Ultra-magnesian olivine-bearing ultramafic lava blocks within Cenozoic accretionary sediments at Shizuoka, Japan: Implications for young, hot plume activity beneath the western Pacific Plate
Ultra-magnesian olivine-bearing ultramafic lava blocks within Cenozoic accretionary sediments at Shizuoka, Japan: Implications for young, hot plume activity beneath the western Pacific Plate
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日本静冈新生代增生沉积物中的超镁橄榄石超镁铁熔岩块：对西太平洋板块下方年轻热羽流活动的影响
DOI：
10.1016/j.lithos.2018.11.009
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发表时间：
2019
期刊：
影响因子：
3.5
通讯作者：
Hokanishi N. and Yamamoto J.
中科院分区：
文献类型：
--
作者：
Nakamura Y.;Ishibashi H.;Yasuda A.;Hokanishi N. and Yamamoto J.
超镁质火成岩橄榄石被认为是从超镁铁质熔体中结晶出来的，因此可以提供有关物理化学条件以及在极热地幔活动背景下源区的地球化学和岩性的信息。本文研究了日本静冈地区中始新世-早中新世增生沉积物中的一系列超镁橄榄石超镁铁质熔岩块体--静冈镁云母岩的岩石学和矿物学特征。在静冈Meimechites橄榄石斑晶具有约的Fo组成。81-92.8摩尔%，其中Fo = 100 Mg/（Mg + Fe）。这些超镁橄榄石的微量元素组合物，是来自超镁铁熔体，橄榄岩地幔橄榄石平衡的指示。橄榄石中铝的地质测温法得出Fo92.5- 92.8橄榄石的结晶温度约为1450 °C，高于现今洋中脊玄武岩源地幔物质的潜在温度，与一些大型火成岩省和洋岛玄武岩的潜在温度相似。利用超镁铁质熔岩的全岩成分估算了与Fo92.5- 92.8橄榄石平衡的初始熔体成分，为变质熔岩，MgO浓度约为21.4-27.0 wt%，SiO2浓度为45.4-44.5 wt%。这些镁云母源区的潜在温度（Tp）估计为~1486 °C-1705 °C，这与考虑岩浆上升过程中绝热冷却时的橄榄石中铝地质测温法相一致。TP和铝的橄榄石温度估计这些熔岩之间的关系是一致的全球性的例子超镁橄榄石轴承熔岩。这些熔岩提供了迄今未知的晚白垩世-早中新世深部地幔活动在西太平洋地区的证据。
Ultra-magnesian igneous olivine is thought to crystallize from ultramafic melts and can therefore provide information about physicochemical conditions and the geochemistry and lithology of the source in the context of extremely hot mantle activity. This study focuses on the petrology and mineralogy of the Shizuoka meimechites, a series of ultra-magnesian olivine-bearing ultramafic lava blocks embedded in middle Eocene–early Miocene accretionary sediments at Shizuoka, Japan. Olivine phenocrysts within the Shizuoka meimechites have Fo compositions of ca. 81–92.8 mol%, where Fo = 100 Mg/(Mg + Fe). These ultra-magnesian olivines have trace-element compositions that are indicative of derivation from ultramafic melts that were in equilibrium with peridotitic mantle olivine. Al-in-olivine geothermometry yielded crystallization temperatures of ~1450 °C for Fo92.5–92.8olivine, higher than the potential temperature of present-day mid-ocean ridge basalt source mantle material and similar to the potential temperatures of some large igneous provinces and ocean island basalts. Primary melt compositions in equilibrium with Fo92.5–92.8olivine were estimated using the whole-rock compositions of the ultramafic lavas and are meimechitic, with MgO concentrations of ~21.4–27.0 wt% and SiO2concentrations of 45.4–44.5 wt%. The potential temperature of the source mantle region for these meimechites (Tp) is estimated to be ~1486 °C–1705 °C, which is consistent with the Al-in-olivine geothermometry when considering adiabatic cooling during magma ascent. The relationship between Tpand Al-in-olivine temperature estimates for these lavas is consistent with global examples of ultra-magnesian olivine-bearing lavas. These lavas provide evidence of hitherto unknown Late Cretaceous–early Miocene deep mantle activity beneath the western Pacific region.
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影响因子：
3.5
作者：
I. Zhukova;H. O’Neill;I. Campbell
通讯作者：
I. Zhukova;H. O’Neill;I. Campbell
卡鲁大型火成岩省南极延伸部分存在极镁亚碱性熔体的矿物化学证据
影响因子：
1.8
作者：
J. Heinonen;A. Luttinen
通讯作者：
A. Luttinen
DOI：
--
发表时间：
2011
期刊：
影响因子：
--
作者：
J. Keiding;R. Trumbull;I. Veksler;D. Jerram
通讯作者：
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DOI：
--
发表时间：
2005
期刊：
影响因子：
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作者：
J. Yamamoto;P. Burnard
通讯作者：
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影响因子：
3.1
作者：
J. Kimura;T. Miyazaki;Q. Chang;B. Vaglarov;R. Senda
通讯作者：
R. Senda