1、表中數(shù)據(jù)為山東濟(jì)南輝長(zhǎng)巖、沂南花崗巖7件樣品的REE組成(ppm)1MJNO6D8MJN06071MJND6D91MJN0606MYN0625MYN06251MYN0607La4.996.066.491S.111680.1110Ce12.415.215.140.6226156209Pr1.752.132.0549822.415.619.5Nd8.3510.49.9821.777.453.461.5Sm2.292.652.&44.9011.57.707.19EuOSO0.B41.111.591.400.981.24Gd2.002.322.334.117.395.333.85lb0.330.360

2、.360.641.060.740.42y2.022.212.314.076.174.271.98Ho0.400.440.460.811.180.840.34Er0.981.101.182.003.122.070.91Tm0.130.140.160.280.460.300.14Yb0.951.031.142.093.172.121.05LuI0.130.130.1510.2810.430300.1511,用球粒隕石值對(duì)樣品的REE組成進(jìn)行標(biāo)準(zhǔn)化，作其分配模式圖，對(duì)圖件中表達(dá)的地球化學(xué)特征進(jìn)行說明；2，計(jì)算各樣品的Eu/Eu*，并對(duì)其地球化學(xué)意義進(jìn)行說明；,3，假設(shè)輝長(zhǎng)巖中造巖礦物的組成為：CPX

3、45%,PL35%,OL20%。結(jié)合課件中提供的REE在礦物和熔體間的分配系數(shù)，計(jì)算與輝長(zhǎng)巖平衡的熔體的REE組成，并作REE配分模式圖。解答:1,如下表1-1為常用球粒隕石和原始地幔稀土元素組成，我采用C1球粒隕石數(shù)據(jù)(Sun&McDonough,1989)對(duì)樣品的REE進(jìn)行標(biāo)準(zhǔn)化，得到了下表1-2,再根據(jù)對(duì)樣品REE標(biāo)準(zhǔn)化的數(shù)據(jù)進(jìn)行作樣品的分配模式圖，得到了圖1-1常用球粒隕石和原始地幔稀土元素組成(ppm)Cl球粒隕石戡詼原始N-MORBE-MORBOIBLa03703670.550.6872.56337Ce0.6120.9571.441.7757.51580Pr0.0950.13702

4、060.2761.322.059.730.4670.7111.4301.3547.3938.5Sm0.15302310.3470.4442.632.610Eu0.0580.0870.1310.1681.020.913Gd0.205503060.4590.5963.682.977.62Tb0.03740.0580.0870.1080.670.531.05Dy0.254003810.5720.737斗予3.555.6Ho0.05660.08510.1280.1641.010.791.06Er0.165502490.3740.4802.972.312.62Tm0.02550.03560.0540.0

5、740.4560.356035Yb0.17002480.3720.4933.052.372.16Lu0.02540.03810.0570.0740.4550.35+0.3來源12211111：Sun&McDonough,1989：2：Taylor&Mclennan985表1-1MJN0608MJN0607MJN0609MJN0606MYN0625MYN0625MYN0607La21.05525.57027.38476.371489.451337.975464.135Ce20.26124.83724.67366.340369.281254.902341.503Pr18.42122.42121.5

6、7952.421235.789164.211205.263Nd17.88022.27021.37046.467165.739114.347131.692Sm14.96717.32016.60132.02675.16350.32746.993Eu13.79314.48319.13827.41424.13816.89721.379Gd9.73211.29011.33820.00035.96125.93718.735Tb8.8249.6269.62617.11228.34219.78611.230Dy7.9538.7019.09416.02424.29116.8117.795Ho7.0677.774

7、8.12714.31120.84814.8416.007Er5.9216.6477.13012.08318.85212.5085.498Tm5.0985.4906.27510.98018.03911.7655.490Yb5.5886.0596.70612.29418.64712.4716.176Lu5.1185.1185.90611.02416.92911.8115.906表1-2樣品配分模式圖圖1-1通過對(duì)樣品配分模式圖進(jìn)行分析可知道，沂南花崗巖樣品中富集輕稀土元素而虧損重稀土元素，這與花崗巖的成分巖性有一定關(guān)系，花崗巖為酸性巖，主要礦物為長(zhǎng)石、石英和云母，而這礦物主要富集輕稀土元素，并且從

8、圖中可以看出Eu的負(fù)異常，說明在巖漿結(jié)晶形成花崗巖之前就有長(zhǎng)石結(jié)晶出來，使巖漿呈Eu的負(fù)異常。濟(jì)南輝長(zhǎng)巖的樣品配分模式圖表現(xiàn)出來的富集輕稀土元素沒有沂南花崗巖樣品那么顯著，富集程度較低，這也與輝長(zhǎng)巖的巖性成分有關(guān)，輝長(zhǎng)巖中主要礦物為輝石和長(zhǎng)石，長(zhǎng)石富集輕稀土元素較為顯著，而輝石相對(duì)較富集重稀土元素，但程度不是很顯著，所以巖石總體表現(xiàn)較為富集輕稀土元素，但程度不是那么顯著。并且從圖中可以看出Eu的正異常，只是不是很顯著，說明長(zhǎng)石結(jié)晶出來使巖石呈Eu的正異常。2，Eu/Eu*=2Eu/(Sm+Gd)(其中Eu、Sm、Gd都是為球粒隕石標(biāo)準(zhǔn)化值)，根據(jù)這個(gè)求出各樣品中的Eu/Eu*，如下表1-3：M

9、JN0608MJN0607MJN0609MJN0606MYN0625MYN0625MYN060711171.0121.3701.0540.4340.4430.051表1-3由上表中的Eu/Eu*值可知山東濟(jì)南的輝長(zhǎng)巖為Eu的正異常，說明在巖漿結(jié)晶時(shí)，長(zhǎng)石和輝石先結(jié)晶出去形成輝長(zhǎng)巖，而長(zhǎng)石中富集Eu兀素，所以在輝長(zhǎng)巖中Eu為正異常，而后期巖漿因長(zhǎng)石的結(jié)晶分異而呈Eu的負(fù)異常，并且逐漸向酸性過渡，結(jié)晶形成酸性巖。可以推測(cè)這樣品為同源巖漿所形成，主要是形成時(shí)間不同導(dǎo)致Eu異常不同和巖性的不同。3,根據(jù)課件可查出REE在CPX、PL、OL等礦物和熔體間的分配系數(shù)，如下表1-4：Table9-1.Par

10、titionCoefficientsforsomecommonlyusedtraceelementsinbasalticandandesiticrocksdatafromHenderson(1982)*Eu3+/Eu2+Italicsareestimated表1-4在根據(jù)總分配系數(shù)的公式計(jì)算出REE在輝長(zhǎng)巖中的總分配系數(shù)，如下表1-5：-*1=1兒糸L(zhǎng)aCeNdSmEuTbErYbLu總分配系數(shù)0.0860.2040.30.4350.9670.4630.4810.1170.400表1-5再根據(jù)固體、熔體和總分配系數(shù)之間的關(guān)系式計(jì)算出熔體中REE的組成，得到數(shù)據(jù)如下表1-6,再C1球粒隕石數(shù)據(jù)(

11、Sun&McDonough,1989)對(duì)熔體的REE進(jìn)行標(biāo)準(zhǔn)化用計(jì)算結(jié)果如下表1-7,對(duì)其有進(jìn)行作配分模式圖，得到圖1-2：MJN0608MJN0607MJN0609MJN0606La58.02370.46575.465210.465Ce60.78474.51074.020199.020Nd27.83334.66733.26772.333Sm5.2646.0915.83911.264Eu0.8270.8691.1481.644Tb0.7130.7780.7781.382Er2.0372.2872.4534.158Yb8.1208.8039.74417.863Lu0.3250.3250.3750.7表1-6MJN0608MJN0607MJN0609MJN0606La244.824297.321318.418888.039Ce99.321121.748120.947325.195Nd59.60074.23171.235154