Geochemistry of re and trace elements in ferromanganese nodules and their genesis

Trace and RE element geochemistry and genesis have been studied with respect to ferromanganese nodules from the sediments of the Pacific, Atlantic and Indian oceans.     

ON THE SOURCE AND GENESIS OF THE MUD IN THE CENTRAL AREA OF THE SOUTH YELLOW SEA

Investigations and studies for years all demonstrated that there is a patch of fine-grained mud in the central area of the South Yellow Sea. However, scientists have different opinions on its material source, genesis, and sedimentation intensity. Some believe that the materials come from the Huanghe River, some think that the mud area represents the depocentre of the South Yellow Sea, and some consider it as "relict mud ". The authors ' geochemical study reveals that the mud is multi-sourced, yet the material supply is not ample, and that a little amount of fine-grained suspended materials deposited slowly under the dynamic action of a cyclonic gyre formed the modern muddy sediment, which is named "multi-source modern mud ".     

我国某些方铅矿中的铅同位素分析

鉛同位素組成的准确測定,是A.O.尼尔(Nier)在1938年开始的。1950年以后主要是由于鉛同位素地貭研究及鈾钍鉛法絕对年龄測定的需要,鉛同位素的貭譜分析技术得到了极其迅速的发展。鉛同位素組成的变化被用来解释一系列地貭問題,成为地貭学中一个新的方法。     

同位素地球化学国家重点实验室（筹）举行揭牌仪式暨李璞先生诞辰100周年纪念会

2011年11月30日同位素地球化学国家重点实验室（筹）在广州举行揭牌仪式暨李璞先生诞辰100周年纪念会。会议主要研讨同位素地球化学国家重点实验室（筹）的定位和发展方向并举行揭牌仪式,同时追思缅怀该实验室的奠基人李璞先生诞辰100周年。     

西南极长城湾NG93-1沉积柱样碳、氧、锶、铅同位素地球化学研究及其古环境意义

对西南极西北海域乔治王岛和纳尔逊岛之间长城湾浅水海区柱长８３ｃｍ的沉积柱样ＮＧ９３－１进行了矿物学、Ｓｒ、Ｐｂ、Ｏ、Ｃ等同位素地球化学研究。揭示了沉积物以陆源碎屑物为主，证实南设德兰群岛火山岩是该海区沉积物的重要控制源。Ｏ、Ｃ同位素记录了早全新世以来两次冰期，一次高温的气候变动信息，并指出Ｓｒ、Ｐｂ同位素组成的剖面变化具有气候演变的示踪意义。     

广东三水盆地古俯冲带地幔源岩石的年代学与Nd-Sr-Pb同位素证据

广东三水盆地火山岩岩石化学资料表明为具岛弧特征的拉斑-钙碱性岩系。K-Ar年龄为43-64Ma,属早第三纪。Nd-S-Pb同位素相关构成两个二元混合趋向,表明其源区为雷琼亏损地幔源与海水和蚀变俯冲沉积物相混合。这一结果表明华南大陆内存在着古俯冲带。它是由中国南部不同地体在缝合过程中产生的。     

海南抱板地区中元古代花岗岩副矿物锆石的特征及U-Pb同位素年龄测定

海南抱板地区中元古代花岗岩体中各种类型锆石的晶体形态、化学成分、U-Pb同位素组成等特征具有典型的岩浆型锆石的特点,不同于沉积锆石及再生锆石。锆石结晶年龄为1440.87Ma左右,属中元古代。前人所谓的抱板混合岩,主体实质上是中元古代的花岗岩。     

东海沉积物中226Ra的分布特征及近岸区沉积速率的测定

海洋沉积物中放射性同位素分布特征的研究,不仅是了解它们在海洋环境中的地球化学性质(如存在状态、沉淀机理、分布过程的动力学等),而且还可以利用它们作为海洋地球化学研究中的天然示踪剂,以探讨海洋化学演化和沉积物的形成进程。因此,积极地开展这项研究工作具有相当重要的意义。     

我国北方前寒武岩石铅同位素年龄测定——兼论中国前寒武地质年表

近十年来,前寒武地质年代学取得了一些显著进展,如格陵兰最古老年龄的发现等,促进了对地壳演化研究的兴趣。我们曾经在研究燕山地区震旦地层的基础上,建立了中国震旦地层同位素地质年表和测定了某些地层的Rb-Sr年龄;迁西36亿年年龄并未得到证实;寻找中国最古老地壳仍是需要解决的重大课题之一。 本文就我们测定的鞍山及其他地区一些前寒武岩石铅同位素数据,结合其他资料初步讨论中国前寒武地层同位素地质年表以及探索我国可能的最古老地壳年龄(图1)。     

印度与欧亚板块东部碰撞边界——腾冲火山岩的Nd-Sr同位素与微量元素研究

The Tengchong volcanies in western Yunnan Province, China, are located in the eastern part of the collision margin between Indian and Eurasian Plates. Alternating extention and compression controlled the eruption, from late Tertiary to Holeeno, of at least 5 groups of volcanics consisting of a Major series of hlgh-Al basalts (3 groups), a high-K andesite-dacite group and a high-Mg basalt group. The Major series has a range of GNd from 0.7 to-6.7 and Sr^87/Sr^86 from 0.70595 to 0.70881, exhibiting good linear correlations between Zr/Ni and Zr as well as between Nd. and both Sm/Nd and 1/Nd and similar chondrite-normalized incompatible element patterns. This suggests an ecologitic source metasomatized with fluids derived from parts of thesubducted Indian plate.The high-K andesite-dacite group shows a more extreme isotopic composition of GNd=-12.3, Sr^87/Sr^66=0.71124. It is chemically comparable to the calc-alkaline lavas in Xizang and could be resulted from mixing between shallow mantle zones and lower crust. The high-Mg basalt group has Sr^87/Sr^86-0.708 and slightly negative GNd (-2). They are similar, in chemical composition and possibly also in source, to the intraplate basalts in east China. A partial melting model of isotopic tmequilibrium system has been proposed to explain the isotope and trace element correlations of Tengchong volcanics.