检索结果-南通市图书馆

Geochemistry and Sr-Nd isotope characteristics of tonalites in Zêtang,Tibet:New evidence for intra-Tethyan subduction

引用

Science China Earth Sciences 2007年第6期50卷 836-846页

作者： WEI DongLiang XIA Bin ZHOU GuoQing YAN Jun WANG Ran ZHONG LiFeng Key Laboratory of Marginal Sea Geology Guangzhou Institute of GeochemistryChinese Academy of SciencesGuangzhou 510640China Graduate University of Chinese Academy of Sciences Beijing 100049China Department of Earth Sciences Nanjing UniversityNanjing 210093China

tonalites from the island arc rock assemblage in the Zêtang segment of the Yarlung Zangbo suture zone were analyzed for major,trace elements (including REE) and Sr-Nd isotope. The experimental data demonstrate that the tonalites have the adakite-like characteristics,including high SiO2 (58%―63%),Al2O3 (18.4%―22.4%),Sr (810×10 6―940×10 6),Sr/Y (77―106),low HREE (Y=9×10 6―11×10 6,Yb= 1×10 6―1.3×10 6),with LREE enrichment and faint Eu positive anomaly. ISr (0.70421―0.70487) is rela-tively low whereas 143Nd/144Nd (0.512896―0.512929) and εNd(t) values (+6.7―+7.3) are high. These fea-tures suggest that Zêtang tonalites were formed by the partial melting of subducted oceanic crust,with involvement of a small amount of oceanic sediments. The identification of Zêtang adakites,derived from slab melting,presents new evidence for the intra-Tethyan subduction and the previous sugges-tion about the existence of intra-oceanic island arc within Tethys.

关键词： adakite Zêtang tonalites subduction Yarlung Zangbo suture zone Tibet

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Recycled oceanic crust as a source for tonalite intrusions in the mantle section of the Khor Fakkan block, Semail ophiolite(UAE)

引用

Geoscience Frontiers 2019年第3期10卷 1187-1210页

作者： Hosung Joun Sotirios Kokkalas Stylianos Tombros Department of Earth Sciences Khalifa University Department of Geology University of Patras

Several types of felsic granitoid rocks have been recognized, intrusive in both the mantle and the crustal sequence of the Semail ophiolite. Several models have been proposed for the source of this suite of tonalites, granodiorites, trondhjemites intrusions, however their genesis is still not clearly *** sampled Dadnah tonalites that intruded in the mantle section of the Semail ophiolite display arctype geochemical characteristics, are high siliceous, low-potassic, metaluminous to weakly peraluminous, enriched in LILE, show positive peaks for Ba, Pb, Eu, negative troughs for U, Ti and occur with low δ^(18)O_(H_2 O), moderate ε_(Sr) and negative eNd values. They have crystallized at temperatures that range from～550 ℃ to ～720 ℃ and pressure ranging from 4.4 kbar to 6.5 kbar. The isotopic ages from our tonalite samples range between 98.6 Ma and 94.9 Ma, slightly older and overlapping with the age of the metamorphic sole. Our field observations, mineralogical, petrological, geochemical, isotopic and melt inclusion data suggest that the Dadnah tonalites formed by partial melting(～10%-15% continuous or ～12% batch partial melting), accumulation of plagioclase, fractional crystallization(～55%-57%), and interaction with their host harzburgites. These tonalites were the end result of partial melting and subsequent contamination and mixing of ～4% oceanic sediments with ～96% oceanic lithosphere from the subducted slab. This MORB-type slab melt composed from ～97% recycled oceanic crust and ～3% of the overlying *** suggest that a possible protolith for these tonalites was the basaltic lavas from the subducted oceanic slab that melted during the initial stages of the supra-subduction zone(SSZ), which was forming synchronously to the spreading ridge axis. The tonalite melts mildly modified due to low degree of mixing and interaction with the overlying lithospheric mantle. Subsequently, the Dadnah tonalites emplaced at the upper part of the mantle sequence of the Se

关键词： tonalites Felsic granitoids Recycled oceanic crust Source contribution Partial melting Melt inclusions

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：