西准噶尔克孜勒巴斯套A型花岗岩地球化学特征、岩石成因及其地质意义
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摘要
新疆西准噶尔构造带分布着大量的中酸性侵入体,其岩石成因和侵位期次对于认识该构造带的岩浆演化具有十分重要的意义。本次研究在详细的野外地质调查基础上,针对西准噶尔南部克孜勒巴斯套岩体8个样品进行地球化学特征分析。结果表明,克孜勒巴斯套岩体出露面积约7km~2,岩性主要为碱长花岗岩。其形成时代为306.4 Ma±3.7Ma,属晚石炭世晚期。岩石主量元素具有高硅(w(SiO_2)=74.30%～77.18%)、富碱且相对富钠(w(Na_2O+K_2O)=7.38%～8.73%,Na_2O/K_2O=0.97～1.39)、贫钙镁(w(CaO)=0.22%～0.48%;w(MgO)=0.19%～0.44%)、相对富铝(w(Al_2O_3)=11.93%～13.42%)的特征,明显富集Rb,K等大离子亲石元素及Zr,Hf等高场强元素,亏损Ba,Sr,P,Eu,Ti等元素,具有较高的TFeO/MgO(5.88～9.07),Zr+Nb+Ce+Y(372.4×10~(-6)～482.7×10~(-6))值及锆石饱和温度(860℃～890℃),属于碱性准铝质-弱过铝质A型花岗岩,为低压高温氧化条件年轻下地壳物质部分熔融的产物。结合区域构造背景和前人研究成果,认为西准噶尔南部地区在晚石炭世晚期仍处于俯冲体制,可能与晚石炭世洋脊俯冲作用有关。
There are large numbers of intermediate to acid intrusions distributed along the tectono-magmatic belt of western Junggar,Xinjiang.It is of great significance on the understanding of the magmatic evolution of this tectono-magmatic belt through their petrogenesis and emplacement periods.Detailed field geological survey has made it available for the study of petrogeochemistry(eight samples)of Kezilebasitao granite.It shows that Kezilebasitao granite is mainly composed of alkali feldspar granite and covers an outcrop area of 7 km~2,with an age of 306.4 Ma±3.7 Ma,representing that the formation time of the alkali feldspar granite is late Late Carboniferous.Major elements of the rock indicate that these alkali feldspar granites are characterized by high Si(w(SiO_2)=74.30%～77.18%),enrichment of alkali and relatively enrichment of Na(w(Na_2O+K_2O)=7.38%～8.73%,Na_2O/K_2O=0.97～1.39),low Ca and Mg(w(CaO)=0.22%～0.48%;w(MgO)=0.19%～0.44%)and relatively enrichment of Al(w(Al_2O_3)=11.93%～13.42%);The trace elements of the rock are rich in Rb,K and other large ion lithophile elements(LILE)and high field strength elements(HFSE)Zr,Hf,and poor in Ba,Sr,P,Eu,Ti,with high TFeO/MgO ratios(5.88～9.07)and Zr+Nb+Ce+Y contents(372.4×10~(-6)～482.7×10~(-6))and high zircon saturation temperatures(860℃～890℃),characteristic of alkaline metaluminous to weakly peraluminous series A-type granite,which was originated from the partial melting of juvenile lower crust under high temperature and low pressure conditions.It is considered that the southwest Junggar region was still in a subduction-dominated setting in the late Carboniferous,and it is related to the oceanic ridge subduction in late Carboniferous period.
There are large numbers of intermediate to acid intrusions distributed along the tectono-magmatic belt of western Junggar,Xinjiang.It is of great significance on the understanding of the magmatic evolution of this tectono-magmatic belt through their petrogenesis and emplacement periods.Detailed field geological survey has made it available for the study of petrogeochemistry(eight samples)of Kezilebasitao granite.It shows that Kezilebasitao granite is mainly composed of alkali feldspar granite and covers an outcrop area of 7 km~2,with an age of 306.4 Ma±3.7 Ma,representing that the formation time of the alkali feldspar granite is late Late Carboniferous.Major elements of the rock indicate that these alkali feldspar granites are characterized by high Si(w(SiO_2)=74.30%～77.18%),enrichment of alkali and relatively enrichment of Na(w(Na_2O+K_2O)=7.38%～8.73%,Na_2O/K_2O=0.97～1.39),low Ca and Mg(w(CaO)=0.22%～0.48%;w(MgO)=0.19%～0.44%)and relatively enrichment of Al(w(Al_2O_3)=11.93%～13.42%);The trace elements of the rock are rich in Rb,K and other large ion lithophile elements(LILE)and high field strength elements(HFSE)Zr,Hf,and poor in Ba,Sr,P,Eu,Ti,with high TFeO/MgO ratios(5.88～9.07)and Zr+Nb+Ce+Y contents(372.4×10~(-6)～482.7×10~(-6))and high zircon saturation temperatures(860℃～890℃),characteristic of alkaline metaluminous to weakly peraluminous series A-type granite,which was originated from the partial melting of juvenile lower crust under high temperature and low pressure conditions.It is considered that the southwest Junggar region was still in a subduction-dominated setting in the late Carboniferous,and it is related to the oceanic ridge subduction in late Carboniferous period.
引文
[1]Xiao W J,Han C M,Yuan C,et al.Middle Cambrian to Permian subduction-related accretionary orogenesis of Northern Xinjiang,NW China:Implications for the tectonic evolution of central Asia[J].Journal of Asian Earth Sciences,2008,32(2):102-117.
[2]Chen B,Arakawa Y.Elemental and Nd-Sr isotopic geochemistry of granitoids from the West Junggar foldbelt(NW China),with implications for Phanerozoic continental growth[J].Geochimica et Cosmochimica Acta,2005,69(5):1 307-1 320.
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[4]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):1 077-1 086.
[5]陈宣华,聂兰仕,丁伟翠,等.西准噶尔走滑断裂系元素分布特征及其成矿意义[J].岩石学报,2015,31(2):371-387.
[6]Gao R,Xiao L,Pirajno F,et al.Carboniferous-Permian extensive magmatism in the West Junggar,Xinjiang,northwestern China:Its geochemistry,geochronology,and petrogenesis[J].Lithos,2014,204:125-143.
[7]柳小明,高山,袁洪林,等.193nm LA-ICP MS对国际地质标准参考物质中42种主量和微量元素的分析[J].岩石学报,2002,18(3):408-418.
[8]Chappell B W,White A J R.Two contrasting granite types[J].Pacific geology,1974,8(2):173-174.
[9]King P L,White A J R,Chappell B W,et al.Characterization and origin of aluminous A-type granites from the Lachlan Fold Belt,southeastern Australia[J].Journal of Petrology,1997,38(3):371-391.
[10]Whalen J B,Currie K L,Chappell B W.A-type granites:Geochemical characteristics,discrimination and petrogenesis[J].Contributions to Mineralogy and Petrology,1987,95(4):407-419.
[11]Dall′agnol R,de Oliveira D C.Oxidized,magnetite-series,rapakivi-type granites of Carajás,Brazil:Implications for classification and petrogenesis of A-type granites[J].Lithos,2007,93(3-4):215-233.
[12]Frost C D,Frost B R.On ferroan(A-type)granitoids:Their compositional variability and modes of origin[J].Journal of Petrology,2011,52(1):39-53.
[13]胡洋,王居里,王建其,等.新疆西准噶尔庙尔沟岩体的地球化学及年代学研究[J].岩石学报,2015,31(2):505-522.
[14]姜芸,肖龙,周佩,等.新疆西准噶尔红山岩体地质地球化学特征及对下地壳性质的启示[J].地球科学,2015,40(7):1 129-1 147.
[15]Sun S S,McDonough W F.Chemical and isotopic systematics of oceanic basalts:Implications for mantle composition and processes[J].Geological Society,Special Publications,1989,42(1):313-345.
[16]Chappell B W,White A J R.I-and S-type granites in the Lachlan Fold Belt[J].Transactions of the Royal Society of Edinburgh:Earth Sciences,1992,83(1-2):1-26.
[17]Sylvester P J,Campbell I H,Bowyer D A.Niobium/Uranium evidence for Early Formation of continental crust[J].Science,1997,275:521-523.
[18]Green T H.Experimental studies of trace-element partitioning applicable to igneous petrogenesis-Sedona 16years later[J].Chemical Geology,1994,117(1-4):1-36.
[19]Watson E B.Zircon saturation in felsic liquids:Experimental results and applications to trace element geochemistry[J].Contributions to Mineralogy and Petrology,1979,70(4):407-419.
[20]Yang G X,Li Y J,Yan J,et al.Geochronological and geochemical constraints on the origin of the 304±5 Ma Karamay A-type granites from West Junggar,Northwest China:Implications for understanding the Central Asian Orogenic Belt[J].International Geology Review,2014,56(4):393-407.
[21]杨钢,肖龙,王国灿,等.西准噶尔别鲁阿嘎希花岗闪长岩年代学、地球化学特征及岩石成因[J].地球科学,2015,40(5):810-823.
[22]Yin J Y,Chen W,Xiao W J,et al.Petrogenesis of Early-Permian sanukitoids from West Junggar,northwest China:Implications for Later Paleozoic crustal growth in Central Asia[J].Tectonophysics,2015,662:385-397.
[23]段丰浩,李永军,支倩,等.新疆西准噶尔庙尔沟地区赞岐岩地球化学特征、成因机制及其地质意义[J].大地构造与成矿学,2018,42(4):759-776.
[24]张连昌,万博,焦学军,等.西准包古图含铜斑岩的埃达克岩特征及其地质意义[J].中国地质,2006,33(3):626-631.
[25]段丰浩,李永军,王冉,等.西准噶尔托里县都伦河东岩体埃达克岩特征及其地质意义[J].矿物岩石,2015,35(4):8-16.
[26]Duan F H,Li Y J,Yang G X,et al.Late Carboniferous adakitic porphyries in the Huangliangzi pluton,West Junggar(Xinjiang),NW China:Petrogenesis and their tectonic implications[J].Geological Journal,2018,53(S2):97-113.
[27]Tang G J,Wyman D A,Wang Q,et al.Asthenosphere-lithosphere interaction triggered by a slab window during ridge subduction:Trace element and Sr-Nd-Hf-Os isotopic evidence from Late Carboniferous tholeiites in the western Junggar area(NW China)[J].Earth and Planetary Science Letters,2012,329:84-96.
[28]晋慧娟,李育慈.准噶尔盆地西北缘石炭纪生物成因的沉积构造研究[J].科学通报,1998,43(17):1 888-1 891.
[29]Pearce J A,Harris N B W,Tindle A G.Trace element discrimination diagrams for the tectonic interpretation of granitic rocks[J].Journal of Petrology,1984,25(4):956-983.
[30]吴福元,李献华,杨进辉,等.花岗岩成因研究的若干问题[J].岩石学报,2007,23(6):1 217-1 238.
(1)也斯道列提幅(L-44-96-C)萨尔卡姆斯什塔普幅(L-44-96-D)1∶5×104区域地质调查报告[R].乌苏:新疆地质矿产局第七地质大队,1990.
[2]Chen B,Arakawa Y.Elemental and Nd-Sr isotopic geochemistry of granitoids from the West Junggar foldbelt(NW China),with implications for Phanerozoic continental growth[J].Geochimica et Cosmochimica Acta,2005,69(5):1 307-1 320.
[3]Geng H Y,Sun M,Yuan C,et al.Geochemical,Sr-Nd and zircon U-Pb-Hf isotopic studies of Late Carboniferous magmatism in the West Junggar,Xinjiang:Implications for ridge subduction?[J].Chemical Geology,2009,266(3-4):364-389.
[4]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):1 077-1 086.
[5]陈宣华,聂兰仕,丁伟翠,等.西准噶尔走滑断裂系元素分布特征及其成矿意义[J].岩石学报,2015,31(2):371-387.
[6]Gao R,Xiao L,Pirajno F,et al.Carboniferous-Permian extensive magmatism in the West Junggar,Xinjiang,northwestern China:Its geochemistry,geochronology,and petrogenesis[J].Lithos,2014,204:125-143.
[7]柳小明,高山,袁洪林,等.193nm LA-ICP MS对国际地质标准参考物质中42种主量和微量元素的分析[J].岩石学报,2002,18(3):408-418.
[8]Chappell B W,White A J R.Two contrasting granite types[J].Pacific geology,1974,8(2):173-174.
[9]King P L,White A J R,Chappell B W,et al.Characterization and origin of aluminous A-type granites from the Lachlan Fold Belt,southeastern Australia[J].Journal of Petrology,1997,38(3):371-391.
[10]Whalen J B,Currie K L,Chappell B W.A-type granites:Geochemical characteristics,discrimination and petrogenesis[J].Contributions to Mineralogy and Petrology,1987,95(4):407-419.
[11]Dall′agnol R,de Oliveira D C.Oxidized,magnetite-series,rapakivi-type granites of Carajás,Brazil:Implications for classification and petrogenesis of A-type granites[J].Lithos,2007,93(3-4):215-233.
[12]Frost C D,Frost B R.On ferroan(A-type)granitoids:Their compositional variability and modes of origin[J].Journal of Petrology,2011,52(1):39-53.
[13]胡洋,王居里,王建其,等.新疆西准噶尔庙尔沟岩体的地球化学及年代学研究[J].岩石学报,2015,31(2):505-522.
[14]姜芸,肖龙,周佩,等.新疆西准噶尔红山岩体地质地球化学特征及对下地壳性质的启示[J].地球科学,2015,40(7):1 129-1 147.
[15]Sun S S,McDonough W F.Chemical and isotopic systematics of oceanic basalts:Implications for mantle composition and processes[J].Geological Society,Special Publications,1989,42(1):313-345.
[16]Chappell B W,White A J R.I-and S-type granites in the Lachlan Fold Belt[J].Transactions of the Royal Society of Edinburgh:Earth Sciences,1992,83(1-2):1-26.
[17]Sylvester P J,Campbell I H,Bowyer D A.Niobium/Uranium evidence for Early Formation of continental crust[J].Science,1997,275:521-523.
[18]Green T H.Experimental studies of trace-element partitioning applicable to igneous petrogenesis-Sedona 16years later[J].Chemical Geology,1994,117(1-4):1-36.
[19]Watson E B.Zircon saturation in felsic liquids:Experimental results and applications to trace element geochemistry[J].Contributions to Mineralogy and Petrology,1979,70(4):407-419.
[20]Yang G X,Li Y J,Yan J,et al.Geochronological and geochemical constraints on the origin of the 304±5 Ma Karamay A-type granites from West Junggar,Northwest China:Implications for understanding the Central Asian Orogenic Belt[J].International Geology Review,2014,56(4):393-407.
[21]杨钢,肖龙,王国灿,等.西准噶尔别鲁阿嘎希花岗闪长岩年代学、地球化学特征及岩石成因[J].地球科学,2015,40(5):810-823.
[22]Yin J Y,Chen W,Xiao W J,et al.Petrogenesis of Early-Permian sanukitoids from West Junggar,northwest China:Implications for Later Paleozoic crustal growth in Central Asia[J].Tectonophysics,2015,662:385-397.
[23]段丰浩,李永军,支倩,等.新疆西准噶尔庙尔沟地区赞岐岩地球化学特征、成因机制及其地质意义[J].大地构造与成矿学,2018,42(4):759-776.
[24]张连昌,万博,焦学军,等.西准包古图含铜斑岩的埃达克岩特征及其地质意义[J].中国地质,2006,33(3):626-631.
[25]段丰浩,李永军,王冉,等.西准噶尔托里县都伦河东岩体埃达克岩特征及其地质意义[J].矿物岩石,2015,35(4):8-16.
[26]Duan F H,Li Y J,Yang G X,et al.Late Carboniferous adakitic porphyries in the Huangliangzi pluton,West Junggar(Xinjiang),NW China:Petrogenesis and their tectonic implications[J].Geological Journal,2018,53(S2):97-113.
[27]Tang G J,Wyman D A,Wang Q,et al.Asthenosphere-lithosphere interaction triggered by a slab window during ridge subduction:Trace element and Sr-Nd-Hf-Os isotopic evidence from Late Carboniferous tholeiites in the western Junggar area(NW China)[J].Earth and Planetary Science Letters,2012,329:84-96.
[28]晋慧娟,李育慈.准噶尔盆地西北缘石炭纪生物成因的沉积构造研究[J].科学通报,1998,43(17):1 888-1 891.
[29]Pearce J A,Harris N B W,Tindle A G.Trace element discrimination diagrams for the tectonic interpretation of granitic rocks[J].Journal of Petrology,1984,25(4):956-983.
[30]吴福元,李献华,杨进辉,等.花岗岩成因研究的若干问题[J].岩石学报,2007,23(6):1 217-1 238.
(1)也斯道列提幅(L-44-96-C)萨尔卡姆斯什塔普幅(L-44-96-D)1∶5×104区域地质调查报告[R].乌苏:新疆地质矿产局第七地质大队,1990.
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