0 引言
1 区域地质背景
图3 川东北地区羊鼓洞剖面二叠系吴家坪组沉积岩野外及镜下照片(a)深灰色灰岩,发育有珊瑚化石;(b)灰岩中广泛发育姜状燧石;(c)灰岩中广泛发育条带状燧石;(d)深灰色硅质岩,发育有双壳类化石; (e)䗴化石,泥晶方解石碳酸盐岩,单偏光;(f)细—微晶灰岩,单偏光;(g)硅质灰岩,单偏光;(h)硅质白云岩,黑色为硅质岩岩屑胶结物,单偏光 Fig.3 Field and microscopic photographs of sedimentary rocks of Permian Wujiaping Formation in Yanggudong section, northeastern Sichuan Basin |
2 吴家坪组岩石学特征
2.1 灰岩类
2.2 白云岩类
3 地球化学特征
3.1 样品采集与分析方法
3.2 测试结果
3.2.1 微量元素特征
表1 川东北地区羊鼓洞剖面二叠系吴家坪组沉积岩微量元素分析结果Table 1 Analytical results of trace elements of sedimentary rocks of Permian Wujiaping Formation in Yanggudong section, northeastern Sichuan Basin |
元素 | 样品编号 | 平均值 | |||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
YG25-1 | YG25-2 | YG26 | YG27-1 | YG27-2 | YG28-1 | YG30 | YG33-1 | YG35-2 | YG37-1 | YG37-2 | YG38-1 | YG38-2 | YG39-1 | YG39-2 | YG40-1 | YG40-2 | YG40-3 | ||
V/10-6 | 138.92 | 108.33 | 90.98 | 77.81 | 95.60 | 67.22 | 73.38 | 48.44 | 109.92 | 84.46 | 78.81 | 81.35 | 95.75 | 70.87 | 108.48 | 78.67 | 86.10 | 89.40 | 88.03 |
Cr/10-6 | 34.29 | 40.00 | 22.86 | 25.71 | 42.86 | 23.43 | 21.43 | 22.86 | 54.29 | 29.43 | 25.43 | 36.29 | 45.71 | 45.71 | 23.71 | 36.00 | 37.14 | 37.14 | 33.57 |
Co/10-6 | 2.50 | 3.10 | 2.40 | 1.70 | 2.40 | 2.10 | 1.60 | 4.20 | 2.07 | 1.40 | 2.60 | 2.30 | 1.50 | 1.80 | 1.20 | 3.40 | 2.10 | 2.00 | 2.24 |
Ni/10-6 | 18.25 | 22.35 | 14.73 | 11.63 | 15.63 | 16.28 | 10.70 | 32.50 | 13.18 | 14.73 | 15.35 | 13.65 | 10.88 | 10.95 | 10.58 | 18.80 | 15.05 | 12.18 | 15.41 |
Cu/10-6 | 9.40 | 8.72 | 11.00 | 10.60 | 13.80 | 9.48 | 46.24 | 16.56 | 94.28 | 98.48 | 35.12 | 34.24 | 39.12 | 40.76 | 36.44 | 64.84 | 200.48 | 37.28 | 44.82 |
Rb/10-6 | 10.99 | 12.71 | 12.19 | 12.72 | 22.61 | 7.33 | 12.85 | 9.12 | 11.71 | 8.79 | 11.79 | 8.05 | 11.65 | 13.88 | 10.97 | 13.00 | 8.17 | 20.55 | 12.17 |
Sr/10-6 | 44.29 | 36.00 | 24.29 | 19.14 | 27.43 | 57.71 | 43.43 | 84.29 | 58.57 | 63.71 | 50.57 | 71.43 | 66.86 | 75.14 | 50.86 | 72.29 | 69.71 | 90.29 | 55.89 |
Ba/10-6 | 12.36 | 8.36 | 14.18 | 10.91 | 10.18 | 10.55 | 11.82 | 10.00 | 8.91 | 11.27 | 8.73 | 11.64 | 13.64 | 11.82 | 15.09 | 12.00 | 14.73 | 11.27 | 11.53 |
Th/10-6 | 8.69 | 8.32 | 1.12 | 3.93 | 2.06 | 1.12 | 2.71 | 1.31 | 1.40 | 0.75 | 8.13 | 6.82 | 1.12 | 2.06 | 3.08 | 0.93 | 1.78 | 8.50 | 3.55 |
U/10-6 | 466.17 | 206.77 | 105.26 | 90.23 | 63.91 | 105.26 | 266.92 | 109.02 | 101.50 | 63.91 | 63.91 | 236.84 | 105.26 | 131.58 | 199.25 | 90.23 | 78.95 | 120.30 | 144.74 |
Sr/Ba | 3.58 | 6.01 | 5.94 | 10.66 | 9.71 | 8.18 | 7.06 | 9.86 | 8.50 | 9.96 | 14.63 | 9.04 | 9.09 | 8.78 | 6.21 | 6.98 | 6.67 | 8.01 | 8.27 |
Th/U | 0.02 | 0.04 | 0.01 | 0.04 | 0.03 | 0.01 | 0.01 | 0.01 | 0.01 | 0.01 | 0.13 | 0.03 | 0.01 | 0.02 | 0.02 | 0.01 | 0.02 | 0.07 | 0.03 |
V/(V+Ni) | 0.88 | 0.83 | 0.86 | 0.87 | 0.86 | 0.81 | 0.87 | 0.60 | 0.89 | 0.85 | 0.84 | 0.86 | 0.90 | 0.87 | 0.91 | 0.81 | 0.85 | 0.88 | 0.85 |
V/Cr | 4.05 | 2.71 | 3.98 | 3.03 | 2.23 | 2.87 | 3.42 | 2.12 | 2.02 | 2.87 | 3.10 | 2.24 | 2.09 | 1.55 | 4.57 | 2.19 | 2.32 | 2.41 | 2.77 |
Ni/Co | 7.30 | 7.21 | 6.14 | 6.84 | 6.51 | 7.75 | 6.69 | 7.74 | 6.36 | 10.52 | 5.90 | 5.93 | 7.25 | 6.08 | 8.81 | 5.53 | 7.17 | 6.09 | 6.99 |
Sr/Cu | 11.78 | 10.65 | 10.28 | 10.97 | 7.16 | 9.10 | 13.37 | 11.52 | 12.06 | 10.71 | 8.45 | 10.27 | 6.49 | 8.13 | 11.10 | 17.30 | 7.88 | 9.73 | 10.39 |
Rb/Sr | 0.25 | 0.25 | 0.14 | 0.11 | 0.23 | 0.08 | 0.15 | 0.09 | 0.15 | 0.08 | 0.09 | 0.08 | 0.09 | 0.13 | 0.12 | 0.16 | 0.08 | 0.23 | 0.14 |
3.2.2 稀土元素特征
表2 川东北羊鼓洞剖面二叠系吴家坪组样品稀土元素含量及特征参数Table 2 Rare earth element content and characteristic parameters of sedimentary rocks of Permian Wujiaping Formation in Yanggudong section, northeastern Sichuan Basin |
元素 | 样品编号 | |||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
YG25-1 | YG25-2 | YG26 | YG27-1 | YG27-2 | YG28-1 | YG30 | YG33-1 | YG35-2 | YG37-1 | YG37-2 | YG38-1 | YG38-2 | YG39-1 | YG39-2 | YG40-1 | YG40-2 | YG40-3 | |
La/10-6 | 17.08 | 19.49 | 1.85 | 7.05 | 3.28 | 2.88 | 11.79 | 5.82 | 12.37 | 4.68 | 3.1 | 7.03 | 1.97 | 5.09 | 3.82 | 1.87 | 2.23 | 5.97 |
Ce/10-6 | 20.78 | 22.55 | 2.51 | 8.46 | 4.85 | 3.76 | 10.15 | 4.51 | 14.98 | 5.32 | 3.14 | 7.23 | 1.93 | 4.15 | 3.52 | 3.73 | 2.66 | 8.73 |
Pr/10-6 | 2.37 | 2.49 | 0.39 | 1.20 | 0.63 | 0.48 | 1.59 | 1.44 | 1.65 | 0.98 | 0.38 | 1.20 | 0.30 | 1.09 | 0.56 | 0.49 | 0.53 | 1.18 |
Nd/10-6 | 9.18 | 9.38 | 1.49 | 5.79 | 2.82 | 2.11 | 8.50 | 6.34 | 4.14 | 3.21 | 1.61 | 6.78 | 1.61 | 5.50 | 2.21 | 1.66 | 2.63 | 5.47 |
Sm/10-6 | 2.00 | 1.97 | 1.21 | 1.02 | 0.99 | 0.85 | 1.66 | 0.76 | 0.67 | 0.95 | 0.59 | 1.13 | 0.45 | 1.06 | 0.76 | 0.45 | 0.69 | 1.17 |
Eu/10-6 | 0.35 | 0.28 | 0.27 | 0.15 | 0.21 | 0.16 | 0.25 | 0.13 | 0.33 | 0.19 | 0.19 | 0.13 | 0.09 | 0.25 | 0.15 | 0.11 | 0.18 | 0.24 |
Gd/10-6 | 2.28 | 2.35 | 1.26 | 1.11 | 1.15 | 1.17 | 2.04 | 0.97 | 1.56 | 0.64 | 0.79 | 1.14 | 0.49 | 1.04 | 0.97 | 0.44 | 0.98 | 1.32 |
Tb/10-6 | 0.38 | 0.40 | 0.14 | 0.19 | 0.17 | 0.16 | 0.33 | 0.26 | 0.32 | 0.15 | 0.13 | 0.21 | 0.08 | 0.23 | 0.16 | 0.07 | 0.14 | 0.18 |
Dy/10-6 | 2.35 | 2.52 | 1.23 | 1.21 | 0.93 | 0.81 | 1.98 | 1.26 | 2.01 | 0.78 | 0.79 | 1.43 | 0.48 | 0.98 | 0.96 | 0.41 | 0.80 | 0.91 |
Ho/10-6 | 0.49 | 0.54 | 0.24 | 0.26 | 0.17 | 0.14 | 0.4 | 0.32 | 0.41 | 0.21 | 0.16 | 0.33 | 0.1 | 0.24 | 0.13 | 0.08 | 0.16 | 0.16 |
Er/10-6 | 1.08 | 1.43 | 0.81 | 0.70 | 0.40 | 0.30 | 1.01 | 1.22 | 1.34 | 0.44 | 0.41 | 0.94 | 0.26 | 0.41 | 0.32 | 0.2 | 0.38 | 0.33 |
Tm/10-6 | 0.16 | 0.20 | 0.11 | 0.10 | 0.05 | 0.03 | 0.14 | 0.145 | 0.156 | 0.063 | 0.06 | 0.14 | 0.03 | 0.034 | 0.05 | 0.03 | 0.05 | 0.04 |
Yb/10-6 | 1.09 | 1.26 | 0.58 | 0.63 | 0.27 | 0.17 | 0.81 | 0.76 | 0.92 | 0.41 | 0.34 | 0.97 | 0.21 | 0.21 | 0.36 | 0.15 | 0.28 | 0.22 |
Lu/10-6 | 0.14 | 0.21 | 0.11 | 0.09 | 0.04 | 0.02 | 0.11 | 0.112 | 0.13 | 0.06 | 0.05 | 0.15 | 0.03 | 0.041 | 0.06 | 0.02 | 0.04 | 0.04 |
∑REE/10-6 | 59.73 | 65.07 | 12.2 | 27.96 | 15.96 | 13.04 | 40.76 | 24.05 | 40.99 | 18.08 | 11.74 | 28.81 | 8.03 | 20.36 | 14.03 | 9.71 | 11.75 | 25.96 |
∑LREE/10-6 | 51.76 | 56.16 | 7.72 | 23.67 | 12.78 | 10.24 | 33.94 | 19.02 | 34.14 | 15.33 | 9.01 | 23.50 | 6.35 | 17.14 | 11.02 | 8.31 | 8.92 | 22.76 |
∑HREE/10-6 | 7.97 | 8.91 | 4.48 | 4.29 | 3.18 | 2.8 | 6.82 | 5.047 | 6.846 | 2.749 | 2.73 | 5.31 | 1.68 | 3.185 | 3.012 | 1.40 | 2.83 | 3.20 |
∑LREE/ ∑HREE | 6.49 | 6.30 | 1.72 | 5.52 | 4.02 | 3.66 | 4.98 | 3.77 | 4.99 | 5.58 | 3.30 | 4.43 | 3.78 | 5.38 | 3.66 | 5.94 | 3.15 | 7.12 |