Changes in dip of subducted slabs at depth: Petrological and geochronological evidence from HP-UHP rocks (Tianshan, NW-China)
文献类型：期刊论文
| 作者 | Klemd, R.1; John, T.2; Scherer, E. E.2; Rondenay, S.3,4; Gao, J.5 |
| 刊名 | EARTH AND PLANETARY SCIENCE LETTERS
 |
| 出版日期 | 2011-10-01 |
| 卷号 | 310期号:1-2页码:9-20 |
| 关键词 | Subduction Slab Dip Steepening Oceanic Crust Lu-hf Geochronology (u)Hp Rocks Tianshan |
| ISSN号 | 0012-821X |
| DOI | 10.1016/j.epsl.2011.07.022 |
| 文献子类 | Article |
| 英文摘要 | High-resolution seismic imaging has previously revealed sudden changes in the dip of subducted oceanic plates. This 'kinking' feature is crucial because in many subduction zones it is thought to coincide with the disappearance of the low-velocity layers associated with subducted oceanic crust. In this study, we present petrological evidence for this phenomenon derived from oceanic blueschist- and eclogite-facies rocks from the Chinese Tianshan. The investigated samples span a large range of peak metamorphic conditions, with temperatures between 330 and 580 degrees C at 1.5 to 23 GPa. Such variable peak metamorphic conditions, together with the intimate interlayering of high- and ultrahigh-pressure rocks, have also been reported from other Tianshan localities. These observations suggest that the rocks were derived from varying depths within the subduction zone and then juxtaposed during exhumation in the subduction channel. Multi-point Lu-Hf isochrons from four high-pressure rocks yield consistent garnet-growth ages of 313 +/- 12, 315.8 +/- 2.9, 313.9 +/- 4.8, and 315.2 +/- 1.6 Ma. These, in conjunction with the similar to 311 Ma cluster of published Ar-40-Ar-39 and Rb-Sr white mica ages from the same vicinities imply fast exhumation rates. The Lu-Hf ages confirm that the eclogite-facies metamorphism of the Tianshan high-pressure rocks occurred during a single subduction event in the Late Carboniferous. However, the previously reported peak metamorphic P-Testimates from UHP metasediments and eclogites all lie on a lower geothermal gradient - and thus on a colder P-T path at the slab-wedge interface - than the HP eclogites and meta-volcaniclastic rocks from this study. This suggests that the slab-subduction angle steepened sharply at a depth greater than approximately 90 km, i.e., between the depths at which the HP and UHP rocks equilibrated. In addition to the negative buoyancy of mafic UHP rocks in subduction zones, the kinking may act as a geometric hindrance to the exhumation of such rocks, thereby explaining their rarity. (C) 2011 Elsevier B.V. All rights reserved. |
| WOS关键词 | PRESSURE/LOW-TEMPERATURE ROCKS ; TRACE-ELEMENT MOBILIZATION ; P-T PATH ; WESTERN TIANSHAN ; SOUTH TIANSHAN ; LU-HF ; PROGRADE METAMORPHISM ; TECTONIC IMPLICATIONS ; NORTHWESTERN CHINA ; ECLOGITIC ROCKS |
| WOS研究方向 | Geochemistry & Geophysics |
| 语种 | 英语 |
| WOS记录号 | WOS:000297493100002 |
| 出版者 | ELSEVIER SCIENCE BV |
| 资助机构 | Deutsche Forschungsgemeinschaft(KL 17-1 ; Deutsche Forschungsgemeinschaft(KL 17-1 ; National Basic Research program of China(2007CB411302 ; National Basic Research program of China(2007CB411302 ; NSF(Continental Dynamics EAR-0409373 ; NSF(Continental Dynamics EAR-0409373 ; KL 17-2 ; KL 17-2 ; 2001CB409803) ; 2001CB409803) ; Earthscope EAR-0544996) ; Earthscope EAR-0544996) ; KL 17-3) ; KL 17-3) ; Deutsche Forschungsgemeinschaft(KL 17-1 ; Deutsche Forschungsgemeinschaft(KL 17-1 ; National Basic Research program of China(2007CB411302 ; National Basic Research program of China(2007CB411302 ; NSF(Continental Dynamics EAR-0409373 ; NSF(Continental Dynamics EAR-0409373 ; KL 17-2 ; KL 17-2 ; 2001CB409803) ; 2001CB409803) ; Earthscope EAR-0544996) ; Earthscope EAR-0544996) ; KL 17-3) ; KL 17-3) ; Deutsche Forschungsgemeinschaft(KL 17-1 ; Deutsche Forschungsgemeinschaft(KL 17-1 ; National Basic Research program of China(2007CB411302 ; National Basic Research program of China(2007CB411302 ; NSF(Continental Dynamics EAR-0409373 ; NSF(Continental Dynamics EAR-0409373 ; KL 17-2 ; KL 17-2 ; 2001CB409803) ; 2001CB409803) ; Earthscope EAR-0544996) ; Earthscope EAR-0544996) ; KL 17-3) ; KL 17-3) ; Deutsche Forschungsgemeinschaft(KL 17-1 ; Deutsche Forschungsgemeinschaft(KL 17-1 ; National Basic Research program of China(2007CB411302 ; National Basic Research program of China(2007CB411302 ; NSF(Continental Dynamics EAR-0409373 ; NSF(Continental Dynamics EAR-0409373 ; KL 17-2 ; KL 17-2 ; 2001CB409803) ; 2001CB409803) ; Earthscope EAR-0544996) ; Earthscope EAR-0544996) ; KL 17-3) ; KL 17-3) |
| 源URL | [http://ir.iggcas.ac.cn/handle/132A11/73532]  |
| 专题 | 中国科学院地质与地球物理研究所 |
| 通讯作者 | Klemd, R. |
| 作者单位 | 1.Univ Erlangen Nurnberg, GeoZentrum Nordbayern, D-91054 Erlangen, Germany 2.Univ Munster, Inst Mineral, D-48149 Munster, Germany 3.Univ Bergen, Dept Earth Sci, N-5007 Bergen, Norway 4.MIT, Dept Earth Atmospher & Planetary Sci, Cambridge, MA 02139 USA 5.Chinese Acad Sci, Inst Geol & Geophys, Beijing, Peoples R China |
| 推荐引用方式 GB/T 7714 | Klemd, R.,John, T.,Scherer, E. E.,et al. Changes in dip of subducted slabs at depth: Petrological and geochronological evidence from HP-UHP rocks (Tianshan, NW-China)[J]. EARTH AND PLANETARY SCIENCE LETTERS,2011,310(1-2):9-20. |
| APA | Klemd, R.,John, T.,Scherer, E. E.,Rondenay, S.,&Gao, J..(2011).Changes in dip of subducted slabs at depth: Petrological and geochronological evidence from HP-UHP rocks (Tianshan, NW-China).EARTH AND PLANETARY SCIENCE LETTERS,310(1-2),9-20. |
| MLA | Klemd, R.,et al."Changes in dip of subducted slabs at depth: Petrological and geochronological evidence from HP-UHP rocks (Tianshan, NW-China)".EARTH AND PLANETARY SCIENCE LETTERS 310.1-2(2011):9-20. |
入库方式： OAI收割
来源：地质与地球物理研究所
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