| 大别山北部卢镇关杂岩的Pb同位素特征及大地构造属性 |
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| 引用本文： | 刘贻灿,江来利,储东如,吴维平.大别山北部卢镇关杂岩的Pb同位素特征及大地构造属性[J].矿物岩石,2004,24(4):53-58. |
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| 作者姓名： | 刘贻灿 江来利 储东如 吴维平 |
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| 作者单位： | 1. 中国科学技术大学地球和空间科学学院,安徽,合肥,230026
2. 安徽省地质调查院,安徽,合肥,230001 |
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| 基金项目： | 国家自然科学基金(编号为40072070)，国家重点基础发展规划项目(TG1999075506)，国家973专项"大陆板块汇聚边界的地幔动力学与现代地壳作用"(2003CB716500)资助成果 |
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| 摘 要： | Pb同位素组成研究表明，卢镇关杂岩中花岗片麻岩的^204Pb为1．366％～1．392％(平均为1．381％)、^206Pb／^204Pb为17．083～17．874(平均为17．463)和^204Pb／^204Pb为38．161～38．794(平均为38．438)；斜长角闪岩的^204Pb为1．386％～1．412％(平均1．400％)，其^206Pb／^204Pb为17．001～17．492(平均17．227)和^208Pb／^204Pb37．390～38．151(平均37．713)。二者的总平均为：^204Pb1．389％，^204Pb／^204Pb17．362，^208Pb／^204Pb38．127。与北部杂岩带和南部超高压变质带比较，卢镇关杂岩明显类似于南部超高压变质带的Ph同位素组成即表现为贫非放射成因铅和富集放射成因铅，表明它们应属于扬子大陆板块的一部分。考虑到北部杂岩带在地壳结构上应位于南部超高压带之下，以及北大别正片麻岩具有中、下地壳性质而南大别花岗片麻岩则具有上地壳特征。因此，卢镇关杂岩也应属于扬子大陆的上地壳，华北与扬子两个陆块之间的缝合线应在卢镇关杂岩以北。但是，由于在北淮阳带中一直未发现榴辉岩或榴辉岩相岩石等高压一超高压岩石以及有关印支期变质作用记录，说明至少卢镇关杂岩在印支期未卷入深俯冲，大别山的印支期俯冲带应位于卢镇关杂岩的南侧即磨子潭晓天断裂附近，大别山印支期深俯冲应属于扬子板块的陆内俯冲。
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| 关 键 词： | 印支期 Pb同位素 大别山 超高压变质带 上地壳 大地构造 花岗片麻岩 北部 南部 成因 |
| 文章编号： | 1001-6872(2004)04-0053-06 |
| 修稿时间： | 2004年6月11日 |
Pb ISOTOPIC CHARACTERISTICS OF THE LUZHENGUAN COMPLEX FROM NORTHERN DABIE MOUNTAINS AND ITS TECTONIC AFFINITY |
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| LIU Yi-can,JIANG Lai-li,CHU Dong-ru,WU Wei-ping.School of Earth and Space Sciences,University of Science and Technology of China,Hefei,China, .Anhui Institute of Geologica Survey,Hefei,China.Pb ISOTOPIC CHARACTERISTICS OF THE LUZHENGUAN COMPLEX FROM NORTHERN DABIE MOUNTAINS AND ITS TECTONIC AFFINITY[J].Journal of Mineralogy and Petrology,2004,24(4):53-58. |
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| Authors: | LIU Yi-can JIANG Lai-li CHU Dong-ru WU Wei-pingSchool of Earth and Space Sciences University of Science and Technology of China Hefei China Anhui Institute of Geologica Survey Hefei China |
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| Institution: | LIU Yi-can~1,JIANG Lai-li~2,CHU Dong-ru~2,WU Wei-ping~11.School of Earth and Space Sciences,University of Science and Technology of China,Hefei230026,China, 2.Anhui Institute of Geologica Survey,Hefei230001,China |
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| Abstract: | The whole rock Pb isotopic compositions of the Luzhenguan complex from northern Dabie Mountains were reported.The results showed that the ~(204)Pb and ~(206)Pb/~(204)Pb and ~(208)Pb/~(204)Pb ratios for the granitic gneisses are 1.366% to 1.392%,17.083 to 17.874 and 38.161 to 38.794; (~(204)Pb ) and ~(206)Pb/~(204)Pb and ~(208)Pb/~(204)Pb ratios for the amphibolites are 1.386% to 1.412%,17.001 to (17.492) and 37.390 to 38.151, respectively. Their average values of ~(204)Pb,~(206)Pb/~(204)Pb and ~(208)Pb/(~(204)Pb) are 1.389%, 17.362 and 38.127, respectively. Compared with the northern Dabie complex and southern Dabie ultrahigh-pressure metamorphic belt, the Pb isotopic compositions for the Luzhenguan complex are characterized by those poor in non-radiogenic Pb and rich in radiogenic Pb, which are similar to those for the southern ultrahigh-pressure metamorphic belt,suggesting that the Luzhenguan complex belong to a part of the Yangtze continental plate. According to the variation model of Pb isotopic composition in crustal vertical section, the northern Dabie complex is beneath the southern Dabie ultrahigh-pressure metamorphic belt and the former is of the middle-lower crustal properties and the latter is of the upper crustal properties. Therefore, the Luzhenguan complex should also be the upper crust of the Yangtze continental plate and the suture line between the Yangtze and North China continental plates may be to North of the Luzhenguan complex. However, there is no high to ultrahigh-pressure rock such as eclogite or eclogitic rock, and norelated Triassic record of the metamorphism, these suggest that the Luzhenguan complex did not experienced the Triassic deep subduction.The Triassic subduction belt may be to the south side of the Luzhenguan complex near Mozitan-Xiaotian fault zone.It is considered that the Triassic deep subduction in the Dabie Mountains was an intracontinental one within the Yangtze continental plate. |
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| Keywords: | Pb isotopic composition tectonic affinity Luzhenguan complex northern Dabie complex |
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