polat, 2007) RI PT 95 Dymek and Klein (1988) classified the BIFs into quartz–magnetite IF, 103 amphibole-rich magnesian IF, calcite- and dolomite-rich carbonate IF and graphite-, 104 ripidolite- and almandine-rich graphitic and aluminous IF, and analyzed the whole-rock 105 REE compositions They suggested that they were precipitated from seawater with 106 inputs of high-temperature (> 300 ˚C) hydrothermal fluid because of positive Eu 107 anomalies of the shale-normalized REE+Y patterns Moreover, they showed that the 108 graphitic and aluminous IFs have higher REE and transition element contents (e.g Sc, V, 109 Cr, Co, Ni, Cu, Zn, Y, REE and U) than others due to inputs of detrital materials Bolhar 110 et al (2004) showed that PAAS-normalized REE + Y patterns of the BIFs share modern 111 seawater-like character such as positive La (LaSN/(3PrSN - 2NdSN) > 1) and Y (Y/Ho >ca 112 26) anomalies and low LREE to HREE ratios (LaSN/YbSN< 1) with the exception of Eu 113 (EuSN/0.67SmSN + 0.33TbSN) and Ce (CeSN/(2PrSN - NdSN)) anomalies However, the 114 relationship of the patterns with lithofacies was still ambiguous due to lack of their 115 mineralogical and major element composition data EP TE D M AN U SC 102 This study presents major and trace element contents of the BIFs systematically 117 collected from stratigraphically lower to upper levels in the ISB to estimate the 118 influences of lithofacies and involvement of clastic and volcanic materials on the 119 whole-rock compositions, and to reconstruct evolutions of transition elements of 120 seawater (e.g V, Co, Ni and U) through time Moreover, we estimated the seawater and 121 hydrothermal processes in the Archean oceans, and sedimentary environments of the 122 ISB BIFs based on the relationship between stratigraphy and REE and Y compositions 123 of the BIFs AC C 116 124 ACCEPTED MANUSCRIPT 125 Geological outline and the BIFs descriptions for this study 126 2.1 Geological outline of the Isua supracrustal belt The 3.8–3.7 Ga Isua supracrustal belt (ISB) is located at approximately 150 km 128 northeast of Nuuk, southern West Greenland The southern West Greenland is underlain 129 mainly by the Archean orthogneisses, supracrustal rocks and various types of intrusions, 130 and is subdivide into three terranes: Akia, Akulleq and Tasiusarsuaq terranes from north 131 to south (Fig 1A) The Akulleq terrane is composed mainly of the Eoarchean Itsaq 132 gneisses (3830–3660 Ma) and old supracrustal rocks (Akilia association), the 133 Paleoarchean mafic intrusions (Ameralik dykes) and the Neoarchean Ikkattoq gneisses 134 (2820 Ma) and young supracrustal rocks (Malene supracrustals) (Friend et al., 1988; 135 McGregor et al., 1991; McGregor, 1993) M AN U SC RI PT 127 The ISB is the largest belt of the Akilia association and forms a 35 km long 137 arcuate tract in the northern end of the Akulleq terrane (Fig 1A) The ISB 138 comprises3.8–3.7 Ga volcanic and sedimentary rocks (Nutman et al., 1993; Nutman et 139 al., 1996; Crowley et al., 2002; Crowley, 2003; Nutman et al., 2007; Nutman and Friend, 140 2009), and it is considered that it occurs as an enclave within the Itsaq Gneiss (Fig 1B) 141 The ISB is composed mainly of four lithofacies (Komiya et al., 1999): (1) mafic–felsic 142 clastic sedimentary rocks including black shale and minor conglomerate, (2) chemical 143 sedimentary rocks of BIFs, chert and carbonate rocks, (3) basaltic and basaltic andesitic 144 volcanic rocks including pillow lava, pillow breccia, and related intrusive rocks and (4) 145 ultramafic rocks They were subsequently intruded by the Paleoarchean Ameralik 146 (Tarssartoq) dykes, and the Proterozoic N–S-trending high-Mg andesite dikes (Nutman, 147 1986) EP AC C 148 TE D 136 Although it was previously considered that the ISB comprises 149 volcano-sedimentary successions, it has, recently, been widely considered that it is 150 composed of some tectonic slices bounded by faults (Nutman, 1986; Appel et al., 1998; 151 Komiya et al., 1999; Myers, 2001; Rollinson, 2002; Rollinson, 2003; Nutman and 152 Friend, 2009).But, the origins of the tectonic slices are controversial, and two ideas 153 were mainly proposed: collision and amalgamation of allochthonous terranes and 154 peeling and accretion of oceanic crusts during successive accretion of oceanic crusts, 155 respectively (e.g Komiya et al., 1999; Nutman and Friend, 2009) The former is that the ACCEPTED MANUSCRIPT slices or panels were formed after the intrusions of the granitic rocks, due to collision 157 and amalgamation of some terranes with different geologic histories (e.g.Nutman, 1986; 158 Nutman et al., 1997a; Rollinson, 2002; Crowley, 2003; Rollinson, 2003; Nutman and 159 Friend, 2009) Especially, Nutman and the colleagues proposed that the ISB comprises 160 two tectonic belts with different origins based on age distributions of detrital zircons in 161 quartzite and felsic sedimentary rocks and orthogneisses intruding into the supracrustal 162 belts (Nutman et al., 1997a;Crowley, 2003; Nutman and Friend, 2009; Nutman et al., 163 2009) The latter is that the tectonic slices are bounded by layer-parallel faults and were 164 formed during accretion of oceanic materials to a continental crust (Komiya et al., 165 1999) SC RI PT 156 The tectonic setting of the ISB isstill controversial Furnes and the colleagues 167 showed an ophiolite-like stratigraphy including pillow lavas and sheeted dykes and 168 estimated that they were formed in the intra-oceanic island arc or mid-oceanic ridge 169 settings based on the geological occurrence and geochemistry of the greenstones 170 (Furnes et al., 2007; Furnes et al., 2009) On the other hand, some groups suggested that 171 the ISB was formed in a subduction zone environment because the greenstones share 172 geochemical signatures with the modern boninites and island arc basalts (Polat et al., 173 2002; Polat and Hofmann, 2003; Polat and Frei, 2005; Dilek and Polat, 2008; Polat et 174 al., 2015) In the case, the BIFs were formed in spreading fore-arc and intra-arc settings 175 associated with trench rollback caused by young and hot oceanic crust (Polat and Frei, 176 2005; Dilek and Polat, 2008; Polat et al., 2015) Komiya and colleagues proposed that 177 the depositional environment ranged from basaltic volcanism at a mid-oceanic ridge 178 through deposition of deep-sea sediments (BIFs/chert) in an open sea to terrigenous 179 sedimentation at the subduction zone based on the OPS-like stratigraphy (Komiya et al., 180 1999; Komiya et al., 2015; Yoshiya et al., 2015) TE D EP AC C 181 M AN U 166 The ISB suffered polyphase metamorphism from greenschist to amphibolite 182 facies (Nutman et al., 1984; Nutman, 1986; Rose et al., 1996; Rosing et al., 1996; 183 Hayashi et al., 2000; Myers, 2001; Komiya et al., 2002;Rollinson, 2002; Rollinson, 184 2003; Arai et al., 2015) Although it is still controversial whether the variation of 185 mineral parageneses and compositions is due to progressive or retrogressive 186 metamorphism (Nutman, 1986), the variation of mineral parageneses and compositions 187 of mafic and pelitic rocks in the northeastern area of the ISB suggested the progressive ACCEPTED MANUSCRIPT 188 metamorphic zonation from greenschist (Zone A) through albite–epidote–amphibolite 189 (Zone B) to amphibolite facies (Zones C and D) The metamorphic pressures and 190 temperatures were estimated 5–7 kbar and 380–550 ˚C in Zones B to D by 191 garnet–hornblende–plagioclase–quartz 192 (Hayashi et al., 2000; Komiya et al., 2002; Arai et al., 2015) garnet–biotite 193 194 2.2 Geological characteristics of the BIFs geothermobarometries RI PT and The BIFs and cherts occur as some layers throughout the ISB (Allaart, 1976; 196 Nutman, 1986; Nutman et al., 1996; Nutman et al., 1997b;Komiya et al., 1999; Nutman 197 et al., 2002; Nutman and Friend, 2009) We studied the BIFs in the northeastern part of 198 the ISB, corresponding to the metamorphic Zone A (Hayashi et al., 2000) (Figs 1B and 199 2A) In this area, the supracrustal rocks have NE-trending strikes with E-dipping, and 200 the stratigraphy of supracrustal rocks in each subunit is composed of pillow lava or 201 massive lava greenstones overlain by BIFs and cherts The BIFs, ca m thick, show 202 mappable-scale syncline structures with underlying pillow lava and hyaloclastite-like 203 greenstones (Fig 2A, B, C) We collected the BIF samples from the bottom on the 204 hyaloclastite-like greenstones to the top in one-side limb of the syncline structures 206 M AN U TE D 205 SC 195 2.3.Lithological characteristics of the BIFs for this study The studied BIFs have sharply-bounded bands with several to tens millimeter 208 thickness The bands are varied in color even within an outcrop: black, white,gray and 209 green in color, dependent on mineral assemblages but independent of their stratigraphy 210 (Fig.3) Mineral assemblages of the BIFs are composed mainly of magnetite + quartz + 211 amphibole (Fig 4), which are typical mineral assemblage of the moderately 212 metamorphosed BIFs (Klein, 2005), but the modal abundances of the constituent 213 minerals are varied so that their colors are variable AC C 214 EP 207 The black bands are composed mainly of euhedral and anhedral magnetite They 215 are elongated in the direction parallel to their banding structure Quartz, actinolitic 216 amphiboles and ripidolitic chlorites are scattered among magnetites (Fig 4A) 217 The white and gray bands are composed mainly of quartz, most of which show 218 sutured grains boundary or wavy extinction suggestive of secondary deformation 219 Magnetites, amphiboles and subordinate amount of calcites ubiquitously occuramong ACCEPTED MANUSCRIPT A GRY B B B B M AN U W GRN SC B cm W RI PT B B TE D GRY W B AC C cm EP B Aoki et al Fig A B ACCEPTED MANUSCRIPT Chl Amp Amp Mgt Qz Qz D Amp M AN U C SC 200 μm RI PT Mgt Amp 200 μm Carb Mgt Mag Qz Amp Mgt Mgt Qz TE D 1000 μm Qz Qz Qz Amp AC C Amp Amp EP E Qz Qz 500 μm Amp Mgt 500 μm Aoki et al Fig ACCEPTED MANUSCRIPT 100 A B 80 60 40 20 0 20 40 60 Fe2O3 (wt.%) 80 C 20 40 60 Fe2O3 (wt.%) M AN U This study Black-type BIF Gray-type BIF 80 100 White-type BIF Green-type BIF 20 40 60 Fe2O3 (wt.%) 80 quartz-magnetite IF magnesian IF aluminous and graphitic IF carbonate-rich IF 100 EP TE D Previous study (Dymek and Klein, 1988)) AC C CaO (wt.%) 100 SC RI PT MgO (wt.%) SiO2 (wt.%) Aoki et al Fig ACCEPTED MANUSCRIPT A Ni (ppm) C 80 Co (ppm) V (ppm) 100 B 60 40 20 D 10 100 80 E RI PT F Rb (ppm) 60 40 20 SC Zn (ppm) Cu (ppm) G 30 15 Y (ppm) Sr (ppm) 20 H 10 20 10 TE D J 15 Sm (ppm) Pr (ppm) EP Ba (ppm) I K 1.0 10 Zr (ppm) M AN U L 0.5 M N O 0.06 0.05 Th (ppm) Yb (ppm) 0.0 U (ppm) AC C 0.1 0.04 0.03 0.02 0.01 0.0 0 20 40 60 Fe2O3 (wt.%) 80 100 0 20 40 60 Fe2O3 (wt.%) 80 100 20 40 60 Fe2O3 (wt.%) 80 100 Aoki et al Fig ACCEPTED MANUSCRIPT 101 10-1 10-2 100 10-1 10-2 10-3 10-3 La Ce Pr Nd PmSm Eu Gd Tb Dy Y Ho Er Tm Yb Lu La Ce Pr Nd PmSm Eu Gd Tb Dy Y Ho Er Tm Yb Lu C PAAS-normalized 100 10-1 TE D 10-2 La Ce Pr Nd PmSm Eu Gd Tb Dy Y Ho Er Tm Yb Lu 100 10-1 10-2 10-3 La Ce Pr Nd PmSm Eu Gd Tb Dy Y Ho Er Tm Yb Lu EP 10-3 D M AN U 101 AC C PAAS-normalized 101 SC 100 B RI PT A PAAS-normalized PAAS-normalized 101 Aoki et al Fig Co (×104) A Ni (×103) B ACCEPTED MANUSCRIPT Fe Cu (×104) D Fe Zn (×103) Mg+Ca Fe Mg+Ca Fe Sm (×105) Fe Pr (×105) Mg+Ca H Fe Yb (×105) AC C EP G Mg+Ca F TE D Y (×103) E M AN U SC C Mg+Ca RI PT Mg+Ca Mg+Ca I Fe Mg+Ca Fe U (×106) This study Black-type BIF White-type BIF Gray-type BIF Green-type BIF Previous study (Dymek and Klein, 1988) quartz-magnetite IF magnesian IF aluminous and graphitic IF carbonate-rich IF Mg+Ca Fe Aoki et al Fig ACCEPTED MANUSCRIPT A 100 B C 80 Ni (ppm) Co (ppm) V (ppm) 60 40 20 E 100 80 Y (ppm) 10 60 40 20 G 1.2 Sm (ppm) Pr (ppm) 0.8 0.6 0.4 0.3 0.2 0.4 H 0.5 1.0 I 0.6 0.4 0.2 J TE D 0.1 0.2 0 L Zr (ppm) 60 0.04 50 Y/Ho EP 0.03 0.02 40 0.01 0 AC C U (ppm) M AN U F SC Zn (ppm) Cu (ppm) RI PT D Yb (ppm) Zr (ppm) (MgO + CaO)/Fe2O3 < 0.1 Black-type BIF White-type BIF Gray-type BIF 30 20 Zr (ppm) (MgO + CaO)/Fe2O3 > 0.1 White-type BIF Gray-type BIF Green-type BIF Aoki et al Fig ACCEPTED MANUSCRIPT 60 50 A 50 B low (MgO+CaO)/Fe2O3 (< 0.1) BIFs regression line 1σ prediction area 40 area encompassing all data 30 30 20 Black-type BIFs 20 Previous study (Frei and Polat, 2007) (Fe2O3 >60wt.%) regression line 1σ prediction area 10 10 area encompassing all data ultramafic rocks (Szilas et al., 2015) basaltic rocks (Polat et al., 2002, 2003) clastic sediments (Bolhar et al., 2005) 0 Zr (ppm) D 10 Zr (ppm) 15 20 M AN U 5 Ni (ppm) 4 3 2 low (MgO+CaO)/Fe2O3 (< 0.1) BIFs low (MgO+CaO)/Fe2O3 (< 0.1) BIFs TE D Ni (ppm) C regression line 1σ prediction area regression line 1σ prediction area area encompassing all data Temagami BIFs (2736 Ma) E 15 Joffre BIFs (2450 Ma) 20 Zr (ppm) 10 Sample No 2.42 AC C 10 Zr (ppm) area encompassing all data EP Ni (ppm) Witwatersrand BIFs (2900 Ma) SC ISB BIFs RI PT Ni (ppm) Ni (ppm) 40 low (MgO+CaO)/Fe2O3 (< 0.1) BIFs regression line 1σ prediction area area encompassing all data Rapitan BIFs (743 Ma) 0 Zr (ppm) Aoki et al Fig 10 ACCEPTED MANUSCRIPT 0.08 0.30 A B 0.25 0.06 0.04 0.15 0.10 0.02 0.05 ISB BIFs 0.4 Zr (ppm) 0.4 15 20 M AN U D 10 Zr (ppm) U (ppm) 0.3 0.2 0.1 TE D U (ppm) C 0.3 Temagami BIFs (2736 Ma) 0.0 0.4 10 Zr (ppm) 15 20 0.2 0.1 Joffre BIFs (2450 Ma) 0 Zr (ppm) 10 EP AC C E 0.3 U (ppm) Witwatersrand BIFs (2900 Ma) SC RI PT U (ppm) U (ppm) 0.20 0.2 0.1 Rapitan BIFs (743 Ma) 0.0 Zr (ppm) Aoki et al Fig 11 ACCEPTED MANUSCRIPT A B 1 ISB BIFs 30 Zr (ppm) C Zr (ppm) 10 M AN U 25 20 15 TE D 10 Rapitan BIFs (743 Ma) Zr (ppm) EP AC C V (ppm) Joffre BIFs (2450 Ma) SC RI PT V (ppm) V (ppm) Aoki et al Fig 12 ACCEPTED MANUSCRIPT 70 12 A 60 10 50 40 30 20 10 ISB BIFs 2 Zr (ppm) 10 TE D M AN U Zr (ppm) EP Joffre BIFs (2450 Ma) SC RI PT Zn (ppm) AC C Zn (ppm) B Aoki et al Fig 13 ACCEPTED MANUSCRIPT 10 A ISB BIFs Zr (ppm) Witwatersrand BIFs (2900 Ma) 1.6 2.5 D 10 Zr (ppm) 15 20 M AN U 1.4 2.0 1.2 Co (ppm) 1.0 0.8 0.4 0.2 TE D 0.6 Temagami BIFs (2736 Ma) 0.0 10 Zr (ppm) 15 20 1.0 0.5 Rapitan BIFs (743 Ma) 0.0 Zr (ppm) EP 1.5 AC C Co (ppm) SC RI PT Co (ppm) Co (ppm) B Aoki et al Fig 14 ACCEPTED MANUSCRIPT 30 10 350 B This study Konhauser et al., 2009 300 25 15 10 Age (Ga) A 2.0 Age (Ga) This study 0.20 350 300 M AN U 0.15 200 U (ppm) Co (ppm) 1.0 Age (Ga) 50 0.10 Age (Ga) C Age (Ga) D Age (Ga) EP 0.0 TE D 0.05 AC C Co (ppm) Partin et al., 2013 100 0.5 Age (Ga) 300 This study Swanner et al., 2014 1.5 V Zn SC RI PT 100 U (ppm) Ni (ppm) 20 V, Zn (ppm) Ni (ppm) 200 Aoki et al Fig 15 ACCEPTED MANUSCRIPT Banded Iron Formation Metabasite A RI PT Y/Ho 60 50 (MgO + CaO)/Fe2O3 < 0.1 Black-type BIF White-type BIF Gray-type BIF SC 40 (MgO + CaO)/Fe2O3 > 0.1 White-type BIF Gray-type BIF Green-type BIF 30 M AN U B (Eu/Eu*)PAAS 4.0 3.0 2.5 10 Distance from the boundary of BIF/underlying greenstone (m) AC C EP TE D 3.5 Aoki et al Fig 16 ACCEPTED MANUSCRIPT Highlights The compositions of BIFs also depend on the lithofacies and contamination We reconstructed the secular variations of V, Co, Ni, Zn and U contents in BIFs The Ni contents in BIFs decreased before 2.7 Ga RI PT The Ni content in the Eoarchean BIFs is much lower than previous estimate AC C EP TE D M AN U SC Chemostratigraphy of the REE+Y contents implies the Eoarchean plate tectonics ... patterns, the contamination results in depletion 344 of LREE in the BIFs, consistent with those of the Green-type BIFs (Fig 7) Despite of the cause of amphibole formation, the occurrence of the amphibole... of contamination- free BIFs more accurately The uranium content of the contamination- free BIF can be also estimated from 444 the Zr vs U content diagram, analogous to the Ni contents of the contamination- free... 35 seawater compositions 38 39 Introduction Coevolution of the surface environment and life through time is one of the most 41 significant features of the earth Decoding of ocean chemistry in the