Skip to main content Accessibility help

Geology and geochemistry of the Yuanjiacun banded iron formation in Shanxi Province, China: constraints on the genesis

  • Yekai Men (a1), Ende Wang (a2), Jianfei Fu (a2), Sanshi Jia (a1), Xinwei You (a2) and Qiangwen He (a2)...


The Yuanjiacun banded iron formation (BIF) is hosted in lower Proterozoic metamorphic strata, and its structures are dominated by bands or streaks. Based on their differences in mineral compositions, the iron ores can be subdivided into haematite quartzite, magnetite quartzite, stilpnomelane magnetite quartzite and stilpnomelane haematite quartzite. The geochemical characteristics of the surrounding rocks show that the protoliths consisted of argillaceous and arenaceous sedimentary rocks. The predominant provenance was a high-maturity felsic sedimentary terrane. The absence of syn-depositional igneous rocks and the tectonic setting discrimination diagrams indicate that the Yuanjiacun BIF formed in a passive continental margin setting. Negligible terrigenous materials were involved in the precipitation of the Yuanjiacun BIF. The precipitation of the Yuanjiacun BIF was predominantly controlled by the mixing of seawater and hydrothermal fluids. Its metallogenic material originated from the leaching of mafic oceanic crust by hydrothermal fluids. The observed Ce anomaly deficiency and heavy Fe isotope enrichment indicate that the Yuanjiacun BIF formed in an anoxic marine environment. In a redox-stratified palaeo-ocean, the Yuanjiacun BIF formed in reducing seawater below the oxidation–reduction transition zone. The Si and O isotope compositions of quartz suggest that the formation of the Yuanjiacun BIF was closely related to submarine hydrothermal activity. The Si and Fe erupted from the seafloor and precipitated by supersaturation and biological oxidation under anoxic conditions, respectively.


Corresponding author

*Author for correspondence: Yekai Men, Email:


Hide All
Alexander, BW, Bau, M, Andersson, P and Dulski, P (2008) Continentally-derived solutes in shallow Archean seawater: rare earth element and Nd isotope evidence in iron formation from the 2.9 Ga Pongola Supergroup, South Africa. Geochimica et Cosmochimica Acta 72, 378–94.
Alibo, DS and Nozaki, Y (1999) Rare earth elements in seawater: particle association, shale-normalization, and Ce oxidation. Geochimica et Cosmochimica Acta 63, 363–72.
Anbar, AD and Rouxel, O (2007) Metal stable isotopes in paleoceanography. Annual Review of Earth and Planetary Sciences 35, 717–46.
Balci, N, Bullen, TD, Witte-Lien, K, Shanks, WC, Motelica, M and Mandernack, KW (2006) Iron isotope fractionation during microbially stimulated Fe(II) oxidation and Fe(III) precipitation. Geochimica et Cosmochimica Acta 70, 622–39.
Bau, M and Dulski, P (1996) Distribution of yttrium and rare-earth elements in the Penge and Kuruman iron-formations, Transvaal Supergroup, South Africa. Precambrian Research 79, 3755.
Bau, M and Dulski, P (1999) Comparing yttrium and rare earths in hydrothermal fluids from the Mid-Atlantic Ridge: implications for Y and REE behaviour during near-vent mixing and for the Y/Ho ratio of Proterozoic seawater. Chemical Geology 155, 7790.
Bau, M, Dulski, P and Mőller, P (1995) Yttrium and holmium in South Pacific seawater: vertical distribution and possible fractionation mechanisms. Chemie der Erde 55, 115.
Bekker, A, Slack, JF, Planavsky, A, Krapez, B, Hofmann, A, Konhauser, KO and Oliver, JR (2010) Iron formation: the sedimentary product of a complex interplay among mantle, tectonic, oceanic, and biospheric processes. Economic Geology 105, 467508.
Bhatia, MR (1983) Plate tectonics and geochemical composition of sandstones. Journal of Geology 91, 611–27.
Bhatia, MR and Crook, KAW (1986) Trace element characteristics of graywackes and tectonic setting discrimination of sedimentary basins. Contributions to Mineralogy and Petrology 92, 181–93.
Boström, K (1973) The origin and fate of ferromanganoan active ridge sediments. Stockholm Contributions in Geology 27, 149243.
Bolhar, R, Kamber, BS, Moorbath, S, Fedo, CM and Whitehouse, MJ (2004) Characterisation of Early Archaean chemical sediments by trace element signatures. Earth and Planetary Science Letters 222, 4360.
Braterman, PS, Cairns-Smith, AG and Sloper, RW (1983) Photo-oxidation of hydrated Fe2+ – significance for banded iron formations. Nature 303, 163–4.
Bullen, TD, White, AF, Childs, CW, Vivit, DV and Schulz, MS (2001) Demonstration of significant abiotic iron isotope fractionation in nature. Geology 29, 699702.
Byrne, RH and Lee, JH (1993) Comparative yttrium and rare earth element chemistries in seawater. Marine Chemistry 44, 121–30.
Byrne, RH and Sholkovitz, ER (1996) Marine chemistry and geochemistry of the lanthanides. In Handbook on the Physics and Chemistry of Rare Earths, Volume 23 (eds Gschneidner, KA Jr. and Eyring, L), pp. 497593. Amsterdam: Elsevier.
Cairns-Smith, AG (1978) Precambrian solution photochemistry, inverse segregation, and banded iron formations. Nature 76, 807–8.
Calvert, SE and Pedersen, TF (1993) Geochemistry of recent oxic and anoxic marine sediments: Implications for the geological record. Marine Geology 113, 6788.
Clout, JMF and Simonson, BM (2005) Precambrian iron formations and iron formation-hosted iron ore deposits. In Economic Geology, One Hundredth Anniversary Volume, 1905–2005 (eds Hedenquist, JW, Thompson, JFH, Goldfarb, RJ and Richards, JP), pp. 643–79. Littleton: Society of Economic Geologists.
Cloud, P (1973) Paleoecological significance of the banded iron-formation. Economic Geology 68, 1135–43.
Cox, R, Lowe, DR and Cullers, RL (1995) The influence of sediment recycling and basement composition on evolution of mudrock chemistry in the southwestern United States. Geochimica et Cosmochimica Acta 59, 2919–40.
Danielson, A, Möller, P and Dulski, P (1992) The europium anomalies in banded iron formations and the thermal history of the oceanic crust. Chemical Geology 97, 89100.
Dauphas, N and Rouxel, O (2006) Mass spectrometry and natural variations of iron isotopes. Mass Spectrometry Reviews 25, 515–50.
Dideriksena, K, Baker, JA and Stipp, SLS (2008) Equilibrium Fe isotope fractionation between inorganic aqueous Fe(III) and the siderophore complex, Fe(III)-desferrioxamine B. Earth and Planetary Science Letters 269, 280–90.
Ding, T, Wan, D, Wang, C and Zhang, F (2004) Silicon isotope compositions of dissolved silicon and suspended matter in the Yangtze River, China. Geochimica et Cosmochimica Acta 68, 205–16.
Douthitt, CB (1982) The geochemistry of the stable isotopes of silicon. Geochimica et Cosmochimica Acta 46, 1449–58.
Douville, E, Bienvenu, P, Charlou, JL, Donval, JP, Fouquet, Y, Appriou, P and Gamo, T (1999) Yttrium and rare earth elements in fluids from various deep-sea hydrothermal systems. Geochimica et Cosmochimica Acta 63, 627–43.
Drever, JI (1974) Geochemical model for the origin of Precambrian banded iron formations. Geological Society of America Bulletin 85, 1099–106.
Du, LL, Yang, CH, Ren, LD, Song, HX, Geng, YS and Wang, YS (2012) The 2.2–2.1Ga magmatic event and its tectonic implication in the Lüliang Mountains, North China Craton. Acta Petrologica Sinica 28, 2751–69 (in Chinese with English abstract).
Dymek, RF and Klein, C (1988) Chemistry, petrology, and origin of banded iron formation lithologies from the 3800 Ma Isua Supracrustal Belt, West Greenland. Precambrian Research 39, 247302.
Finlayson, VA, Konter, JG and Ma, L (2015) The importance of a Ni correction with ion counter in the double spike analysis of Fe isotope compositions using a 57Fe/58Fe double spike. Geochemistry, Geophysics, Geosystems 16, 4209–22.
Floyd, PA and Leveridge, BE (1987) Tectonic environment of the Devonian Gramscatho basin, south Cornwall: framework mode and geochemical evidence from turbiditic sandstones. Journal of the Geological Society, London 144, 531–42.
Floyd, PA, Winchester, JA and Park, RG (1989) Geochemistry and tectonic setting of Lewisian clastic metasediments from the Early Proterozoic Loch Maree Group of Gairloch, N.W. Scotland. Precambrian Research 45, 203–14.
Fralick, PW and Kronberg, BI (1997) Geochemical discrimination of clastic sedimentary rock sources. Sedimentary Geology 113, 111–24.
Geng, YS, Yang, CH andWan, YS (2006) Paleoproterozoic granitic magmatism in the Lüliang area, North China Craton: constraint from isotopic geochronology. Acta Petrologica Sinica 22, 305–14 (in Chinese with English abstract).
German, CR and Elderfield, H (1990) Application of the Ce-anomaly as a paleoredox indicator: the ground rules. Paleoceanography 5, 823–33.
Goodwin, AM (1973) Archean iron-formations and tectonic basins of the Canadian Shield. Economic Geology 68, 915–33
Govett, GJS (1966) Origin of banded iron formations. Geological Society of America Bulletin 77, 1191–212.
Gross, GA and McLeod, CR (1980) A preliminary assessment of the chemical composition of iron formation in Canada. Canadian Mineralogist 18, 223–9.
Heimann, A, Johnson, CM, Beard, BL, Valley, JW, Roden, EE, Spicuzza, MJ and Beukes, NJ (2010) Fe, C, and O isotope compositions of banded iron formation carbonates demonstrate a major role for dissimilatory iron reduction in ∼2.5 Ga marine environments. Earth and Planetary Science Letters 294, 818.
Hou, K, Ma, X, Li, Y, Liu, F and Han, D (2017) Chronology, geochemical, Si and Fe isotopic constraints on the origin of Huoqiu banded iron formation (BIF), southeastern margin of the North China Craton. Precambrian Research 298, 351–64.
Hu, J, Wang, H and Wang, M (2017) Geochemistry and origin of the Neoproterozoic Dahongliutan banded iron formation (BIF) in the Western Kunlun orogenic belt, Xinjiang (NW China). Ore Geology Reviews 89, 836–57.
Huston, DL and Logan, GA (2004) Barite, BIFs and bugs: evidence for the evolution of the Earth’s early hydrosphere. Earth and Planetary Science Letters 220, 4155.
Isley, AE (1995) Hydrothermal plumes and the delivery of iron to banded iron formation. Journal of Geology 103, 169–85.
James, HL (1954) Sedimentary facies of iron-formation. Economic Geology 49, 235–93.
Jiang, SY, Ding, TP, Wang, DF and Li, YH (1993) Silicon isotopic compositions of Archean Banded Si–Fe Formation (BIF) in the Gongchangling ore deposit, Liaoning Province, China. Science in China (Series B) 36, 482–9.
Johnson, CM, Beard, BL, Klein, C, Beukes, NJ and Roden, EE (2008) Iron isotopes constrain biologic and abiologic processes in banded iron formation genesis. Geochimica et Cosmochimica Acta 72, 151–69.
Kappler, A, Pasquero, C, Konhauser, KO and Newman, DK (2005) Deposition of banded iron formations by anoxygenic phototrophic Fe(II)-oxidizing bacteria. Geology 33, 865–8.
Kholodov, VN and Butuzova, GY (2001) Problems of iron and phosphorus geochemistry in the Precambrian. Lithology Mineral Resources 36, 291302.
Klein, C (2005) Some Precambrian banded iron-formations (BIF) from around the world: their age, geologic setting, mineralogy, metamorphism, geochemistry, and origins. American Mineralogist 90, 1473–99.
Klinkhammer, G, Elderfield, H and Hudson, A (1983) Rare earth elements in seawater near hydrothermal vents. Nature 305, 185–8.
Knauth, LP (2005) Temperature and salinity history of the Precambrian ocean: implications for the course of microbial evolution. Palaeogeography, Palaeoclimatology, Palaeoecology 219, 5369.
Knauth, LP and Lowe, DR (2003) High Archean climatic temperature inferred from oxygen isotope geochemistry of cherts in the 3.5 Ga Swaziland Supergroup, South Africa. Geological Society of America Bulletin 115, 566–80.
Konhauser, KO, Amskold, L, Lalonde, SV, Posth, NR, Kappler, A and Anbar, A (2007) Decoupling photochemical Fe (II) oxidation from shallow-water BIF deposition. Earth and Planetary Science Letters 258, 87100.
Lan, TG, Fan, HR, Hu, FF, Yang, KF, Zheng, XL and Zhang, HD (2012) Geological and geochemical characteristics of Paleoproterozoic Changyi banded iron formation deposit, Jiaodong Peninsula of eastern China. Acta Petrologica Sinica 28, 3595–611 (in Chinese with English abstract).
Lascelles, DF (2006) The genesis of the Hope Downs iron ore deposit, Hamersley Province, Western Australia. Economic Geology 101, 1359–76.
Lepp, HS and Goldich, SS (1964) Origin of Precambrian iron formations. Economic Geology 59, 1025–60.
Li, YH, Ding, TP and Wan, DF (1995) Experimental study of silicon isotope dynamic fractionation and its application in geology. Chinese Journal of Geochemistry 14, 212–19.
Li, Y, Hou, K, Wan, D, Zhang, Z and Yue, G (2014) Precambrian banded iron formations in the North China Craton: silicon and oxygen isotopes and genetic implications. Ore Geology Reviews 57, 299307.
Li, YH, Hou, KJ, Wan, DF and Zhang, ZJ (2012) A compare geochemistry study for Algoma- and Superior-type banded iron formations. Acta Petrologica Sinica 28, 3513–9 (in Chinese with English abstract).
Li, YH, Hou, KJ, Wang, DF, Zhang, ZJ and Le, GL (2010) Formation mechanism of Precambrian banded iron formation and atmosphere and ocean during early stage of the Earth. Acta Geologica Sinica 84, 1359–73 (in Chinese with English abstract).
Li, HM, Wang, DH, Li, LX, Cheng, J, Yang, XQ and Liu, MJ (2012) Metallogeny of iron deposits and resource potential of major iron minerogenetic units in China. Geology in China 39, 559–80 (in Chinese with English abstract).
Li, ZH, Zhu, XK and Tang, SH (2012) Fe isotope compositions of banded iron formation from Anshan-Benxi area: constraints on the formation mechanism and Archean ocean environment. Acta Petrologica Sinica 28, 3545–58 (in Chinese with English abstract).
Liu, SW, Zhang, J, Li, QG, Zhang, LF, Wang, W and Yang, PT (2012) Geochemistry and U-Pb zircon ages of metamorphic volcanic rocks of the Paleoproterozoic Lüliang Complex and constraints on the evolution of the Trans-North China Orogen, North China Craton. Precambrian Research 222–223, 173–90.
Maliva, RG, Knoll, AH and Simonson, BM (2005) Secular change in the Precambrian silica cycle: insights from chert petrology. Geological Society of America Bulletin 117, 835–45.
McLennan, SM (1989) Rare earth elements in sedimentary rocks: influence of provenance and sedimentary processes. Reviews in Mineralogy and Geochemistry 21, 169200.
McLennan, SM, Hemming, S, McDaniel, DK and Hanson, GN (1993) Geochemical approaches to sedimentation, provenance and tectonics. Geological Society of America Special Paper 284, 2140.
McLennan, SM and Taylor, SR (1980) Th and U in sedimentary rocks: crustal evolution and sedimentary recycling. Nature 285, 621–4.
McLennan, SM and Taylor, SR (1991) Sedimentary rocks and crustal evolution: tectonic setting and secular trends. Journal of Geology 99, 121.
Michard, A, Michard, G, Stüben, D, Stoffers, P, Cheminée, JL and Binard, N (1993) Submarine thermal springs associated with young volcanoes: the Teahitia vents, Society Islands, Pacific Ocean. Geochimica et Cosmochimica Acta 57, 4977–86.
Mloszewska, AM, Pecoits, E, Cates, NL, Mojzsis, SJ, O’Neil, J, Robbins, LJ and Konhauser, KO (2012) The composition of Earth’s oldest iron formations: the Nuvvuagittuq Supracrustal Belt (Québec, Canada). Earth and Planetary Science Letters 317, 331–42.
Nesbitt, HW and Young, GM (1982) Early Proterozoic climates and plate motions inferred from major element chemistry of lutites. Nature 299, 715–7.
Nozaki, Y, Alibo, DS, Amakawa, H, Gamo, T and Hasumoto, H (1999) Dissolved rare earth elements and hydrography in the Sulu Sea. Geochimica et Cosmochimica Acta 63, 2171–81.
Nozaki, Y, Zhang, J and Amakawa, H (1997) The fractionation between Y and Ho in the marine environment. Earth and Planetary Science Letters 148, 329–40.
Polat, A and Frei, R (2005) The origin of early Archean banded iron formations and of continental crust, Isua, southern West Greenland. Precambrian Research 138, 151–75.
Rao, TG and Naqvi, SM (1995) Geochemistry, depositional environment and tectonic setting of the BIF’s of the Late Archaean Chitradurga Schist Belt, India. Chemical Geology 121, 217–43.
Robert, F and Ali, P (2007) Source heterogeneity for the major components of 3.7 Ga Banded Iron Formations (Isua Greenstone Belt, Western Greenland): tracing the nature of interacting water masses in BIF formation. Earth and Planetary Science Letters 253, 266–81.
Robert, F and Chaussidon, M (2006) A palaeotemperature curve for the Precambrian oceans based on silicon isotopes in cherts. Nature 443, 969–72.
Rollinson, HR (1993) Using Geochemical Data: Evolution, Presentation, Interpretation. Harlow: Longman, 352 pp.
Roser, BP and Korsch, RJ (1986) Determination of tectonic setting of sandstone-mudstone suite using SiO2 content and K2O/Na2O ratio. Journal of Geology 94, 635–50.
Roser, BP and Korsch, RJ (1988) Provenance signatures of sandstone-mudstone suites determined using discrimination function analysis of major-element data. Chemical Geology 67, 119–39.
Rouxel, OJ, Bekker, A and Edwards, KJ (2005) Iron isotope constraints on the Archean and Paleoproterozoic ocean redox state. Science 307, 1088–91.
Shaw, DM (1980) Development of the early continental crust. Part III. Depletion of incompatible elements in the mantle. Precambrian Research 10, 281–99.
Shen, BF, Song, LS and Li, HZ (1982) An analysis of the sedimentary facies and the formation condition of the Yuanjiacun iron formation, Lanxian County, Shanxi Province, China. Journal of Changchun Geological Institution 25, 3151 (in Chinese with English abstract).
Shen, QH, Song, HX, Yang, CH and Wan, YS (2011) Petrochemical characteristics and geological significations of banded iron formations in the Wutai Mountain of Shanxi and Qian’an of eastern Hebei. Acta Petrologica et Mineralogica 30, 161–71 (in Chinese with English abstract).
Simonen, A (1953) Stratigraphy and sedimentation of the Svecofennidic, Early Archean supracrustal rocks in southwestern Finland. Bulletin of the Geological Society of Finland 160, 164.
Steinhoefel, G, von Blanckenburg, F, Horn, I, Konhauser, KO, Beukes, NJ and Gutzmer, J (2010) Deciphering formation processes of banded iron formations from the Transvaal and the Hamersley successions by combined Si and Fe isotope analysis using UV femtosecond laser ablation. Geochimica et Cosmochimica Acta 74, 2677–96.
Sugitani, K (1992) Geochemical characteristics of Archean cherts and other sedimentary rocks in the Pilbara Block, Western Australia: evidence for Archean seawater enriched in hydrothermally-derived iron and silica. Precambrian Research 57, 2147.
Sun, SS and McDonough, WF (1989) Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and processes. In Magmatism in the Ocean Basalts (eds Saunders, AD and Norry, MJ), pp. 313–45. Geological Society of London, Special Publication no. 42.
Valkiers, S, Ding, T, Inkret, M, Ruße, K and Taylor, P (2005) Silicon isotope amount ratios and molar masses for two silicon isotope reference materials: IRMM-018a and NBS28. International Journal of Mass Spectrometry 242, 319–21.
Wan, YS, Geng, YS, Shen, QH and Zhang, RX (2000) Khondalite series – geochronology and geochemistry of the Jiehekou Group in Luliang area, Shanxi province. Acta Petrologica Sinica 16, 4958 (in Chinese with English abstract).
Wang, CL, Zhang, LC, Dai, YP and Lan, CY (2015a) Geochronological and geochemical constraints on the origin of clastic meta-sedimentary rocks associated with the Yuanjiacun BIF from the Lüliang Complex, North China. Lithos 212–215, 231–46.
Wang, CL, Zhang, LC, Lan, CY and Dai, YP (2014) Rare earth element and yttrium compositions of the Paleoproterozoic Yuanjiacun BIF in the Lüliang area and their implications for the Great Oxidation Event (GOE). Science China: Earth Sciences 57, 2469–85 (in Chinese with English abstract).
Wang, CL, Zhang, LC, Lan, CY, Li, HZ and Huang, H (2015b) Analysis of sedimentary facies and depositional environment of the Yuanjiacun banded iron formation in the Lüliang area, Shanxi Province. Acta Petrologica Sinica 31, 1671–93 (in Chinese with English abstract).
Whitehouse, MJ and Fedo, CM (2007) Microscale heterogeneity of Fe isotopes in >3.71 Ga banded iron formation from the Isua Greenstone Belt, Southwest Greenland. Geology 35, 719–22.
Wise, SA and Watters, JRL (2005) National Institute of Standards and Technology Report of Investigation, Reference Materials 8535, 8536, 8537. Gaithersburg, Maryland: National Institute of Standards and Technology, United States Department of Commerce, 2 pp.
Wronkeiwicz, DJ and Condie, KC (1989) Geochemistry and provenance of sediments from the Pongola Surpergroup, South Africa: evidence for a 3.0 Ga old continental craton. Geochimica et Cosmochimica Acta 53, 1537–49.
Wu, FY, Zhang, YB, Yang, JH, Xie, LW and Yang, YH (2008) Zircon U–Pb and Hf isotopic constraints on the Early Archean crustal evolution in Anshan of the North China Craton. Precambrian Research, 167, 339–62.
Yu, JH, Wang, DZ and Wang, CY (1997) Ages of the Lüliang Group and its main metamorphism in the Lüliang Mountains, Shanxi: evidence from single-grain zircon U–Pb ages. Geological Review 43, 403–8.
Zhai, MG,Bian, AG and Zhao, TP (2000) Amalgamation of the supercontinental of the North China Craton and its break up during late-middle Proterozoic. Science in China (Series D) 43, 219–32.
Zhang, YS, Amakawa, H and Nozaki, Y (1994) The comparative behaviors of yttrium and lanthanides in the seawater of the North Pacific. Geophysical Research Letters 21, 2677–80.
Zhang, LC, Zhai, MG, Wan, YS, Guo, JH, Dai, YP, Wang, CL and Liu, L (2012) Study of the Precambrian BIF-iron deposits in the North China Craton: progresses and questions. Acta Petrologica Sinica 28, 3431–45 (in Chinese with English abstract).
Zhao, GC, Sun, M, Wilde, SA and Li, SZ (2005) Late Archean to Paleoproterozoic evolution of the North China Craton: key issues revisited. Precambrian Research 136, 177202.
Zhao, GC, Wilde, SA, Guo, JH, Cawood, PA, Sun, M and Li, XP (2010) Single zircon grains record two continental collisional events in the North China Craton. Precambrian Research 177, 266276.
Zhao, GC, Wilde, SA, Sun, M, Li, SZ, Li, XP and Zhang, J (2008) SHRIMP U–Pb zircon ages of granitoid rocks in the Lüliang complex: implications for the accretion and evolution of the Trans-North China Orogen. Precambrian Research 160, 213–26.
Zhu, JC, Zhang, FS and Xu, KQ (1988) Depositional environment and metamorphism of early Proterozoic iron formation in the Lüliangshan Region, Shanxi Province, China. Precambrian Research 39, 3950.


Related content

Powered by UNSILO

Geology and geochemistry of the Yuanjiacun banded iron formation in Shanxi Province, China: constraints on the genesis

  • Yekai Men (a1), Ende Wang (a2), Jianfei Fu (a2), Sanshi Jia (a1), Xinwei You (a2) and Qiangwen He (a2)...


Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed.