巖石中礦物的關(guān)系

巖石中礦物的關(guān)系野外產(chǎn)狀和手標本特征是巖相學最重要的工作基礎(chǔ)鏡下工作：

(1)鏡下有什么：即由哪些礦物組成？各種礦物的相對多少？以確定巖石的名稱

(2)鏡下礦物之間的相互關(guān)系：

同種礦物（時間關(guān)系，確定不同的世代）不同種礦物（空間關(guān)系）

(3)礦物之間復雜關(guān)系所反映的巖石演化歷史：

以主期礦物作為基準，殘余礦物－早期礦物內(nèi)部包裹裂隙中的礦物－－后期填充出溶礦物－－早期殘余或后期變化反應邊外部變化后成合晶重結(jié)晶部分熔融或殘余巖漿后的結(jié)晶黃尾河榴輝巖

主要由石榴子石、綠輝石、金紅石組成，同時還有后期退變礦物：斜長石、角閃石、尖晶石、橄欖石、斜方輝石等。GarnetPl+AmpSp+Ol+PlOlPlSp石榴石的退變質(zhì)反應（a)Garnet－－→Ol+Sp+Pl(2)

榴輝巖相麻粒巖相(b)Ol+Sp+Pl(2)－→Pl（1)＋Amp麻粒巖相角閃巖相EnstatiteOl+Silica（游離態(tài)）－→Enstatite（a)Garnet－－→En+Sp+Pl(2)

榴輝巖相麻粒巖相(b)En+Sp+Pl(2)－→Pl（1)＋Amp麻粒巖相角閃巖相三個階段榴輝巖相：石榴石麻粒巖相:尖晶石+橄欖石+斜長石尖晶石+頑火輝石+斜長石角閃巖相:斜長石+角閃石圖１黃尾河榴輝巖中的綠輝石單斜輝石中的電子探針分析及計算結(jié)果SampleNo.InclusioningarnetInclusioninapatite

Inmatrix

1

2

3

4

5

6

7

8

9

Wt％oxidesSiO255.7254.6953.9453.2752.8853.2654.5956.3356.21TiO20.090.090.090.070.090.070.090.070.07Al2O34.184.024.093.883.923.884.054.194.18Cr2O30.050.030.070.050.030.050.050.050.07FeO5.766.215.968.027.758.446.785.655.63MnO0.030.000.050.140.080.190.030.030.05MgO12.2712.9413.7113.9512.8713.7513.8512.2012.52CaO17.8617.2617.7118.1418.4117.0516.7416.5218.01Na2O4.393.794.002.813.212.634.064.354.28K2O0.010.020.020.010.010.010.010.020.01Total100.3699.0599.64100.3499.2599.33100.2599.41101.03

CationspersixoxygenatomsSi1.9991.9941.9541.9381.9451.9601.9672.0272.002Altotal0.1770.1730.1750.1660.1700.1680.1720.1780.176AlⅣ0.0010.0060.0460.0620.0550.0400.0330.0000.000AlⅥ0.1760.1670.1290.1050.1150.1280.1390.1780.176Fe2+0.1750.1910.1830.2460.2410.2610.2070.1720.169Mg0.6560.7030.7400.7560.7060.7540.7440.6540.665Ca0.6860.6740.6870.7070.7260.6720.6460.6370.687Na0.3050.2860.2810.1980.2290.1880.2840.3030.296∑cations4.0014.0064.0244.0194.0214.0124.0223.9743.998續(xù)上表CaTs0.10.64.66.25.54.03.30.00.0Jd30.528.628.119.822.918.828.430.329.6CaEs-13-12.5-19.8-15.5-16.9-10-17.8-12.5-12Aug68.466.259.558.361.659.258.063.768.7Opx7.411.616.430.016.621.218.69.47.4續(xù)上表

CationspersixoxygenatomsSi1.9981.9931.9761.9781.9921.9721.9811.9791.9181.891Altotal0.1960.2120.2100.1990.2030.2020.2050.2110.1950.193AlⅣ0.0020.0070.0240.0220.0080.0280.0190.0210.0820.109AlⅥ0.1940.2040.1860.1770.1950.1740.1860.1910.1140.084Fe2+0.1780.1750.1810.1790.1760.1850.1880.1850.2670.311Mg0.6730.6880.6980.7010.6870.7040.7050.6910.8060.838Ca0.7370.7190.7240.7370.7230.7320.7230.7240.7420.718Na0.2160.2090.2150.2070.2110.2050.1980.2080.0840.053CaTs0.20.72.42.20.82.81.92.18.210.9Jd21.620.921.520.721.120.519.820.88.45.3CaEs-2.4-1.2-5.3-5.2-2.4-5.9-3.1-3.8-5.3-7.8Aug73.771.972.473.772.373.272.372.457.861.8Opx5.77.27.87.27.07.98.57.624.821.6綠輝石的邊緣：后成合晶綠輝石的退變質(zhì)反應：

－－邊緣的后成合晶(a)Omphacite－→Pl(1)＋{Amp}

榴輝巖相角閃巖相(b){Amp}－→Ens+Sp

角閃巖相麻粒巖相Omphacite→Pl(1)＋{Amp}→Pl(1)+Ens+Sp榴輝巖相

角閃巖相麻粒巖相綠輝石中出溶包裹體的化學組成NoSiO2TiO2Al2O3Cr2O3FeOMnOMgOCaONa2OK2OTotMin198.560.030.040.000.180.000.320.420.210.0099.76Quar-tz298.930.010.020.000.100.000.210.240.170.0099.68368.240.0618.720.000.520.000.381.3410.420.0099.68Feld-spar467.460.0013.760.031.500.003.056.237.750.0099.78564.850.0016.640.080.750.001.612.687.174.1497.84669.940.0710.750.001.430.003.065.723.180.0094.23重新計算的長石包裹體的化學組成

NO.SiO2Al2O3FeOCaONa2OK2O

Mol％QzOrAbAn368.9219.220.360.8110.690.0018.850.0077.903.25471.7116.800.092.109.300.0039.230.0054.036.74563.6021.480.000.319.065.549.8525.5363.431.19681.1413.840.001.523.490.0087.260.0010.272.47具有出溶包裹體的單斜輝石組成MantleAnalysedwithbroadbeam

Analysedwithsmallbeam(～μm)Core-------------Mantle------------------RimSampleNo.12345678910

wt％oxidesSiO254.6254.7354.4854.4054.8254.1854.4854.2051.5250.79TiO20.100.060.050.090.110.210.070.070.140.05Al2O34.544.934.904.644.754.704.784.914.454.39Cr2O30.050.080.020.040.160.010.030.020.020.03FeO5.805.755.955.875.786.066.176.068.579.93MnO0.000.040.060.050.040.000.000.110.160.16MgO12.3512.6812.9112.9412.6912.9813.0112.6914.5215.10CaO18.8118.4418.6218.9118.5818.7718.5618.4918.5918.01Na2O3.052.963.052.933.002.902.812.941.160.73K2O0.000.000.000.020.000.010.000.000.000.00Total99.3299.69100.0499.8999.9399.8299.8699.4999.1399.19綠輝石的退變質(zhì)反應

－－殘留的綠輝石的出溶綠輝石（次）透輝石+石英+富鈉長石麻粒巖相分解反應:綠輝石透輝石+石英+長石嚴格來說是分解反應，關(guān)鍵在于綠輝石中六配位的Al由于溫度的升高而變成四配位的Al，從而在T位取代Si，因此有游離的石英析出。這應該是麻粒巖相時的高溫反應。綠輝石的退變質(zhì)反應(a)Garnet－－→Plagioclase（1)＋Amp

榴輝巖相角閃巖相(b)Pl(1)＋Amp－→Ol+Sp+Pl(2)

角閃巖相麻粒巖相

Ol+Silica－→Enstatite（a)Garnet－－→Ol+Sp+Pl(2)

榴輝巖相麻粒巖相(b)Ol+Sp+Pl(2)－→Pl（1)＋Amp麻粒巖相角閃巖相Route2Route1結(jié)論三個階段榴輝巖相

:石榴石+綠輝石角閃巖相:斜長石+角閃石麻粒巖相:尖晶石+橄欖石+斜長石尖晶石+頑火輝石+斜長石透輝石+石英+富鈉長石北大別榴輝巖退變質(zhì)過程北大別榴輝巖巖相學特征表明榴輝巖在折返