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基底岩系和花岗岩类Pb-Nd同位素组成限制祁连山带的构造属性 被引量:30
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作者 张宏飞 靳兰兰 +3 位作者 张利 袁洪林 周炼 张本仁 《地球科学(中国地质大学学报)》 EI CAS CSCD 北大核心 2006年第1期57-65,共9页
对扬子陆块的西北部边界至今尚未得到有效的限定.中央山系西段祁连山带基底岩系和花岗岩类的Pb-Nd同位素组成为限定扬子陆块的西北边界提供限制.祁连山带前寒武纪基底岩系的Nd同位素亏损地幔模式年龄(TDM)主要分布于 0.75-2.5 Ga之... 对扬子陆块的西北部边界至今尚未得到有效的限定.中央山系西段祁连山带基底岩系和花岗岩类的Pb-Nd同位素组成为限定扬子陆块的西北边界提供限制.祁连山带前寒武纪基底岩系的Nd同位素亏损地幔模式年龄(TDM)主要分布于 0.75-2.5 Ga之间,峰值为2.1 Ga左右;该带古生代花岗岩类的TDM变化于1.07-2.14 Ga之间.由此表明,祁连山带地壳增长主要发生于元古宙,缺乏太古宙地壳增长的信息.祁连山带前寒武纪基底和花岗岩类全岩均以高放射成因的铅同位素组成为特征,极大多数样品的206Pb/204Pb>18.0,207Pb/204Pb>15.5,208Pb/204Pb>38.0.因此,祁连山带地壳增长特征和铅同位素组成特征与华北陆块存在明显的差异,而与扬子陆块一致,从而表明祁连山带具有扬子型陆块的构造属性.因此,扬子陆块的西北部边界扩大至祁连山带的北侧.自新元古代以来,祁连山带经历了岩石圈裂解作用,并有洋盆形成,但这些构造事件均发生在扬子型陆块内部的地质背景. 展开更多
关键词 祁连山 基底岩系 花岗岩类 pb-nd同位素 构造属性
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控制北太平洋深水中Pb、Nd同位素演化的不同因素
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作者 凌洪飞 蒋少涌 +4 位作者 M.Frank 周怀阳 周枫 陆尊礼 陈小明 《地球学报》 EI CAS CSCD 北大核心 2005年第B09期198-198,共1页
近年研究表明,大洋中溶解的Pb和Nd以陆源来源占主导。但对Pb和Nd进入大洋的途径存在很大争议。笔者研究了3块中北太平洋铁锰结壳(CJ01,CLD01,CB12)的元素含量和Pb、Nd同位素组成。根据Co含量经验公式法定年,结合几块结壳的剖面Pb... 近年研究表明,大洋中溶解的Pb和Nd以陆源来源占主导。但对Pb和Nd进入大洋的途径存在很大争议。笔者研究了3块中北太平洋铁锰结壳(CJ01,CLD01,CB12)的元素含量和Pb、Nd同位素组成。根据Co含量经验公式法定年,结合几块结壳的剖面Pb同位素演化曲线与Os同位素演化曲线,确定所研究的中北太平洋铁锰结壳的底部年龄约为75Ma。3块结壳不论磷酸盐化与否,其Pb、Nd同位素随时间的演变曲线均十分相似,且Pb同位素演化趋势与北太平洋岩心(LL44-GPC3)中的风沙的Pb同位素演化趋势相似。这些结壳的Nd同位素演化趋势也相似,但与岩心LL44-GPC3中风沙的Nd同位素的演化曲线完全不同。由此得到以下结论: 展开更多
关键词 pb-nd同位素演化 Fe-Mn结壳 北太平洋 PB同位素 ND同位素 同位素演化 铁锰结壳 深水 控制 演化趋势
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Petrology,Geochemistry and Nd-Sr-Pb Isotopic Properties of Volcanic Rocks in Daheishan Island,Penglai,Shandong Province 被引量:3
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作者 傅永涛 李安春 《Marine Science Bulletin》 CAS 2003年第2期29-39,共11页
The major elements, trace elements. K-Ar age and Sr-Nd-Pb isotopie systems ofthe Cenozoic volcanic rocks in Daheishan Island and Cishan, Penglai, Shandong Province aremeasured. The volcanic rocks ( olivine-nephelinite... The major elements, trace elements. K-Ar age and Sr-Nd-Pb isotopie systems ofthe Cenozoic volcanic rocks in Daheishan Island and Cishan, Penglai, Shandong Province aremeasured. The volcanic rocks ( olivine-nephelinite and nephcline-basanite ) in Daheishan Islanderupted periodically in an interval of 0.32 Ma, from 8.72 Ma. 8.39 Ma. 8.08 Ma to 7.73 Ma. Thevolcanic rocks arc all rich in light REEs. They are similar to the OIB-type alkali basalt in thetrace elements normalized model by primordial mantle: rich in high field elements such as Nb and Ta,and imcompatible elements such as Cs. Rb, Ba, Th. U. The volcanic rocks show a depletion of K andRb elements. It is suggested by the trace elements that the olivine-nephelinite in Daheishan Islandis originated from deep resources under the continental mantle. ε Nd (0) values of the volcanicrocks in Daheishan Island and Cishan are 5.31~8.51 and 7.33 respectively, suggesting that thevolcanic rocks are from the depleted mantle resources, which have higher Sm/Nd ratios than the CHUR.^(143)Nd /^(144)Nd ratios ot Daheishan Island olivine-nephelinite and Cishan alkali basalts are0.512 910~0.513 074 and 0.513 014 respectively. The ^(87)Sr /^(86)Sr of Daheishan Island volcanicrocks are lower than that of Cishan, 0.703 427 ~0.703 482 and 0.703 895 respectively. The DaheishanIsland olivine-nephelinite has the Pb isotopie values as follows: ^(206)Pb/^(204)Pb= 18.028 9~17.972 8. ^(207)Pb / ^(204)Pb = 15.435 8 ~15.402 2 and ^(208)Pb /^(204)Pb = 38.087 6~37.997 5.lower than those of Cishan basanite. The Cishan basanite has ^(206)Pb/^(204)Pb= 18.240 1. ^(207)Pb/^(204)Pb= 15.564 5 and ^(208)Pb /^(204)Pb = 38.535. The authors suggest that theolivine-nephelinite in Daheishan Island is similar to the E-type MORB or Hawaii OIB, and the alkalibasalts in Cishan similar to the Kerguelen OIB. The dominant mantle components of DM+PREMA andperhaps DM ( Dupal type ) are the dominant mantle components for volcanic rocks in Daheishan Islandand Cishan. The PREMA component plays an important role. 展开更多
关键词 daheishan island penglai cenozoic volcanic rocks K-ar age DM PREMA
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Zircon U-Pb age,geochemical and Nd isotopic data of Middle Jurassic high-Mg dioritic dike in Liaodong Peninsula,NE China 被引量:3
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作者 LI Zhuang PEI Fuping MENG En 《Global Geology》 2014年第3期143-154,共12页
Zircon LA-ICP-MS U-Pb age, geochemical and Nd isotopic data are presented for a newly recognized high-Mg dioritic dike from Haicheng, Liaodong Peninsula, NE China, to constrain its petrogenesis. The zircons from the h... Zircon LA-ICP-MS U-Pb age, geochemical and Nd isotopic data are presented for a newly recognized high-Mg dioritic dike from Haicheng, Liaodong Peninsula, NE China, to constrain its petrogenesis. The zircons from the high-Mg diorite exhibit striped absorption and oscillatory growth zoning in the cathodoluminescence (CL) images, and have high Th/U ratios (0. 05-0.9), indicating a magma origin. Zircon LA-ICP-MS U-Pb dating indicates that 206pb/238U ages of 12 spots of zircons are between 167 Ma and 178 Ma, yielding a weighted mean 206pb/238U age of 172 + 2 Ma (MSWD =4. 1 ), which represents the forming age of the high-Mg dioritic dike, i. e. Middle Jurassic. Geochemically, the samples have SiO2 =55.4-60. 6 wt. % , Na20 =2. 2-2.76 wt. % , K20 = 1.32-2. 02 wt. % and (Na2O + K2O) =3.82--4. 47 wt. %, belonging to sub-alkaline series and displaying a calc-alkaline evolutionary trend. They are characterized by high MgO (4. 75-6.85 wt. % ), Mg# (55-61), Cr(130-262 ppm), Ni(63-130 ppm), Sr(568-857 ppm), and Ba(484-1 130 ppm) contents, with geochemical features analogous to those of high-Mg adakites. They show variable end (t) values ( - 1.3 to - 3.9) , with a weighted value of - 2. 7, which plot intermediately between the field of the ancient continental crust and the depleted mantle source, indicating that both the lower crust and mantle source are necessary for the generation of the parent magma of the Haicheng high-Mg diorites. The Haicheng high-Mg dioritic dike in the Liaodong Peninsula and the Jurassic magmatism in the eastern North China Craton formed under a continental crustal thickening setting that may be related to subduction of the Paleo-Pacific oceanic plate. 展开更多
关键词 Liaodong Peninsula high-Mg diorite zircon U-Pb age GEOCHEMICAL Nd isotope
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Zircon SHRIMP U-Pb age, geochemical, Sr-Nd isotopic, and in-situ Hf isotopic data of the Late Carboniferous-Early Permian plutons in the northern margin of the North China Craton 被引量:27
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作者 MA Xu CHEN Bin +1 位作者 CHEN JiaFu NIU XiaoLu 《Science China Earth Sciences》 SCIE EI CAS 2013年第1期126-144,共19页
The main rock types of the Boluonuo and Daguangding plutons are diorite, quartz diorite, tonalite, granodiorite, and subordi- nate plagioclase-bearing hornblendite and hornblende gabbro. Zircon SHRIMP U-Pb dating for ... The main rock types of the Boluonuo and Daguangding plutons are diorite, quartz diorite, tonalite, granodiorite, and subordi- nate plagioclase-bearing hornblendite and hornblende gabbro. Zircon SHRIMP U-Pb dating for a quartz diorite of the Boluo- nuo pluton suggests that the pluton was emplaced at about 296 ± 4 Ma. Plagioclase-bearing hornblendites show typical cumu- lative textures, which, in combination with their convex-upward REE patterns and the large variation of compatible elements such as Co, V and Sc, suggests that these hornblendites formed through accumulation of hornblende during magma evolution. Microgranular mafic enclaves (MMEs) are common in the Boluonuo and Daguangding intermediate to felsic plutons. Many plagioclase grains show compositional and textural disequilibrium, with calcium-rich cores (An46-50) mantled abruptly by sodium-rich plagioclase (An26-33). Whole-rock samples of the plutons are characterized by quite negative εNd(t) values (-16.5 to -11.8) and εNt(t) values (-22.5 to -16.8), and the εNd(t) values are negatively correlated with silica contents. All these fea- tures suggest that the intermediate to felsic plutons formed through magma mixing of enriched mantle-derived, evolved basal- tic magma with granitic, crustal melts, followed by fractional crystallization of mainly hornblende and small amounts of py- roxene, apatite and zircon. The hornblende-dominated fractionation contributed significantly to the adakite-like features of the intermediate to felsic plutons, like the high Sr and Sr/Y ratios and low Yb abundance. In addition, the Boluonuo and Daguang- ding plutons are highly enriched in LILEs (e.g., Ba and Sr), but depleted in HFSEs (e.g., Nb, Zr and Ti), which is typical of arc magmas. Therefore, the formation of Boluonuo and Daguangding plutons was probably related to the subduction of the Paleo-Asian oceanic slab beneath the North China Craton in the Paleozoic. 展开更多
关键词 Late Paleozoic Andean-type continental arc Sr-Nd-Hf isotopes magma mixing fractionation of hornblende
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