地幔转换带橄榄石高压相变实验研究
摘要
橄榄石是上地幔的主要矿物之一,它的相变对于认识地幔不连续面的成因,整个地幔的物质组成和演化、地幔对流、俯冲板片深源地震等地球深部动力学问题具有重要意义.本研究使用中国地质大学地球深部研究实验室多面砧压机进行了2种成分的橄榄石(Fo100和Fo90)在压力为14.1～20GPa,温度为1400℃的相变实验研究.压力为14.8～15.6GPa时,Fo90和Fo100均转变为瓦兹利石(α);而在14.1GPa实验中,Fo90完全转变为瓦兹利石,Fo100则仍为橄榄石(α).瓦兹利石具有2种产状:破碎的粒状结构(粒度大于100μm)和微晶集合体(微晶粒度小于10μm).瓦兹利石拉曼谱图中显示722～723和917～919cm-1特征峰.随着压力升高,实验产物中出现更多的呈微晶集合体结构产出的瓦兹利石,表明实验压力离橄榄石相变边界越远,瓦兹利石成核密度越大,导致体系Gibbs自由能下降,高压相矿物颗粒生长受到抑制.但由于瓦兹利石成核活化能很小,因此实验产物中均有大量呈微晶集合体产出的瓦兹利石.实验产物的显微结构特征对解释陨石中出现瓦兹利石的产状提供高温高压实验启示.压力为19.5和20GPa时实验产物为林伍德石(γ),其中压力为19.5GPa的实验中Fo100中瓦兹利石和林伍德石共存.实验产物林伍德石为自形粒状(颗粒度为10～20μm),三联点结构发育.798和840cmμ1为林伍德石的拉曼特征峰.综合本次研究以及前人地震探测结果表明,中国东部上地幔复杂结构无法用单一的橄榄石体系相变来解释,其他矿物(如辉石-石榴石)的相变及其与橄榄石体系相变的相互影响可能导致了该地区上地幔具有复杂的结构.因此进一步开展复杂体系(如橄榄石+辉石体系)的高温高压相变实验研究,并在已有地球物理探测成果的基础上建立合理的地质-岩石学模型,对探讨中国东部地区上地幔复杂结构形成的物理机理,影响因素及其深部动力学机制具有重要意义.
引文
1Ringwood A E.A Model for the upper mantle.J Geophys Res,1962,67:857–867
2Sun S-S.Chemical composition and origin of the earth’s primitive mantle.Geochim Cosmochim Acta,1982,46:179–192
3Ringwood A E,Major A.The system Mg2SiO4-Fe2SiO4at high pressures and temperatures.Phys Earth Planet Inter,1970,3:89–108
4Agee C B.Phase transformations and seismic structure in the upper mantle and transition zone.Rev Mineral Geochem,1998,37:165–203
5Akoagi M.Phase transitions of minerals in the transition zone and upper part of the lower mantle.In:Ohtani E,ed.Advances in High-Pressure Mineralogy.New York:Geological Society of America,2007.1–13
6Fei Y,Bertka C M.Phase transitions in the Earth’s mantle and mantle mineralogy.In:Fei Y,Bertka C M,Mysen B O,eds.Mantle Petrology:Field Observations and High Pressure Experimentation(A tribute to Francis R Boyd).Houston:Geochemical Society Special Publication6,1999.189–207
7Katsura T,Yamada H,Nishikawa O,et al.Olivine-wadsleyite transition in the system(Mg,Fe)2SiO4.J Geophys Res,2004,109:B02209
8Inoue T,Irifune T,Higo Y,et al.The phase boundary between wadsleyite and ringwoodite in Mg2SiO4determined by in situ X-ray diffraction.Phys Chem Mineral,2006,33:106–114
9Yu Y G,Wu Z,Wentzcovitch R M.α-β-γtransformations in Mg2SiO4in Earth’s transition zone.Earth Planet Sci Lett,2008,273:115–122
10Liu L G.The post-spinel phase of forsterite.Nature,1976,262:770–772
11Katsura T,Yamada H,Shinmei T,et al.Post-spinel transition in Mg2SiO4determined by high P-T in situ X-ray diffractometry.Phys Earth Planet Inter,2003,136:11–24
12Yu Y G,Wentzcovitch R M,Tsuchiya T,et al.First principles investigation of the postspinel transition in Mg2SiO4.Geophys Res Lett,2007,34:L10306
13Liu L G.The mineralogy of an eclogitic earth mantle.Phys Earth Planet Inter,1980,23:262–267
14Weidner D J,Wang Y.Phase transformations:implications for mantle structure.In:Karato S,Forte A M,Liebermann R C,et al,eds.Earth’s Deep Interior:Mineral Physics and Tomography from the Atomic to the Global Scale(Geophysical Monograph).Washington DC:American Geophysical Union,2000.215–235
15Zhang J,Li B,Utsumi W,et al.In situ X-ray observations of coesite-stishovite transition:Reversed phase boundary and kinetics.Phys Chem Mineral,1996,23:1–10
16Akaogi M,Ito E,Navrotsky A.Olivine-modified spinel-spinel transitions in the system Mg2SiO4-Fe2SiO4:Calorimetric measurements,ther-mochemical calculation,and geophysical application.J Geophys Res,1989,94:15671–15685
17Suzuki A,Ohtani E,Morishima H,et al.In situ determination of the phase boundary between Wadsleyite and Ringwoodite in Mg2SiO4.Geo-phys Res Lett,2000,27:803–806
18Bertka M,Fei Y W.Mineralogy of the Martian interior up to core-mantle boundary pressures.J Geophys Res,1997,102:5251–5264
19McMillan P,Akaogi M.Raman spectra ofβ-Mg2SiO4(modified spinel)andγ-Mg2SiO4(spinel).Am Mineral,1987,72:361–364
20陈鸣.冲击变质陨石橄榄石晶内高压多形转变特征与条件.矿物学报,2009,29:1–6
21Kuno T,Ohtani E,Fulakoshi K.Nucleation and growth kinetics of theα-βtransformation in Mg2SiO4detemined by in situ synchrotron pow-der X-ray diffraction.Am Mineral,2004,89:285–293
22Sung C M,Burns R G.Kinetics of the olivine-spinel transition:Implications to deep focus earthquake genesis.Earth Planet Sci Lett,1976,32:165–170
23Mosenfelder J L,Marton F C,Ross C R,et al.Experimental constraints on the depth of olivine metastability in subducting lithosphere.Phys Earth Planet Inter,2001,127:165–180
24Kerschhofer L,Sharp T G,Rubie D.Intracrystalline transformation of olivine to wadsleyite and ringwoodite under subduction zone condi-tions.Science,1996,274:79–81
25Dziewonski A M,Anderson D L.Preliminary reference earth model.Phys Earth Planet Inter,1981,25:297–356
26Shearer P M.Seismic imaging of upper-mantle structure with new evidence for a520km discontinuity.Nature,1990,344:121–126
27Shearer P M.Transition zone velocity gradients and the520-km discontinuity.J Geophys Res,1996,101:3035–3066
28Gu Y,Dziewonski A M,Agee C B.Global de-correlation of the topography of transition zone discontinuities.Earth Planet Sci Lett,157:57–67
29Deuss A,Woodhouse J.Seismic observations of splitting of the mid-transition zone discontinuity in Earth’s Mantle.Science,2001,294:354–357
30Katsura T,Ito E.The system Mg2SiO4-Fe2SiO4at high pressures and temperatures:Precise determination of stabilities of olivine,modified spinel,and spinel.J Geophys Res,1989,94:15663–15670
31Helffrich G.Topography of the transition zone seismic discontinuities.Rev Geophys,2000,38:141–158
32Weidner D J,Wang Y.Chemical-and Clapeyron-induced buoyancy at the660km discontinuity.J Geophys Res,1998,103:7431–7441
33Irifune T,Isshiki M.Iron partitioning in a pyrolite mantle and the nature of the410-kmseismic discontinuity.Nature,1998,392:702–705
34Ai Y,Zheng T.The upper mantle discontinuity structure beneath eastern China.Geophys Res Lett,2003,30:2089,doi:10.1029/2003GL017678
35Gilbert H J,Sheehan A F,Dueker K G,et al.Receiver functions in the western United States,with implications for upper mantle structure and dynamics.J Geophys Res,2003,108:2229,doi:10.1029/2001JB001194
36van der Meijde M,van der Lee S,Giardini D.Seismic discontinuities in the Mediterranean mantle.Phys Earth Planet Inter,2005,148:233–250
37Saikia A,Frost D,Rubie D.Splitting of the520-kilometer seimic discontinuity and chemical heterogeneity in the mantle.Nature,2008,139:1515–1518
38周春银,金振民,章军峰.地幔转换带:地球深部研究的重要方向.地学前缘,2010,17:90–113
39杨翠平,金振民,吴耀.地幔转换带中的水及其地球动力学意义.地学前缘,2010,17:114–126
40Ai Y,Zheng T,Xu W,et al.A complex660km discontinuity beneath northeast China.Earth Planet Sci Lett,2003,212:63–71
41Chen L,Zheng T,Xu W.Receiver function migration image of the deep structure in the Bohai Bay Basin,eastern China.Geophys Res Lett,2006,33:L20307,doi:10.1029/2006GL027593
42Chen L,Ai Y.Discontinuity structure of the mantle transition zone beneath the North China Craton from receiver function migration.J Geophys Res,2009,114:B06307,doi:10.1029/2008JB006221
43Gao S S,Silver P G,Liu K H,et al.Mantle discontinuities beneath Southern Africa.Geophys Res Lett,2002,29:1491,doi:10.1029/2001GL013834
44Huang J,Zhao D.High-resolution mantle tomography of China and surrounding regions.J Geophys Res,2006,111:B09305,doi:10.1029/2005JB004066
2Sun S-S.Chemical composition and origin of the earth’s primitive mantle.Geochim Cosmochim Acta,1982,46:179–192
3Ringwood A E,Major A.The system Mg2SiO4-Fe2SiO4at high pressures and temperatures.Phys Earth Planet Inter,1970,3:89–108
4Agee C B.Phase transformations and seismic structure in the upper mantle and transition zone.Rev Mineral Geochem,1998,37:165–203
5Akoagi M.Phase transitions of minerals in the transition zone and upper part of the lower mantle.In:Ohtani E,ed.Advances in High-Pressure Mineralogy.New York:Geological Society of America,2007.1–13
6Fei Y,Bertka C M.Phase transitions in the Earth’s mantle and mantle mineralogy.In:Fei Y,Bertka C M,Mysen B O,eds.Mantle Petrology:Field Observations and High Pressure Experimentation(A tribute to Francis R Boyd).Houston:Geochemical Society Special Publication6,1999.189–207
7Katsura T,Yamada H,Nishikawa O,et al.Olivine-wadsleyite transition in the system(Mg,Fe)2SiO4.J Geophys Res,2004,109:B02209
8Inoue T,Irifune T,Higo Y,et al.The phase boundary between wadsleyite and ringwoodite in Mg2SiO4determined by in situ X-ray diffraction.Phys Chem Mineral,2006,33:106–114
9Yu Y G,Wu Z,Wentzcovitch R M.α-β-γtransformations in Mg2SiO4in Earth’s transition zone.Earth Planet Sci Lett,2008,273:115–122
10Liu L G.The post-spinel phase of forsterite.Nature,1976,262:770–772
11Katsura T,Yamada H,Shinmei T,et al.Post-spinel transition in Mg2SiO4determined by high P-T in situ X-ray diffractometry.Phys Earth Planet Inter,2003,136:11–24
12Yu Y G,Wentzcovitch R M,Tsuchiya T,et al.First principles investigation of the postspinel transition in Mg2SiO4.Geophys Res Lett,2007,34:L10306
13Liu L G.The mineralogy of an eclogitic earth mantle.Phys Earth Planet Inter,1980,23:262–267
14Weidner D J,Wang Y.Phase transformations:implications for mantle structure.In:Karato S,Forte A M,Liebermann R C,et al,eds.Earth’s Deep Interior:Mineral Physics and Tomography from the Atomic to the Global Scale(Geophysical Monograph).Washington DC:American Geophysical Union,2000.215–235
15Zhang J,Li B,Utsumi W,et al.In situ X-ray observations of coesite-stishovite transition:Reversed phase boundary and kinetics.Phys Chem Mineral,1996,23:1–10
16Akaogi M,Ito E,Navrotsky A.Olivine-modified spinel-spinel transitions in the system Mg2SiO4-Fe2SiO4:Calorimetric measurements,ther-mochemical calculation,and geophysical application.J Geophys Res,1989,94:15671–15685
17Suzuki A,Ohtani E,Morishima H,et al.In situ determination of the phase boundary between Wadsleyite and Ringwoodite in Mg2SiO4.Geo-phys Res Lett,2000,27:803–806
18Bertka M,Fei Y W.Mineralogy of the Martian interior up to core-mantle boundary pressures.J Geophys Res,1997,102:5251–5264
19McMillan P,Akaogi M.Raman spectra ofβ-Mg2SiO4(modified spinel)andγ-Mg2SiO4(spinel).Am Mineral,1987,72:361–364
20陈鸣.冲击变质陨石橄榄石晶内高压多形转变特征与条件.矿物学报,2009,29:1–6
21Kuno T,Ohtani E,Fulakoshi K.Nucleation and growth kinetics of theα-βtransformation in Mg2SiO4detemined by in situ synchrotron pow-der X-ray diffraction.Am Mineral,2004,89:285–293
22Sung C M,Burns R G.Kinetics of the olivine-spinel transition:Implications to deep focus earthquake genesis.Earth Planet Sci Lett,1976,32:165–170
23Mosenfelder J L,Marton F C,Ross C R,et al.Experimental constraints on the depth of olivine metastability in subducting lithosphere.Phys Earth Planet Inter,2001,127:165–180
24Kerschhofer L,Sharp T G,Rubie D.Intracrystalline transformation of olivine to wadsleyite and ringwoodite under subduction zone condi-tions.Science,1996,274:79–81
25Dziewonski A M,Anderson D L.Preliminary reference earth model.Phys Earth Planet Inter,1981,25:297–356
26Shearer P M.Seismic imaging of upper-mantle structure with new evidence for a520km discontinuity.Nature,1990,344:121–126
27Shearer P M.Transition zone velocity gradients and the520-km discontinuity.J Geophys Res,1996,101:3035–3066
28Gu Y,Dziewonski A M,Agee C B.Global de-correlation of the topography of transition zone discontinuities.Earth Planet Sci Lett,157:57–67
29Deuss A,Woodhouse J.Seismic observations of splitting of the mid-transition zone discontinuity in Earth’s Mantle.Science,2001,294:354–357
30Katsura T,Ito E.The system Mg2SiO4-Fe2SiO4at high pressures and temperatures:Precise determination of stabilities of olivine,modified spinel,and spinel.J Geophys Res,1989,94:15663–15670
31Helffrich G.Topography of the transition zone seismic discontinuities.Rev Geophys,2000,38:141–158
32Weidner D J,Wang Y.Chemical-and Clapeyron-induced buoyancy at the660km discontinuity.J Geophys Res,1998,103:7431–7441
33Irifune T,Isshiki M.Iron partitioning in a pyrolite mantle and the nature of the410-kmseismic discontinuity.Nature,1998,392:702–705
34Ai Y,Zheng T.The upper mantle discontinuity structure beneath eastern China.Geophys Res Lett,2003,30:2089,doi:10.1029/2003GL017678
35Gilbert H J,Sheehan A F,Dueker K G,et al.Receiver functions in the western United States,with implications for upper mantle structure and dynamics.J Geophys Res,2003,108:2229,doi:10.1029/2001JB001194
36van der Meijde M,van der Lee S,Giardini D.Seismic discontinuities in the Mediterranean mantle.Phys Earth Planet Inter,2005,148:233–250
37Saikia A,Frost D,Rubie D.Splitting of the520-kilometer seimic discontinuity and chemical heterogeneity in the mantle.Nature,2008,139:1515–1518
38周春银,金振民,章军峰.地幔转换带:地球深部研究的重要方向.地学前缘,2010,17:90–113
39杨翠平,金振民,吴耀.地幔转换带中的水及其地球动力学意义.地学前缘,2010,17:114–126
40Ai Y,Zheng T,Xu W,et al.A complex660km discontinuity beneath northeast China.Earth Planet Sci Lett,2003,212:63–71
41Chen L,Zheng T,Xu W.Receiver function migration image of the deep structure in the Bohai Bay Basin,eastern China.Geophys Res Lett,2006,33:L20307,doi:10.1029/2006GL027593
42Chen L,Ai Y.Discontinuity structure of the mantle transition zone beneath the North China Craton from receiver function migration.J Geophys Res,2009,114:B06307,doi:10.1029/2008JB006221
43Gao S S,Silver P G,Liu K H,et al.Mantle discontinuities beneath Southern Africa.Geophys Res Lett,2002,29:1491,doi:10.1029/2001GL013834
44Huang J,Zhao D.High-resolution mantle tomography of China and surrounding regions.J Geophys Res,2006,111:B09305,doi:10.1029/2005JB004066
版权所有：© 2023 中国地质图书馆 中国地质调查局地学文献中心