东太平洋海隆1°N洋中脊玄武岩斜长石斑晶的化学特征及其对岩浆作用的指示意义
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摘要
东太平洋海隆为世界典型的扩张脊,其上的洋中脊玄武岩为研究快速扩张作用下的岩浆作用提供了机会。在东太平洋海隆1°N采集到的洋中脊玄武岩内发现了大量结晶状况良好的斜长石斑晶。基于玄武岩的常量元素测试分析,洋脊下部的原始岩浆经历了以橄榄石为主的结晶分离过程,并未发生大规模的斜长石结晶分离。对样品中斜长石斑晶的电子探针测试表明,这些斜长石斑晶为岩浆自生矿物,而非捕掳晶。部分环带斜长石斑晶成分的规律性的变化主要受控于原始岩浆温度的变化,而非岩浆混合作用。我们推测Galapagos三联点下部可能存在一个相对封闭的岩浆体系,为斜长石矿物的结晶提供了时间和空间条件。这些斜长石斑晶形成后并未分离成岩,而是被岩浆带至洋底喷发形成玄武岩。
The East Pacific Rise( EPR) is a typical fast spreading ridge,which provides a good opportunity to further understanding of the magmatism under ridges. Mid Ocean Ridge Basalts( MORBs) from EPR 1°N were collected with amounts of well crystallized plagioclase phenocrysts. The major elements analysis on these MORBs show that the magma experienced fractional crystallization on olivine without plagioclase. The electron probe micro-analyzer( EPMA) analysis on these plagioclase indicates that these phenocrysts are authigenic minerals. Liner scan on some zoned plagioclases discovers relevant compositional changes,which are mainly the result of the temperature variation on magma rather than magma contamination. We infer the existence of a closed magmatism under the Galapagos triple junction,which provides conditions for crystallization of plagioclase minerals in space and time,leading to generation of the MORBs in the EPR 1°N.
The East Pacific Rise( EPR) is a typical fast spreading ridge,which provides a good opportunity to further understanding of the magmatism under ridges. Mid Ocean Ridge Basalts( MORBs) from EPR 1°N were collected with amounts of well crystallized plagioclase phenocrysts. The major elements analysis on these MORBs show that the magma experienced fractional crystallization on olivine without plagioclase. The electron probe micro-analyzer( EPMA) analysis on these plagioclase indicates that these phenocrysts are authigenic minerals. Liner scan on some zoned plagioclases discovers relevant compositional changes,which are mainly the result of the temperature variation on magma rather than magma contamination. We infer the existence of a closed magmatism under the Galapagos triple junction,which provides conditions for crystallization of plagioclase minerals in space and time,leading to generation of the MORBs in the EPR 1°N.
引文
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Binderman I N,Davis A M,Drake M J.1998.Ion microprobe study of plagioclase-basalt partition experiments at natural concentration levels of trace elements[J].Geochimica et Cosmochimica Acta,62:1175-1193.
Detrick R S,Harding A J,Kent G M,Orcutt J A,Mutter J C,Buhl P.1993.Seismic structure of the southern East Pacific Rise[J].Science,259:499-503.
Choukroune P,Francheteau J,Hekinian R.1984.Tectonics of the East Pacific Rise near 12°50'N:A submersible study[J].Earth Planet(Sci.Lett),68:115-127.
Ginibre C,Kronz A,Worner G.2002.High-resolution quantitative imaging of plagioclase composition using accumulated backscattered electron images:New constraints on oscillatory zoning[J].Contributions to Mineralogy and Petrology,142:436-448.
Goldstein S J,Murrell M T,Janecky D R,Delaney J R,Clague D A.1991.Geochronology and petrogenesis of MORB from the Juan de Fuca and Gorda ridges by238U-230Th disequilibrium[J].Earth and Planetary Science Letters,107:25-41.
Goss A R,Perfit M R,Ridley W I,Rubin K H,Kamenov G D,Soule S A,Fundis A,Fornari D J.2010.Geochemistry of lavas from the 2005-2006 eruption at the East Pacific Rise,9°46'-9°56'N:Implications for ridge crest plumbing and decadal changes in magma chamber compositions[J].Geochemistry Geophysics Geosystems,11:1-35.
Haase K M.2002.Geochemical constraints on magma sources and mixing processes in Easter Microplate MORB(SE Pacific):A case study of plume-ridge interaction[J].Chemical Geology,182:335-355.
Hajash A,Chandle G W.1981.An experimental investigation of hightemperature interaction between seawater and rhyolite,andesite,basatl and peridotite[J].Contributions to Mineralogy and Petrology,78(3):240-254.
Hanan B B,Schilling J G.1989.Easter microplate evolution:Pb isotope evidence[J].J.Geophys.Res,94:7432-7448.
Humphreys M C S,Blundy J D,Sparks S J.2006.Magma evolution and opensystem processes at Shiveluch volcano:Insights from phenocryst zoing[J].Journal of Petrology,47(12):2303-2334.
Klein E M,Smith D K,Williams C M,Schouten H.2005.Counter-rotating microplates at the Galápagos triple junction[J].Nature,433:855-858.
Kurz M D,Geist D.1999.Dynamics of the Galápagos hotspot from helium isotope geochemistry[J].Geochimica et Cosmochimica Acta,63:4139-4156.
Kurz M D,Curtice J,Fornari D,Geist D,Moreira M.2009.Primitive neon from the center of the Galápagos hotspot[J].Earth and Planetary Science Letters,286:23-34.
Li Jilin,Zhang Yongmei,Gu Xuexiang,Meng Fujun,Gao Haijun,Wan Lu.2017.Geological characteristics of sulfides of the Xiyi MVT-type Pb-Zn ore deposit in Yunnan and EPMA analysis of the sulfides[J].Geology and Exploration,53(1):23-34(in Chinese with English abstract).
Lonsdale P.1988.Structural pattern of the Galápagos microplate and evolution of the Galápagos triple junctions[J].Journal of Geophysical Research,93:13511-13574.
Macdonald K C,Fox P J,Miller S,Carbotte S,Edwards M H,Eisen M,Fornari D J,Perram L,Pockalny R,Scheirer D,Tighe S,Weiland C,Wilson D.1992.The East Pacific Rise and its flanks 8-18°N:History of segmentation,propagation and spreading direction based on SeaMARC II and sea beam studies[J].Marine Geophysical Researches 14(4),299-344.
Niu Y L,Hekinian R.1997.Spreading-rate dependence of the extent of mantle melting beneath ocean ridges[J].Nature,385:326-329.
Niu Y L,Batiza R,1997.Trace element evidence from seamounts for recycled oceanic crust in the Eastern Pacific mantle[J].Earth and Planetary Science Letters,148:471-483.
Regelous M,Niu Y L,Wendt J L,Batiza R,Greig A,Collerson K D.1999.Variations in the geochemistry of magmatism on the East Pacific Rise at 10°30'N since 800 ka[J].Earth and Planetary Sciences Letters,168:45-63.
Rollinson H R.1993.Using geochemical data,evolution,presentation,interpretation.Longman scientific&technical[M].New York:Oxford/John Wiley:1-206.
Schouten H,Smith D K,Montesi L G J,Zhu W L,Klein E M.2008.Cracking of lithosphere north of the Galápagos triple junction[J].Geology,36:339-342.
Searle R C,Francheteau J.1986.Morphology and tectonics of the Galápagos triple junction[J].Marine Geophysical Researches,8:95-129.
She Chuanjing.1981.Mineralization activities of Cenozoic hot spring on in East Pacific Rise[J].Geology and Exploration,3:68-69(in Chinese).
Smith D K,Schouten H,Montesi L,Zhu W L.2013.The recent history of the Galápagos triple junction preserved on the Pacific plat[J].Earth and Planetary Sciences Letters,371:6-15.
Viccaro M,Giacomoni P P,Ferlito C,Cristofolin R.2010.Dynamics of magma supply at Mt.Etana volcano(Southern Italy)as revealed by textural and compositional features of plagioclase phenocrysts[J].Lithos,115:77-91.
Wilke M,Behrens H.1999.The dependence of the partitioning of iron and europium between plagioclase and hydrous tonalitic melt on oxygen fugacity[J].Contrib Mineral Petrol,137:102-114.
Yu Miao,Su Xin,Tao Chuanhui,Wu Guanghai,Ni Jianyu,LüShihui,Li Huaiming.2013.Petrologic features and magma activity along the East Pacific Rise(1.23°N-5.70°S)[J].Earth Science Frontiers20(5),87-105(in Chinese with English abstract).
Zhang W,Zeng Z G,Cui L K,Yin X B.2018.Geochemical constrains on MORB composition and magma sources at East Pacific Rise between1°S and 2°S[J].Journal of Ocean University of China,17:297-304.
Zindler A,Hart S.1986.Chemical geodynamics[M].Annual Review of Earth and Planetary Science,14:493-571.
Zhang G L,Chen L H,Li S Z.2013.Mantle dynamics and generation of a geochemical mantle boundary along the East Pacific Rise-Pacific/Antarctic ridge[J].Earth and Planetary Science Letters,383:153-163.
李季霖,章永梅,顾雪祥,孟富军,高海军,王路.2017.云南西邑MVT型铅锌矿床地质特征与硫化物电子探针分析[J].地质与勘探,53(1):23-34.
佘传菁.1981.东太平洋中脊现代热泉成矿活动[J].地质与勘探,3:68-69.
于淼,苏新,陶春辉,武光海,倪建宇,吕士辉,李怀明.2013.东太平洋海隆1.23°N~5.70°S区域洋脊玄武岩特征及岩浆作用探讨[J].地学前缘,20(5):87-105.
Binderman I N,Davis A M,Drake M J.1998.Ion microprobe study of plagioclase-basalt partition experiments at natural concentration levels of trace elements[J].Geochimica et Cosmochimica Acta,62:1175-1193.
Detrick R S,Harding A J,Kent G M,Orcutt J A,Mutter J C,Buhl P.1993.Seismic structure of the southern East Pacific Rise[J].Science,259:499-503.
Choukroune P,Francheteau J,Hekinian R.1984.Tectonics of the East Pacific Rise near 12°50'N:A submersible study[J].Earth Planet(Sci.Lett),68:115-127.
Ginibre C,Kronz A,Worner G.2002.High-resolution quantitative imaging of plagioclase composition using accumulated backscattered electron images:New constraints on oscillatory zoning[J].Contributions to Mineralogy and Petrology,142:436-448.
Goldstein S J,Murrell M T,Janecky D R,Delaney J R,Clague D A.1991.Geochronology and petrogenesis of MORB from the Juan de Fuca and Gorda ridges by238U-230Th disequilibrium[J].Earth and Planetary Science Letters,107:25-41.
Goss A R,Perfit M R,Ridley W I,Rubin K H,Kamenov G D,Soule S A,Fundis A,Fornari D J.2010.Geochemistry of lavas from the 2005-2006 eruption at the East Pacific Rise,9°46'-9°56'N:Implications for ridge crest plumbing and decadal changes in magma chamber compositions[J].Geochemistry Geophysics Geosystems,11:1-35.
Haase K M.2002.Geochemical constraints on magma sources and mixing processes in Easter Microplate MORB(SE Pacific):A case study of plume-ridge interaction[J].Chemical Geology,182:335-355.
Hajash A,Chandle G W.1981.An experimental investigation of hightemperature interaction between seawater and rhyolite,andesite,basatl and peridotite[J].Contributions to Mineralogy and Petrology,78(3):240-254.
Hanan B B,Schilling J G.1989.Easter microplate evolution:Pb isotope evidence[J].J.Geophys.Res,94:7432-7448.
Humphreys M C S,Blundy J D,Sparks S J.2006.Magma evolution and opensystem processes at Shiveluch volcano:Insights from phenocryst zoing[J].Journal of Petrology,47(12):2303-2334.
Klein E M,Smith D K,Williams C M,Schouten H.2005.Counter-rotating microplates at the Galápagos triple junction[J].Nature,433:855-858.
Kurz M D,Geist D.1999.Dynamics of the Galápagos hotspot from helium isotope geochemistry[J].Geochimica et Cosmochimica Acta,63:4139-4156.
Kurz M D,Curtice J,Fornari D,Geist D,Moreira M.2009.Primitive neon from the center of the Galápagos hotspot[J].Earth and Planetary Science Letters,286:23-34.
Li Jilin,Zhang Yongmei,Gu Xuexiang,Meng Fujun,Gao Haijun,Wan Lu.2017.Geological characteristics of sulfides of the Xiyi MVT-type Pb-Zn ore deposit in Yunnan and EPMA analysis of the sulfides[J].Geology and Exploration,53(1):23-34(in Chinese with English abstract).
Lonsdale P.1988.Structural pattern of the Galápagos microplate and evolution of the Galápagos triple junctions[J].Journal of Geophysical Research,93:13511-13574.
Macdonald K C,Fox P J,Miller S,Carbotte S,Edwards M H,Eisen M,Fornari D J,Perram L,Pockalny R,Scheirer D,Tighe S,Weiland C,Wilson D.1992.The East Pacific Rise and its flanks 8-18°N:History of segmentation,propagation and spreading direction based on SeaMARC II and sea beam studies[J].Marine Geophysical Researches 14(4),299-344.
Niu Y L,Hekinian R.1997.Spreading-rate dependence of the extent of mantle melting beneath ocean ridges[J].Nature,385:326-329.
Niu Y L,Batiza R,1997.Trace element evidence from seamounts for recycled oceanic crust in the Eastern Pacific mantle[J].Earth and Planetary Science Letters,148:471-483.
Regelous M,Niu Y L,Wendt J L,Batiza R,Greig A,Collerson K D.1999.Variations in the geochemistry of magmatism on the East Pacific Rise at 10°30'N since 800 ka[J].Earth and Planetary Sciences Letters,168:45-63.
Rollinson H R.1993.Using geochemical data,evolution,presentation,interpretation.Longman scientific&technical[M].New York:Oxford/John Wiley:1-206.
Schouten H,Smith D K,Montesi L G J,Zhu W L,Klein E M.2008.Cracking of lithosphere north of the Galápagos triple junction[J].Geology,36:339-342.
Searle R C,Francheteau J.1986.Morphology and tectonics of the Galápagos triple junction[J].Marine Geophysical Researches,8:95-129.
She Chuanjing.1981.Mineralization activities of Cenozoic hot spring on in East Pacific Rise[J].Geology and Exploration,3:68-69(in Chinese).
Smith D K,Schouten H,Montesi L,Zhu W L.2013.The recent history of the Galápagos triple junction preserved on the Pacific plat[J].Earth and Planetary Sciences Letters,371:6-15.
Viccaro M,Giacomoni P P,Ferlito C,Cristofolin R.2010.Dynamics of magma supply at Mt.Etana volcano(Southern Italy)as revealed by textural and compositional features of plagioclase phenocrysts[J].Lithos,115:77-91.
Wilke M,Behrens H.1999.The dependence of the partitioning of iron and europium between plagioclase and hydrous tonalitic melt on oxygen fugacity[J].Contrib Mineral Petrol,137:102-114.
Yu Miao,Su Xin,Tao Chuanhui,Wu Guanghai,Ni Jianyu,LüShihui,Li Huaiming.2013.Petrologic features and magma activity along the East Pacific Rise(1.23°N-5.70°S)[J].Earth Science Frontiers20(5),87-105(in Chinese with English abstract).
Zhang W,Zeng Z G,Cui L K,Yin X B.2018.Geochemical constrains on MORB composition and magma sources at East Pacific Rise between1°S and 2°S[J].Journal of Ocean University of China,17:297-304.
Zindler A,Hart S.1986.Chemical geodynamics[M].Annual Review of Earth and Planetary Science,14:493-571.
Zhang G L,Chen L H,Li S Z.2013.Mantle dynamics and generation of a geochemical mantle boundary along the East Pacific Rise-Pacific/Antarctic ridge[J].Earth and Planetary Science Letters,383:153-163.
李季霖,章永梅,顾雪祥,孟富军,高海军,王路.2017.云南西邑MVT型铅锌矿床地质特征与硫化物电子探针分析[J].地质与勘探,53(1):23-34.
佘传菁.1981.东太平洋中脊现代热泉成矿活动[J].地质与勘探,3:68-69.
于淼,苏新,陶春辉,武光海,倪建宇,吕士辉,李怀明.2013.东太平洋海隆1.23°N~5.70°S区域洋脊玄武岩特征及岩浆作用探讨[J].地学前缘,20(5):87-105.