新疆东天山二红洼岩体岩浆演化特征与成矿潜力分析

段星星，杜辉，刘拓，李文明，夏明哲

(1.中国地质地质调查局西安地质调查中心，陕西 西安　710054； 2.长安大学地球科学与资源学院，陕西 西安　710054；3.西部矿产资源与地质工程教育部重点实验室，陕西 西安　710054)



新疆东天山二红洼岩体岩浆演化特征与成矿潜力分析

段星星1，杜辉1，刘拓1，李文明1，夏明哲2,3

(1.中国地质地质调查局西安地质调查中心，陕西 西安710054； 2.长安大学地球科学与资源学院，陕西 西安710054；3.西部矿产资源与地质工程教育部重点实验室，陕西 西安710054)

二红洼岩体位于康古尔-黄山韧性剪切带东段，主要由含长二辉橄榄岩、橄榄辉长岩、辉长苏长岩和淡色辉长岩组成。岩石相对富集LREE，亏损高场强元素(Nb、Ta、Ti)。岩体原生岩浆为普通拉斑玄武岩(MgO=7.3%)。通过对元素地球化学和Nd、Sr、Pb同位素体系研究证明，岩浆源区以软流圈物质为主，混入了少量富集岩石圈地幔组分，岩浆遭受了约5%上地壳物质的混染。与同岩带典型含矿岩体对比研究表明，岩体在岩石组合、原生岩浆性质、同化混染程度等方面存在显著差异，这些因素可能制约了成矿潜力。

成矿潜力；岩浆演化；二红洼岩体；东天山

东天山北部的镁铁-超镁铁质岩带主要沿康古尔深大断裂产出，从西到东依次有土墩、二红洼、香山、黄山南、黄山东、葫芦、图拉尔根等典型含矿岩体(图1a)。目前，在该带发现的铜镍资源储量大于1×106t,仅次于金川矿床，已成为中国第二个世界级的岩浆铜镍硫化物矿床成矿带。近年来，对黄山、黄山东、香山、图拉尔根等岩体岩石成因及成矿作用方面的研究取得了显著进展(秦克章等，2002；毛景文等，2002；韩宝福等，2002；ZHOU et al.，2004；PIRAJNO et al.，2004；夏明哲等，2008)。然而，位于该带西段二红洼岩体研究相对程度相对较低，王润民等对岩体初步评价认为二红洼岩体属于铁质系列基性-超基性岩体，有一定的成矿潜力(王润民，1987)。仲勇研究表明岩浆起源于上地幔，原生岩浆属于拉斑玄武岩，对形成铜镍硫化物矿床是有利的(仲勇，1991,1993)。孙涛等依据橄榄石组分特征论证在岩浆结晶过程中母岩浆达到了硫饱和，并发生有硫化物的熔离作用(孙涛等，2014)。通常岩体类型、构造环境、岩浆源区性质、原生岩浆、岩浆分异程度、质量平衡、岩浆含水量和同化混染等特征是筛选有利于赋含岩浆硫化物矿床岩体的关键因素。因此，笔者在岩石学、矿物学和地球化学研究基础上，论证岩浆源区性质和岩浆演化过程，并与同一岩带典型含矿岩体特征进行对比研究，深入探讨岩体成矿前景。

1　地质概况

二红洼岩体位于新疆省哈密市东南约115km处，是沿康古尔深大断裂分布的镁铁-超镁铁岩群中出露面积较大的岩体之一。二红洼岩体由南、北两部分组成，中间被第三系葡萄沟组覆盖(图1b)。岩体平面形态成椭圆状，出露面积约8km2。其中，岩体南部侵位于中元古界的黑云母片岩，而北部基本被第三系和第四系覆盖，接触关系不清。

图1　二红洼岩体地质略图Fig.1　Simplified geological map of Erhongwa

2　岩相学及造岩矿物晶体化学

2.1岩相学特征

二红洼岩体属于复式岩体，分为2个侵入期次：第一侵入期次以辉长苏长岩和淡色辉长岩为主，岩性稳定，分布于岩体南北边缘；第二侵入期次为由北向南依次为含长二辉橄榄岩、橄榄辉长岩，基性程度依次降低。钻孔显示含长二辉橄榄岩和橄榄辉长岩构成韵律旋回重复出现，在750m处二辉橄榄岩相中赋存稀疏浸染状硫化物。第二侵入期次形成的含长二辉橄榄岩和橄榄辉长岩与第一侵入期次岩石界限截然，岩石结构和矿物组合突变。综合分析各岩相的侵位顺序为淡色辉长岩—辉长苏长岩—橄榄辉长岩—含长二辉橄榄岩—橄榄岩。

岩体岩石新鲜，蚀变作用较弱。常见的结构有辉长结构、自形-半自形粒状结构、包含结构等典型的基性-超基性岩结构(图2)，以块状构造为主。各岩相结晶作用末期均有褐色普通角闪石晶出，反映了挥发分在岩浆晚期阶段富集。

图2　二红洼橄榄辉长岩中的包橄结构和含长结构图Fig.2　Microphotographs of ol-gabbro of the Erhongwa intrusion

2.2矿物晶体化学特征

岩体主要造岩矿物有橄榄石、辉石、斜长石和少量普通褐色角闪石，矿物晶体化学组成见表1。其中，橄榄石Fo值为72～79，均属贵橄榄石。黄山东、黄山、香山和葫芦岩体的橄榄石Fo值为80～89，明显高于二红洼岩体(图3a)。

辉石以单斜辉石为主，见有少量的斜方辉石。单斜辉石主要为透辉石、顽火辉石。而黄山东、黄山、香山和葫芦岩体中斜方辉石数量较多(图3b)，二辉橄榄岩和苏长岩为主要的含矿岩相。此外，岩体中斜长石An为71.4～84.1，Ab为13.1～28.7，Or为0.4～1.1，均为培长石。

图3　(a)橄榄石Fo特征及(b)辉石的Wo-En-Fs图解(MORIMOTO et al.,1988)Fig.3　(a) Fo of olivine (b) Wo-En-Fs diagram( After MORIMOTO et al.,1988)

岩性样号矿物SiO2TiO2Al2O3Cr2O3FeOMnOMgONiOCaONa2OK2OTotal组成淡色辉长岩ehw6-1-2Ol38.730.010.020.0024.100.3537.40.050.000.010.01100.67Fo74Fa26淡色辉长岩ehw6-1-4Ol38.050.020.080.0025.550.4035.840.130.080.030.03100.21Fo72Fa28淡色辉长岩ehw6-1-5Ol38.090.000.050.0023.380.4037.810.090.000.010.0199.83Fo74Fa26淡色辉长岩ehw6-1-6Ol38.320.000.000.0323.560.3737.60.040.030.010.0199.97Fo74Fa26含长二辉橄榄岩ehw2-3-2Ol36.620.000.050.0618.940.3338.830.070.060.010.0194.97Fo79Fa21含长二辉橄榄岩ehw2-3-5Ol39.150.000.020.0020.910.1640.070.050.000.000.00100.35Fo78Fa22含长二辉橄榄岩ehw2-3-6Ol39.030.010.020.0020.050.0940.110.050.030.010.0199.41Fo78Fa22含长二辉橄榄岩ehw3-3-2Ol39.010.000.000.0321.870.2539.650.060.050.010.01100.95Fo77Fa23橄榄辉长岩ehw4-1-1Ol39.110.000.010.0521.240.2639.220.040.000.010.0199.96Fo77Fa23橄榄辉长岩ehw4-1-3Ol38.890.000.010.0521.240.4839.840.060.030.000.00100.62Fo77Fa23橄榄辉长岩ehw4-1-4Ol38.810.000.020.0021.400.2540.080.060.050.000.00100.67Fo77Fa23橄榄辉长岩ehw4-1-5Ol39.050.010.000.0020.430.3440.330.020.000.000.00100.19Fo78Fa22含长二辉橄榄岩ehw2-3-3cpx51.230.403.130.066.360.2115.010.0022.240.360.0299.09En44Fs10Wo46含长二辉橄榄岩ehw2-3-4cpx50.660.384.210.085.100.2015.820.0022.750.480.0099.74En45Fs8Wo46含长二辉橄榄岩ehw3-3-1cpx51.620.393.100.086.820.2316.20.0020.530.340.0199.33En47Fs11Wo42含长二辉橄榄岩ehw3-3-2cpx50.50.332.070.125.590.1310.310.0024.730.440.0299.25En33Fs10Wo47橄榄辉长岩ehw4-1-8opx49.640.251.7816.9111.290.2318.570.001.060.320.27100.43En72Fs25Wo3淡色辉长岩ehw6-1-3pl52.110.0233.120.000.260.050.000.0011.642.530.0799.81An72Ab28淡色辉长岩ehw6-1-3pl47.350.0233.460.000.260.050.000.0016.422.130.0799.77An81Ab19淡色辉长岩ehw6-2pl49.330.0231.470.080.350.000.250.0015.582.090.1399.31An80Ab20淡色辉长岩ehw7-1-1pl48.180.0532.420.020.360.000.030.0015.732.030.1598.97An81Ab19淡色辉长岩epw7-1-2pl48.460.0631.590.110.390.000.030.0016.22.30.1999.33An79Ab21橄榄辉长岩ehw4-1-1pl48.920.0031.770.030.280.000.010.0016.012.070.0699.15An81Ab19橄榄辉长岩ehw4-1-4pl49.060.0131.260.030.250.040.070.0016.651.750.0099.11An84Ab16橄榄辉长岩ehw4-1-5pl48.920.0232.590.000.240.010.030.0015.782.130.0699.77An80Ab20橄榄辉长岩ehw4-1-7pl49.220.0031.290.000.290.000.010.0015.902.190.0898.98An80Ab20含长二辉橄榄岩ehw2-3-3pl48.050.0432.390.020.250.030.030.0016.731.410.1199.05An86Ab14含长二辉橄榄岩ehw2-3-4pl49.80.0231.060.040.260.030.000.0015.572.250.0999.12An79Ab21

3　岩石地球化学

3.1主量元素地球化学

岩体中各岩相主量元素、微量元素分析数据见表2。其中SiO2为46.54%～50.29%，属基性岩。与岩相学特征变化相对应，Al2O3、FeO+Fe2O3、MgO、CaO、Na2O含量变化大。MgO为6.54%～16.02%，平均为9.75%。各类岩石的m/f值为2.38～3.43，为铁质超基性岩。在SiO2-Na2O+K2O图上(图4a)，它们都投影于亚碱性区。在图4b上，样品均落入拉斑玄武岩系列区。

3.2微量元素地球化学

岩石稀土元素丰度较低，∑REE=10.54×10-6～17.46×10-6，平均为14.32×10-6，为球粒陨石的3～8倍。(La/Sm)N=0.64～1.46，(La/Yb)N=0.9～2.08，(Gd/Yb)N=1.23～1.5，表明轻重稀土元素之间和轻、重两组稀土元素内部的元素之间分馏程度较弱。δEu=1.34～2.09，显示不同程度的正Eu异常。若不考虑Eu异常，稀土元素配分曲线大体表现为平坦型特征(图5a、表3)。

表2　岩体主量元素分析数据表(%)

图4　岩石化学分类图解Fig.4　Petrogeochemical classification diagram

岩体的原始地幔标准化的蛛网图(图5b)型式基本一致，岩石普遍富集大离子亲石元素(Cs、Rb、Ba、Sr)，显著亏损Nb，适度亏损Zr、Hf、Ti，部分亏损Ta。此外，大部分样品的不相容元素、适度不相容元素与原始地幔相应元素的比值均不超过10，说明这些岩石相对亏损大多数不相容元素和适度不相容元素。

图5　(a)球粒陨石标准化的稀土元素配分曲线图;(b)原始地幔标准化的多元素蛛网图(标准值据SUN et al., 1989)Fig.5　(a)Chondrite-normalized REE patterns；(b)PM-normalized trace elements spider diagram

北 岩 体样品EHW1/1EHW3/3EHW2/1EHW2/3EHW1/2EHW1/3EHW3/1EHW3/2岩性含长二辉橄榄岩橄榄辉长岩南 岩 体EHW4/1EHW5/1EHW5/2EHW7/1EHW6/1EHW6/2橄榄辉长岩辉长苏长岩淡色辉长岩Li2.632.061.281.192.53.232.542.64.911.452.243.971.861.93Sc45.7543.5814.8511.8238.8529.3449.7251.9341.4519.0630.6615.2519.221.24V149.8122.175.2481.8310282.18149.1143.8109.383.2978.18128.448.155.99Cr1300338.4558.2668.6835.2406.5409.5425.9905.61002984.8112.8307.3383.4Mn838.8813.5624.8679.51065838898.5907.1749.1732.5548.9964.2475.7450.4Co54.5259.7458.9857.9380.0266.8860.7964.2154.9552.0949.8152.7752.8344.68Ni117.768.33105.397.04165122.863.7366.4193.46109.7105.122.1493.0680.3Cu54.3959.1941.0542.8155.1747.5949.5946.6454.5467.1843.3532.9934.2837.35Zn46.6338.6836.4339.0555.0350.3545.2541.2538.142.2534.1251.5431.229.8Rb1.411.411.762.242.262.851.370.962.162.012.253.151.861.7Sr414.9424.2478.6444.8337.6441.4390.5380.2436.7447.6484.9452564.6557.8Y7.336.965.265.066.4668.657.76.585.895.925.353.53.78Zr16.0713.4714.7215.6718.2821.9417.2512.617.1516.8516.4115.5510.189.97Hf0.520.450.410.430.550.60.560.430.530.490.50.460.290.28Nb0.260.20.270.280.340.530.280.160.30.290.240.240.160.14Ta0.020.020.240.230.020.010.020.020.020.240.210.240.250.23Cs0.210.090.150.130.170.30.10.070.120.150.120.430.090.1Ba25.0825.3426.2728.6824.833.2824.1219.7326.5128.2831.6637.7141.6631.76Pb0.540.580.650.610.660.920.630.450.660.690.780.90.70.81Th0.290.290.270.30.410.510.250.170.350.460.340.420.320.27U0.050.070.050.070.080.10.050.070.070.080.080.260.070.09La1.281.271.351.311.541.871.421.081.451.561.551.71.381.39

续表3

北 岩 体样品EHW1/1EHW3/3EHW2/1EHW2/3EHW1/2EHW1/3EHW3/1EHW3/2岩性含长二辉橄榄岩橄榄辉长岩南 岩 体EHW4/1EHW5/1EHW5/2EHW7/1EHW6/1EHW6/2橄榄辉长岩辉长苏长岩淡色辉长岩Ce3.413.193.443.363.934.653.963.053.753.83.73.922.963.08Pr0.520.50.480.470.540.650.610.480.540.530.520.530.410.43Sm1.10.960.790.81.0111.151.060.980.90.840.830.620.6Nd3.243.062.732.743.283.563.763.123.192.992.882.922.192.34Eu0.560.530.470.460.490.520.580.530.520.50.480.480.470.47Gd1.31.230.951.031.221.21.481.311.281.091.081.040.70.79Tb0.230.230.150.170.210.190.270.240.20.180.180.170.110.12Dy1.531.511.121.41.261.731.581.441.141.171.150.680.79Ho0.290.280.190.20.260.240.330.290.250.230.220.230.130.15Er0.90.880.580.660.790.741.040.930.840.670.670.730.410.47Tm0.110.110.070.080.10.090.130.120.10.090.080.090.050.06Yb0.820.780.540.60.720.660.880.80.690.650.590.680.390.45Lu0.110.110.080.080.10.090.120.110.10.080.090.090.050.05∑REE15.414.6212.8213.0715.616.7417.4614.7115.3214.3914.0614.5610.5411.18

3.3Nd、Sr、Pb同位素地球化学

岩体的Nd、Sr同位素组成相对均一，εNd(t) =+6.3～+7.7，εSr(t) =-9～-11.5(t=274Ma)，显示亏损型地幔特征。在εNd(t) -(87Sr/86Sr)i相关图上，二红洼岩体均投影在了第二象限，位于OIB范围内，而黄山东、黄山、葫芦和香山岩体Nd、Sr同位素组成变化较大，具有EMII的演化趋势(图6a)。

岩体的(206Pb/204Pb)i=17.814～17.927，(207Pb/204Pb)i=15.445～15.494，(208Pb/204Pb)i=37.296～37.395，在初始Pb同位素相关图中，数据点都落在地球等时线右侧，表明富含放射成因的Pb同位素(图6b、图6c)。在初始Pb同位素以及Pb与Nd、Sr同位素相关图上，数据点位于MORB范围内和其附近，充分证明岩浆源区具有与MORB相似的Nd、Sr、Pb同位素组成(图6d、表4)。

4　讨论

4.1同化混染

世界级铜镍硫化物矿床研究表明，同化混染作用(如岩浆演化过程中陆壳、围岩中Si、Fe、S组分的加入)是形成岩浆硫化物矿床的关键因素之一。二红洼岩体内捕虏体或残留顶盖不发育，表明岩体形成过程中同化混染作用弱。一般来说，经过地壳物质混染的岩浆其Nd、Sr同位素都会发生变化。然而，由于同化混染过程中的混染物往往是具有低固相线温度的花岗岩、沉积岩及其变质等价物，这些岩石都具有较高的Sr丰度和87Sr/86Sr值，所以，同化混染作用对Sr同位素组成的影响往往比对Nd同位素组成的影响大。二红洼岩体Nd、Sr同位素相对均一，εNd(t)=+6.3～+7.7，(87Sr/86Sr)i=0.703 4～0.703 5，对同化混染作用敏感的207Pb/204Pb值也没有明显升高，表明岩浆演化过程中同化混染作用较弱。采用MORB地幔端元和上地壳的Nd、Sr同位素特征定量模拟获得岩浆演化过程中受到小于5%地壳物质混染，与其他典型含矿岩体相比混染程度最低(图7)。

表4　二红洼岩体Nd、Sr、Pb同位素分析数据表

注： Pb初始同位素计算参数λ1=1.551 25×10-10，λ1=9.848 5×10-10，λ1=0.494 75×10-10，t=274Ma。

图6　(a)εNd(t)-(87Sr/86Sr)i相关图(据ZINDER et al.,1986) ;(b)207Pb/204Pb-206Pb/204Pb相关图；(c)208Pb/204Pb-206Pb/204Pb相关图(据ALLEGRE et al.,1988;ZINDER et al.,1986) ;(d)εNd(t)-(208Pb/204Pb)i相关图(据ALLEGRE et al.,1988;ZINDER et al.,1986) (岩体Nd、Sr、Pb同位素数据来自夏明哲博士论文)Fig.6　(a)εNd(t) versus initial 87Sr/86Sr of the Erhongwa intrusion (After ZINDER et al.,1986) ；(b) 207Pb/204Pb and 206Pb/204Pb of the Erhongwa;(c) 208Pb/204Pb versus 206Pb/204Pb of the Erhongwa (After ALLEGRE et al.,1988;ZINDER et al.,1986)；(d)(208Pb/204Pb)i versus εNd(t) of the Erhongwa(After ALLEGRE et al.,1988;ZINDER et al.,1986)

4.2原生岩浆

通常与镁铁-超镁铁质岩浆有关的铜镍硫化物矿床的原生岩浆是成矿作用的关键。与铜镍硫化物矿床相关的原生岩浆系列主要可分为两类：一类是科马提岩岩浆；一类是苦橄-拉斑玄武岩岩浆。在二红洼岩体中单斜辉石的SiO2-Al2O3图解中，所有的单斜辉石位于亚碱性岩区，表明其原生岩浆属于亚碱性系列。Mg#(Mg#=Mg/(Mg+Fe))也是鉴别原生岩浆的重要标志之一。GREEN认为，与地幔橄榄岩平衡的原生岩浆的Mg#=0.63～0.73(GREEN，1975)；FREY认为，Mg#=0.68～0.73(FREY，1978)；HESS认为Mg#>0.68(HESS，1992)。如果以Mg#=0.65～0.73代表了原生岩浆和近于原生岩浆的Mg#范围，二红洼岩体中3件样品的Mg#=0.71～0.73，基本接近原生岩浆范围，其MgO含量平均值为7.45%。利用橄榄石-熔体平衡原理也可以估算进入岩浆房中原生岩浆的MgO含量。Mg-Fe在橄榄石-熔体之间的分配系数为一相对稳定的值，即KdOl-Melt=(FeO/MgO)Ol/(FeO/MgO)melt=0.3～0.33(ROEDER,1970)。然而，由于早期结晶的橄榄石与残余晶间液体之间要发生再平衡作用，使得早期结晶橄榄石比其在原生岩浆中结晶时的橄榄石中的Mg含量低，因此，Fo值最高的橄榄石组分可能更接近于液相线橄榄石的组成。以岩体中橄榄石最高的Fo=79估算出与其处于平衡状态岩浆MgO含量为7.1%。两种方法约束原生岩浆MgO含量基本一致，明显低于该岩带典型含矿岩体原生岩浆MgO含量(11.9%～9.6%)。由此可见，二红洼岩体原生岩浆应为普通的拉斑玄武岩。

[亏损地幔值DM(N-MORB)：εNd(300Ma)=9；(87Sr/86Sr)i=0.702 2；上地壳值UC：εNd(300Ma)=-9；(87Sr/86Sr)i=0.715]图7　二红洼岩体同化混染模拟图Fig.7　Contamination modeling diagram of Erhongwa

4.3岩浆源区

二红洼岩体的(87Sr/86Sr)i值为0.703 4～0.703 5，

εNd(t)值为+6.3～+7.7，且Pb同位素组成与MORB型亏损地幔Pb同位素一致。此外，岩体中除一件样品外，其余样品Zr/Nb值为42～59，这在MORB的Zr/Nb值(10～60)范围内(DAVIDSON，1996)，Sm/Nd值为0.27～0.30，平均值为0.32，基本上位于MORB的范围(ANDERSON，1994)。这些证据表明岩浆源区主体应属于软流圈地幔。而且在主量元素中，TiO2、K2O、Na2O的相容性最低，岩体各种岩石的TiO2平均含量仅为0.31%，K2O的平均含量为0.1%，Na2O为1.67%，说明不相容的主量元素也是亏损的。然而，岩体在没有受到明显的陆壳组分的混染的情况下，其(87Sr/86Sr)i明显高于正常洋中脊玄武岩的(87Sr/86Sr)i=0.702 29～0.703 11；(143Nd/144Nd)i低于正常洋中脊玄武岩(143Nd/144Nd)i0.513 0～0.513 3(SUNDERS，1988)。岩体普遍含有一定量的普通褐色角闪石，具有Nb、Ti的亏损，部分也有Ta亏损，暗示其源区可能受到早期俯冲板片/俯冲沉积物所释放流体的交代作用。在Nb/Zr-Th/Zr和Th/Yb-Nb/Yb相关图上显示岩浆源区存在被俯冲改造的富集岩石圈地幔(图8)。由此可见，岩体源区主体应该是软流圈地幔，可能同时也有很少量俯冲流体改造的富集岩石圈地幔的组分加入。

图8　(a)Th/Yb-Nb/Yb图解;(b)Nb/Zr-Th/Zr 图解Fig.8　(a)Th/Yb vs Nb/Yb diagram ;(b)Nb/Zr vs Th/Zr diagram

5　成矿潜力

黄山、黄山南、黄山东、香山、二红洼等岩体位于同一构造带，沿康古尔深大断裂分布，岩体形成时限约270～285Ma，应为后碰撞时期的产物。Nd、Sr同位素地球化学研究表明它们的岩浆源区性质基本一致，以亏损地幔组分为主，含有一定数量流体交代改造的富集型岩石圈地幔。除此之外，二红洼岩体在岩石组合、原生岩浆性质、同化混染程度等方面与该带典型含矿岩体存在显著差异。

世界上重要的岩浆硫化物矿床都赋存在高度分异的岩体中，而分异弱的岩体往往不成矿或贫矿。二红洼岩体地表出露面积大，岩浆分异差，岩体以辉长岩相为主，超基性岩石数量有限，仅见少量含长二辉橄榄岩。此外，赋存岩浆硫化物矿床的岩体原生岩浆均为高镁拉斑玄武岩、苦橄岩和科马提岩，岩浆演化过程中普遍受到一定程度的同化混染作用，而二红洼岩体原生岩浆为普通拉斑玄武岩，并且岩浆岩浆过程中受到较弱同化混染作用。现有钻探成果显示深部二辉橄榄岩相中赋存星点状硫化物，未见稀疏侵染状或稠密侵染状矿石。依据岩体分布特征、岩石组合、地球化学等综合判断，二红洼岩体与该带典型含矿岩体比较，关键成矿指标存在明显差异，这可能不同程度制约了成矿潜力，岩体浅部找矿难度大。

6　结论

(1) 二红洼岩体主要由含长二辉橄榄岩、橄榄辉长岩、辉长苏长岩和淡色辉长岩组成。岩石化学组成属拉斑玄武岩系列。岩石相对富集LREE，普遍富集普遍富集大离子亲石元素(Cs、Rb、Ba、Sr)，显著亏损Nb，适度亏损Zr、Hf、Ti，部分样品亏损Ta。

(2) 岩体Nd、Sr、Pb同位素组成属亏损型地幔，原生岩浆为普通拉斑玄武岩，岩浆演化过程中发生了较弱的同化混染作用程度，遭受约5%上地壳物质混染。

(3) 与同一岩带的典型含矿岩体对比研究发现，二红洼岩体在岩石组合、原生岩浆性质、同化混染程度等方面存在显著差异，综合研究表明岩体浅部找矿难度大。

秦克章,方同辉,王书来,等.东天山板块构造分区、演化与成矿地质背景研究[J].新疆地质,2002,20(4): 302-308.

QIN Kezhang,FANG Tonghui,WANG Shulai,et al.Plate tectonics division,evolution and metallogenic settings in Eastern Tianshan mountains,NW-China[J].Xinjiang Geology,2002,20(4):302-308.

毛景文,杨建民,屈文俊,等.新疆黄山东铜镍硫化物矿床Re-Os同位素测定及其地球动力学意义[J].矿床地质,2002,21(4):323-330.

MAO Jingwen,YANG Jianmin,QU Wenjun,et al.Re-Os dating of Cu-Ni sulfide ore from Huangshan dong deposit in Xinjiang and its geodynamic significance[J]. Mineral Deposits,2002,21(4):323-330.

韩宝福,季建清,宋彪, 等.新疆喀拉通克和黄山东含铜镍矿镁铁-超镁铁杂岩体的SHRIMP锆石U-Pb年龄及其地质意义[J]. 科学通报,2004,49(2): 2324-2328.

夏明哲,姜常义,钱壮志,等.新疆东天山葫芦岩体岩石学与地球化学研究[J].岩石学报,2008,24(12): 2749-2760.

XIA Mingzhe,JIANG Changyi,QIAN Zhuangzhi,et al.Geochemistry and petrogenesis for Hulu intrusion in East Tianshan, Xinjiang[J].Acta Petrologica Sinica,2008,24(12):2749-2760.

毛景文, FRANCO Pirajno,张作衡,等.天山—阿尔泰东部地区海西晚期后碰撞铜镍硫化物矿床:主要特点及可能与地幔柱的关系[J].地质学报, 2006,80(7): 925-942.

MAO Jingwen,FRANCO Pirajno,ZHANG Zuoheng,et al.Late variscan post-collisional Cu-Ni sulfide deposits in East Tianshan and Altay in China: principal characteristics and possible relationship with mantle plume[J]. Acta Geologica Sinica,2006,80(7):925-942.

王润民,刘德权,殷定泰.新疆哈密土墩—黄山一带铜镍硫化物矿床成矿控制条件及找矿方向的研究[J].矿物岩石,1987,7(1):1-152.

WANG Runmin,LIU Dequan,YIN Dingtai.The conditions of controlling metallogny of Cu-Ni sulphide ore deposits and the orientation of finding ore Hami,Xinjiang,China[J].Journal of Mineralogy and Petrology,1987,7(1):1-152.

仲勇. 二红洼镁铁-超镁铁杂岩体特征及成因[J].新疆地质,1991,9(2):150-170.

ZHONG Yong.Characteristics and genesis of Erhongwa mafic-ultramafic complexes[J].Xinjiang Geology, 1991,9(2):150-170.

仲勇.新疆二红洼基性—超基性杂岩体矿物、岩石化学及岩石学意义[J].中国地质科学院院报，1993,(Z1):43-54.

ZHONG Yong.Mineralogy, petrochemistry and petrology of the Erhongwa basic-ultrabasic complex in Xinjiang[J]. Journal of Earth,1993,(Z1):43-54.

张旗.镁铁-超镁铁岩与威尔逊旋回[J]. 岩石学报,1992,8(2):168-176.

ZHANG Qi.The mafic-ultramafic rocks and Wilson cycle[J]. Acta Petrologica Sinica,1992,8(2):168-176.

赵振华,王强,熊小林,等.新疆北部的两类埃达克岩[J].岩石学报,2006,22(5):1249-1265.

ZHAO Zhenhua,WANG Qiang,XIONG Xiaolin,et al.Two types of adakites in north Xinjiang,China[J]. Acta Petrologica Sinica,2006,22(5):1249-1265.

吴昌志,张遵忠,KHIN Z,等.东天山觉罗塔格红云滩花岗岩年代学、地球化学及其构造意义[J].岩石学报,2006,22(5):1121-1134.

WU Changzhi,ZHANG Zunzhong,KHIN Z,et al. Geochronology,geochemistry and tectonic significances of the Hongyuntan granitoids in the Qoltag area, Eastern Tianshan[J].Acta Petrologica Sinica, 2006, 22(5):1121-1134.

韩宝福,季建清,宋彪,等.新疆准噶尔晚古生代陆壳垂向生长(Ⅰ)——后碰撞深成岩浆活动的时限[J].岩石学报,2006,22(5):1077-1086.

HAN Baofu,JI Jianqing,SONG Biao,et al.Late Paleozoic vertical growth of continental crust around the Junggar Basin, Xinjiang, China (PartⅠ):Timing of post-collisional plutonism[J].Acta Petrologica Sinica,2006,22(5):1077-1086.

顾连兴,张遵忠,吴昌志,等.关于东天山花岗岩与陆壳垂向增生的若干认识[J].岩石学报,2006,22(5):1103-1120.

GU Lianxing,ZHANG Zunzhong,WU Changzhi,et al.Some problems on granites and vertical growth of the continental crust in the eastern Tianshan Mountains,NW China[J].Acta Petrologica Sinica, 2006, 22(5):1103-1120.

朱永峰,周晶,郭璇.西天山石炭纪火山岩的岩石学及Sr-Nd同位素地球化学研究[J].岩石学报,2006，22(5):1341-1350.

ZHU Yongfeng,ZHOU Jing,GUO Xuan.Petrology and Sr-Nd isotopic geochemistry of the Carboniferous volcanic rocks in the western Tianshan Mountains,NW China[J]. Acta Petrologica Sinica, 2006, 22(5):1314-1350.

ZHONG H,ZHU W G.Geochronology of layered mafic intrusions from the Pan-Xi area in the Emeishan large igneous province,SW China[J].Mineralium Deposita,2006,41:599-606.

ZHOU M F, LESHER C M, YANG Z X. Geochemistry and petrogenesis of 270Ma Ni-Cu-(PGE) sulfide-bearing mafic intrusions in the Huangshan district, Eastern Xinjiang,Northwest China: implications for the tectonic evolution of the Central Asian orogenic belt[J]. Chemical Geology.2004,209:233-257.

PIRAJNO F, MAO J W, ZHANG Z C.The association of mafic-ultramafic intrusions and A-type magmatism in the Tianshan and Altay orogens, NW China: implications for geodynamic evolution and potential for the discovery of new ore deposits[J]. Journal of Asian Earth Sciences，2008,32:165-183.

MORIMOTO N.Nomenclature of pyroxense[J]. Mineralogical Magazine,1988,52:535-550.

TAYLOR S R,MCLEMAN S M.The continental crust Its composition and evolution[M].London: Blackwell, 1985:1-312.

SUN S S,MCDONOUGH W F.Chemical and isotopic systematics of ocean basalts: Implications for mantle composition and processes Geological Society[M]. London:Special Publication,1989,42:313-345.

ZHENG Yongfei, LI Shuguang,CHEN Jiangfeng. Chemical geodynamics[J] . Advance in Earth Sciences, 1998, 13(2): 121-128.

ALLEGREC J ,LEWIN E,DUPRE B A.Coherent crust-mantle model for the uranium-thorium-lead isotopic system [J].Chem Geol.,1988,70:211-234.

RUDNICK R L, GAO S. Composition of the continental crust. In: Rudnick RL (ed.). Treatise on Geochemistry, the Crust. Amsterdam[J].Elsevier,2003,3:1-64.

ROEDER P L,EMSLIE R F.Olivine-liquid equilibrium[J]. Contributions to Mineralogy and Petrology,1970,29:275-289.

GREEN D H.Genesis of archean peridotic magmas and constraints on archean geothermal gradients and tectonics[J].Geology,1975,3:15-18.

FREY F A,GREEN D H,et al.Integrated models of basalt petrogenesis:A study of quarti Tholeiitesto olivine melilities from south eastern Australia utilizing geochemical petrological data[J].Journal of Petrology,1978,19:463-513.

HESSP C. Phase equilibria constraints on the origin of ocean floor basalts.In:Morgan Jp ,Blackman DK Simon JM(eds).Mantle flow and Melt Generaion at Mid-Ocean Rides,Geophysical Monogrph [J]. American Geophysical Union,1992,71:67-102.

FARMERG L, PERRY F V, SEMKEN S,et al.Isotopic evidence on the tructure and origin of subcontinental lithospheric mantle in Southern Nevada[J]. Journal of Geophysical Research,1989,94:7885-7898.

MENZIES A.Cratonic cirumcratonic and oceanic mantle domains beneath the western United States[J]. Journal of Geophysical Research,1989,94:7899-7915.

SUNDERSA D,Storey M, KENT RW,et al.Consequence of plume lithosphere interacions.In:Storey BC, Alabaster T and Pankhurst RJ(eds). Magmatism and the Cause of Continental Breakup[M]. London: Geological Society of Special Publication,1992,68:41-60.

DAVIDSONJ P. Deciphering mantle and crustal signature sinsubduction zone magmatism Subduction top to bottom[M].WashingtonDC:Gephys.Monogr.,American Geophysical Union, 1996,251-262.

ANDERSOND L,Komatites,picrites.Evidence that “plume” source is depleted[J].Earth and Planetary Science Letters,1994,128:303-311.

SUNDERS A D,NORRY M J,TARNEY J. Origin of MORB and Chemically-Depleted Mantle Reservoirs: Trace Element Constraints [J].J Petrology,1988,425-445.

Magmatic Evolution and Mineralization Potential of the Erhongwa Intrusion in East Tianshan Mountains, Xinjiang

DUAN Xingxing1, DU Hui1, LIU Tuo1, LI Wenming1, XIA Mingzhe2,3

(1.Xi’an Center of Geological Survey,China Geological Survey,Xi’an 710054, Shaanxi,China;2.College of Earth Science and Resources, Chang’an University,Xi’an 710054, Shaanxi,China;3.Key Laboratory of Western China’s Mineral Resources and Geological Engineering, Ministry of Education, Xi’an 710054, Shaanxi,China)

Erhongwa intrusion lies in the eastern part of Kongguer-Huangshan fault belt. It consists of pl-bearing iherzolite, olivine gabbro,gabbronorite and leucogabbro. Most of these rocks are slightly enriched in LREE and depleted in HFSE(Nb, Ta and Ti).The primary magma of this intrusion may be ordinary tholeiite (MgO=7.3%). Element geochemistry and Nb, Sr, Pb isotope characters suggest that this magma source is composed of asthenosphere components, mixed with a small amount of lithospheric mantle components, and this magma was subjected to becontaminated about 5% by contiental crust. Compared with others intrusion in this mafic-ultrumafic belt, the Erhongwa intrusion has some significant differences in rock association, primary magma nature and assimilation,which may restrict the mineralization potential in this area.

mineralization potential;magmatic evolution;Erhongwa intrusion;East Tianshan Mountains

2015-12-02；

2016-05-16

国家自然基金项目(41102045)和中央高校基本科研业务费专项资金(2013G1271100)资助

段星星(1983-)，男，湖南郴州人，工程师，2012年毕业于长安大学岩石学、矿物学、矿床学专业，现从事矿床勘查及勘查地球化学工作。E-mail: 86000536@qq.com

P588.12

A

1009-6248(2016)03-0050-11