Back to article

Figures and tables

A secular increase in continental crust nitrogen during the Precambrian

B.W. Johnson1,2,

1School of Earth and Ocean Sciences, University of Victoria, Victoria BC, Canada
2Department of Geological Sciences, University of Colorado, Boulder, Boulder CO, USA

C. Goldblatt1

1School of Earth and Ocean Sciences, University of Victoria, Victoria BC, Canada

Affiliations  |  Corresponding Author  |  Cite as  |  Funding information

Johnson, B.W., Goldblatt, C. (2017) A secular increase in continental crust nitrogen during the Precambrian. Geochem. Persp. Let. 4, 24–28.

NSERC, Virtual Planetary Library.

Geochemical Perspectives Letters v4  |  doi: 10.7185/geochemlet.1731
Received 22 March 2017  |  Accepted 26 July 2017  |  Published 1 September 2017
Copyright © 2017 European Association of Geochemistry




Table 1 Proportion of till samples in each age group that have high (>400 ppm), low (<54 ppm), and moderate (in between) N.
Age% low% moderate% high
Archean10000
Palaeoproterozoic75250
Neoproterozoic106030
Phanerozoic05050
Back to article | Download in Excel


Figure 1 Nitrogen concentration in glacial tills through time. Means of triplicate analyses of each sample, with standard deviation, are shown with shapes representing modern continent of exposure. Black lines and coloured boxes show mean and standard deviation of Archean-Palaeoproterozoic, Neoproterozoic, and Phanerozoic samples. Low N samples from units that have eroded primarily igneous terranes in North America are noted, and discussed in the text.
Back to article | Download in Powerpoint


Figure 2 Nitrogen isotope values (‰) in glacial tills through time. Averages (black lines) for each time period (Archean-Palaeoproterozoic, Neoproterozoic, and Phanerozoic) are equivalent within error (one standard deviation, coloured boxes), indicating no change in the isotopic character of the continental crust through time.
Back to article | Download in Powerpoint

Table 2 Distribution of upper continental crust ages after Goodwin (1991

Goodwin, A.M. (1991) Precambrian Geology: the Dynamic Evolution of the Continental Crust. Academic Press, London.

, 1996

Goodwin, A.M. (1996) Principles of Precambrian geology. Academic Press, London.

). We assume that tills accurately sample crust of each age, and that the Mesoproterozoic has the same N concentration as the Archean/Palaeoproterozoic.
Age% crustN (ppm)
Phanerozoic28380
Neoproterozoic31250
Mesoproterozoic1666
Palaeoproterozoic1566
Archean1066

Total upper crust

[N] = 210 ppm mass = 2.5 x 1018 kg N
Back to article | Download in Excel

Back to article

Supplementary Figures and Tables


Table S-1 Nitrogen concentration and stable isotopic data. Samples analysed are from Gaschnig et al. (2016) and sample names herein are those used in the original publication. Age is in Ga, N concentration is in ppm and δ15N is in per mille. Non-N data is from Gaschnig et al. (2016) with SiO2 and K2O in wt. % with all others in ppm. CIA is Al2O3/(Al2O3 + CaO + K2O + Na2O) corrected to remove carbonate and apatite CaO. Continent indicates continent where sample was collected. AF – Africa, NA – North America, AS – Asia, SA – South America.
Stratigraphic unitContinentAgeNδ15N SiO2Al2O3CaONa2OK2OCIARbZrCs
Mozaan GroupAF2.9244.358.88.950.380.781.677149.793.1
Mozaan GroupAF2.9315.658.18.750.520.631.427235.184.91.32
Mozaan GroupAF2.9285.858.98.940.130.080.968833.41032.53
Mozaan GroupAF2.9

59.39.070.140.721.787475.81664.09
Mozaan GroupAF2.9

549.520.760.661.517237.789.21.38
Mozaan GroupAF2.9

57.68.511.250.561.697037.4891.18
Mozaan GroupAF2.9

55.97.820.160.510.88117.366.30.94
Afrikander FrmAF2.993.1648.495.940.50.41809.292.70.31
Afrikander FrmAF2.9112.864.18.246.090.380.4982


Afrikander FrmAF2.9164.863.98.325.990.420.34838.1450.30.31
Afrikander FrmAF2.9

62.18.535.870.91.0767


Promise Formation West Rand Group WitwatersrandAF2.9224.26115.50.540.542.437897.71595.01
Promise Formation West Rand Group WitwatersrandAF2.9214.185.67.181.250.931.486057.244.13.34
Promise Formation West Rand Group WitwatersrandAF2.9284.563.411.10.660.440.598425.51201.26
Coronation Formation West Rand Group WitwatersrandAF2.933274.315.10.210.353.29781241929.07
Coronation Formation West Rand Group WitwatersrandAF2.9352.572.315.10.460.333781101818.77
Coronation Formation West Rand Group WitwatersrandAF2.930-0.968.815.70.470.382.728097.61917.14
Coronation Formation West Rand Group WitwatersrandAF2.9

72.215.70.70.32.578193.72137.32
Coronation Formation West Rand Group WitwatersrandAF2.9

71.713.90.140.232.6580


Bottle Creek FormationNA2.4102.872.213.10.614.391.8257661301.84
Bottle Creek FormationNA2.4420.970.613.40.493.92259682001.73
Bottle Creek FormationNA2.4482.771.713.20.523.971.8959562151.66
Bottle Creek FormationNA2.4

70.913.50.464.11.7659552091.23
Gowganda FormationNA2.4113.469.313.80.345.081.45750.785.41.27
Gowganda FormationNA2.4100.570.513.80.264.132.215991.12562.43
Gowganda FormationNA2.4132.1








Bruce FormationNA2.419-0.971.314.10.354.232.95796.51530.93
Bruce FormationNA2.4123.662.317.40.413.63.84621591971.89
Bruce FormationNA2.4306.670.5130.323.511.466368.71411.38
Ramsay Lake FormationNA2.4143.161.215.80.532.311.8671711632.31
Ramsay Lake FormationNA2.4203.662.612.92.511.431.386868.11432.4
Ramsay Lake FormationNA2.414359.2150.711.411.557677.31542.35
Gowganda FormationNA2.4113.465.514.90.454.522.075966.71381.07
Gowganda FormationNA2.4100.565.315.10.484.82.175876.21611.22
Gowganda FormationNA2.4132.170.213.60.374.962.065648.11520.61
Gowganda FormationNA2.4

66.714.20.274.641.665960.11480.80
Gowganda FormationNA2.4

65.215.21.165.622.2753671541.12
Gowganda FormationNA2.4

64.715.31.155.672.395372.41481.08
Gowganda FormationNA2.4

71.813.50.724.983.145295.61371.43
Gowganda FormationNA2.4

65.214.70.714.752.25757.7128
Gowganda FormationNA2.4

66.714.50.685.340.915833.71310.77
Gowganda FormationNA2.4

74.1111.132.523.8352


Gowganda FormationNA2.4

66.712.63.163.91.244935.394.80.46
Gowganda FormationNA2.4

66.912.52.142.311.565837.61291.25
Makganyene FormationAF2.3154.950.97.046.50.060.549217.11012
Makganyene FormationAF2.3154.853.38.185.370.080.749122.51092.12
Makganyene Formation Transvaal/GriqualandAF2.3182.753.25.966.110.030.2987.1993.41.59
Makganyene Formation Transvaal/GriqualandAF2.3

60.310.60.590.051.2789361062.08
Makganyene FormationAF2.3

618.811.690.031.458654.81051.54
Makganyene FormationAF2.3

61.49.042.070.041.8183461211.54
Timeball Hill FormationAF2.22955.261.819.60.830.225.437526620218.3
Timeball Hill FormationAF2.23064.563.8160.911.073.267117318013.6
Timeball Hill FormationAF2.23055.563.415.90.971.243.17016814913.2
Timeball Hill FormationAF2.2

71113.333.210.914849.386.23.72
Timeball Hill FormationAF2.2

64.115.12.421.383.016615815912.6
Timeball Hill FormationAF2.2

64.515.51.451.273.096817014813.7
Duitschland FormationAF2.42305.856.824.50.230.146.147819822417
Duitschland FormationAF2.42395.355.123.30.250.155.387918329715.1
Duitschland FormationAF2.42205.363.110.91.40.061.98469.91134.01
Duitschland FormationAF2.4

63.9112.150.051.888572.41294.08
Duitschland FormationAF2.4

31.77.5710.420.050.799128.871.91.79
Konnarock FormationNA0.75412.264.7150.652.075.45602203525.66
Konnarock FormationNA0.73619.368.114.20.522.225.22592023925.3
Konnarock FormationNA0.74516.468.214.20.683.064.26581623342.57
Konnarock FormationNA0.7

6813.61.443.093.64551393002.43
Konnarock FormationNA0.7

67.613.81.623.13.69541403312.44
Konnarock FormationNA0.7

67.713.81.63.13.73541363362.31
Konnarock FormationNA0.7

68.913.91.562.754.39541543873.78
Konnarock FormationNA0.7

69.113.91.772.854.58531533603.51
Gucheng Formation near bottom of unitAS0.75243.366.514.41.371.243.556599.11723.64
Gucheng FormationAS0.75453.465.614.12.111.373.1764911943.36
Gucheng FormationAS0.75423.16814.10.991.253.226790.81973.22
Gucheng Formation top of unitAS0.7

66.2150.470.633.63731012053.88
Gucheng FormationAS0.7

67.913.70.420.583.367390.82083.97
Nantuo Formation lower part of unitAS0.645394.366.714.81.081.313.536696.61873.97
Nantuo Formation middle part of unitAS0.645193.26614.71.391.253.62651022134.24
Nantuo Formation top of unitAS0.645303.867.314.51.571.193.76651052384.46
Nantuo FormationAS0.64

58.716.32.312.273.160941593.81
Nantuo FormationAS0.64

64.613.82.60.973.29681002165.31
Nantuo FormationAS0.64

66.113.21.790.962.946890.32114.71
Nantuo FormationAS0.64

66.213.41.780.813.126994.12054.83
Nantuo FormationAS0.64

66.613.81.680.853.386998.91795.04
Nantuo FormationAS0.64

64.514.621.673.32621081844.81
Nantuo FormationAS0.64

65.114.62.181.443.436493.91903.92
Nantuo FormationAS0.64

64.914.21.970.993.63671031934.4
Nantuo FormationAS0.64

63.814.42.40.813.8691071884.71
Nantuo FormationAS0.64

64.914.22.460.83.76681061994.48
Pocatello Formation upper diamictiteNA0.7994.671.111.81.710.313.89711323884.23
Pocatello Formation upper diamictiteNA0.7784.170.712.70.490.733.95681363404.36
Pocatello Formation upper diamictiteNA0.7785.472.611.60.760.883.48651203003.89
Pocatello Formation upper diamictiteNA0.7

72.411.90.461.073.43671223253.64
Pocatello Formation lower diamictiteNA0.7

63.814.80.741.484.3671896783.96
Pocatello Formation lower diamictiteNA0.7

6613.40.621.433.89661525323.24
Blaubeker FormationAF0.7106476.9100.321.523.02621102042.38
Blaubeker FormationAF0.7864.7759.851.422.132.835392.72431.67
Blaubeker FormationAF0.7744.477.510.30.331.473.39621182424.2
Kaigas FormationAF0.753153.862.216.50.962.583.41641922289.74
Kaigas FormationAF0.753533.762.315.43.093.132.79541612506.86
Kaigas FormationAF0.751933.366.513.53.213.323.044918917913
Numees FormationAF0.6966.473.711.31.661.333.55581571515.04
Numees FormationAF0.6897.868.512.22.892.083.3954

4.5
Numees FormationAF0.61008.557.418.31.412.044.564


Numees FormationAF0.6

71.113.21.322.213.33591742376
Numees FormationAF0.6

70.614.50.392.174.92612311883.85
Numees FormationAF0.6

70.814.60.312.35.14612322195.28
Ghaub FormationAF0.64163-0.438.78.4420.760.652.696410113711.5
Ghaub FormationAF0.644632.2255.1635.350.491.456352.363.75.63
Ghaub FormationAF0.643201.25013.59.611.143.366512719311.9
Chuos FormationAF0.73062.842.27.7714.030.712.84601361259.27
Chuos FormationAF0.7467346.77.9511.791.122.58561021504.12
Chuos FormationAF0.73972.5








Gaskiers FormationNA0.58831.365.515.51.072.894.46581132038.28
Gaskiers FormationNA0.581092.667.9140.883.52.885877.11795.2
Gaskiers FormationNA0.581032.164.915.81.644.592.555652054.44
Gaskiers FormationNA0.58

65.115.31.213.523.455789.72204.67
BoliviaSA0.33213.267.215.90.370.853.23751251557.06
BoliviaSA0.33572.665.116.20.491.133.6721462329.47
BoliviaSA0.33142.178.49.660.481.62.376284.72763.15
BoliviaSA0.3

77.2110.211.022.7701062575.21
BoliviaSA0.3

77.910.10.20.732.77701102695.84
BoliviaSA0.3

78.19.520.781.242.256385.32523.72
DwykaEast GroupAF0.33732.1419.8610.251.131.816666.71093.62
DwykaEast GroupAF0.34613.354.912.43.311.632.316182.31354.35
DwykaEast GroupAF0.33862.853.612.43.521.582.326286.51474.3
DwykaEast GroupAF0.3

53.9131.790.953.28661361278.64
DwykaEast GroupAF0.3

29.85.7316.470.461.16945.159.52.47
DwykaEast GroupAF0.3

27.94.5218.890.490.916431.473.31.63
DwykaEast GroupAF0.3

386.4317.660.651.156740.474.31.6
DwykaEast GroupAF0.3

45.17.179.740.311.17833.285.71.08
DwykaWestAF0.3340863.9151.693.063.27571252012.12
DwykaWestAF0.3372875.310.60.83.192.1855


DwykaWestAF0.3332869.412.61.223.152.415680.92321.28
DwykaWestAF0.3

65.814.62.073.073.26551142042.97
DwykaWestAF0.3

6714.21.992.973.1955


DwykaWestAF0.3

64.715.11.932.953.44571352276.72
DwykaWestAF0.3

68.813.51.263.572.775695.92451.69
DwykaWestAF0.3

676.3810.511.610.9950


Till4NA0.0014404.36514.41.253.043.256616138512
Back to article | Download in Excel


Figure S-1 Nitrogen isotope values plotted against N concentration. Lack of correlation between isotopes and concentrations from samples of all ages suggests that there has not been N loss during diagenesis. Nitrogen loss tends to result in samples with low N concentration having high δ15N values, which is not observed.
Back to article | Download in Powerpoint


Figure S-2 Nitrogen concentration plotted against Chemical Index of Alteration (CIA). See text for details, but lack of correlation suggests that aqueous alteration alone cannot explain the increase in N concentration through time.
Back to article | Download in Powerpoint


Figure S-3 Nitrogen concentration plotted against Cs/Zr. See text for details, but lack of correlation suggests that aqueous alteration alone cannot explain the increase in N concentration through time, with the possible exception of the lowest N samples. There is no change in the Cs/Zr ratio through time, suggesting that geographic and temporal evolution of Cs and Zr does not explain variation seen.
Back to article | Download in Powerpoint


Figure S-4 Nitrogen concentration plotted against Al2O3/SiO2.
Back to article | Download in Powerpoint


Figure S-5 Nitrogen concentration plotted against Rb and K2O. We note that for low N samples there is a positive correlation, but for moderate and high N samples, no correlation is observed.
Back to article | Download in Powerpoint


Figure S-6 Histograms of detrital zircons from Africa, South America, North America, and Asia through time. African zircons have two peaks at 2.1 and 0.75 Ga, while South America has the peak at 2.1 Ga, and perhaps a peak from 0 to 0.5 Ga. Both North America and Asia have a single dominant peak, at 1.2 Ga and 0–0.5 Ga, respectively. It is possible that peaks in ages correspond to periods of continental growth and, by extension, periods of N-sequestration in the crust.
Back to article | Download in Powerpoint


Figure S-7 Nitrogen concentration and δ15N values of granitic rocks through time. These data are consistent with an increase in N content of continental crust through time, with increase in isotopic values consistent with a biologically processed source for said N.
Back to article | Download in Powerpoint