Nd isotopic characteristics of Proterozoic metasedimentary rocks and constraints on their provenance in the eastern segment of Central Tianshan Belt, Xinjiang  

作　　者：LIQiugen LIUShuwen HANBaofu ZHANGJian CHUZhuyin 

机构地区：[1]TheKeyLaboratoryofOrogenicBeltsandCrustalEvolution,MinistryofEducation,SchoolofEarthandSpaceSciences,PekingUniversity,Beijing100871,China [2]InstituteofGeologyandGeophysics,ChineseAcademyofSciences,Beijing100029,China

出　　处：《Progress in Natural Science:Materials International》2003年第12期908-913,共6页自然科学进展·国际材料（英文版）

基　　金：SupportedbytheNationalNaturalScienceFoundationofChina (GrantNo .40 0 72 0 65 )

摘　　要：Sm Nd isotopic characteristics, ε Nd ( t ) values and Nd model ages ( T DM ) of Proterozoic metasedimentary rocks in the eastern segment of Central Tianshan Belt (ESCTB), Xinjiang, are used to constrain the sedimentary provenance as well as to evaluate their tectonic implications. ε Nd ( t ) and T DM values of these samples range from -4.00 to +6.36 and from 1.29 to 2.29 Ga, respectively. These feature values are distinguished from those of Archean Tarim Craton. Their average ε Nd ( t ) values of the Weiya, the Kumishi and the south to the Dikar samples are -2.46, +2.06 and +1.37, respectively. Nd model ages of the Weiya samples vary between 1.86 and 2.29 Ga , but those of the Kumishi and the south to the Dikar samples show a significant concentration at 1.6～1.9 Ga and the youngest Nd model age is 1.29 Ga. Those Nd isotopic characteristics suggest that these metasedimentary rocks could be derived from a significant proportion of Paleoproterozoic crustal source and a participation of young arc materials, rather than Archean Tarim Craton. Furthermore, the data also indicate that these two sources were paleogeographically separated. Thus we can deduce that the Kumishi and the south to the Dikar metasedimentary rocks were formed proximal to the arc side of the back arc basin, but the Weiya metasedimentary rocks were closer to the continental side of the back arc basin.Sm Nd isotopic characteristics, ε Nd ( t ) values and Nd model ages ( T DM ) of Proterozoic metasedimentary rocks in the eastern segment of Central Tianshan Belt (ESCTB), Xinjiang, are used to constrain the sedimentary provenance as well as to evaluate their tectonic implications. ε Nd ( t ) and T DM values of these samples range from -4.00 to +6.36 and from 1.29 to 2.29 Ga, respectively. These feature values are distinguished from those of Archean Tarim Craton. Their average ε Nd ( t ) values of the Weiya, the Kumishi and the south to the Dikar samples are -2.46, +2.06 and +1.37, respectively. Nd model ages of the Weiya samples vary between 1.86 and 2.29 Ga , but those of the Kumishi and the south to the Dikar samples show a significant concentration at 1.6～1.9 Ga and the youngest Nd model age is 1.29 Ga. Those Nd isotopic characteristics suggest that these metasedimentary rocks could be derived from a significant proportion of Paleoproterozoic crustal source and a participation of young arc materials, rather than Archean Tarim Craton. Furthermore, the data also indicate that these two sources were paleogeographically separated. Thus we can deduce that the Kumishi and the south to the Dikar metasedimentary rocks were formed proximal to the arc side of the back arc basin, but the Weiya metasedimentary rocks were closer to the continental side of the back arc basin.

关 键 词：Nd isotopic features metasedimentary rocks Xingxingxia group provenance and forming time Tectonic setting the ESCTB of Xinjiang. 

分 类 号：P588.2[天文地球—岩石学] P597.2[天文地球—地质学]