Origin and characteristics of grain dolomite of Ordovician Ma5 5 Member in the northwest of Ordos Basin, NW China

ZHANG Xi,ZHANG Tingshan,LEI Bianjun,ZHANG Jingxuan,ZHANG Ji,ZHAO Zhongjun,YONG Jinjie

Table 1 Geochemical analysis data of rock samples from Ma55.

Well Depth/m Rock type Mineral type Mass fraction of major elements/10-2 Mass fraction of trace elements/10-6 δ13C/ ‰ δ18O/ ‰ Mn/ Sr Mg2+/ Ca2+ Homogeni- zation temperature/°C Sali- nity/ % Order degree Molar ratio of Ca/% Na2O MgO CaO Fe Ba Sr Mn SD39-62C 3 133.06 Limestone Calcite 0.66 3.62 42.31 33.50 7.90 77.12 42.13 -3.2 -9.1 0.55 0.09 41.0 8.36 SD39-62C 3 135.63 0.13 4.98 44.82 31.30 16.90 67.11 50.09 -2.3 -7.2 0.75 0.11 56.1 8.62 SD39-62C 3 118.01 0.03 5.19 47.86 0.25 10.05 64.43 81.22 -2.6 -8.5 1.26 0.11 67.2 9.58 SD39-62C 3 119.26 0.02 0.32 54.91 0.06 10.79 102.02 42.63 -2.6 -9.9 0.42 0.01 55.9 12.38 SD39-62C 3 119.88 0.03 3.21 55.41 0.07 9.82 80.53 62.38 -2.6 -8.9 0.78 0.06 63.7 10.25 SD39-57 3 123.76 0.03 0.60 52.88 0.16 28.26 75.71 55.61 -2.9 -9.8 0.73 0.01 47.1 11.84 SD39-57 3 123.97 0.02 0.95 54.32 0.06 10.46 81.92 48.17 -2.9 -10.0 0.59 0.02 55.9 8.99 SD39-57 3 125.83 0.04 6.25 41.34 0.37 13.41 68.81 118.04 -2.6 -7.2 1.71 0.15 66.3 9.32 SD39-57 3 127.85 0.03 7.68 42.37 2.53 15.02 112.13 64.41 -2.8 -8.4 0.57 0.18 69.4 7.16 SD39-57 3 129.86 0.03 5.46 49.03 0.17 10.84 89.32 65.37 -3.2 -8.4 0.73 0.11 62.7 11.32 SD39-57 3 131.02 0.02 0.36 55.27 0.05 12.00 99.04 24.02 -3.1 -9.9 0.24 0.01 74.2 9.91 SD39-57 3 132.24 0.02 3.11 53.42 0.03 9.75 100.03 27.13 -3.0 -9.4 0.27 0.06 79.1 11.37 L28 3 890.70 0.03 4.21 56.54 1.98 37.50 93.21 99.31 -2.7 -8.1 1.07 0.07 65.1 9.76 S346 3 739.40 0.03 4.37 58.55 2.00 39.50 89.14 103.03 -2.5 -9.2 1.16 0.07 69.3 9.69 S379 3 905.70 0.03 4.39 59.51 2.34 36.86 83.21 89.42 -2.5 -9.3 1.08 0.07 61.2 6.38 S381 4 005.36 0.03 4.56 54.42 2.07 34.40 92.23 109.03 -2.5 -9.3 1.18 0.08 60.3 11.24 S383 3 923.60 0.04 5.65 57.32 1.00 44.50 99.24 93.41 -3.0 -10.1 0.94 0.10 56.3 10.74 SD37-58 3 108.36 0.03 5.76 53.28 1.03 47.30 102.16 87.32 -2.7 -9.1 0.85 0.11 56.6 9.26 S203 3 916.90 0.03 5.47 52.33 1.06 57.60 83.22 78.47 -2.7 -7.7 0.94 0.10 55.3 10.35 S343 3 803.60 0.02 5.53 50.72 1.07 55.40 89.61 81.59 -2.6 -8.8 0.91 0.11 60.3 7.92 S345 3 983.40 0.03 5.42 58.41 0.06 8.85 76.28 58.51 -2.4 -7.7 0.77 0.09 58.3 11.29 S352 3 743.51 0.04 4.61 52.73 0.15 28.26 73.78 57.32 -2.7 -9.3 0.78 0.09 63.1 10.27 S355 3 813.20 0.03 4.53 51.28 0.14 25.15 72.13 53.54 -2.7 -8.7 0.74 0.09 45.3 8.25 SD39-62C1 3 115.37 Dolomicrite Micrite dolo- mite 0.22 19.22 36.21 0.15 12.40 64.02 61.08 -0.9 -7.2 0.95 0.53 117.0 0.65 48.20 SD39-62C1 3 141.43 0.22 17.21 38.14 0.17 9.10 110.04 56.02 -1.6 -7.4 0.51 0.45 97.1 0.59 51.88 SD39-62C1 3 132.63 0.03 17.66 36.21 0.16 11.49 96.28 48.63 -1.3 -5.3 0.50 0.49 98.4 0.77 48.17 L28 3 894.50 Grain dolomite (spherical particles) Micrite to silt dolomite 0.03 16.28 32.36 0.28 49.50 87.09 89.57 -1.5 -6.2 1.03 0.50 115.0 25.36 0.81 48.30 L28 3 897.00 0.07 20.91 37.71 0.31 54.02 70.88 71.91 -1.4 -6.1 1.01 0.55 109.0 24.59 0.73 52.40 S346 3 978.10 0.05 25.32 36.47 0.31 10.42 77.61 130.02 -1.6 -6.8 1.67 0.69 98.6 22.48 0.74 48.36 S346 3 994.75 0.06 16.32 36.12 0.26 18.83 82.33 78.91 -1.2 -7.2 0.96 0.45 113.0 23.09 0.74 51.65 S346 3 743.80 0.06 21.01 30.50 0.20 20.81 79.11 46.11 -1.6 -5.7 0.58 0.69 109.0 26.59 0.78 48.25 S379 3 802.50 0.10 19.44 34.31 0.12 67.43 93.34 53.62 -1.8 -5.8 0.57 0.56 113.0 25.15 0.57 52.14 S379 3 919.70 0.06 19.71 32.36 0.10 9.40 76.32 48.76 -1.2 -6.9 0.64 0.61 92.3 26.98 0.79 48.72 S381 3 976.60 0.07 20.92 30.91 0.11 20.37 89.68 42.61 -0.9 -6.0 0.48 0.68 123.0 22.37 0.78 49.12 S381 4 000.47 0.05 21.08 30.31 0.14 11.53 78.09 44.88 -1.9 -6.5 0.57 0.70 116.0 21.36 0.79 52.04 S383 3 956.90 0.10 17.31 33.77 0.25 43.66 109.04 136.02 -1.2 -6.5 1.25 0.51 104.0 23.52 0.81 51.25 SD37-58 3 112.66 0.06 23.70 27.71 0.14 10.56 69.37 46.43 -1.7 -5.5 0.67 0.86 117.0 24.12 0.78 48.23 SD37-58 3 113.87 0.05 24.62 28.28 0.13 9.56 76.32 49.61 -1.9 -6.4 0.65 0.87 114.0 24.18 0.69 48.60 SD37-58 3 114.39 0.05 23.61 29.47 0.12 8.74 80.81 45.71 -2.0 -7.0 0.57 0.80 123.0 25.74 0.79 47.36 SD37-58 3 114.95 0.04 22.43 27.61 0.11 7.63 77.62 43.27 -1.7 -7.6 0.56 0.81 128.0 22.98 0.77 47.67 SD37-58 3 116.23 0.04 22.69 30.11 0.13 8.59 79.33 44.61 -1.9 -7.7 0.56 0.75 122.0 25.34 0.81 48.36 S203 3 920.90 0.04 22.72 30.13 0.13 8.59 79.34 44.63 -1.9 -7.7 0.56 0.75 127.0 25.18 0.58 48.30 S343 3 806.50 0.04 21.57 32.50 0.13 8.12 73.68 41.31 -1.5 -5.4 0.56 0.66 125.0 24.37 0.79 48.25 S343 3 810.00 0.03 22.42 33.67 0.13 7.95 72.62 43.32 -1.6 -5.5 0.60 0.66 120.0 24.38 0.79 48.60 S345 3 980.70 0.03 23.31 36.31 0.14 7.56 87.31 34.47 -1.4 -4.4 0.40 0.64 123.0 25.39 0.67 48.30 S345 3 981.80 0.03 22.08 31.23 0.16 8.45 83.32 35.51 -1.9 -4.6 0.43 0.71 128.0 26.78 0.76 48.60 S352 3 741.35 0.05 26.37 32.19 0.15 7.65 82.19 47.58 -1.7 -7.6 0.58 0.82 124.0 28.75 0.79 48.70 S355 3 810.70 0.04 23.53 31.32 0.14 6.570 77.33 42.42 -1.6 -6.6 0.55 0.75 146.0 25.44 0.82 50.14 S196 3 048.10 0.02 22.34 37.72 0.18 7.320 76.37 43.21 -1.5 -5.8 0.57 0.59 113.0 23.11 0.77 48.80 L28 3 894.50 0.03 16.31 32.42 0.21 49.500 87.11 89.61 -1.5 -6.2 1.03 0.50 115.0 26.37 0.76 48.30 L28 3 894.50 Grain dolomite (interstitial material between spherical particles) Fine to medium dolomite 0.02 26.08 21.31 1.42 13.500 41.13 282.02 -2.2 -9.3 6.84 1.23 136.0 23.48 0.89 50.30 L28 3 897.00 0.04 20.79 30.31 1.35 5.360 45.24 275.04 -2.2 -9.9 6.09 0.69 133.0 21.05 0.92 49.68 S346 3 978.10 0.03 20.47 31.17 0.63 5.170 43.28 235.02 -2.3 -9.0 5.44 0.66 140.0 24.19 0.91 49.37 S346 3 994.75 0.02 19.31 30.31 0.74 6.280 51.22 247.82 -2.1 -10.4 4.84 0.64 143.0 23.49 0.89 49.26 S346 3 743.80 0.03 27.42 22.32 0.93 7.350 39.24 264.04 -2.6 -11.0 6.74 1.23 143.0 25.19 0.89 49.45 S379 3 802.50 0.02 22.61 27.28 1.13 8.650 43.47 254.79 -2.8 -10.1 5.86 0.83 146.0 24.36 0.91 49.63 S379 3 919.70 0.03 22.42 30.29 0.93 6.320 49.53 265.02 -2.2 -9.9 5.36 0.74 158.0 23.32 0.88 49.30 S381 3 976.60 0.03 21.42 26.23 0.76 7.330 46.43 266.88 -2.0 -10.7 5.76 0.82 145.0 25.04 0.92 49.59 S381 4 000.47 0.03 24.39 25.62 0.86 8.260 42.72 258.03 -2.1 -9.2 6.04 0.95 156.0 28.34 0.89 50.14 S383 3 956.90 0.04 21.51 32.31 0.75 7.350 46.54 244.78 -2.3 -8.9 5.27 0.67 139.0 25.17 0.91 49.63 SD37-58 3 112.66 0.04 28.21 22.09 1.12 12.220 53.19 355.02 -2.1 -8.8 6.68 1.28 149.0 25.29 0.89 49.14 SD37-58 3 113.87 0.04 21.07 30.42 1.35 4.515 38.11 268.19 -1.6 -9.0 7.05 0.69 150.0 24.66 0.91 49.69 SD37-58 3 114.39 0.03 21.22 30.32 1.38 5.121 40.52 261.44 -2.1 -11.1 6.44 0.70 133.0 22.19 0.88 50.17 SD37-58 3 114.95 0.03 21.04 30.14 1.68 5.288 42.57 294.34 -2.1 -9.9 6.90 0.70 140.0 26.38 0.89 50.74 SD37-58 3 116.23 0.04 23.52 32.09 0.68 14.720 61.78 289.21 -2.2 -11.1 4.68 0.73 146.0 26.14 0.90 50.25 S196 3 048.10 0.02 31.42 19.29 1.27 8.390 41.32 257.19 -1.8 -11.7 6.23 1.62 148.0 21.05 0.93 49.59 S203 3 920.90 0.06 20.82 30.31 1.04 21.990 69.62 371.03 -1.9 -10.0 5.33 0.69 145.0 24.39 0.89 50.14 S343 3 806.50 0.05 20.91 31.42 0.78 5.064 61.01 341.13 -1.9 -8.8 5.59 0.67 138.0 22.38 0.91 49.78 S343 3 810.00 0.06 20.83 30.32 0.83 10.390 76.03 380.02 -1.7 -7.9 5.00 0.69 156.0 25.55 0.88 49.25 S345 3 980.70 0.05 21.09 31.07 0.57 9.979 72.21 298.32 -1.7 -10.2 4.12 0.68 146.0 24.98 0.91 50.26 S345 3 981.80 0.05 20.91 29.91 0.78 7.626 74.52 296.31 -2.2 -10.9 3.97 0.70 158.0 25.33 0.88 50.67 S352 3 741.35 0.07 21.11 30.43 0.78 19.140 58.02 248.28 -1.8 -9.2 4.27 0.69 163.0 23.38 0.89 49.66 S355 3 810.70 0.06 28.63 18.31 0.62 29.830 44.81 243.42 -2.0 -9.8 5.42 1.57 155.0 25.66 0.91 49.78