Volatile-rich Metasomatism in the Cratonic Mantle beneath SW Greenland: Link to Kimberlites and Mid-lithospheric Discontinuities
文献类型：期刊论文
| 作者 | Aulbach, Sonja1; Sun, Jing1,2; Tappe, Sebastian3; Hoefer, Heidi E.1; Gerdes, Axel1 |
| 刊名 | JOURNAL OF PETROLOGY
 |
| 出版日期 | 2017-12-01 |
| 卷号 | 58期号:12页码:2311-2338 |
| 关键词 | mantle peridotite xenoliths trace element partitioning small-volume melts spinel-garnet peridotite transition |
| ISSN号 | 0022-3530 |
| DOI | 10.1093/petrology/egy009 |
| 文献子类 | Article |
| 英文摘要 | The cratonic part of Greenland has been a hotspot of scientific investigation since the discovery of some of the oldest crust on Earth and of significant diamond potential in the underlying lithospheric mantle, the characterization of which remains, however, incomplete. We applied a detailed petrographic and in situ analytical approach to a new suite of fresh kimberlite-borne peridotite xenoliths, recovered from the North Atlantic craton in SW Greenland, to unravel the timing and nature of mantle metasomatism, and its link to the formation of low-volume melts (e.g. kimberlites) and to geophysically detectible discontinuities. Two types of mineralogies and metasomatic styles, occurring at two depth intervals, are recognized. The first type comprises lherzolites, harzburgites and dunites, some phlogopite-bearing, which occur from similar to 100-170 km depth. They form continuous trends towards lower mineral Mg# at increasing TiO2, MnO and Na2O and decreasing NiO contents. These systematics are ascribed to metasomatism by a hydrous silicate melt precursor to c. 150 Ma kimberlites, in the course of rifting, decompression and lithosphere thinning. This metasomatism was accompanied by progressive garnet breakdown, texturally evident by pyroxene-spinel assemblages occupying former coarse grains and compositionally evident by increasing concentrations of elements that are compatible in garnet (Y, Sc, In, heavy rare earth elements) in newly formed clinopyroxene. Concomitant sulphide saturation is indicated by depletion in Cu, Ni and Co. The residual, more silica-undersaturated and potentially more oxidizing melts percolated upwards and metasomatized the shallower lithospheric mantle, which is composed of phlogopite-bearing, texturally equilibrated peridotites, including wehrlites, showing evidence for recent pyroxene-breakdown. This is the second type of lithology, which occurs at similar to 90-110 km depth and is inferred to have highly depleted protoliths. This type is compositionally distinct from lherzolites, with olivine having higher Ca/Al, but lower Al and V contents. Whereas low Al may in part reflect lower equilibration temperatures, low V is ascribed to a combination of intrinsically more oxidizing mantle at lower pressure and oxidative metasomatism. The intense metasomatism in the shallow cratonic mantle lithosphere contrasts with the strong depletion recorded in the northwestern part of the craton, which at 590-550 Ma extended to >210 km depth, and suggests loss of, similar to 40 km of lithospheric mantle, also recorded in the progressive shallowing of magma sources during the breakup of the North Atlantic craton. The concentration of phlogopite-rich lithologies in a narrow depth interval (similar to 90-110 km) overlaps with a negative seismic velocity gradient that is interpreted as a mid-lithospheric discontinuity beneath western Greenland. This is suggested to be a manifestation of small-volume volatile-rich magmatism, which paved the way for Mesozoic kimberlite, ultramafic lamprophyre, and carbonatite emplacement across the North Atlantic craton. |
| WOS关键词 | NORTH-ATLANTIC CRATON ; SPINEL HARZBURGITE XENOLITHS ; TRACE-ELEMENT COMPOSITIONS ; UDACHNAYA-EAST KIMBERLITE ; PLATINUM-GROUP ELEMENT ; WEST GREENLAND ; PERIDOTITE XENOLITHS ; CARBONATITE METASOMATISM ; SIBERIAN CRATON ; OXYGEN FUGACITY |
| WOS研究方向 | Geochemistry & Geophysics |
| 语种 | 英语 |
| WOS记录号 | WOS:000430736700001 |
| 出版者 | OXFORD UNIV PRESS |
| 资助机构 | German Research Foundation (DFG)(GE1152/9) ; German Research Foundation (DFG)(GE1152/9) ; CIMERA DST-NRF Centre of Excellence, South Africa ; CIMERA DST-NRF Centre of Excellence, South Africa ; German Research Foundation (DFG)(GE1152/9) ; German Research Foundation (DFG)(GE1152/9) ; CIMERA DST-NRF Centre of Excellence, South Africa ; CIMERA DST-NRF Centre of Excellence, South Africa ; German Research Foundation (DFG)(GE1152/9) ; German Research Foundation (DFG)(GE1152/9) ; CIMERA DST-NRF Centre of Excellence, South Africa ; CIMERA DST-NRF Centre of Excellence, South Africa ; German Research Foundation (DFG)(GE1152/9) ; German Research Foundation (DFG)(GE1152/9) ; CIMERA DST-NRF Centre of Excellence, South Africa ; CIMERA DST-NRF Centre of Excellence, South Africa |
| 源URL | [http://ir.iggcas.ac.cn/handle/132A11/88279]  |
| 专题 | 地质与地球物理研究所_岩石圈演化国家重点实验室 |
| 通讯作者 | Aulbach, Sonja |
| 作者单位 | 1.Goethe Univ, Inst Geowissensch, Altenhoferallee 1, D-60438 Frankfurt, Germany 2.Chinese Acad Sci, Inst Geol & Geophys, State Key Lab Lithospher Evolut, Beijing 100029, Peoples R China 3.Univ Johannesburg, Dept Geol, POB 524, ZA-2006 Auckland Pk, South Africa |
| 推荐引用方式 GB/T 7714 | Aulbach, Sonja,Sun, Jing,Tappe, Sebastian,et al. Volatile-rich Metasomatism in the Cratonic Mantle beneath SW Greenland: Link to Kimberlites and Mid-lithospheric Discontinuities[J]. JOURNAL OF PETROLOGY,2017,58(12):2311-2338. |
| APA | Aulbach, Sonja,Sun, Jing,Tappe, Sebastian,Hoefer, Heidi E.,&Gerdes, Axel.(2017).Volatile-rich Metasomatism in the Cratonic Mantle beneath SW Greenland: Link to Kimberlites and Mid-lithospheric Discontinuities.JOURNAL OF PETROLOGY,58(12),2311-2338. |
| MLA | Aulbach, Sonja,et al."Volatile-rich Metasomatism in the Cratonic Mantle beneath SW Greenland: Link to Kimberlites and Mid-lithospheric Discontinuities".JOURNAL OF PETROLOGY 58.12(2017):2311-2338. |
入库方式： OAI收割
来源：地质与地球物理研究所
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