四川大水沟碲矿床成矿物质来源研究

四川大水沟碲矿床是世界首例独立碲矿床。通过对其进行矿床地质、常量与微量元素、矿物包裹体地质及稳定同位素测试分析研究 ,认为该矿床成矿物质具有多源性 ,且不同矿化期的成矿元素、成矿流体来源亦不相同 :主成矿期 Te主要源于地幔岩浆脱气 ,少量来源于基性岩或大理岩 ,S可能主要源于早期形成的磁黄铁矿 ,Bi可能与中酸性、基性岩浆有关 ;成矿流体主要为岩浆气液。     

激光原子法同位素分离中三维原子分布函数的计算

在激光同位素分离中 ,激光作用区内原子的密度和速度分布对分离过程有重要影响。目前 ,理论上对这个问题的研究还都限于二维情形。该文根据激光同位素分离装置中激光作用区原子密度较低的特点 ,在忽略原子碰撞的条件下给出了一种计算三维空间内原子速度分布函数的方法。利用该方法对小尺度蒸发实验进行计算所获得的结果在定性和定量上都与实验测量符合的很好。     

Carbon isotopic records in paleosols over the Pliocene in Northern China: Implication on vegetation development and Tibetan uplift

Carbon isotopic composition of pedogenic carbonate can be used to estimate the proportion of C₄ and C₃ plants. Here we present carbon isotopic data of carbonate in a red earth section at Xifeng, central Loess Plateau. Results show that C₄ vegetation increased in ∼4.4 Ma B.P., stabilized between 4.0 and 3.0 Ma B.P. The character and timing of C₄ expansion on the Loess Plateau are similar, but different with other localities, e.g. Pakistan and Africa, implying that regional climate changes were main factors driving the expansion of C₄ plants. This event is comparable in timing with increased aridity evidenced by Xifeng grain size and North Pacific eolian dust records. Therefore we argue that the Pliocene expansion of C₄ plants in northern China might have been caused by the increased aridity, which in turn might be related to rapid uplift of the Tibetan Plateau.     

Potash-rich volcanic rocks and lamprophyres in western Shandong Province: 40Ar39Ar dating and source tracing

Highly precise 40Ar39Ar dating results demonstrate that the ages of potash-rich volcanic rocks in western Shandong Province are 114.7-124.3 Ma, and that of the lamprophyres is 119.6 Ma. The potash-rich volcanic rocks have relatively high (87Sr/86Sr)i ratios ( 0.708715-0.711418)and distinctly negative εNd values ( -11.47 - -17.54), and are enriched in radiogenic lead (206Pb/204pb=17.341-17.622,207pb/204Pb=15.525-15.538, 208Pb/204pb = 37.563-37.684).Similarly, the lamprophyres also have quite low εNd values ( -11.57 - -19.64). Based on the fact that the Sr, Nd and Pb isotopic compositions of potash-rich volcanic rocks are very consistent with that of the clinopyroxene separates, and by integrating comprehensive analyses of their tectonic settings,and extensive comparisons of the Sr, Nd isotopic compositions with that of the related simultaneous rocks, it is concluded that the potash-rich volcanic rocks and lamprophyres in western Shandong Province were most possibly derived from the partial melting of enriched mantle which was caused by source contamination and metasomatism of subducted continental crustal materials.``     

Heterocyclization of compounds containing diazo and cyano groups. 6. Theoretical and experimental investigations of cyclization of 2-cyano-2-diazoacetamides to 5-hydroxy-1,2,3-triazole-4-carbonitriles

A series of N-alkyl- and N-aryl-2-cyano-2-diazoacetamides was synthesized by the reaction of 2-amino-2-cyanoacetamides with sodium nitrite in hydrochloric acid. The mechanism of their heteroclectrocyclization to 5-hydroxy-1,2,3-triazoles was investigated kinetically and theoretically by the B3LYP/6-31+G^* method. The conclusion was made on the basis of the determined activation energy of the cyclization process. reaction parameters , and kinetic isotope effects, that there is a difference between the mechanisms of cyclization of the N-alkyl and N-aryl derivatives of 2-cyano-2-diazoacetamide; cyclization of the N-alkyl derivatives takes place by a monorotatory mechanism, while cyclization of the N-aryl derivatives takes place by a mechanism where one of the stages is heteroelectrocyclization of 2-diazoacetimidates.For Communication 5, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 26–41, January, 2000.     

河台韧性剪切带型金矿床成矿作用地球化学研究

河台韧性剪切带型金矿床产于糜梭岩之中。石英中包裹体成分及氢、氧和碳同位素研究揭示,成矿流体为雨水和变质流体的混合体,富硫和碳,早期成矿流体主要为变质作用、混合岩化和花岗岩化作用过程中产生的变质流体,成矿晚期有大量雨水参与;流体成分以 K~ 、Na~ 、HCO_3~-、SO_4~=、CO、CO_2、CH_4和水为主.硫、铅同位素研究揭明,金等成矿物质来源于云开群上亚群.结合地层中金丰度和区域性金分布研究得出,在变质作用、混合岩化和花岗岩化作用过程中,矿源层中金发生明显活化转移,并在构造扩容带聚集成矿.     

龙门山地区泥盆纪锶、碳同位素与海平面变化

文章将龙门山地区泥盆系划分为四个沉积旋回,即四个地层层序,建立了该区泥盆纪海相碳酸盐锶、碳同位素地层曲线,并将同位素演化与沉积旋回结合起来研究该区泥盆纪的海平面变化。     

四川石棉大水沟碲矿床的同位素地质研究

石棉大水沟相矿是世界首例独立的破多金属矿床。矿体严格产于变质岩中，成矿作用在时间上与赋矿围岩经受的区域动热变质作用相一致。成矿输液的６Ｄ值为一６８．７％－一４１．６％，８＇勺值为２·６１‰～１１．９３‰，它最可能来源于变质水，是赋矿围岩在区域动热变质过程中发生的脱挥发反应形成的。Ｐｈ，Ｓｒ，Ｓ，Ｃ同位素研究表明，成矿物质具多来源特点，成矿组分是在区域动热变质的有利条件下，通过变质热液对围岩的浸取而它集成矿。     

福建平和大望山等铅、锌、银(金)矿床稳定同位素地球化学

对福建平和大望山等铅、锌、银(金)矿床的氧、氢、硫、铅稳定同位素分析测定结果,脉石矿物氧同位素δ~(18)O(‰)=+2.54～+10.05,其中包裹体氢同位素δD_(H_2O)(‰)=-46.6～-111.8矿石硫同位素δ~(34)Si(‰)=-3.60～+4.90,铅同位素~(206)Pb/~(204)Pb=18.3817～18.8747,~(207)Pb/~(204)Pb=15.5932～15.8328,~(206)Pb/~(204)Pb=38.5152～39.9802.据硫、铅同位素研究认为,矿质来自花岗闪长岩浆:氢、氧同位素研究认为,成矿溶液主要为演化的混合型初始岩浆水(MCIMW),局部有大气降水或演化的大气降水的混入,并讨论了水/岩作用以及矿床所在地区地质地球化学的某些特点。     

中国东部温泉水和井水的氢氧同位素初步研究

对安徽、山东、辽宁的几处温泉水和井水的氧和氢同位素进行了对比研究,发现温泉水的氧和氢同位素值都低于井水的氧和氢同位素值。温泉水和井水的氧和氢同位素值都落在大气降水线附近,与Craig所作的大气降水线较为吻合。这一结果说明该地区温泉水和井水的补给源都来自大气降水。温泉水的δ~(18)O值变化范围很小,说明δ~(18)O值可能受该地区地质构造控制。温泉水和井水氧和氢同位素值具有明显的纬度效应,它们的氧和氢同位素值随纬度的增大而增加。