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水在雪中下渗的数学模拟 被引量:20
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作者 周石硚 中尾正义 +1 位作者 桥本重将 成田英器 《水利学报》 EI CSCD 北大核心 2001年第1期6-10,共5页
对于融雪水在雪中下渗过程的模拟 ,虽然已有大量研究 ,但理论较多 ,模拟实例很少 ,边界条件一般也由资料外推而来 ,而且由于建模中某些参数的简化 ,使具体应用条件变得模糊 .本文在现有理论的基础上 ,利用全套实测资料对积雪表面融化和... 对于融雪水在雪中下渗过程的模拟 ,虽然已有大量研究 ,但理论较多 ,模拟实例很少 ,边界条件一般也由资料外推而来 ,而且由于建模中某些参数的简化 ,使具体应用条件变得模糊 .本文在现有理论的基础上 ,利用全套实测资料对积雪表面融化和融雪水下渗进行了全过程多日模拟 ,并对模拟结果进行了检验 .结果证明 ,该模型及其具体计算方法在当雪中水流流量大于 0 0 5cm3/cm2 /h时完全符合实际水流下渗过程 。 展开更多
关键词 积雪 融雪水 下渗 数学模拟
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东秦岭松树沟超镁铁质岩体地球化学和铂族元素特征:对成因的指示 被引量:8
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作者 刘军锋 孙卫东 +2 位作者 孙勇 孙亚莉 刘方杰 《地质论评》 CAS CSCD 北大核心 2008年第1期57-64,共8页
商南县松树沟超镁铁质岩体位于秦岭造山带商州—丹凤断裂以北,出露面积超过20km2,是中国境内出露最大的阿尔卑斯型橄榄岩体,并以侵位方式与秦岭杂岩接触。该岩体主要由细粒纯橄榄岩、中粗粒纯橄榄岩和方辉橄榄岩等组成。地球化学特征显... 商南县松树沟超镁铁质岩体位于秦岭造山带商州—丹凤断裂以北,出露面积超过20km2,是中国境内出露最大的阿尔卑斯型橄榄岩体,并以侵位方式与秦岭杂岩接触。该岩体主要由细粒纯橄榄岩、中粗粒纯橄榄岩和方辉橄榄岩等组成。地球化学特征显示明显亏损特征,同时不相容元素(从Rb到Nb)和LREE等元素相对HREE富集;纯橄榄岩的PGE含量明显低于方辉橄榄岩。与典型蛇绿岩的地幔橄榄岩对比研究,认为该岩体是经过熔体渗滤过程形成的纯橄榄岩体。 展开更多
关键词 超镁铁质岩体 地球化学 PGE 熔体渗滤 松树沟
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苏北盘石山、练山地幔捕虏体的PGE地球化学 被引量:5
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作者 杨雪英 孙亚莉 +1 位作者 孙卫东 徐夕生 《地球化学》 CAS CSCD 北大核心 2008年第3期197-205,共9页
通过锍镍火试金预富集法,分析了位于郯庐断裂带东侧的盘石山、练山地幔橄榄岩包体中铂族元素(PGE)和Au含量。不同于部分熔融残留成因地幔橄榄岩中通常所观察到的负斜率型或平坦型的分布模式,这两地的地幔橄榄岩以Pt、Pd、Ru相对富集,Ir... 通过锍镍火试金预富集法,分析了位于郯庐断裂带东侧的盘石山、练山地幔橄榄岩包体中铂族元素(PGE)和Au含量。不同于部分熔融残留成因地幔橄榄岩中通常所观察到的负斜率型或平坦型的分布模式,这两地的地幔橄榄岩以Pt、Pd、Ru相对富集,Ir、Rh相对亏损的"燕子型"分布模式为特征。Pt、Pd等不相容元素富集说明上地幔除经历过早期的部分熔融外,还经历了后期富Pt、Pd的高熔/岩比的熔(流)体的层析分离交代作用影响。盘石山地幔橄榄岩的PGE总量比练山高,Os的含量也比原始地幔值高;而练山地幔橄榄岩的Os含量比原始地幔值低,说明交代作用带走了练山地幔橄榄岩中的Os,却没有很大改变盘石山地幔橄榄岩中的Os含量,这可能与交代熔(流)体含硫量饱和程度有关。Rh的负异常可能与部分熔融过程中熔体较低的fO2有关。 展开更多
关键词 地幔橄榄岩 铂族元素 原始地幔 部分熔融 熔体渗滤
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内蒙古柯单山蛇绿岩地幔橄榄岩铂族元素(PGEs)的分布特征及分异机制探讨 被引量:4
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作者 李晖 刘庆 +3 位作者 侯泉林 徐辉煌 朱貌贤 曾桂华 《岩石学报》 SCIE EI CAS CSCD 北大核心 2011年第6期1759-1769,共11页
采用Carius管结合MC-ICPMS法分析了内蒙古柯单山蛇绿岩地幔橄榄岩中Ir、Ru、Pt和Pd的含量,与典型的地幔橄榄岩进行对比研究,发现柯单山地幔橄榄岩中Ir和Ru明显亏损,Pt和Pd强烈富集,具有极高的Pd/Ir值,PGEs地幔标准化配分模式具有较陡的... 采用Carius管结合MC-ICPMS法分析了内蒙古柯单山蛇绿岩地幔橄榄岩中Ir、Ru、Pt和Pd的含量,与典型的地幔橄榄岩进行对比研究,发现柯单山地幔橄榄岩中Ir和Ru明显亏损,Pt和Pd强烈富集,具有极高的Pd/Ir值,PGEs地幔标准化配分模式具有较陡的正斜率,明显不同于通常观测到的代表部分熔融残留相中铂族元素配分模式(负斜率或平坦型)。柯单山地幔橄榄岩的Ir和Ru与MgO呈正相关关系,表明Ir和Ru的亏损可能与部分熔融过程中硫化物的消耗程度有关,而与PGEs在硫化物/硅酸盐间的能斯特分配系数没有直接关系;Pt、Pd的富集表明本区的地幔橄榄岩不仅仅是经历过部分熔融的残余,而与来自深海的橄榄岩和大陆岩石圈地幔(SCLM)中的方辉橄榄岩相似,因此推测,本区地幔橄榄岩在部分熔融后又经历了富Pd的熔/流体交代,而熔/流体的来源可能是在岩浆分异演化过程中"熔离"出来的硫化物。 展开更多
关键词 铂族元素 柯单山蛇绿岩 地幔橄榄岩 部分熔融 熔/流体交代 硫化物
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Xenoliths Evidence of Alkaline Magmatic Infiltrations Beneath Lake Nyos (Cameroon Volcanic Line, West Africa)
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作者 Merlin Isidore Teitchou Joseph Legrand Tchop +4 位作者 Michel Grégoire Pauline Wokwenmendam Nguet Eddy Ferdinand Mbossi Jacques Dili-Rake Joseph Victor Hell 《Open Journal of Geology》 2022年第6期433-459,共27页
Xenoliths enclosed in Lavas of the Nyos volcano (Cameroon Volcanic Line, continental sector) range from fertile lherzolites to harzburgites. One spinel-free wehrlite has been also sampled. The occurrence of phlogopite... Xenoliths enclosed in Lavas of the Nyos volcano (Cameroon Volcanic Line, continental sector) range from fertile lherzolites to harzburgites. One spinel-free wehrlite has been also sampled. The occurrence of phlogopites and pargasites in some harzburgites together with specific textural rock-type (lherzolites transitional porphyroclastic to equigranular), including major and trace element compositions both in peridotites bulk rocks and minerals point out interactions between the mantle and basaltic magmas responsible for the formation of wehrlites beneath the Nyos volcano. Hydrous minerals (phlogopites and pargasites) and metasomatic events are their main petrogeochemical signatures different from group 1 samples which are characterized by spoon-shaped REE patterns. Later on, hydrous phases, Ti-rich Cpx, CaO rich Ol, Ti, and V rich Ol wehrlite precipitated from melt enrichments due to the percolation of the mantle by basaltic magmas of alkaline affinity. The metasomatic liquid which percolates the Nyos mantle column was a dense alkaline silicate rich in volatile, displaying low HFSE abundances in the metasomatic hydrous melts compared to the LILE. It is suggested that Nyos mantle peridotites have experienced: 1) variable metasomatic events related to the percolating of the depleted mantle by a alkaline silicate liquid, 2) the spinel-free wehrlite is a group 2 sample corresponding to a cumulate of a similar melt, 3) amphibole may be a potassium-bearing mineral instead of or in addition to phlogopite at shallower levels of Nyos upper mantle and 4) transitional textural rock facies express also the fingerprint of rising mantle plume which were percolated by alkaline magma during their transit to the surface. 展开更多
关键词 Nyos Wehrlites Hydrous Minerals Alkaline Silicate melt percolation
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Effects of melt percolation on the Re-Os systematics of continental mantle lithosphere: A case study of spinel peridotite xenoliths from Heilongjiang, NE China 被引量:1
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作者 YU SongYue SONG XieYan +2 位作者 XU YiGang CHEN LieMeng LI Jie 《Science China Earth Sciences》 SCIE EI CAS 2012年第6期949-965,共17页
Os isotope ratios of mantle peridotites have been considered to be largely immune to recent melt-rock interaction. However, Os isotope ratios and PGE (Platinum group elements) concentrations of the Yong'an xenolit... Os isotope ratios of mantle peridotites have been considered to be largely immune to recent melt-rock interaction. However, Os isotope ratios and PGE (Platinum group elements) concentrations of the Yong'an xenoliths have been significantly modified by melt percolation, and are not suitable for determining the formation age of lithosphere mantle in Yong'an. In this study, the Yong'an spinel peridotite xenoliths are divided into two groups: N-Type and E-Type. The N-Type group including cpx (clinopyroxene)-poor lherzolite and harzburgite, shows a large variation of Cr#(sp) (13.2-48) and sulfur contents (from 171 ppm to below detection limit), whereas the E-Type peridotites are mainly refractory harzburgites and are characterized by high Cr#(sp) (35.3-42.2) and overall low sulfur contents (below 51 ppm). Both types show similar major and REE (rare earth element) patterns. Furthermore, the N-Type peridotites display a restricted range of iridium-group PGE (IPGE), Os/Ir and Ru/Ir ratios (Os/Ir = 0.64-1.12, Ru/Ir = 1.52-1.79) and variable palladium-group PGE (PPGE) contents (3.4-14.9 ppb), whereas the E-Type peridotites show a large variation of Os/Ir and Ru/Ir ratios (Os/Ir = 0.33-0.84, Ru/Ir = 0.94-1.6), and a restricted range of PPGE (4.3-6.9 ppb). 187Os/188Os ratios of E-Type peridotites are higher than those of N-Type peridotites at comparable fertility levels. These results suggest that N-Type peridotites may have been overprinted by metasomatism via small melt fractions, in which the percolation of the volatile-rich, small melt fractions only resulted in LILE (large ion lithophile element) enrichment of clinopyroxene, and their whole rock PGE contents and Re-Os isotope values were little changed. Moreover, E-Type peridotites may have been modified by melt-rock reaction involving relatively large melt fractions, which may result in the formation of secondary cpx and olivine and the removal of IPGE-bearing minerals such as Ru-Os-(Ir) alloys or laurite, followed by precipitation of secondary sulfides from melt with 展开更多
关键词 PERIDOTITES highly siderophile element melt percolation sulfides NE China
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