青藏高原东南缘腾冲来利山A型花岗岩地球化学特征、锆石U-Pb定年及其构造意义
|
摘要
腾冲地块处于滇西复合造山带和青藏高原东南缘,研究区发育的花岗岩携带了大量的构造信息。腾冲来利山二长花岗岩锆石U-Pb年龄为50.4±0.4 Ma,是新生代早期印度-欧亚陆陆碰撞的产物。花岗岩Si O2含量较低(67.52%~68.99%),高钾(K2O=5.13%~5.70%),AR值为2.02~2.14,A/CNK值为0.95~0.99,属于准铝质高钾钙碱性系列;Fe OT/Mg O(4.03~4.54)、10000×Ga/Al(5.18~5.59)比值较高,相对富集LILE(Rb、Th、U、K、Pb)和HFSE(Zr、Hf),相对亏损Ba、Nb、Sr、P、Ti、Eu,而且稀土总量较高(∑REE=381.38×10–6~471.47×10–6),较富集轻稀土,稀土元素配分曲线呈右倾型。以上特征均指示来利山二长花岗岩具有A型花岗岩的特征,且属于A2亚型花岗岩。岩石的εHf(t)=–11.44~–8.01,Hf同位素二阶段模式年龄tDM2=1625~1845 Ma,反应其源岩物质单一,主要由地壳增厚引起中元古代的古老大陆地壳熔融形成。在早始新世(50 Ma左右),滇西腾冲-梁河地区正好处于印度-欧亚板块同碰撞-后碰撞的过渡构造环境,揭示了该地区从挤压机制向拉张机制转变的动力学过程。因此,作者推断自印度-欧亚板块陆陆碰撞高峰期至早始新世,青藏高原东南缘的板块应处于同碰撞挤压构造环境,之后进入后碰撞短暂拉张构造环境,并在滇西腾梁地区形成了来利山A型花岗岩。
The Tengchong block located in the conjunction of West Yunnan composite orogenic belt and southeastern margin of the Tibetan Plateau, and the granites in the block are important way to explore its tectonic evolution. U-Pb dating of zircon from the monzogranites in Lailishan at Tengchong county yields an age of 50.4±0.4 Ma, indicating that the pluton is related to the Early Cenozoic Indian-Eurasian continental collision. The Lailishan granites are characterized by high-K calc-alkaline and metaluminous, with Si O2=67.52%-68.99%, K2O=5.13%-5.70%, Al2O3=14.03%-14.98%, K2O/Na2O=1.66-1.89, A/CNK=0.95-0.99, A/NK=1.32-1.40. The rocks have high Fe OT/Mg O(4.03-4.54) and 10000×Ga/Al(5.18-5.59) ratios, enrich in Rb, Th, U, K, Pb(LILE) and Zr, Hf(HFSE), but deplete in Ba, Nb, Sr, P, Ti, Eu, and right oblique REE type. All these characteristics suggest that the Lailishan granites are A-type granite and belonging to A2 sub-type. The εHf(t) values( –11.44-–8.01) and the two-stage model ages(tHf2)(1.63–1.85 Ga) of the Lailishan granites suggest that the granites were mainly derived from remelting of the thickened Mesoproterozoic continental crust. At the Early Eocene, around 50 Ma, the Tengchong-Lianghe area in West Yunnan was not in post-orogenic environment that traditionally representedby A2 type granites, but just in the transition tectonic setting of Indian-Eurasian plate from syn-collision to post-collision, revealing a geodynamic processe of enduring from extrusive mechanism to tensive mechanism in this area. Therefore, we consider that southeastern margin of the Tibetan Plateau are in the syn-collision tectonic setting since the peak of Indian-Eurasian continental collision to the Early Eocene, following in the short-lived relaxation of post-collision setting, then the Lailishan A-type Granites was formed in the Tengliang area of Western Yunnan.
The Tengchong block located in the conjunction of West Yunnan composite orogenic belt and southeastern margin of the Tibetan Plateau, and the granites in the block are important way to explore its tectonic evolution. U-Pb dating of zircon from the monzogranites in Lailishan at Tengchong county yields an age of 50.4±0.4 Ma, indicating that the pluton is related to the Early Cenozoic Indian-Eurasian continental collision. The Lailishan granites are characterized by high-K calc-alkaline and metaluminous, with Si O2=67.52%-68.99%, K2O=5.13%-5.70%, Al2O3=14.03%-14.98%, K2O/Na2O=1.66-1.89, A/CNK=0.95-0.99, A/NK=1.32-1.40. The rocks have high Fe OT/Mg O(4.03-4.54) and 10000×Ga/Al(5.18-5.59) ratios, enrich in Rb, Th, U, K, Pb(LILE) and Zr, Hf(HFSE), but deplete in Ba, Nb, Sr, P, Ti, Eu, and right oblique REE type. All these characteristics suggest that the Lailishan granites are A-type granite and belonging to A2 sub-type. The εHf(t) values( –11.44-–8.01) and the two-stage model ages(tHf2)(1.63–1.85 Ga) of the Lailishan granites suggest that the granites were mainly derived from remelting of the thickened Mesoproterozoic continental crust. At the Early Eocene, around 50 Ma, the Tengchong-Lianghe area in West Yunnan was not in post-orogenic environment that traditionally representedby A2 type granites, but just in the transition tectonic setting of Indian-Eurasian plate from syn-collision to post-collision, revealing a geodynamic processe of enduring from extrusive mechanism to tensive mechanism in this area. Therefore, we consider that southeastern margin of the Tibetan Plateau are in the syn-collision tectonic setting since the peak of Indian-Eurasian continental collision to the Early Eocene, following in the short-lived relaxation of post-collision setting, then the Lailishan A-type Granites was formed in the Tengliang area of Western Yunnan.
引文
陈吉琛,林文信,陈良忠.1991.腾冲?梁河地区含锡花岗岩序列?单元研究.云南地质,10(3):241-289.
董方浏,侯增谦,高永丰,曾普胜,蒋成兴.2006.滇西腾冲新生代花岗岩:成因类型与构造意义.岩石学报,22(4):927-937.
耿建珍,李怀坤,张健,周红英,李惠民.2011.锆石Hf同位素组成的LA-MC-ICP-MS测定.地质通报,30(10):1508-1513.
侯增谦,曲晓明,王淑贤,高永丰,杜安道,黄卫.2003.西藏高原冈底斯斑岩铜矿带辉钼矿Re-Os年龄:成矿作用时限与动力学背景应用.中国科学(D辑),33(7):10.
江彪,龚庆杰,张静,马楠.2012.滇西腾冲大松坡锡矿区晚白垩世铝质A型花岗岩的发现及其地质意义.岩石学报,28(5):1477-1492.
罗君烈.1991.滇西锡矿的花岗岩类及其成矿作用.矿床地质,10(1):81-96,80.
莫宣学,赵志丹,邓晋福,董国臣,周肃,郭铁鹰,张双全,王亮亮.2003.印度?亚洲大陆主碰撞过程的火山作用响应.地学前缘,10(3):135-148.
戚学祥,朱路华,胡兆初,李志群.2011.青藏高原东南缘腾冲早白垩世岩浆岩锆石SHRIMPU-Pb定年和Lu-Hf同位素组成及其构造意义.岩石学报,27(11):3409-3421.
施光海,苗来成,张福勤,简平,范蔚茗,刘敦一.2004.内蒙古锡林浩特A型花岗岩的时代及区域构造意义.科学通报,49(4):384-389.
苏玉平,唐红峰,侯广顺,刘丛强.2006.新疆西准噶尔达拉布特构造带铝质A型花岗岩的地球化学研究.地球化学,35(1):55-67.
王成善,李祥辉,胡修棉.2003.再论印度?亚洲大陆碰撞的启动时间.地质学报,77(1):16-24.
王德滋,赵广涛,邱检生.1995.中国东部晚中生代A型花岗岩的构造制约.高校地质学报,1(2):13-21.
吴元保,郑永飞.2004.锆石成因矿物学研究及其对U-Pb年龄解释的制约.科学通报,49(16):1589-1604.
肖庆辉,邓晋福,马大铨,洪大卫,莫宣学,卢欣祥,李志昌,汪雄武,马昌前,吴福元,罗照华,王涛.2002.花岗岩研究思维与方法.北京:地质出版社:1-294.
徐成彦,王豪,刘粤湘,孟宪国.1991.构造分析、遥感、物化探方法综合研究腾冲?梁河锡成矿区的控矿构造及隐伏矿床预测.云南地质,10(4):394-416.
杨启军,徐义刚,黄小龙,罗震宇,石玉若.2009.滇西腾冲?梁河地区花岗岩的年代学、地球化学及其构造意义.岩石学报,25(5):1092-1104.
朱弟成,潘桂棠,莫宣学,段丽萍,廖忠礼.2004.印度大陆和欧亚大陆的碰撞时代.地球科学进展,19(4):564-571.
Amelin Y,Lee D C and Halliday A N.2000.Early-middle archaean crustal evolution deduced from Lu-Hf and U-Pb isotopic studies of single zircon grains.Geochimica et Cosmochimica Acta,64(24):4205-4225.
Barbarin B.1999.A review of the relationships between granitoid types,their origins and their geodynamic environments.Lithos,46:605-626.
Batchelor R A and Bowden P.1985.Petrogenetic interpretation of granitoid rock series using multicationic parameters.Chemical Geology,48(1-4):43-55.
Blichert-Toft J and Albarède F.1997.The Lu-Hf isotope geochemistry of chondrites and the evolution of the mantle-crust system.Earth and Planetary Science Letters,148(1-2):243-258.
Blisniuk P M,Hacker B R,Glodny J,Ratschbacher L,Bi SW,Wu Z H,Mcwilliams M O and Calvert A.2001.Normal faulting in central Tibet since at least 13.5 Myr ago.Nature,412(6847):628-632.
Collins W J,Beams S D,White A J R and Chappell B W.1982.Nature and origin of A-type granites with particular reference to southeastern Australia.Contributions to Mineralogy and Petrology,80(2):189-200.
De Celles P G,Gehrels G E,Najman Y,Martin A J,Carter Aand Garzanti E.2004.Detrital geochronology and geochemistry of Cretaceous-Early Miocene strata of Nepal:Implications for timing and diachroneity of initial Himalayan orogenesis.Earth and Planetary Science Letters,227(3-4):313-330.
Eby G N.1992.Chemical subdivision of the A-type granitoids:Petrogenetic and tectonic implications.Geology,20(7):641-644.
Griffin W L,Pearson N J,Belousova E,Jackson S E,van Achterbergh E,O’Reilly S Y and Shee S R.2000.The Hf isotope composition of cratonic mantle:LA-MC-ICPMS analysis of zircon megacrysts in kimberlites.Geochimica et Cosmochimica Acta,64(1):133-147.
Liu Y,Hu Z,Zong K,Gao C,Gao S,Xu J and Chen H.2010.Reappraisement and refinement of zircon U-Pb isotope and trace element analyses by LA-ICP-MS.Chinese Science Bulletin,55(15):1535-1546.
Ludwig K R.2003.User’s Manual for Isoplot/Ex Version 2.05.Berkeley,US:Berkeley Geochronology Center:1-272.
Maniar P D and Piccoli P M.1989.Tectonic discrimination of granitoids.Geological Society of America Bulletin,101(5):635-643.
Mc Donough W F and Sun S S.1995.The composition of the earth.Chemical Geology,120(3-4):223-253.
Morel M L A,Nebel O,Nebel J Y J,Miller J S and Vroon PZ.2008.Hafnium isotope characterization of the GJ-1zircon reference material by solution and laser-ablation MC-ICP-MS.Chemical Geology,255(1-2):231-235.
Pearce J A.1996.Sources and settings of granitic rocks.Episodes,19(4):120-125.
Rowley D B.1996.Age of initiation of collision between India and Asia:A review of stratigraphic data.Earth and Planetary Science Letters,145(1-4):1-13.
Rubatto D.2002.Zircon trace element geochemistry:Partitioning with garnet and the link between U-Pb ages and metamorphism.Chemical Geology,184(1-2):123-138.
S?derlund U,Patchett P J,Vervoort J D and Isachsen C E.2004.The 176Lu decay constant determined by Lu-Hf and U-Pb isotope systematics of Precambrian mafic intrusions.Earth and Planetary Science Letters,219(3-4):311-324.
Vervoort J D and Jonathan P P.1996.Behavior of hafnium and neodymium isotopes in the crust:Constraints from Precambrian crustally derived granites.Geochimica et Cosmochimica Acta,60(19):3717-3733.
Whalen J B,Currie K L and Chappell B W.1987.A-type granites:Geochemical characteristics,discrimination and petrogenesis.Contributions to Mineralogy and Petrology,95(4):407-419.
Williams H,Turner S,Kelley S and Harris N.2001.Age and composition of dikes in Southern Tibet:New constraints on the timing of,east-west extension and its relationship to postcollisional volcanism.Geology,29(4):339-342.
Wright J B.1969.A simple alkalinity ratio and its application to questions of non-orogenic granite genesis.Geological Magazine,106(4):370-384.
董方浏,侯增谦,高永丰,曾普胜,蒋成兴.2006.滇西腾冲新生代花岗岩:成因类型与构造意义.岩石学报,22(4):927-937.
耿建珍,李怀坤,张健,周红英,李惠民.2011.锆石Hf同位素组成的LA-MC-ICP-MS测定.地质通报,30(10):1508-1513.
侯增谦,曲晓明,王淑贤,高永丰,杜安道,黄卫.2003.西藏高原冈底斯斑岩铜矿带辉钼矿Re-Os年龄:成矿作用时限与动力学背景应用.中国科学(D辑),33(7):10.
江彪,龚庆杰,张静,马楠.2012.滇西腾冲大松坡锡矿区晚白垩世铝质A型花岗岩的发现及其地质意义.岩石学报,28(5):1477-1492.
罗君烈.1991.滇西锡矿的花岗岩类及其成矿作用.矿床地质,10(1):81-96,80.
莫宣学,赵志丹,邓晋福,董国臣,周肃,郭铁鹰,张双全,王亮亮.2003.印度?亚洲大陆主碰撞过程的火山作用响应.地学前缘,10(3):135-148.
戚学祥,朱路华,胡兆初,李志群.2011.青藏高原东南缘腾冲早白垩世岩浆岩锆石SHRIMPU-Pb定年和Lu-Hf同位素组成及其构造意义.岩石学报,27(11):3409-3421.
施光海,苗来成,张福勤,简平,范蔚茗,刘敦一.2004.内蒙古锡林浩特A型花岗岩的时代及区域构造意义.科学通报,49(4):384-389.
苏玉平,唐红峰,侯广顺,刘丛强.2006.新疆西准噶尔达拉布特构造带铝质A型花岗岩的地球化学研究.地球化学,35(1):55-67.
王成善,李祥辉,胡修棉.2003.再论印度?亚洲大陆碰撞的启动时间.地质学报,77(1):16-24.
王德滋,赵广涛,邱检生.1995.中国东部晚中生代A型花岗岩的构造制约.高校地质学报,1(2):13-21.
吴元保,郑永飞.2004.锆石成因矿物学研究及其对U-Pb年龄解释的制约.科学通报,49(16):1589-1604.
肖庆辉,邓晋福,马大铨,洪大卫,莫宣学,卢欣祥,李志昌,汪雄武,马昌前,吴福元,罗照华,王涛.2002.花岗岩研究思维与方法.北京:地质出版社:1-294.
徐成彦,王豪,刘粤湘,孟宪国.1991.构造分析、遥感、物化探方法综合研究腾冲?梁河锡成矿区的控矿构造及隐伏矿床预测.云南地质,10(4):394-416.
杨启军,徐义刚,黄小龙,罗震宇,石玉若.2009.滇西腾冲?梁河地区花岗岩的年代学、地球化学及其构造意义.岩石学报,25(5):1092-1104.
朱弟成,潘桂棠,莫宣学,段丽萍,廖忠礼.2004.印度大陆和欧亚大陆的碰撞时代.地球科学进展,19(4):564-571.
Amelin Y,Lee D C and Halliday A N.2000.Early-middle archaean crustal evolution deduced from Lu-Hf and U-Pb isotopic studies of single zircon grains.Geochimica et Cosmochimica Acta,64(24):4205-4225.
Barbarin B.1999.A review of the relationships between granitoid types,their origins and their geodynamic environments.Lithos,46:605-626.
Batchelor R A and Bowden P.1985.Petrogenetic interpretation of granitoid rock series using multicationic parameters.Chemical Geology,48(1-4):43-55.
Blichert-Toft J and Albarède F.1997.The Lu-Hf isotope geochemistry of chondrites and the evolution of the mantle-crust system.Earth and Planetary Science Letters,148(1-2):243-258.
Blisniuk P M,Hacker B R,Glodny J,Ratschbacher L,Bi SW,Wu Z H,Mcwilliams M O and Calvert A.2001.Normal faulting in central Tibet since at least 13.5 Myr ago.Nature,412(6847):628-632.
Collins W J,Beams S D,White A J R and Chappell B W.1982.Nature and origin of A-type granites with particular reference to southeastern Australia.Contributions to Mineralogy and Petrology,80(2):189-200.
De Celles P G,Gehrels G E,Najman Y,Martin A J,Carter Aand Garzanti E.2004.Detrital geochronology and geochemistry of Cretaceous-Early Miocene strata of Nepal:Implications for timing and diachroneity of initial Himalayan orogenesis.Earth and Planetary Science Letters,227(3-4):313-330.
Eby G N.1992.Chemical subdivision of the A-type granitoids:Petrogenetic and tectonic implications.Geology,20(7):641-644.
Griffin W L,Pearson N J,Belousova E,Jackson S E,van Achterbergh E,O’Reilly S Y and Shee S R.2000.The Hf isotope composition of cratonic mantle:LA-MC-ICPMS analysis of zircon megacrysts in kimberlites.Geochimica et Cosmochimica Acta,64(1):133-147.
Liu Y,Hu Z,Zong K,Gao C,Gao S,Xu J and Chen H.2010.Reappraisement and refinement of zircon U-Pb isotope and trace element analyses by LA-ICP-MS.Chinese Science Bulletin,55(15):1535-1546.
Ludwig K R.2003.User’s Manual for Isoplot/Ex Version 2.05.Berkeley,US:Berkeley Geochronology Center:1-272.
Maniar P D and Piccoli P M.1989.Tectonic discrimination of granitoids.Geological Society of America Bulletin,101(5):635-643.
Mc Donough W F and Sun S S.1995.The composition of the earth.Chemical Geology,120(3-4):223-253.
Morel M L A,Nebel O,Nebel J Y J,Miller J S and Vroon PZ.2008.Hafnium isotope characterization of the GJ-1zircon reference material by solution and laser-ablation MC-ICP-MS.Chemical Geology,255(1-2):231-235.
Pearce J A.1996.Sources and settings of granitic rocks.Episodes,19(4):120-125.
Rowley D B.1996.Age of initiation of collision between India and Asia:A review of stratigraphic data.Earth and Planetary Science Letters,145(1-4):1-13.
Rubatto D.2002.Zircon trace element geochemistry:Partitioning with garnet and the link between U-Pb ages and metamorphism.Chemical Geology,184(1-2):123-138.
S?derlund U,Patchett P J,Vervoort J D and Isachsen C E.2004.The 176Lu decay constant determined by Lu-Hf and U-Pb isotope systematics of Precambrian mafic intrusions.Earth and Planetary Science Letters,219(3-4):311-324.
Vervoort J D and Jonathan P P.1996.Behavior of hafnium and neodymium isotopes in the crust:Constraints from Precambrian crustally derived granites.Geochimica et Cosmochimica Acta,60(19):3717-3733.
Whalen J B,Currie K L and Chappell B W.1987.A-type granites:Geochemical characteristics,discrimination and petrogenesis.Contributions to Mineralogy and Petrology,95(4):407-419.
Williams H,Turner S,Kelley S and Harris N.2001.Age and composition of dikes in Southern Tibet:New constraints on the timing of,east-west extension and its relationship to postcollisional volcanism.Geology,29(4):339-342.
Wright J B.1969.A simple alkalinity ratio and its application to questions of non-orogenic granite genesis.Geological Magazine,106(4):370-384.