巴颜喀拉地块当俄花岗岩体地球化学特征及锆石年龄
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摘要
巴颜喀拉地块夹持于昆南缝合带、金沙江缝合带及龙门山断裂带之间,出露了较多的花岗岩体。当俄花岗岩体的岩石地球化学特征表明,当俄岩体具有较高SiO_2含量(w(SiO_2)=65.78%～70.22%)、过铝质(A/CNK=1.58～1.95,>1.1)特征,属过铝质高钾钙碱性A型花岗岩;该岩体总体形成温度为700℃—800℃,总体形成压力为0.05GPa—0.2GPa,为低压高温环境;岩石具有Rb、Th强正异常,Ba、Nb、Sr、P、Ti强烈亏损,轻稀土强烈富集特征,且具有一定的负Eu异常,显示出有壳源的特征;花岗岩锆石SHRIMP U-Pb测年为211.9 Ma±1.9Ma,表明岩浆侵位时代为中生代晚三叠世。当俄花岗岩体形成于碰撞造山后期地壳减薄环境中,属于印支晚期岩浆活动的产物。
Bayanhar terrain is held by the Southern Kunlun suture and Jinshajiang suture and Longmenshan fault.There are many granite outcrops in the terrain and Dang'e granite body is one of them.Geochemical analysis shows that Dang'e granite body is characterized by higher SiO_2 contents(65.78% to70.22%)and peraluminous(A/CNK=1.58 to 1.95>1.1)belonging to the peraluminous-high K calc-alkaline A-type granites.It is formed under the low pressure(0.05 GPa—0.2 GPa)and high temperature(700℃—800℃)environment with strong Rb,Th positive anomaly,strong Ba,Nb,Sr,P,Ti depletion,strong LREE enrichment and a certain negative Eu anomly.All this are the characteristic of the crustal source.The zircon SHRIMP U-Pb dating(211.9 Ma±1.9 Ma)indicates that emplacement age of the granite body is the Mesozoic Late Triassic Epoch.It is formed during the crust thinning of late to post orogenic collision,and is the product of late Indo-China magmatic activity.
Bayanhar terrain is held by the Southern Kunlun suture and Jinshajiang suture and Longmenshan fault.There are many granite outcrops in the terrain and Dang'e granite body is one of them.Geochemical analysis shows that Dang'e granite body is characterized by higher SiO_2 contents(65.78% to70.22%)and peraluminous(A/CNK=1.58 to 1.95>1.1)belonging to the peraluminous-high K calc-alkaline A-type granites.It is formed under the low pressure(0.05 GPa—0.2 GPa)and high temperature(700℃—800℃)environment with strong Rb,Th positive anomaly,strong Ba,Nb,Sr,P,Ti depletion,strong LREE enrichment and a certain negative Eu anomly.All this are the characteristic of the crustal source.The zircon SHRIMP U-Pb dating(211.9 Ma±1.9 Ma)indicates that emplacement age of the granite body is the Mesozoic Late Triassic Epoch.It is formed during the crust thinning of late to post orogenic collision,and is the product of late Indo-China magmatic activity.
引文
[1]陈文,Arnau N.巴颜喀拉地体POG型花岗岩同位素年代学研究[J].地球学报:中国地质科学院院报,1997,18(3):261-266.
[2]雷裕红,马昌前,王国灿.巴颜喀拉沉积盆地基底为扬子地台西缘的一部分:来自花岗岩的证据[J].高校地质学报,2006,12(3):298-309.
[3]Collins W J,Beams S D,White A J R,et al.Nature and origin of A-type granites with particular reference to southeastern Australia[J].Contributions to Mineralogy and Petrology,1982,80:189-200.
[4]Whalen J B,Currie K L,Chappell B W.A-type granites:geochemica characteristics,discriminations and Petrogenesis[J].Contributions to Mineralogy and Petrology,1987,95:407-419.
[5]Anderson J L.Proterozoic anorogenic granite plutonism of North America in Medaris[C]∥Jr L G,Byers C W,Mickelson D Mand hanks W C(eds).Proterozoic Geology Selected Papers from an International Proterozoic Symposium.Geol Soc Am Memoir,1983,161:133-152.
[6]Clemens J D,Holloway J R,White A J R.Origin of A-type granites:Experimental constraints[J].Am Mineral,1986,71:317-324.
[7]R.DALL’AGNOL,B.SCAILLET,M.PICHAVANT.An Experimental Study study of a Lower Proterozoic A-type Granite from the Eastern Amazonian Craton,Brazil[J].Journal of Petrology,1999,40(11):1673-1698.
[8]Klimm K,Holtz F,Johannes W,et al.Fractionation of metalu-minous A-type granites:An experimental study of the Wangrah Suite,Lachlan Fold Belt,Australia[J].Precambrian Res,2003,124:327-341.
[9]Scaillet B,Macdonald R.Phase relations of peralkaline silicic magmas and petrogenetic implications[J].Journal of Petrology,2001,42:825-845.
[10]Scaillet B,Macdonald R.Experimental constraints on the rela-tionships between peralkaline rhyolites of the Kenya Rift Valley[J].Journal of Petrology,2003,44(10):1867-1894.
[11]张旗,冉白皋,李承东.A型花岗岩的实质是什么?[J].岩石矿物学杂志,2012,31(4):621-626.
[12]Williams I S,Cleasson S.Isotope evidence for the Precambrian province and Caledonian metamorphism of high grade paragenesis from the Seve Nappes,Scandinacian caledonides,Ⅱ:for microprobe zircon U-Th-Pb[J].Contrib Mineral Petrology,1987,97:205-217.
[13]Compston W,Williams I S,Kirschvink J L,Zhang Z,Guo gan M A.Zircon U-Pb ages of early Cambrian time-scale[J].Journal of Geol Soc,1992,149:171-184.
[14]宋彪,张玉海,万渝生,等.锆石SHRIMP样品靶制作、年龄测定及有关现象讨论[J].地质论评,2002,48(增刊):26-30.
[15]简平,刘敦一,孙小猛.滇川西部金沙江石炭纪蛇绿岩SHRIMP测年:古特提斯洋盆演化的同位素年代学制约[J].地质学报,2003,77(2):217-228.
[16]付建明,程顺波,卢友月,等.湖南锡田云英岩-石英脉型钨锡矿的形成时代及其赋矿花岗岩锆石SHRIMP U-Pb定年[J].地质与勘探,2012,48(2):313-320.
[17]陈娟,马润则,张腊梅,等.龙门山北段水磨地区辉绿岩锆石U-Pb年龄及地球化学特征[J].地质与勘探,2015,51(1):133-142.
[18]沙淑清,王宗秀,郭通珍,等.巴颜喀拉山东段花岗岩锆石SHRIMP定年及其地球化学特征[J].地球学报,2007,28(3):261-269.
[19]Eby G N.Chemical subdivision of the A-type granitoids:petrogenetic and tectonic implication[J].Geology,1992,20:641-644.
[20]洪大卫,王式洸,韩宝福,等.碱性花岗岩的构造环境分类及其鉴别标志[J].中国科学B辑,1995,25(4):418-426.
[21]Chen Wen,Li Haibin,Xu Zhiqin.Using the laser microprobe39 Ar/40 Ar dating technique and the 39 Ar/40 Ar stepwise incrimental heating technique to date the ages of Xidatan shear zone(Kunlun Terrane,Tibetan Plateau)[J].Acta Geoscientia Sinica,Special Issue,1996:228-232.
[22]贾小辉,王强,唐功建.A型花岗岩的研究进展及意义[J].大地构造与成矿学,2009,33(3):465-480.
(1)四川省地质调查院.色达县幅1/25万区域地质调查报告[R].成都:四川省地质调查院,2005.
[2]雷裕红,马昌前,王国灿.巴颜喀拉沉积盆地基底为扬子地台西缘的一部分:来自花岗岩的证据[J].高校地质学报,2006,12(3):298-309.
[3]Collins W J,Beams S D,White A J R,et al.Nature and origin of A-type granites with particular reference to southeastern Australia[J].Contributions to Mineralogy and Petrology,1982,80:189-200.
[4]Whalen J B,Currie K L,Chappell B W.A-type granites:geochemica characteristics,discriminations and Petrogenesis[J].Contributions to Mineralogy and Petrology,1987,95:407-419.
[5]Anderson J L.Proterozoic anorogenic granite plutonism of North America in Medaris[C]∥Jr L G,Byers C W,Mickelson D Mand hanks W C(eds).Proterozoic Geology Selected Papers from an International Proterozoic Symposium.Geol Soc Am Memoir,1983,161:133-152.
[6]Clemens J D,Holloway J R,White A J R.Origin of A-type granites:Experimental constraints[J].Am Mineral,1986,71:317-324.
[7]R.DALL’AGNOL,B.SCAILLET,M.PICHAVANT.An Experimental Study study of a Lower Proterozoic A-type Granite from the Eastern Amazonian Craton,Brazil[J].Journal of Petrology,1999,40(11):1673-1698.
[8]Klimm K,Holtz F,Johannes W,et al.Fractionation of metalu-minous A-type granites:An experimental study of the Wangrah Suite,Lachlan Fold Belt,Australia[J].Precambrian Res,2003,124:327-341.
[9]Scaillet B,Macdonald R.Phase relations of peralkaline silicic magmas and petrogenetic implications[J].Journal of Petrology,2001,42:825-845.
[10]Scaillet B,Macdonald R.Experimental constraints on the rela-tionships between peralkaline rhyolites of the Kenya Rift Valley[J].Journal of Petrology,2003,44(10):1867-1894.
[11]张旗,冉白皋,李承东.A型花岗岩的实质是什么?[J].岩石矿物学杂志,2012,31(4):621-626.
[12]Williams I S,Cleasson S.Isotope evidence for the Precambrian province and Caledonian metamorphism of high grade paragenesis from the Seve Nappes,Scandinacian caledonides,Ⅱ:for microprobe zircon U-Th-Pb[J].Contrib Mineral Petrology,1987,97:205-217.
[13]Compston W,Williams I S,Kirschvink J L,Zhang Z,Guo gan M A.Zircon U-Pb ages of early Cambrian time-scale[J].Journal of Geol Soc,1992,149:171-184.
[14]宋彪,张玉海,万渝生,等.锆石SHRIMP样品靶制作、年龄测定及有关现象讨论[J].地质论评,2002,48(增刊):26-30.
[15]简平,刘敦一,孙小猛.滇川西部金沙江石炭纪蛇绿岩SHRIMP测年:古特提斯洋盆演化的同位素年代学制约[J].地质学报,2003,77(2):217-228.
[16]付建明,程顺波,卢友月,等.湖南锡田云英岩-石英脉型钨锡矿的形成时代及其赋矿花岗岩锆石SHRIMP U-Pb定年[J].地质与勘探,2012,48(2):313-320.
[17]陈娟,马润则,张腊梅,等.龙门山北段水磨地区辉绿岩锆石U-Pb年龄及地球化学特征[J].地质与勘探,2015,51(1):133-142.
[18]沙淑清,王宗秀,郭通珍,等.巴颜喀拉山东段花岗岩锆石SHRIMP定年及其地球化学特征[J].地球学报,2007,28(3):261-269.
[19]Eby G N.Chemical subdivision of the A-type granitoids:petrogenetic and tectonic implication[J].Geology,1992,20:641-644.
[20]洪大卫,王式洸,韩宝福,等.碱性花岗岩的构造环境分类及其鉴别标志[J].中国科学B辑,1995,25(4):418-426.
[21]Chen Wen,Li Haibin,Xu Zhiqin.Using the laser microprobe39 Ar/40 Ar dating technique and the 39 Ar/40 Ar stepwise incrimental heating technique to date the ages of Xidatan shear zone(Kunlun Terrane,Tibetan Plateau)[J].Acta Geoscientia Sinica,Special Issue,1996:228-232.
[22]贾小辉,王强,唐功建.A型花岗岩的研究进展及意义[J].大地构造与成矿学,2009,33(3):465-480.
(1)四川省地质调查院.色达县幅1/25万区域地质调查报告[R].成都:四川省地质调查院,2005.