Andesitic arc magmas derived from two contrasting melange origins: Evidence from central Tibetan dioritic porphyries
文献类型：期刊论文
| 作者 | Hao, Lu -Lu1,2; Wang, Qiang1,2,4; Kerr, Andrew C.5; Huang, Fang6,7; Xiao, Ming2; Ma, Xiao-Long3; Zhang, Wan-Feng2; Wang, Wen-Yu6; Liu, Mao-Rui2,4 |
| 刊名 | CHEMICAL GEOLOGY
 |
| 出版日期 | 2024-04-05 |
| 卷号 | 650页码:10 |
| 关键词 | Subductionmelange Andesitic arc magmas Crustal growth Mg isotopes Tibetan plateau |
| ISSN号 | 0009-2541 |
| DOI | 10.1016/j.chemgeo.2023.121920 |
| 英文摘要 | Numerous studies have argued that the andesitic model (i.e., the arc directly produces andesitic magmas) rather than the basaltic-input model (i.e., andesitic magmas were derived by fractionation from basaltic magmas) better explains the composition of continental crust. However, it remains controversial as to how andesitic magmas are directly produced in subduction zones, and this weakens the basis of the andesitic model. Recently, the m & eacute;lange-diapir model has been increasingly considered to be an important mechanism for the direct generation of arc andesites, and would thus support the andesitic model for crustal growth. Moreover, melting experiments on m & eacute;lange rocks show that varying the composition of m & eacute;lange rocks (e.g., serpentinite-dominated and sediment-dominated m & eacute;lange) can produce a range of primary andesitic arc magmas, from tholeiitic, calc-alkaline, to high-K calc-alkaline and shoshonitic magma types. However, it remains challenging to determine the different m & eacute;lange sources for low-K to high-K arc andesites. Here we verify these experimental results using data from early Cretaceous dioritic porphyries in the southern Qiangtang block of central Tibetan plateau. The generation of these dioritic rocks cannot be linked to any coeval basaltic rocks in this region and so they may represent primary andesitic magmas. These dioritic porphyries are divided into low-K type-1 and high-K type-2. Type-1 has higher delta Mg-26 values (-0.16 to -0.08 parts per thousand) than MORBs (mid-ocean ridge basalt, delta Mg-26 = -0.25 +/- 0.06 parts per thousand), which can be ascribed to the contribution of subducted bulk/un-differentiated serpentinite in their source. Combined with their low K contents and La/Sm ratios, and high NdHf isotope ratios (epsilon Nd(t) = 3.36-5.03; epsilon Hf(t) = 12.88-13.76), we suggest a serpentine-dominated m & eacute;lange for their origin. The type-2 and type-1 rocks have similar trace-element distribution patterns, the same ages (similar to 124 Ma), and are indistinguishable in field outcrops, indicating their common petrogenesis. However, compared to type-1, type-2 has higher K and Th contents, and La/Sm and Th/Nd ratios with lower NdHf isotope values (epsilon Nd(t) = -1.61 to +0.30; epsilon Hf(t) = 3.78-4.39), and mantle-like delta Mg-26 values (-0.28 to -0.17 parts per thousand). This likely indicates derivation from a sediment-dominated m & eacute;lange for type-2. This study thus verifies the experimental results of melting of different m & eacute;lange from natural rock record and shows that the m & eacute;lange model provides an important mechanism for generating variable andesitic arc magmas and so the formation of the andesitic continental crust. |
| WOS研究方向 | Geochemistry & Geophysics |
| 语种 | 英语 |
| WOS记录号 | WOS:001197526100001 |
| 源URL | [http://ir.gig.ac.cn/handle/344008/77227]  |
| 专题 | 同位素地球化学国家重点实验室 |
| 通讯作者 | Hao, Lu -Lu |
| 作者单位 | 1.CAS Ctr Excellence Deep Earth Sci, Guangzhou 510640, Peoples R China 2.Chinese Acad Sci, State Key Lab Isotope Geochem, Guangzhou Inst Geochem, Guangzhou 510640, Peoples R China 3.Australian Natl Univ, Res Sch Earth Sci, Canberra, ACT 2601, Australia 4.Univ CAS, Coll Earth & Planetary Sci, Beijing 100049, Peoples R China 5.Cardiff Univ, Sch Earth & Environm Sci, Cardiff CF10 3AT, Wales 6.Univ Sci & Technol China USTC, Sch Earth & Space Sci, CAS Key Lab Crust Mantle Mat & Environm, Hefei 230026, Peoples R China 7.USTC, CAS Ctr Excellence Comparat Planetol, Hefei 230026, Anhui, Peoples R China |
| 推荐引用方式 GB/T 7714 | Hao, Lu -Lu,Wang, Qiang,Kerr, Andrew C.,et al. Andesitic arc magmas derived from two contrasting melange origins: Evidence from central Tibetan dioritic porphyries[J]. CHEMICAL GEOLOGY,2024,650:10. |
| APA | Hao, Lu -Lu.,Wang, Qiang.,Kerr, Andrew C..,Huang, Fang.,Xiao, Ming.,...&Liu, Mao-Rui.(2024).Andesitic arc magmas derived from two contrasting melange origins: Evidence from central Tibetan dioritic porphyries.CHEMICAL GEOLOGY,650,10. |
| MLA | Hao, Lu -Lu,et al."Andesitic arc magmas derived from two contrasting melange origins: Evidence from central Tibetan dioritic porphyries".CHEMICAL GEOLOGY 650(2024):10. |
入库方式： OAI收割
来源：广州地球化学研究所
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