阿尔巴尼亚布尔其泽纯橄岩壳中橄榄石的包裹体研究
|
摘要
阿尔巴尼亚布尔其泽纯橄岩壳非常新鲜,主要由橄榄石、尖晶石和单斜辉石等矿物组成.其中橄榄石存在单斜辉石和铬尖晶石(磁铁矿)共生包裹体现象,包裹体矿物粒度在1~10μm,有些甚至为纳米级200~500nm.纯橄岩橄榄石的Fo值为94.7~96.0,铬尖晶石的Cr#为76.5~82.4,远高于蛇绿岩地幔橄榄岩中常见纯橄岩的铬值(Cr#>60).基于前人研究结果,提出这种现象是由于亏损方辉橄榄岩与含钛、铬、铁熔体发生交代作用,从而形成橄榄石的固溶体并存在Ti 4+、Al 3+、Ca2+、Fe3+,而部分Cr3+进入铬尖晶石结晶.后期由于岩体在抬升过程中降温,橄榄石中混溶的组分析出包裹体形成磁铁矿和铬尖晶石.并且依据铬尖晶石-橄榄石的矿物化学成分,识别出岩体内方辉橄榄岩相对较低的部分熔融程度约为30%~40%,纯橄岩部分熔融程度约为40%,表明不同岩相间其形成背景存在明显差异.因此,认为布尔奇泽蛇绿岩具有多阶段的过程,首先是在洋中脊环境下经历部分熔融作用形成了方辉橄榄岩,后受到俯冲环境(SSZ)的岩石-熔体反应生成更富Mg、Si和Cr等的熔体,致使地幔橄榄岩高度部分熔融,形成此类纯橄岩.
Cinopyroxene and spinel(magnetite)occur as oriented intergrowths within olivine of the dunite in the Bulqiza ophiolite,Albania.The size of the inclusion minerals is 1-10μm,and some of them are nanoscale in 200-500 nm.The fresh dunite has a mineral assemblage of olivine,spinel and cinopyroxene.The Fo content of its olivine is 94.7-96.0,and the Cr#of spinel is about 76.5-82.4,higher than that in the spinel in common dunite from ophiolite mantle(Cr#>60).Thus it is proposed that previously depleted mantle harzburgite reacted with the melt containing Ti,Cr,Fe,and produced an olivine solid solution added with Ti 4+,Al 3+,Ca2+,Fe3+,and some of Cr3+entered interstitial chromite.Due to the fast cooling rate of the rock or rapid tectonic emplacement,the exsolution textures in olivine and compositional zones of chromite are preserved.Based on the mineral compositions of chromian spinel-olivine,it is found that the relatively low partial melting degree of the harzburgite is30%-40%,and the degree of partial melting of dunite is about 40%,indicating a significant difference of tectonic setting.It is suggested that the Bulqiza ophiolite had multi-stage evolution processes.When oceanic crustal slabs were trapped in mid oceanridge,they were modified by tholeiitic magmas or partial melting,which occurred interaction or metasomatism,then later reaction with boninitic magma in suprasubduction zones(SSZ)generated more Mg,Si and Cr melt,resulting in high degree of partial melting for the mantle peridotite and dunite.
Cinopyroxene and spinel(magnetite)occur as oriented intergrowths within olivine of the dunite in the Bulqiza ophiolite,Albania.The size of the inclusion minerals is 1-10μm,and some of them are nanoscale in 200-500 nm.The fresh dunite has a mineral assemblage of olivine,spinel and cinopyroxene.The Fo content of its olivine is 94.7-96.0,and the Cr#of spinel is about 76.5-82.4,higher than that in the spinel in common dunite from ophiolite mantle(Cr#>60).Thus it is proposed that previously depleted mantle harzburgite reacted with the melt containing Ti,Cr,Fe,and produced an olivine solid solution added with Ti 4+,Al 3+,Ca2+,Fe3+,and some of Cr3+entered interstitial chromite.Due to the fast cooling rate of the rock or rapid tectonic emplacement,the exsolution textures in olivine and compositional zones of chromite are preserved.Based on the mineral compositions of chromian spinel-olivine,it is found that the relatively low partial melting degree of the harzburgite is30%-40%,and the degree of partial melting of dunite is about 40%,indicating a significant difference of tectonic setting.It is suggested that the Bulqiza ophiolite had multi-stage evolution processes.When oceanic crustal slabs were trapped in mid oceanridge,they were modified by tholeiitic magmas or partial melting,which occurred interaction or metasomatism,then later reaction with boninitic magma in suprasubduction zones(SSZ)generated more Mg,Si and Cr melt,resulting in high degree of partial melting for the mantle peridotite and dunite.
引文
Ashworth,J.R.,Chambers,A.D.,2000.Symplectic Reaction in Olivine and the Controls of Intergrowth Spacing in Symplectites.Journal of Petrology,41(2):285-304.https://doi.org/10.1093/petrology/41.2.285
Batanova,V.G.,Sobolev,A.V.,2000.Compositional Heterogeneity in Subduction-Related Mantle Peridotites,Troodos Massif,Cyprus.Geology,28(1):55-58.https://doi.org/10.1130/0091-7613(2000)28<55:CHISMP>2.0.CO;2
Dick,H.J.B.,Bullen,T.,1984.Chromian Spinel as a Petrogenetic Indicator in Abyssal and Alpine-Type Peridotites and Spatially Associated Lavas.Contributions to Mineralogy and Petrology,86(1):54-76.https://doi.org/10.1007/BF00373711
Dilek,Y.,Furnes,H.,Shallo,M.,2008.Geochemistry of the Jurassic Mirdita Ophiolite(Albania)and the MORB to SSZ Evolution of a Marginal Basin Oceanic Crust.Lithos,100(1-4):174-209.https://doi.org/org/10.1016/j.lithos.2007.06.026
Dobrzhinetskaya,L.,Green,H.W.,Wang,S.,1996.Alpe Arami,a Peridotite Massif from Depths of More than 300Kilometers.Science,271(5257):1841-1845.https://doi.org/org/stable/2889372
Dyar,M.D.,Delaney,J.S.,Sutton,S.R.,et al.,1998.Fe3+Distribution in Oxidized Olivine:A Synchrotron MicroXANES Study.American Mineralogist,83:1361-1365.https://doi.org/org/10.2138/am-1998-1227
Feng,Y.L.,Zheng,Z.,Guo,Y.J.,et al.,2003.Discovery of Native Iron in Olivine of Garnet Lherzolite in Chijiadian and Its Significance.Acta Petrologica Sinica,19(4):701-706(in Chinese with English abstract).
Hwang,S.L,Shen,P.,Chu,H.T,et al.,2015.Origin of Rutile Needles in Star Garnet and Implications for Interpretation of Inclusion Textures in Ultrahigh-Pressure Metamorphic Rocks.Journal of Metamorphic Geology,33(3):249-272.https://doi.org/10.1111/jmg.12119
Hwang,S.L.,Shen,P.,Yui,T.F.,et al.,2007a.TiO2 Nanoparticle Trails in Garnet:Implications of Inclusion Pressure-Induced Microcracks and Spontaneous Metamorphic Reaction Healing during Exhumation.Journal of Metamorphic Geology,25(4):451-460.https://doi.org/10.1111/j.1525-1314.2007.00705.x
Hwang,S.L.,Yui,T.F.,Chu,H.T.,et al.,2007b.On the Origin of Oriented Rutile Needles in Garnet from UHP Eclogites.Journal of Metamorphic Geology,25(3):349-362.https://doi.org/10.1111/j.1525-1314.2007.00699.x
Irvine,T.N.,1967.Chromian Spinel as a Petrogenetic Indicator:Part2.Petrologic Applications.Canadian Journal of Earth Sciences,4(1):71-103.https://doi.org/10.1139/e67-004
Leblanc,M.,1980.Chromite Growth,Dissolution and Deformation from a Morphological View Point:SEM Investigations.Mineralium Deposita,15(2):201-210.https://doi.org/10.1007/BF00206514
Li,J.Y.,Yang,J.S.,Ba,D.Z.,et al.,2012.Origin of Different Dunites in the Luobusa Ophiolite,Tibet.Acta Petrologica Sinica,28(6):1829-1845(in Chinese with English abstract).
Liang,F.H.,Yang,J.S.,Xu,Z.Q.,et al.,2014.Chromium in the Olivine Lattice:Chromium-Rich Olivines and Their Implication of Deep Mantle Origin in the Luobusa Mantle Peridotite and Chromitite,Tibet.Acta Petrologica Sinica,30(8):2125-2136(in Chinese with English abstract).
Libourel,G.,1999.Systematics of Calcium Partitioning between Olivine and Silicate Melt:Implications for Melt Structure and Calcium Content of Magmatic Olivines.Contributions to Mineralogy and Petrology,136(1-2):63-80.https://doi.org/10.1007/s004100050524
Malpas,J.,Zhou,M.F.,Robinson,P.T.,et al.,2003.Geochemical and Geochronological Constraints on the Origin and Emplacement of the Yarlung Zangbo Ophiolites,Southern Tibet.Geological Society,London,Special Publications,218(1):191-206.https://doi.org/10.1144/GSL.SP.2003.218.01.11
Markl,G.,Marks,M.,Schwinn,G.,et al.,2001.Phase Equilibrium Constraints on Intensive Crystallization Parameters of the Ilímaussaq Complex,South Greenland.Journal of Petrology,42(12):2231-2257.https://doi.org/10.1093/petrology/42.12.2231
Mikouchi,T.,Yamada,I.,Miyamoto,M.,2000.Symplectic Exsolution in Olivine from the Nakhla Martian Meteorite.Meteoritics and Planetary Science,35(5):937-942.https://doi.org/10.1111/j.1945-5100.2000.tb01483.x
Pearce,J.A.,Barker,P.F.,Edwards,S.J.,et al.,2000.Geochemistry and Tectonic Significance of Peridotites from the South Sandwich Arc-Basin System,South Atlantic.Contributions to Mineralogy and Petrology,139(1):36-53.https://doi.org/10.1007/s004100050572
Pearce,J.A.,Lippard,S.J.,Roberts,S.,1984.Characteristics and Tectonic Significance of Supra-Subduction Zone Ophiolites.In:Kokelaar,B.P.,Howells,M.F.,eds.,Marginal Basin Geology.Geological Society,London,Special Publication,16(1):77-89.https://doi.org/10.1144/GSL.SP.1984.016.01.06
Petaev,M.I.,Brearley,A.J.,1994.Exsolution in Ferromagnesian Olivine of the Divnoe Meteorite.Science,266(5190):1545-1547.https://doi.org/org/stable/2885183
Ren,Y.F.,Chen,F.Y.,Yang,J.S.,et al.,2008.Exsolutions of Diopside and Magnetite in Olivine from Mantle Dunite,Luobusa Ophiolite,Tibet,China.Acta Geologica Sinica(English Edition),2(82):377-384.https://doi.org/10.1111/j.1755-6724.2008.tb00587.x
Song,S.,Zhang,L.,Niu,Y.,2004.Ultra-Deep Origin of Garnet Peridotite from the North Qaidam UltrahighPressure Belt,Northern Tibetan Plateau,NW China.A-merican Mineralogist,89(8-9):1330-1336.https://doi.org/10.2138/am-2004-8-922
van Roermund,H.L.M.,Drury,M.R.,Barnhoorn,A.,et al.,,2000.Non-Silicate Inclusions in Garnet from an UltraDeep Orogenic Peridotite.Geological Journal,35(3-4):209-229.https://doi.org/10.1002/gj.858
Xiong,F.,Yang,J.,Paul,R.T.,et al.,2016.Diamonds and Other Exotic Minerals Recovered from Peridotites of the Dangqiong Ophiolite,Western Yarlung-Zangbu Suture Zone,Tibet.Acta Geologica Sinica(English Edition),90(2):425-439.
Xiong,F.H.,Yang,J.S.,Robinson,P.T.,et al.,2015.Petrology and Geochemistry of High Cr#Podiform Chromitites of Bulqiza,Eastern Mirdita Ophiolite(EMO),Albania.Ore Geology Reviews,70:188-207.https://doi.org/10.1016/j.oregeorev.2015.04.011
Zhang,R.Y.,Liou,J.G.,1999.Exsolution Lamellae in Minerals from Ultrahigh-Pressure Rocks.International Geology Review,41(11):981-993.
Zhang,R.Y.,Liou,J.G.,Yang,J.S.,et al.,2004.Garnet Peridotites in UHP Mountain Belts of China.International Geology Review,46(11):981-1004.https://doi.org/org/10.2747/0020-6814.46.11.981
Zhao,W.X.,Hu,Y.X.,Li,X.M.,et al.,2006.The Compositional Inhomogeneity of the Needle-Exsolution Magnetites in Olivine from Bixiling Garnet Peridotite.Acta Petrologica et Mineralogica,25(1):40-44(in Chinese with English abstract).
Zhou,M.F.,Robinson,P.T.,Malpas,J.,et al.,1996.Podiform Chromitites in the Luobusa Ophiolite(Southern Tibet):Implications for Melt-Rock Interaction and Chromite Segregation in the Upper Mantle.Journal of Petrology,37(1):3-21.https://doi.org/10.1093/petrology/37.1.3
Zhou,M.F.,Robinson,P.T.,Malpas,J.,et al.,2005.REE and PGEGeochemical Constraints on the Formation of Dunites in the Luobusa Ophiolite,Southern Tibet.Journal of Petrology,46(3):615-639.https://doi.org/10.1093/petrology/egh091
冯有利,郑辙,郭延军,等,2003.在迟家店石榴石二辉橄榄岩的橄榄石中发现自然铁及其意义.岩石学报,19(4):701-706.
李金阳,杨经绥,巴登珠,等,2012.西藏罗布莎蛇绿岩中不同产出的纯橄岩及成因探讨.岩石学报,28(6):1829-1845.
梁凤华,杨经绥,许志琴,等,2014.铬在橄榄石中的赋存状态:西藏罗布莎地幔橄榄岩和铬铁矿中的富铬橄榄石及对深部地幔成因的启示.岩石学报,30(8):2125-2136.
赵文霞,胡育贤,李雪梅,等,2006.碧溪岭石榴石橄榄岩的橄榄石中针状磁铁矿出溶体成分的不均匀性.岩石矿物学杂志,25(1):40-44.
Batanova,V.G.,Sobolev,A.V.,2000.Compositional Heterogeneity in Subduction-Related Mantle Peridotites,Troodos Massif,Cyprus.Geology,28(1):55-58.https://doi.org/10.1130/0091-7613(2000)28<55:CHISMP>2.0.CO;2
Dick,H.J.B.,Bullen,T.,1984.Chromian Spinel as a Petrogenetic Indicator in Abyssal and Alpine-Type Peridotites and Spatially Associated Lavas.Contributions to Mineralogy and Petrology,86(1):54-76.https://doi.org/10.1007/BF00373711
Dilek,Y.,Furnes,H.,Shallo,M.,2008.Geochemistry of the Jurassic Mirdita Ophiolite(Albania)and the MORB to SSZ Evolution of a Marginal Basin Oceanic Crust.Lithos,100(1-4):174-209.https://doi.org/org/10.1016/j.lithos.2007.06.026
Dobrzhinetskaya,L.,Green,H.W.,Wang,S.,1996.Alpe Arami,a Peridotite Massif from Depths of More than 300Kilometers.Science,271(5257):1841-1845.https://doi.org/org/stable/2889372
Dyar,M.D.,Delaney,J.S.,Sutton,S.R.,et al.,1998.Fe3+Distribution in Oxidized Olivine:A Synchrotron MicroXANES Study.American Mineralogist,83:1361-1365.https://doi.org/org/10.2138/am-1998-1227
Feng,Y.L.,Zheng,Z.,Guo,Y.J.,et al.,2003.Discovery of Native Iron in Olivine of Garnet Lherzolite in Chijiadian and Its Significance.Acta Petrologica Sinica,19(4):701-706(in Chinese with English abstract).
Hwang,S.L,Shen,P.,Chu,H.T,et al.,2015.Origin of Rutile Needles in Star Garnet and Implications for Interpretation of Inclusion Textures in Ultrahigh-Pressure Metamorphic Rocks.Journal of Metamorphic Geology,33(3):249-272.https://doi.org/10.1111/jmg.12119
Hwang,S.L.,Shen,P.,Yui,T.F.,et al.,2007a.TiO2 Nanoparticle Trails in Garnet:Implications of Inclusion Pressure-Induced Microcracks and Spontaneous Metamorphic Reaction Healing during Exhumation.Journal of Metamorphic Geology,25(4):451-460.https://doi.org/10.1111/j.1525-1314.2007.00705.x
Hwang,S.L.,Yui,T.F.,Chu,H.T.,et al.,2007b.On the Origin of Oriented Rutile Needles in Garnet from UHP Eclogites.Journal of Metamorphic Geology,25(3):349-362.https://doi.org/10.1111/j.1525-1314.2007.00699.x
Irvine,T.N.,1967.Chromian Spinel as a Petrogenetic Indicator:Part2.Petrologic Applications.Canadian Journal of Earth Sciences,4(1):71-103.https://doi.org/10.1139/e67-004
Leblanc,M.,1980.Chromite Growth,Dissolution and Deformation from a Morphological View Point:SEM Investigations.Mineralium Deposita,15(2):201-210.https://doi.org/10.1007/BF00206514
Li,J.Y.,Yang,J.S.,Ba,D.Z.,et al.,2012.Origin of Different Dunites in the Luobusa Ophiolite,Tibet.Acta Petrologica Sinica,28(6):1829-1845(in Chinese with English abstract).
Liang,F.H.,Yang,J.S.,Xu,Z.Q.,et al.,2014.Chromium in the Olivine Lattice:Chromium-Rich Olivines and Their Implication of Deep Mantle Origin in the Luobusa Mantle Peridotite and Chromitite,Tibet.Acta Petrologica Sinica,30(8):2125-2136(in Chinese with English abstract).
Libourel,G.,1999.Systematics of Calcium Partitioning between Olivine and Silicate Melt:Implications for Melt Structure and Calcium Content of Magmatic Olivines.Contributions to Mineralogy and Petrology,136(1-2):63-80.https://doi.org/10.1007/s004100050524
Malpas,J.,Zhou,M.F.,Robinson,P.T.,et al.,2003.Geochemical and Geochronological Constraints on the Origin and Emplacement of the Yarlung Zangbo Ophiolites,Southern Tibet.Geological Society,London,Special Publications,218(1):191-206.https://doi.org/10.1144/GSL.SP.2003.218.01.11
Markl,G.,Marks,M.,Schwinn,G.,et al.,2001.Phase Equilibrium Constraints on Intensive Crystallization Parameters of the Ilímaussaq Complex,South Greenland.Journal of Petrology,42(12):2231-2257.https://doi.org/10.1093/petrology/42.12.2231
Mikouchi,T.,Yamada,I.,Miyamoto,M.,2000.Symplectic Exsolution in Olivine from the Nakhla Martian Meteorite.Meteoritics and Planetary Science,35(5):937-942.https://doi.org/10.1111/j.1945-5100.2000.tb01483.x
Pearce,J.A.,Barker,P.F.,Edwards,S.J.,et al.,2000.Geochemistry and Tectonic Significance of Peridotites from the South Sandwich Arc-Basin System,South Atlantic.Contributions to Mineralogy and Petrology,139(1):36-53.https://doi.org/10.1007/s004100050572
Pearce,J.A.,Lippard,S.J.,Roberts,S.,1984.Characteristics and Tectonic Significance of Supra-Subduction Zone Ophiolites.In:Kokelaar,B.P.,Howells,M.F.,eds.,Marginal Basin Geology.Geological Society,London,Special Publication,16(1):77-89.https://doi.org/10.1144/GSL.SP.1984.016.01.06
Petaev,M.I.,Brearley,A.J.,1994.Exsolution in Ferromagnesian Olivine of the Divnoe Meteorite.Science,266(5190):1545-1547.https://doi.org/org/stable/2885183
Ren,Y.F.,Chen,F.Y.,Yang,J.S.,et al.,2008.Exsolutions of Diopside and Magnetite in Olivine from Mantle Dunite,Luobusa Ophiolite,Tibet,China.Acta Geologica Sinica(English Edition),2(82):377-384.https://doi.org/10.1111/j.1755-6724.2008.tb00587.x
Song,S.,Zhang,L.,Niu,Y.,2004.Ultra-Deep Origin of Garnet Peridotite from the North Qaidam UltrahighPressure Belt,Northern Tibetan Plateau,NW China.A-merican Mineralogist,89(8-9):1330-1336.https://doi.org/10.2138/am-2004-8-922
van Roermund,H.L.M.,Drury,M.R.,Barnhoorn,A.,et al.,,2000.Non-Silicate Inclusions in Garnet from an UltraDeep Orogenic Peridotite.Geological Journal,35(3-4):209-229.https://doi.org/10.1002/gj.858
Xiong,F.,Yang,J.,Paul,R.T.,et al.,2016.Diamonds and Other Exotic Minerals Recovered from Peridotites of the Dangqiong Ophiolite,Western Yarlung-Zangbu Suture Zone,Tibet.Acta Geologica Sinica(English Edition),90(2):425-439.
Xiong,F.H.,Yang,J.S.,Robinson,P.T.,et al.,2015.Petrology and Geochemistry of High Cr#Podiform Chromitites of Bulqiza,Eastern Mirdita Ophiolite(EMO),Albania.Ore Geology Reviews,70:188-207.https://doi.org/10.1016/j.oregeorev.2015.04.011
Zhang,R.Y.,Liou,J.G.,1999.Exsolution Lamellae in Minerals from Ultrahigh-Pressure Rocks.International Geology Review,41(11):981-993.
Zhang,R.Y.,Liou,J.G.,Yang,J.S.,et al.,2004.Garnet Peridotites in UHP Mountain Belts of China.International Geology Review,46(11):981-1004.https://doi.org/org/10.2747/0020-6814.46.11.981
Zhao,W.X.,Hu,Y.X.,Li,X.M.,et al.,2006.The Compositional Inhomogeneity of the Needle-Exsolution Magnetites in Olivine from Bixiling Garnet Peridotite.Acta Petrologica et Mineralogica,25(1):40-44(in Chinese with English abstract).
Zhou,M.F.,Robinson,P.T.,Malpas,J.,et al.,1996.Podiform Chromitites in the Luobusa Ophiolite(Southern Tibet):Implications for Melt-Rock Interaction and Chromite Segregation in the Upper Mantle.Journal of Petrology,37(1):3-21.https://doi.org/10.1093/petrology/37.1.3
Zhou,M.F.,Robinson,P.T.,Malpas,J.,et al.,2005.REE and PGEGeochemical Constraints on the Formation of Dunites in the Luobusa Ophiolite,Southern Tibet.Journal of Petrology,46(3):615-639.https://doi.org/10.1093/petrology/egh091
冯有利,郑辙,郭延军,等,2003.在迟家店石榴石二辉橄榄岩的橄榄石中发现自然铁及其意义.岩石学报,19(4):701-706.
李金阳,杨经绥,巴登珠,等,2012.西藏罗布莎蛇绿岩中不同产出的纯橄岩及成因探讨.岩石学报,28(6):1829-1845.
梁凤华,杨经绥,许志琴,等,2014.铬在橄榄石中的赋存状态:西藏罗布莎地幔橄榄岩和铬铁矿中的富铬橄榄石及对深部地幔成因的启示.岩石学报,30(8):2125-2136.
赵文霞,胡育贤,李雪梅,等,2006.碧溪岭石榴石橄榄岩的橄榄石中针状磁铁矿出溶体成分的不均匀性.岩石矿物学杂志,25(1):40-44.