Sources of material for the Linxi granitoids, the southern segment of the Da Hinggan Mts. : when and how continental crust grew?
文献类型：期刊论文
| 作者 | Liu W; Pan X F; Xie L W; Li H |
| 刊名 | ACTA PETROLOGICA SINICA
 |
| 出版日期 | 2007-02-01 |
| 卷号 | 23期号:2页码:441-460 |
| 关键词 | continental crust growth inherited/antecrystal zircon from juvenile source rocks oceanic crust subduction accretion complex underplating |
| ISSN号 | 1000-0569 |
| 文献子类 | Article |
| 英文摘要 | Sensitive high-resolution ion microprobe ( SHRIMP) U-Pb dating and laser-ablation multi-collector ICPMS Hf isotope analyses are conducted on inherited/antecrystal and magmatic zircons from the Linxi granitoids, in the southern segment of the Da Hinggan Mts. of China. SHRIMP dating establishes an Early Cretaceous (135 similar to 125Ma) age for most Linxi granitoids and the age of their source rocks at similar to 146Ma. However, some granitoids were intruded in the Early Triassic (241Ma) and the terminal Late Jurassic ( 146Ma), whilst their respective Source rocks were generated at 263Ma and 165Ma. A total of 100 SHRIMP analyses yield Ph-206/U-238 ages younger than 300Ma, whereas all 175 Hf isotope analyses give high positive epsilon(Hf)(t) values. These results indicate juvenile source materials in the lower crust with a notable absence of Precambrian basement. At a given epsilon(Nd)(t), Linxi granitoids exhibit distinctly higher zircon epsilon(Hf)(t) than both the terrestrial array and the Hawaiian basalt array. This Hf-Nd isotopic decoupling suggests a source component of pelagic sediments, i. e. Paleozoic subduction accretion complexes. Zircon epsilon(Hf)(t) values (t = 263 similar to 165 Ma) form a trend sub-parallel to the depleted mantle Hf isotope evolution curve, but those ( t = 146 similar to 125Ma) markedly fall below the latter. The first trend indicates a provenance from essentially the MORBs. However, the abrupt epsilon(Hf)( t) decrease, together with extensive Early Cretaceous magmatism, is interpreted as reflecting mantle upwelling and resultant underplating, and exhumation of subducted oceanic crust. Quantitative simulation shows that Suite 2 granitoids derive from underplated mafic rock, Paleozoic subduction accretion complex, and subducted MORB slices in descending order of mass fractions. However, the Xiaocbengzi intrusion ( Suite I) occurring southwest of Linxi derives mainly from Paleozoie suhduction accretion complex with a quantity of underplated mafic rocks. Among each of these 5 intrusions, magmatic zircons exhibit systematically decreased Hf-176/Hf-177 as compared with that of inherited/antecrystal zircons. Growth stages of zircons with t = 146 similar to 125Ma tend to decrease in Hf-176/Hf-177 from center to margin, or show systematic variations. The above results suggest that expansion of the melting region and widening of compositional range occurred in the lower crust over the period between incipient source rock melting and the terminal melting episode during production of Linxi granitoids. The magnesian or I-type geochemical characteristics of Suite I granitoids is attributed to a source reservoir of relatively oxidized and hydrous oceanic crust. However, a heterogeneous source that consists of relatively reduced, anhydrous underplated tholeiites and hydrous Paleozoic subduction-accretion complex causes geochemical signatures of Suite 2 granitoids that exhibit affinity to A-type granites but range from typical to less pronounced ferroan. |
| WOS关键词 | A-TYPE GRANITES ; METAMORPHIC CORE COMPLEX ; NORTHERN INNER-MONGOLIA ; U-PB ; LU-HF ; ISOTOPIC EVIDENCE ; TECTONIC IMPLICATIONS ; NORTHEASTERN CHINA ; SEDIMENTARY SYSTEM ; JIAODONG PENINSULA |
| WOS研究方向 | Geology |
| 语种 | 英语 |
| WOS记录号 | WOS:000245763200022 |
| 出版者 | SCIENCE CHINA PRESS |
| 源URL | [http://ir.iggcas.ac.cn/handle/132A11/68558]  |
| 专题 | 中国科学院地质与地球物理研究所 |
| 通讯作者 | Liu W |
| 作者单位 | Chinese Acad Sci, Inst Geol & Geophys, Key Lab Mineral Resources, Beijing 100029, Peoples R China |
| 推荐引用方式 GB/T 7714 | Liu W,Pan X F,Xie L W,et al. Sources of material for the Linxi granitoids, the southern segment of the Da Hinggan Mts. : when and how continental crust grew?[J]. ACTA PETROLOGICA SINICA,2007,23(2):441-460. |
| APA | Liu W,Pan X F,Xie L W,&Li H.(2007).Sources of material for the Linxi granitoids, the southern segment of the Da Hinggan Mts. : when and how continental crust grew?.ACTA PETROLOGICA SINICA,23(2),441-460. |
| MLA | Liu W,et al."Sources of material for the Linxi granitoids, the southern segment of the Da Hinggan Mts. : when and how continental crust grew?".ACTA PETROLOGICA SINICA 23.2(2007):441-460. |
入库方式： OAI收割
来源：地质与地球物理研究所
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