北淮阳庐镇关岩浆岩锆石U-Pb年龄和氧同位素组成
Zircon U-Pb ages and oxygen isotope compositions of the Luzhenguan magmatic complex in the Beihuaiyang zone
-
摘要: 对大别造山带北麓的北淮阳庐镇关浅变质岩浆杂岩进行了锆石阴极发光显微结构观察、激光剥蚀等离子质谱锆石U-Pb定年以及单矿物激光氟化氧同位素分析。锆石阴极发光图像显示,这些样品中的锆石具有明显的振荡环带或片状分带,为典型的岩浆锆石。少数样品的锆石具有窄的蚀变边。锆石U-Pb定年结果表明,这些岩浆岩有较一致的形成年龄,变化范围为739±8Ma~754±5Ma。岩浆岩单矿物的氧同位素组成具有较大的变化范围,其中锆石δ~(18)O为1.39‰~6.81‰,石英为3.12‰~12.47‰,斜长石为0.71‰~8.38‰。锆石的δ~(18)O值在不同岩体和/或同一岩体的不同样品之间具有明显差别,反应了其初始岩浆在氧同位素组成上的不均一性。锆石与其它矿物之间表现出显著的氧同位素不平衡,说明它们经历了岩浆期后的扰动,其中部分样品受到了亚固相条件下高温热液蚀变作用的影响,还有部分样品在岩浆后期演化过程中可能同化混染了高δ~(18)O值的围岩。大多数锆石具有低于典型地慢锆石的δ~(18)O值,表现出~(18)O亏损特征。低δ~(18)O锆石的内部结构和化学组成表现出典型岩浆锆石的特征,表明这些低δ~(18)O锆石是从亏损~(18)O的岩浆中结晶出来的,而非热液蚀变成因。这一结果证明,扬子板块北缘新元古代低δ~(18)O锆石形成于热液蚀变岩石经部分熔融所形成的低δ~(18)O岩浆。结合这些样品的形成年龄,我们认为这些低δ~(18)O岩浆的形成与Rodinia超大陆裂解有关的地幔柱裂谷岩浆活动有关,并对应于全球性的雪球地球事件。此外,这些岩石中锆石U-Pb年龄与矿物δ~(18)O分布与大别造山带高压-超高压变火成岩原岩相似,指示北淮阳单元属于俯冲的扬子板块北缘
-
Key words:
- Luzhenguan /
- Zircon /
- Oxygen isotope /
- U-Pb age /
- Neoproterozoic
-
[1] [1]Ames L, Tilton G, Zhou G. 1993. Timing of collision of the Sino-Korean and Yangtse cratons: U-Pb zircon dating of coesite-bearing eclogites.Geology, 21:339-342
[2] [2]Ames L, Zhou G Z, Xiong B C. 1996. Geochronology and isotopic character of ultrahigh-pressure metamorphism with implications for collision of the Sino-Korean and Yangtze cratons, central China.Tectonics, 15(2): 472 -489
[3] [3]Anderson T. 2002. Correction of common lead in U-Pb analyses that do not report 204pb. Chemical Geology, 192:59 -79
[4] [4]Ayers J C, Dunkle S, Gao S, Miller C F. 2002. Constraints on timing of peak and retrograde metamorphism in the Dabie Shan UltrahighPressure Metamorphic Belt, east-central China, using U-Th-Pb dating of zircon and monazite. Chemical Geology, 186:315 -331
[5] [5]Baker J, Mathews A, Mattey D, Rowley D, Xue F. 1997. Fluid-rock interactions during ultra high pressure metamorphism, Dabie Shan,China. Geochim. Cosmoohim. Acta., 61: 1685-1696
[6] [6]Bindeman I N, Valley J W, Wooden J L. 2001. Post-caldera volcanism:in situ measurement of U-Pb age and oxygen isotope ratio in Pleistocene zircons from Yellowstone caldera. Earth and Planet.Science Letters, 189:197-206
[7] [7]Chen D G, Etienne D, Cheng H, Xia Q K, Wu Y B. 2003. Preliminary study of micro-scale zircon oxygen isotopes for Dabie-Sulu metamorphic rocks: Ion probe in situ analyses. Chinese Sci. Bull. ,48(16): 1670-1678
[8] [8]Chen F K, Guo J H, Jiang L L, Siebel W, Cong B L, Satir M. 2003. Provenance of the Beihuaiyang lower-grade metamorphic zone of the Dabie ultrahigh-pressure collisional orogen, China: evidence from zircon ages. J. Asian Earth Sci. , 22:343 -352
[9] [9]Cherniak D J, Watson E B, 2000. Pb diffusion in zircon. Chemical Geology, 172:5-24
[10] [10]Compston W, Williams I S, Kirschvink J L. Zircon U-Pb ages for the Early Cambrian time-scale. J. Geol. Soc. London, 149:171-184
[11] [11]Cong B L. 1996. Ultrahigh-Pressure Metamorphic Rocks in the Dabieshan-Sulu Region of China. Beijing: Science Press, 224 pp
[12] [12]Faure M, Lin W, Sbu L, Sun Y, Scharer U. 1999. Tectonics of the Dabieshan (eastern China) and possible exhumation mechanism of ultrahigh-pressure rocks. Terra Nova, 11 (6): 251 -258
[13] [13]Fortier S M, Giletti B J. 1989. An empirical model for predicting diffusion coefficients in silicate minerals, Science, 245:1481 -1484
[14] [14]Gao S, Liu X M, Yuan H L, 2002. Analysis of forty-two major and trace elements of USGS and NIST SRM Glasses by LA-ICP-MS.Geostandarcl Newslett. , 22: 181-195
[15] [15]Gilliam C E, Valley J W. 1997. Low δ18O magmas, Isle of Skye,Scotland: evidence from zircons. Geochim. Cosmochim. Acta, 61:4975-4981
[16] [16]Gong B, and Zheng Y F. 2003. A CO2-laser technique for oxygen isotope analysis of silicates. Earth Science Frontiers, 10(2): 279 -286 (in Chinese with English abstract)
[17] [17]Grimmer J C, Ratschbacher L, McWilliams M, Franz L, Gaitzsch I.2003. When did the ultrahigh-pressure rocks reach the surface? A 207 pb/206 Pb zircon, 4o Ar/39 Ar white mica, Si-in-white mica, singlegrain provenance study of Dabie Shun synorogenic foreland sediments, Chem. Geol. , 197: 87-100
[18] [18]Hacker B R, Ratshbacher L, Webb L, Ireland T, Walker D, Dong S.1998. U/Pb zircon ages constrain the architecture of the ultrahighpressure Qinling-Dabie Orogen, China. Earth Planet. SCi. Lett.,161:215 -230
[19] [19]Hacker B, Ratschbacher L, Webb L, McWilliams M, Ireland T, Calvert A, Dong S, Wenk H R. 2000. Exhumation of ultrahigh-pressure continental crust in east central China: Late Triassic-Early Jurassic tectonic unroofing. J. Geophysical Research, 105: 13339-13364
[20] [20]Hirajima T, Ishiwatari A, Cong B. 1990. Coesite from Mengzhoug eclogite at Donghai county, northern Jiangsu province, China.Mineral. Mag. , 54: 579-583
[21] [21]Hoffman P F, Kaufmann A J, Halverson G P, Schrag D P. 1998. A Neoproterozoic snowball earth. Science, 281: 1342-1346
[22] [22]Hoffman P F. 1999. The break-up of Rodinia, birth of Gondwana, ture polar wander and the snowball earth. J. Afr. Earth Sci. , 28, 17 -33
[23] [23]JiangL L, Wu W P, Chu R D, Liu Y C, Zhang Y. 2003. Postcollisional extensional and thrust-nappe structures in northern part of Dabie Mountains. Chinese Sci. Bull. , 48:2378 -2385
[24] [24]Kennedy M J, Runnegar B, Prave A R. 1998. Two or four Neoproterozoic glaciations.? Geology, 26:1059 -1063
[25] [25]King E M, Barrie C T, Valley J W. 1997. Hydrothermal alteration of oxygen isotope ratios in quartz phenocrystals, Kidd Creek mine,Ontario: magmatic values are preserved in zircon. Geology, 25:1079-1082
[26] [26]King E M, Valley J W, Davis D W, Edwards G R. 1998. Oxygen isotope ratios of Archean plutonic zircons from granite-greenstone belts of the Superior Province: indicator of magmatic source. Precambrian Research, 92: 365-387
[27] [27]King E M, Valley J W, 2001. The source, magmatic contamination, and alteration of the Idaho batholith. Contrib. Mineral. Petrol. , 142: 72-88
[28] [28]Lackey J S, Hinke H J, and Valley J. 2002. Tracking contamination in felsic magma chambers with δ18 O of magmatic garnet and zircon.Geochim. Cosmochim. Acta. , 66:A428
[29] [29]Lee J, Williams I, Ellis D. 1997 Pb, U and Th diffusion in nature zircon. Nature, 390(13): 159-162
[30] [30]Li X H. 1999. U-Pb zircon ages of granites from the southern margin of the Yangtze block: timing of the Neoproterozoic Jinning Orogeny in SE China and implications for Rodinia assembly. Precambrain Res. ,97: 43-57
[31] [31]Li X H, Li Z X, Zhou H W. 2002. U-Pb zircon geochronology,geochemistry and Nd isotopic study of neoproterozoic bimodal volcanic rocks in the Kangdian Rift of South China: implications for the initial rifting of Rodinia. Precambrian Res. , 113:135 -154
[32] [32]Li X H, Li Z X, Ge W C. 2003. Neoproterozoic granitoids in South China: crustal melting above a mantle plume at ca. 825 Ma?Precambrain Res. , 122: 45-83.
[33] [33]Li Z X, Li X H, Kinney P D, Wang J. 1999. The breakup of Rodinia:did it start with a mantle plume beneath South China? Earth Planet.Sci. Lett. , 173:171-181
[34] [34]LiZ X, Li X H, Kinndy P D, Wang J, Zhang S, Zhou H. 2003. Geochronology of Neoproterozoic syn-rift magmatism in the Yangtze Craton, South China and correlations with other continents: evidence for a mantle superplume that broke up Rodinia. Precambrain Res. ,122: 85-109
[35] [35]Liati A, Gebauer D, and Wysoczanski R, 2002. U-Pb SHRIMP-dating of zircon domains from UHP garnet-rich maric rocks and late pegmatoids in the Rhodope zone (N Greece); evidence for Early Cretaceous crystallization and Late Cretaceous metamorphism. Chemical Geology, 184:281-299
[36] [36]Liou J G, Zhang R Y, Eide E A. 1996. Metamorphism and tectonics of high-pressure and ultra high-pressure belts in the Dabie-Sulu region,China. In Harrison, M T, Yin A (eds.) , The Tectonics of Asia.Cambridge Univ. Press, Cambridge, pp. 300 -344
[37] [37]Ma G G, Li H Q, Zhang Z C. 1984. An investigation of the age limits of the Sinian system in South China. Bull. Yichang Inst. Geol.Mineral. Res. , 8:1 -29 (in Chinese)
[38] [38]Ma W P, Wang G Y, and Wang G S. 2001. Jinningian plutonic belt in the Fuziling Group and its tectonic implication. Geol. Rev. , 47(5): 476 -481 (in Chinese with English abstract)
[39] [39]Mojzsis S J, Harrison T M, Pidgeon R T, 2001. Oxygen-isotope evidence from ancient zircons for liquid water at the earth\' s surface 4,300 Myr ago. Nature, 409:178-181
[40] [40]Monani S, Valley J W, 2001. Oxygen isotope ratios of zircon: magma genesis of low δ18 O granites from the British Tertiary Igneous Province, western Scotland. Earth Planet. Sci. Lett., 184:377 -392
[41] [41]O\'Connor Y L, and Morrison J. 1999. Oxygen isotope constraints on the petrogenesis of the Sybille Intrusion of the Proterozoic Laramie anorthosite complex. Contrib. Mineral. Petrol. , 136:81 -91
[42] [42]Okay A, Xu S and Sengor A M C. 1989. Coesite from the Dabie Shan eclogites, central China, Eur. J. Mineral., 1:595-598
[43] [43]Peck W H, Valley J W. Graham C M, 2003. Slow oxygen diffusion rates in igneous zircons from metamorphic rocks. Am. Mineral. , 88 (in press)
[44] [44]Prave A R. 1999. Two diamictites, two cap carbonates, two δ13C excursions, two rifts: the Neoproterozoic Kingston Peak Formation,Death Valley, California. Geology, 27: 339- 342
[45] [45]Rowley D B, Xue F,Tucker R D, Peng Z X, Baker J, Davis A. 1997. Ages of ultrahigh pressure metamorphism and protolith orthogneisses from the eastern Dabie Shan: U/Ph zircon geochronology, Earth and Planet. Science Letters, 151:191-203
[46] [46]Rumble D, Yui T F. 1998. The Qinglongshan oxygen and hydrogen isotope anomaly near Donghai in Jiangsu Province, China. Geochim.Cosmochim. Acta., 62:3307-3321
[47] [47]Rumble D, Giorgis D, Ireland T, Zhang Z M, Xu H F, Yui T F, Yang J S, Xu Z Q. 2002. Low δ18O zircons, U-Pb dating, and the age of the Qinglongshan oxygen and hydrogen isotope anomaly near Donghai in Jiangsu province, China. Geochim. Cosmochim. Acta., 66:2299-2306
[48] [48]Sheppard S M F, Taylor H P Jr. 1974. Hydrogen and oxygen isotope evidence for the origin of water in the Boulder batholith and the Butte ore deposits. Econ. Geol. , 69: 926-946
[49] [49]Taylor H P. 1977. Water/rock interactions and the origin of H2O in granitic batholiths. J. Geol. Soc. Lond., 133:509-558
[50] [50]Taylor H P. 1986. Igneous rocks. I I. Isotopic case studies of Circumpacific magmatism. In: Valley J W, Taylor H P, O\' Niel J R (eds.). Stable isotopes in high-temperature geological processes.Mineral. Soc. Am. , Rev. Mineral. , 16:273-317
[51] [51]Taylor H P, Sheppard S M F. 1986. Igneous rocks. I. Processes of isotopic fractionation and isotopic systematics. In: Valley J W,Taylor H P, O\' Niel J R (eds.) Stable isotopes in high-temperature geological processes. Mineral. Soc. Am., Rev. Mineral., 16:227-271
[52] [52]Valley J W, Chiarenzeli J R, McLelland J M. 1994. Oxygen isotope geochemistry of zircon. Earth Planet. Sci. Lett. , 126:187-206
[53] [53]Valley J W, Graham C M. 1996. Ion microprobe analysis of oxygen isotope ratios in quartz from Skye granite: healed micro-cracks, fluid flow, and hydrothermal exchange. Contrib. Mineral. Petrol., 124:225-234
[54] [54]Valley J W, Kinney P D, Schulze D J, Spicuzza M J. 1998. Zircon megacrysts from kimberlite: oxygen isotope variability among mantle melts. Contrib. Mineral. Petrol., 133:1-11
[55] [55]Valley J W, Peck W H, King E M, Wilde S. 2002. A cool early earth.Geology, 30:351 -354
[56] [56]Valley J W, Bindeman I N, and Peck W H. 2003. Empirical calibration of oxygen isotope fractionation in zircon. Geochim. Cosmochim.Acta. , 67: 3257-3266
[57] [57]Wang X, Liou J, Mao H. 1989. Coesite-bearing eclogites from the Dabie Mountains in central China. Geology, 17:1085 -1088
[58] [58]Wang X M, and Liou J. 1991. Regional ultrahigh-pressure coesitebearing eclogitic terrane in central China: evidence from country rocks,gneiss, marble, and metapelite. Geology, 19: 933-936
[59] [59]Wang X M, Zhang R Y, Liou J G. 1995. UHP terrane in east central China. In: Coleman R, Wang X (eds.), Ultrahigh Pressure Metamorphism. Cambridge Univ. Press, Cambridge, 356-390 pp
[60] [60]Watson E B, Cherniak D J. 1997. Oxygen diffusion in zircon. Earth Planet. Sci. Lett., 148:527-54
计量
- 文章访问数: 7863
- PDF下载数: 6747
- 施引文献: 0