Ultra-depleted peridotite xenoliths in the Northern Taihang Mountains: Implications for the nature of the lithospheric mantle beneath the North China Craton
Ultra-depleted peridotite xenoliths in the Northern Taihang Mountains: Implications for the nature of the lithospheric mantle beneath the North China Craton
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太行山北部超贫化橄榄岩捕虏体：对华北克拉通岩石圈地幔性质的启示
DOI：
10.1016/j.gr.2017.04.009
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发表时间：
2017-08
影响因子：
6.1
通讯作者：
Hu Bo
中科院分区：
文献类型：
--
作者：
Zhang Haidong;Liu Jianchao;Santosh M.;Tao Ni;Zhou Qunjun;Hu Bo
报道了华北中部北方太行山早白垩世龙门沟含橄榄岩闪长岩（138 Ma）中橄榄岩捕虏体的发现。根据橄榄石、单斜辉石、角闪石和钙长石的众数比例，这些橄榄岩捕虏体可分为含单斜辉石的橄榄石带（COZ）、橄榄石-单斜辉石带（OCZ）和含角闪石的钙长石-单斜辉石带（AACZ）。含单斜辉石橄榄石带中的橄榄石颗粒核具有较高的Mg#（>95）、SiO_2（41.80- 42.53wt.%）以及较低的CaO（95）和较低的NiO含量（<0.04重量%）含单斜辉石橄榄石带中的橄榄石来源于超亏损地幔，后经低Ni高Mg#熔体/岩浆蚀变。两代橄榄石颗粒出现在OCZ中，第一代显示出溶的钛铁矿和磁铁矿棒，含有高达0.35wt.% TiO 2，可能来自水化的石榴橄榄岩。第二代样品具有高Mg#（96.2-97.1）和碎裂结构，可能是COZ分解形成的。铝尖晶石的出现表明具有极高Al和Mg的熔体的作用。AACZ中的单斜辉石表现出系统的核-环成分变化，CaO和SiO2含量向环增加，MgO和Fe 2 O3含量从核向环减少，表明含角闪石的钙长石-单斜辉石带是地幔捕虏体与基性岩浆反应的产物。斜长石具有较高的An值（92.0-99.95，平均97.79），表明交代熔体具有较高的Ca/Na和Al/Si比值，可能是超亏损地幔在“湿”条件下部分熔融的产物。结合华北克拉通中发现的其他地幔捕虏体的资料，我们认为华北克拉通中部北太行山下中生代岩石圈地幔是由超亏损的太古代和古元古代橄榄岩和纯橄榄岩组成，并受到复杂熔体的改造。华北克拉通东部的破坏主要发生在早白垩世，岩石圈的破坏边界与太行山一致。
We report the finding of peridotite xenoliths in the Early Cretaceous Longmengou olivine-bearing diabase (138 Ma) in the Northern Taihang Mountains in the central North China Craton. Based on the modal proportions of olivine, clinopyroxene, amphibole and anorthite, these peridotite xenoliths can be divided into three zones: clinopyroxene-bearing olivine zone (COZ), olivine-clinopyroxene zone (OCZ), and amphibole-bearing anorthite-clinopyroxene zone (AACZ). The core of olivine grains in clinopyroxene-bearing olivine zone have higher Mg# (>95), SiO2 (41.80-42.53 wt.%) and lower CaO (95) and lower NiO content (<0.04 wt.%) in the clinopyroxene-bearing olivine zone was derived from ultra-depleted mantle subsequently altered by high Mg# melts/magma with low Ni. Two generations of olivine grains occur in the OCZ where the first generation shows exsolution of ilmenite and magnetite rods containing up to 0.35 wt.% TiO2, and was likely derived from garnet peridotite hydrated by water. The second generation shows high Mg# (96.2-97.1) and cataclastic texture, and was possibly formed by decomposition of the COZ. The occurrence of aluminous spinel suggests the role of melts with extremely high Al and Mg. Clinopyroxene in the AACZ shows systematic core-rim compositional variation with CaO and SiO2 contents increasing towards the rim, and MgO and Fe2O3 concentrations decreasing from the core to the rim, indicating that the amphibole-bearing anorthite-clinopyroxene zone is a product of the reaction between mantle xenoliths and mafic magma. Plagioclase with high An value (92.0-99.95, average 97.79) indicates that the metasomatic melts have high Ca/Na and Al/Si ratios, possibly produced by the partial melting of ultra-depleted mantle under “wet” conditions. Combined with the data on other mantle xenoliths discovered in the NCC, our results suggest that the Mesozoic lithospheric mantle beneath the North Taihang Mountains within the central NCC is composed of ultra-depleted Archean and Paleoproterozoic peridotites and dunites modified by complex melts. We also propose that the destruction of eastern part of the NCC mainly occurred during Early Cretaceous, and that the boundary of the lithospheric destruction coincides with the Taihang Mountains.
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影响因子：
6.1
作者：
Guochun Zhao;M. Zhai
通讯作者：
Guochun Zhao;M. Zhai
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影响因子：
3.3
作者：
Sheng-Rong Li, M. Santosh
通讯作者：
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影响因子：
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作者：
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通讯作者：
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影响因子：
3.8
作者：
Guochun Zhao;S. Wilde;Peter A. Cawood;M. Sun
通讯作者：
Guochun Zhao;S. Wilde;Peter A. Cawood;M. Sun
影响因子：
3.9
作者：
Wenliang Xu;De‐Bin Yang;Shan Gao;F. Pei;Yang Yu
通讯作者：
Wenliang Xu;De‐Bin Yang;Shan Gao;F. Pei;Yang Yu