Carbonated Big Mantle Wedge Extending to the NE Edge of the Stagnant Pacific Slab:Constraints from L

来源 :地球科学学刊(英文版) | 被引量 : 0次 | 上传用户:nienie123nie
下载到本地 , 更方便阅读
声明 : 本文档内容版权归属内容提供方 , 如果您对本文有版权争议 , 可与客服联系进行内容授权或下架
论文部分内容阅读
It has been suggested that the carbonated mantle reflected by Mg-Zn isotopic anomalies of Cenozoic intraplate basalts from East Asia coincides with the stagnant West Pacific slab in the man- tle transition zone. However, the northern boundary of such carbonated domain beneath East Asia is uncertain. Late Mesozoic-Cenozoic intraplate basalts are widespread in far eastern Russia and thus provide an opportunity to examine this issue. Here we report major-trace element contents and Sr-Nd- Mg-Zn isotopic compositions for 9 Late Mesozoic-Cenozoic basaltic samples from the Khanka Block and Sikhote-Alin accretionary complex. They are characterized by large variations in SiO2 contents (41 wt.% to 50 wt.%) and CaO/Al2O3 (0.50 to 0.97), enrichments of large-ion lithophile elements (LILE), positive Nb-Ta anomalies and strongly negative K, Pb, Zr, Hf, Ti, Y anomalies in primitive mantle-nor- malized trace element spider diagram. Furthermore, the rocks show good correlations of Ti/Ti* with Hf/Hf*, La/Yb, Fe/Mn and trace element contents (e. g., Nb). In addition, they have lighter Mg and heavier Zn isotope compositions than the BSE estimates, coupled with depleted Sr-Nd isotope composi- tions. These elemental and isotopic characteristics cannot be explained by alteration, magma differenti- ation or diffusion, but are consistent with the partial melting of carbonated peridotite. By and large, the Late Mesozoic-Cenozoic basalts from far eastern Russia bear very similar geochemical characteris- tics as those Na-series Cenozoic basalts from eastern China. The extended region of Mg-Zn isotopic anomalies is roughly coincident with the stagnant West Pacific slab beneath East Asia, and all of these alkali basalts can be generated from mantle sources hybridized by recycled Mg-carbonates from the Pacific slab stagnant in the mantle transition zone. We infer that (1) the carbonated big mantle wedge extends to the NE edge of the West Pacific slab and may have also appeared in the Late Mesozoic due to the effect of the Paleo-Pacific slab beneath this region, and (2) decarbonation of stagnant slabs in the mantle transition zone is a key mechanism for carbon outgassing from deep mantle to surface via intra- plate alkali melts.
其他文献
资源和环境约束对我国能源消费提出了严峻挑战.雾霾在一定程度上可以看做是终端能源消费结构性矛盾长期积累的集中爆发.本文借助K-means聚类、空间相关分析等方法,对30个省级单元的终端能源消费量的时空特征及其结构演变进行了系统研究.进一步,运用空间计量模型多角度探讨终端能源消费对环境污染的影响.研究发现:①从人均终端能源消费量来看,在研究时段内各省级单元均有不同程度提升,但省际差异依然显著.②从终端能源消费量来看,在研究时段内具有显著的空间正相关性,表明了空间集聚特征的存在,并形成了多种空间集聚类型.③从终
2021年12月18-19日,由中国行政区划与区域发展促进会*(以下简称促进会)主办,中国科学院地理科学与资源研究所(以下简称地理资源所)承办的“中国行政区划与区域发展促进会第三次会员代表大会暨2021年学术年会”,以线上腾讯会议的方式举行,来自国内外近百所教学科研机构的专家学者、学生及各界研究人员500余人线上参会.大会会期一天半,分为会员代表大会和2021年学术年会两大板块.
期刊
This work evaluates the use of femtosecond laser ablation multiple collector inductively coupled plasma mass spectrometry (fs-LA-MC-ICP-MS) for Zr isotopic analysis in zircons. The mass fractionation caused by instrumental mass discrimination was correcte
This study investigates the behavior of Mo and Mo isotopes (δ98Mo) in shales following leaching with HCl and HNO3 with the aim of simplifying the shale dissolution procedure. Up to 6%of the Mo was lost and the Mo isotopes were unaffected when shales were
Radiogenic uranium isotope disequilibrium (234U/238U) has been used to trace a variety of Earth surface processes, and is usually attributed to direct recoil of 234Th and preferential dissolution of radioactively damaged lattices at the mineral surface. H
The geochemical cycling of copper in the hydrosphere and soil environments primarily involves the transport of Cu from rocks to rivers via weathering. Understanding the factors controlling Cu isotope fractionation during weathering is crucial for the purp
The rate of net primary production in the Proterozoic ocean was suggested to be no more than 10%of its modern value (Laakso and Schrag, 2019), however, in the Mesoproterozoic Xiamaling Formation, the export production values could reach 20%-150%of the pre
The Niangzhong diabase dikes, dated at 138.1 ± 0.4 Ma, are located within the outcrop area of the Comei large igneous province (LIP). These diabase samples can be divided into two groups:samples in Group 1 show varying MgO (1.50 wt.%-10.25 wt.%) and TiO2
The loess depositions in Shandong Province are important parts of loess records in east- ern China, but their origin and genetic linkage between the Yellow River and the Chinese Loess Plateau are still unclear. This paper presents the detrital-zircon evid
Emeishan large igneous province (ELIP), one of the largest continental volcanic provinc-es worldwide (e. g., Karoo), is extensively distributed along the western margin of the Yangtze Block. Even though the consensus that the ELIP is of a plume-related or