大陆碰撞和超高压变质的化学地球动力学:来自中国大陆科学钻探的结果
Geodynamics of continental collision and ultrahigh-pressure metamorphism: Constraints from Chinese Continental Scientific Drilling project
-
摘要: 利用中国大陆科学钻探工程连续取样的优势,对主孔200~4000m超高压变质岩进行了系统的地球化学研究.结果对大陆俯冲带变质的化学地球动力学提供了新的制约.目前取得的主要成果如下(1)建立了200~4000m深度的超高压矿物氧同位素变化剖面,发现18O亏损深度达3300m.结合大别-苏鲁造山带地表露头岩石达30000km2的18O亏损,表明扬子陆块北缘曾发生三维空间巨量物质(~100000km3)的18O亏损;(2)钻孔超高压变质岩的原岩形成于新元古代中期(~780Ma),属于双重双峰式岩浆活动的产物;原岩既有中元古代晚期新生地壳,也有古元古代中期古老地壳.这种双重双峰式岩浆活动出现在弧-陆碰撞带基础上发育的裂谷构造带,是对Rodinia超大陆开始裂解的响应;(3)高压榴辉岩相重结晶作用发生在216±3Ma,高压榴辉岩相重结晶作用持续的时间为1.9~9.3Myr或更短;(4)不同岩性接触带的矿物O同位素、H同位素、全水含量以及羟基含量的研究表明,退变质流体在同位素组成上是内部缓冲的,且退变质流体主要来自于名义上无水矿物中结构羟基和分子水的出溶.定量计算表明,这些出溶的结构羟基和分子水能为角闪岩相退变质作用提供足够的流体来源;(5)在不同岩性接触带,稳定同住素、水含量及岩相学上出现同步变化,表明不同岩性接触带可能是流体活动最剧烈的地方.对于远离榴辉岩-片麻岩接触带的榴辉岩,退变质流体主要来自榴辉岩内部名义上无水矿物中结构羟基和分子水的出溶.对于靠近接触带的榴辉岩,则可能主要受来自比榴辉岩更富水的片麻岩中矿物的脱水作用.根据相邻样品之间的距离、岩相学和δ18O值,可以确定出不同岩性和相同岩性之间氧同位素不均一性的尺度为20到50cm,对应于大陆碰撞过程中流体活动的最大尺度;(6)对两个连续岩芯段的主量和微量元素剖面研究表明,在大陆俯冲带变质过程中,大离子亲石元素(LILE)和轻稀土(LREE)具有较高的活动性,而高场强元素(HFSE)和重稀土(HREE)是不活动的.这些元素的活动可能是由折返过程中大陆地壳的部分熔融导致的,因此指示了超临界流体的出现.折返过程中大陆地壳的这种部分熔融作用导致了不同板片组分之间的质量迁移,但是这种有效的迁移只发生在很小的尺度范围内,在岩相学接触带和裂隙带的局部开放系统中.
-
[1] Ames L,Zhon GZ and Xiang BC.1996. Geochronology and isotopic character of ultrahigh-pressure metamorphism with implications for the collision of the Sino-Korcan and Yangtze cratons,central China.Technics,15:472 -489
[2] Arculus RJ,Lapierre H and Jaillard E.1999. Geochemical window into subduction and accretion processes; Respas metamorphic complexm Ecuador.Geology,27:547-550
[3] Auzanneau E,Vielzonf D and Sohmidt MW.2006. Experimental evidence of decompression melting during exhumation of subducted continental crust.Contrib.Mineral.Petrol.,152:125 -148
[4] Becker H,Jochum KP and Carlson RW.2000. Trace element fractionation during dehydration of eclogites from high-preesure terranes and the implications for element fluxes in subduction zones.Chem.Geol.,163:65 -99
[5] Bell DR,Rossman GR and Moore RO.2004. Abundance and partitioning of OH in a high-pressure magmatic system:Megacrysts from the Monastery kimberlite,South Africa.J.Petrol.,45:1539-1564
[6] Chalot-Prat F,Ganne J and Lombard A.2003. No significant element transfer from the oceanic plate to the mantle wedge during subduction and exhumation of the Tethys lithosphere (Western Alps).Lithos,69:69-103
[7] Chavagnac V,Jahn B-m,Villa IM,Whitehanse MJ and Lin DY.2001. Multichronometric evidence for an in situ origin of the ultrahigh-pressure metamorphic terrane of Dabieshan,China.J.Geol.,109:633 -646
[8] Chen RX,Zheng YF,Gong B,Zhan ZF,Gao TS,Chen B and Wu YB.2007a.Oxygen isotope geochemistry fo ultrahigh-pressure metamorphic rocks from 200~4000m core samples of the Chinese Continental Scientific Drilling.Chemical Geology,242:51-75
[9] Chert PX,Zhang YF,Zhao ZF,Tang J,Wu FY and Liu XM.2007b.Zircon U-Pb ages and Hf isotopes in ultrahigh-pressure metamorphic rocks from the Chinese Continental Scientific Drilling project.J.Metamorph.Geol.,25:873-894
[10] Chen RX,Zheng YF,Gong B,Zhan ZF,Gan 1S,Chen B and Wu YB.2007c.Origin of retrogrede fluid in ultrahigh-pressure metamorphic rocks:Constraints from mineral hydrogen isotope and water content changes in eclogite-gneiss transitions in the Sulu orogen.Geochim.Cosmochim.Acta,71:2299-2325
[11] Chopin C,Henry C and Michard A.1991. Geology and Petrology of the Coesite-Bearing Terrain,Dora-Maira Massif,Western Alps.Eur.J.Mineral.,3:263-291
[12] Chopin C.2003. Ultrahigh-pressure metamorphism:Tracing continental crust into the mantle.Earth Planet.Sci.Lett.,212:1 -14
[13] Dewey JF.1988. Extensional collapse of orogens.Tectonics,7:1123-1139
[14] Doremus RH.2004. Transport of oxygen in silicate glasses.J.Non-Crys.Solids,349:242-247
[15] Ernst WG.2006. Presorvation/exhumation of ultrahigh-preasure subduction complexes.Lithus,92:321-335
[16] Fortier SM and Gilletti BJ.1989. An empirical model for predicting diffusion coefficients in silicate minerals.Science,245:1481-1484
[17] Fu B,Touter JLR and Zheng YF.2001. Fluid inclusious in coesite-bearing eclogites and jadeite quartzites at Schuanghe,Dabie Shan,China.J.Metamorph.Geol.,19:531 -548
[18] Gong B,Zheng YF,Chen RX.2007a.TC/EA-MS online determination of hydrogen isotope composition and water concentration in eclogitic garnet.Phys.Chem.Minerals.,34,doi:10.1007/s00269-007-0184-4
[19] Gong B,Zheng YF,WuYB,Zhao ZF,GOo TS,Tang J,Chen RX,Fu B and Liu XM.2007b.Geochronology and stable isotope geochemistry of UHP metamorphic rocks at Tachang in the Sulu orogen,east-central China.Int.Geol.Rev.,49:259 -286
[20] Grant K,Glceson SA and Roberts S.2003. The high temperature behavior of defect hydrogen species in quartz:Implications for hydrogen isotope studies.Am.Mineral.,88:262 -270
[21] Hacker BR,Ratschbacher L,Webb L,Ireland T,Walker D and Dong S.1998. U/Pb zircon ages constrain the architecture of the ultrahigh-pressure Qinling-Dabie orogen,China.Earth Planet.Sci.Lett.,161:215 -230
[22] Hermann J and Green DH.2001. Experimental constraints on high pressure melting in subducted crust.Earth Planet.Sci.Lett.,188:149-168
[23] Hermann J.2002a.Allanite:Thorium and light rare earth element carrier in subducted crust.Chem.Geol.,192:289 -306
[24] Hermann J.2002b.Experimental constraints on phase relations in subducted continental crust.Contrib.Mineral.Petrol.,143:219-235
[25] Hermann J.2003. Experimental evidence for diamond-facies metamorphism in the Dora-Maira massif.Lithos,70:163 -182
[26] Hermann J,Spandler C,Hack A and Korsakov AV.2006. Aqueous fluids and hydrous melts in high-pressure and ultra-high pressure rocks:Implications for element transfer in subduetion zones.Lithes,92:399-417
[27] Holtz F,Becker A,Freise M and Johannes W.2001. The water-undersaturated and dry Qz Ab Or system revisited.Experimental results at very low water activities and geological implications.Contrib.Mineral.Petrol.,141:347-357
[28] Hnang WL and Wyllie PJ.1981. Phase relationships of S-type granite with H2O to 35 kbar:Muscovite granite from Harney Peak,south Dakota.J.Geophys.Res.,86:10515 -10529
[29] Hnang J,Zheng YF,Zhan ZF,Wu YB,Zhou JB and Liu XM.2006. Melting of subdueted continent:Element and isotopic evidence for a genetic relationship between Necproterosoic and Mesozoic granitoids in the Sulu orogen.Chem.Geol.,229:227 -256
[30] Jahn Bm.1998. Geochemical and isotopic characteristics of UHP eclogites and ultramafic rocks of the Dabie orogen:Implications for continental subduetion and collisional tectonics.In:Hacker BR and Lion JG (eds).When Continents Collide:Geodynamies and Geochemistry of Ultrabigh-Presanre Racks.Kluwer Academic Publishers,Dordrecht pp.203-239
[31] Jahn Bm,Rumble D and Liou JG.2003. Geochemistry and isotope tracer study of UHP metamorphic rocks.In:Carswell DA and Compagnoni R (eds).Ultrahigh Pressure Metamorphism.EMU Notes in Mineralogy pp.365 -414
[32] John T,Scherer,EE,Haase K and Schenk V.2004. Trace element fructionation during fluid-inducod eclogitization in a subdueting slab:Trace element and Lu-Hf-Sm-Nd isotope systematics.Earth Planet.Sci.Lett.,227:441 -456
[33] Johnson EA and Rossman GR.2004. A survey of hydrous species and concentrations in igneous feldspars.Am.Mineral.,89:586 -600
[34] Kogizo T,Tatsumi Y and Nakano S.1997. Trace element transport during dehydration processes in the subdueted oceanic crust 1. Experiments and implications for the origin of ocean island basalts.Earth Planet.Sol.Lett.,148:193 -205
[35] Li XH,Li ZX,Ge W,Li WX,Liu Y and Wingate MTD.2003a.Necproterozoic granitoids in South China:Crustal melting above a mantle plume at ca.825 Ma? Precambrian Res.,122:45 -83
[36] Li ZX,Li XH,Kinny PD,Wang J,Zhang S and Zhou H.2003b.Geochronology of Neopreterezoic syn-rift magmatism in the Yangtze Craton,South China and correlations with other continents:Evidence for a mantle superplume that broke up Rodinia.Precambrian Res.,122:85-109
[37] Li XP,Zheng YF,Wu YB,Chen FK,Gong B and Li YL.2004. Low-T eclogite in the Dabie terrane of China:Petrological and isotopic constraints on fluid activity and radiometric dating.Contrib.Mineral.Petrol.,148:443 -470
[38] Liou JG,Zhang RY and Ernst WG.1997. Lack of fluid during ultrabigh-P metamorphism in the Dabie-Sulu region,Eastern China.Proceedings of the International Geological Congress 30,Vol.17:141-155
[39] Lion JG,Zhang RY,Ernst WG,Rumble D and Maruyama S.1998. High-preasure minerals from deeply subdueted metamorphic recks.Rev.Mineral.,37:33-96
[40] Liu DY,Jian P,Kr her A and Xu ST.2006. Dating of prngrade metumorphie events deciphered from episodic zircon growth in recks of the Dabie Sulu UHP complex,China.Earth Planet.Sci.Lett.,250:650-666
[41] Liu FL,Xu ZQ,Katayama I,Yang JS,Maruyama S and Lion JG.2001. Mineral inclusions in zircons of para-and orthogneiss from pre-pilot drillhole CCSD-PP1,Chinese Continental Scientific Drilling Project.Lithos,59:199-215
[42] Liu FL,Xu ZQ,Lion JG,Katayama I,Masago H,Maruyama S and Yang JS.2002. Ultrabigh-pressure mineral inclusions in zircons from gneissic core samples of the Chinese Continental Scientific c Drilling Site in eastern China.Eur.J.Mineral.,14:499 -512
[43] Liu FL and Xu ZQ.2004. Fluid inclusions hidden in coesite-bcaring zircons in ultrahigh-pressure metamorphic rocks from southwestern Sulu terrune in eastern China.Chinese Sci.Bull.,49:396 -404
[44] Liu FL,Xu ZQ and Xue HM.2004a.Tracing the protolith,UHP metamorphism,and exhumation ages of orthogneiss from the SW Sulu terrane (eastern China):SHRIMP U-Pb dating of mineral inclusion-bearing zircons.Lithes,78:411 -429
[45] Liu FL,Xu ZQ,Lion JG and Song B.2004b.SHRIMP U-Pb ages of ultrahigh-pressure and retrograde metamorphism of gneisses,south-western Suh terrane,eastern China.J.Metamorph.Geol.,22:315-326
[46] Liu FL,Xu ZQ and Liou JG.2004c.Tracing the boundary between UHP and HP metamorphic belts in the southwestern Sulu terrane,eastern China:Evidence from mineral inclusions in zircons from metamorphic rocks.Int.Geol.Rev.,46:409 -425
[47] Miller C,Zanetti A,Thoni M and Konzett J.2007. Eclogitisation of gabbroic rocks:Redistribution of trace elements and Zr in futile thermometry in an Eo-Alpine subduction zone (Eastern Alps).Chem.Geol.,239:96-123
[48] Munyanyiwa H,Hanson RE,Blenkinsop TG and Trelcar PJ.1997. Geochemistry of amphibolites and quartzofeldspathic gneisses in the Pan-African Zambezi belt,northwest Zimbabwe:Evidence for bimodal magmatism in a continental rift setting.Precambr.Res.,81:179-196
[49] Murphy JB,Gutierrez-Alonso G,Nance RD,Fernandez-Suerez J,Keppie JD,Quesada C,Strachan RA and Dostal J.2006. Orion of the Rheic Ocean:Rifling along a Neoproterozoie suture? Geology,34:325-328
[50] Nakamura D and Hirajima T.2000. Granulite-facios overprinting of ultrabigh-pressure metamorphic rocks,northeastern Su-Lu region,eastern China.J.Petrol.,41:563 -582
[51] Okay AI,Xu ST and Scngor AMC.1989. Coesite from the Dabie Shan eclogites,central China.Eur.J.Mineral.,1:595 -598
[52] Patino Donce AE and McCarthy TC.1998. Melting of crustal rocks during continental collision and subdaction.In:Hacker BR,Linu JG (eds).When continents collide.Correct,Netherlands,Kluwer Academic,27-55
[53] Patino Donce AE.2005. Vapor-absent mehing of tonalite at 15~32kbar.J.Petrol.,46:275 -290
[54] Rossman GR.1996. Studies of OH in nominally anhydrous minerals.Phys.Chem.Miner.,23:299-304
[55] Rumble D and Yui TF.1998. The Qinglongshan oxygen and hydrogen isotope anomaly near Donghai in Jiangsu province,China.Geochimica et Cosmochimica Acta,62:3307-3321
[56] Rumble D,Wang QC and Zhang RY.2000. Stable isotope geochemistry of marbles from the coesite UHP terrains of Dabieshan and Sulu,Chins.Lithos,52:79 -95
[57] Rumble D,Giorgis D,Oreland T,Zhang ZM,Xu HF,Yui TF,Yang JS,Xu ZQ and Liou JG.2002. Low δ18 O zircons,U-Pb dating,and the age of the Qinglongshan oxygen and hydrogen isotope anomaly near Donghai in Jiangsu province,China.Geachim.Cosmochim.Acta,66:2299-2306
[58] Schmidt MW,Viehenf D and Ausannean E.2004. Melting and dissolution of subducting crust at high pressures:The key role of white mica.Earth Planet.Sci.Lett.,228:65 -84
[59] Spandler C,Hermann J,Arculns R and Mavrogenes J.2003. Redistribution of trace elements during prograde metamorphism from lawsonite blueschist to eclogite facies:Implications for deep sunduction-zone processes.Contrib.Mineral.Petrol.,146:205-222
[60] Spandler C,Hermann J,Arculns R and Mavrngencs J.2004. Geochemical heterogeneity and element mobility in deeply subducted oceanic crust:Insights from high-pressure mafic rocks from New Caledonia.Chem.Geol.,206:21-42
计量
- 文章访问数: 5834
- PDF下载数: 7093
- 施引文献: 0