貝葉斯(Bayes) 兩組判別方法對次生火山巖含礦性判別分析

1、貝葉斯(Bayes) 兩組判別方法對次生火山巖含礦性判別分析武漢地質(zhì)學院巖石教研室 寧蕪盆地位于淮陽山字型構(gòu)造的前弧東翼與新華夏構(gòu)造復合處，為地跨蘇皖的中生代繼承式陸相火山巖盆地。盆地明顯受北北東及北西向斷裂控制，呈北北東向延伸。邊緣主要由三迭侏羅系地層組成，中部則廣泛分布火山巖系?；鹕綆r系及少數(shù)下伏沉積巖系中發(fā)育有次火山巖，它們晚于該火山誰知盤中旋回侵入，并與火山巖在成分上相似。以Fe、Cu、S、P為主的多種礦產(chǎn)與次火山巖有直接關(guān)系。在寧蕪中段取得31件次火山巖樣品，其中115為含礦次火山巖及晚期脈巖，1631為非礦次火山巖及侵入巖。每個樣品分析SiO2、TiO2、Ai2O3、Fe2O3、F

2、eO、MnO、MgO、CaO、Na2O、K2O、H2O+等11項指標。原始數(shù)據(jù)見表6-9-7。表6-9-7 原 始 數(shù) 據(jù)樣品/變量1234567891011154.140.8917.863.854.390.153.466.205.361.241.80252.480.8817.305.206.030.172.575.045.721.640.57356.420.8219.593.632.250.101.544.487.820.781.78455.480.8016.654.545.230.093.034.086.002.241.73557.120.7517.984.253.840.092.043.

3、116.252.831.30645.860.8814.2413.807.830.082.562.926.441.360.97761.840.6016.182.853.880.082.221.725.003.482.04852.280.6615.357.041.740.042.835.064.002.182.22954.780.8920.121.653.130.042.843.846.142.192.041060.660.6415.784.863.120.082.140.854.703.202.281157.980.8116.654.604.640.063.140.945.311.093.561

4、251.240.8516.769.727.610.052.900.558.000.251.941364.220.6517.171.821.330.031.691.988.250.981.721465.250.5517.151.932.050.031.661.928.040.550.681558.680.6515.503.536.220.202.091.343.904.102.541652.900.9218.806.353.580.422.096.542.892.411.161755.940.8616.843.195.190.202.944.274.123.002.121856.691.0615

5、.2411.551.530.011.230.513.344.792.911954.340.8218.549.610.550.020.760.300.6511.541.402053.070.8017.458.553.610.081.904.726.140.831.602158.521.0120.151.121.730.042.644.947.000.771.322258.661.0019.481.761.730.112.554.266.710.630.682354.720.8518.068.253.460.081.102.077.031.881.942454.020.6818.706.703.1

6、80.071.621.346.701.460.762562.340.5515.282.395.710.082.141.953.254.002.262673.460.0213.081.621.110.030.170.110.437.592.342772.250.2513.941.231.820.050.521.090.776.321.542866.200.2313.491.181.860.081.513.560.264.802.592967.360.3614.591.622.340.061.652.613.904.390.463060.260.6515.592.664.330.062.223.2

7、74.124.780.803148.121.2017.284.936.160.184.869.203.802.010.86經(jīng)過30次迭代，得到有關(guān)參數(shù)如表6-9-8。表6-9- 8 由迭代法求出的各極小值角度FIMIN0.2583996函數(shù)值RMIN9.22829E-02一類判別函數(shù)均值3.041054二類判別函數(shù)均值-4.515806一類判別函數(shù)方差3.145484二類判別函數(shù)方差17.67206此時的線性判別函數(shù)的系數(shù)如表6-9-9。樣品回代判別結(jié)果如表6-9-10。從回代結(jié)果看，90%以上的樣品歸類適當，僅有含礦類第二號樣品（輝長閃長玢巖，采自南由504孔），不含礦類第17號樣品（角閃安

8、由玢巖，采自鶯子山龍王山組），第24號樣呂（鈉長斑巖，李洼大王山組）三件樣品歸屬有誤。具體原因待查。當然，并不排隊統(tǒng)計分析方法本身的概率風險。此外，從線性判別函數(shù)（表6-9-9）可以看到，對于判斷含礦與不含礦時的11項分析指標中，MnO、Na2O、MgO、H2O+及TiO2起重要作用。其中關(guān)于Na2O的正作用可以理解為鈉化蝕變是與鐵的富集緊密相關(guān)聯(lián)的。 表6-9-9判別函數(shù)系數(shù)(b0)=64.3643(b1)=-0.9825(b2)=-18.3450(b3)=-1.5013(b4)=-0.8754(b5)=-0.8883(b6)= 26.9320(b7)= 2.8232(b8)= -0.3699(b9)= 4.0971(b10)=1.9838(b11)=2.5511表6-9-10 樣品回代和判別結(jié)果樣品號原類別判別函數(shù)值判別類別樣品號原類別判別函數(shù)值判別類別111.63651162-6.8664221-0.850421721.58471312.96911182-10.84042414.77611192-9.02422512.13641202-2.49312612.86621212-3.88472712.97041222-4.54302813.99471232-0.10802912.538012420.463