与花岗岩有关锡矿成岩成矿作用研究若干问题讨论

文章基于近年来大量典型锡矿床和成矿区带成岩成矿作用及高温高压实验研究成果,对锡矿成矿年代学、成矿花岗岩类型、物质来源、源区物质的熔融条件及锡在岩浆中的存在形式、熔体-流体相间分配行为及热液流体中的存在形式等方面的研究进展及存在问题进行了系统综述,指出:①锡石原位U-Pb测年已成为直接测定锡成矿年龄的有效手段,近年来发展起来的多种矿石矿物U-Pb测年方法与传统蚀变矿物测年方法的结合,将为研究锡多金属矿床多期次成矿作用叠加、矿集区内不同类型矿床成因联系及区域矿床组合模型的建立提供关键的年代学依据;②锡的富集成矿不仅与花岗质岩浆的高程度的结晶分异密切相关,而且受源区组成及部分熔融条件的制约;③全球锡多金属矿床的不均匀分布、与准铝质花岗岩有关锡矿的富集成矿机制以及各类复杂的锡-钨-铜-钼-铅-锌银多金属矿种组合差异及其金属元素富集机制亟待查明;④已有的关于锡在花岗质熔体、热液流体相中的存在形式及两相间的分配行为的高温高压实验结果受锡与贵金属容器间合金效应的影响,人工合成流体包裹体等新的实验方法的开发及XAS同步辐射和激光拉曼等原位分析技术的应用,将为研究花岗岩浆-热液过程锡的迁移、富集及沉淀成矿机制提供更为直接、可靠的实验依据。     

浏阳永和磷矿沉积环境与成矿机理

永和磷矿的磷质主要来自南华洋前湘锰期的海底火山活动 ,上升洋流是磷质运移的主要营力。根据本区的 2个冰海—含磷建造的旋回组合特征 ,本文提出了“冰期磷质储集库”的新解说 ,揭示了“大冰期成磷说”的内涵机理。     

Metallogenic age and fluid evolution of the Kangshan Au-polymetallic deposit in the southern margin of the North China Craton: Constraints from monazite U-Pb age,and in-situ trace elements and S isotopes of pyriteSCIEI北大核心CSCD

小秦岭-熊耳山金矿集区位于华北克拉通南缘,发育众多伴生铅锌银等金属的金矿,成为揭示克拉通破坏型金矿成因的天然实验室。产于小秦岭-熊耳山金矿集区内的康山金多金属矿床受控于北东向的中生代脆性断裂,赋存于新太古代变质岩和中元古代火山岩中。成矿过程可分为4个热液阶段:石英±黄铁矿阶段、石英-黄铁矿-黄铜矿-自然金阶段、多金属硫化物-自然金-石英-铁白云石阶段、石英-方解石±萤石阶段。本文获得康山金多金属矿床金成矿阶段热液独居石LA-ICP-MS U-Pb年龄为131.7±4.6Ma,与晚中生代华北克拉通破坏有关的岩浆热液成矿作用时代一致。本次研究开展的各阶段黄铁矿原位微量元素单点和扫面分析,发现第2阶段Au与Co、Ni、As呈正相关关系,且有明显的振荡环带,Cu、Ag、Sb、Pb、Bi这几种元素从黄铁矿颗粒的核部向边缘含量逐渐降低,且黄铁矿颗粒中出现富含这些元素的矿物包裹体,说明该阶段发生流体沸腾作用;而第3阶段黄铁矿中各微量元素含量为所有阶段中最低,黄铁矿无振荡环带且裂隙中有富含各微量元素的硫化物充填,说明各种元素在该阶段均得到充分卸载,且成矿流体的化学性质较稳定。结合前人关于该矿床各阶段流体包裹体分析结果,表明流体沸腾是Au的主要沉淀机制,而流体混合是Pb、Zn、Ag的主要沉淀机制。黄铁矿中微量元素含量指示,从第1阶段到第3阶段流体温度依次降低;第2和第3阶段流体fO2比第1阶段高且后两者相差不大。根据黄铁矿Co、Ni含量及比值的计算,认为第1和第2阶段黄铁矿为岩浆热液成因,第3阶段黄铁矿受围岩物质影响。黄铁矿原位S同位素分析得到第1至第3阶段黄铁矿δ34S分别为+6.6‰-+8.9‰、+5.0‰-+7.2‰和+6.0‰-+8.7‰,均与区域花岗岩类的S同位素值类似。综上所述,本文得出康山金多金属矿床形成于早白垩世与华北克拉通破坏有关的岩浆热液成矿作用。     

Fifty-five-year longevity for the largest member of the family Sparidae: the endemic red steenbras Petrus rupestris from South Africa

A previous study that explored the age and growth of red steenbras Petrus rupestris (Valenciennes, 1830), a large sparid (family Sparidae, seabreams or porgies) endemic to South Africa and reported to approach 2 m in length, provided estimates as a moderately slow-growing species with a maximum age near 30 years. The stock is considered collapsed and a fishing moratorium was imposed in 2012, resulting in this species being assessed as Endangered by the IUCN. One consideration in addressing population status is validation of life-history traits. In this study, estimates of age for red steenbras from thin-sectioned otoliths were reassessed visually in terms of both the original ages and revised estimates using a different age-reading pattern. The revised ages exceeded the original ages by up to 30 years, with a maximum estimated age of 55 years from a well-defined otolith section that provided a basis for the revised age-reading procedure. Bomb radiocarbon (¹⁴C) dating revealed there was an offset in the timing of the ¹⁴C rise on the Agulhas Bank that, when coupled with considerations for regional oceanography, provided support for the revised age-reading pattern and an estimated longevity that exceeds 50 years. These findings were further supported by the fortuitous recapture of a tagged red steenbras that was at liberty for 22 years.     

Biochemical‐genetic and meristic evidence that blue and copper moki (Teleostei: Latridae: Latridopsis) are discrete species

Specimens of blue moki Latridopsis ciliaris (Forster in Bloch & Schneider, 1801) from New Zealand were shown to differ from specimens of copper moki Latridopsis forsteri (Castelnau, 1872) using two genetic methods—allozymes and muscle proteins. Allozyme techniques revealed fixed differences between blue and copper moki at 4 out of 15 loci. There was a genetic distance of 0.31–0.34 between population samples of the two colour morphs. The two morphs were also distinguished by iso‐electric focusing of muscle proteins. Meristic characters, counted in the specimens studied with genetic markers, revealed diagnostic markers in tubed lateral line scales and scales in the lower transverse series. It is concluded that specimens of blue moki from New Zealand and copper moki from New Zealand and Tasmania are valid species.     

海底热液沉积物中流体包裹体的研究进展

最近几个新兴起的海底热液沉积物中流体包裹体的研究可以解决许多利用常规矿物学和地球化学方法无法解决的重要科学问题,本文总结了该领域研究工作的进展,探讨了技术手段或方法上的发展及局限性,提出对热液沉积物中透明矿物的大范围显微测温对比分析和非透明矿物分温度段释放包裹体气候相结合,从而获取不同类型和不同成矿阶段包裹体物化指标及成分特征,进而研究热液循环机制及成矿作用过程的思路,对热液沉积物中流体包裹体研究     

邓阜仙钨矿成矿构造特征及深部成矿预测

邓阜仙钨矿位于湘赣地洼系衡山地穹内地洼型花岗岩中。矿床构造为典型的脉状构造。单脉,脉列,脉群在空间上严格按一定的几何关系分布。矿脉雁列脉,侧羽脉的三维形态特征,反映它们剪切形成的机制。经我们对该区航片、卫片分析,发现NNW向构造带与环形影像带,由此而确立了NNW向矿带的新认识。结合矿化与蚀变强度的空间分布,以及发现客观存在的构造等距性、对称性、梯级面,预测出新矿床(体)的空间位置,并得到物探与工程的验证。     

Sensitivity to stress of the estuarine bivalve Macoma balthica from areas between the Netherlands and its southern limits (Gironde)

Variation in the sensitivity to stress of Macoma balthica was measured in several French and Dutch estuaries. For adult and juvenile Macoma balthica exposed to copper under conditions of starvation, differences in mortality rate, condition, glycogen, burrowing rate and copper content were assessed. No significant differences were observed between adults and juveniles; the influence of treatment and origin was always evident. Animals from the most southern estuaries, Loire and Gironde, near to the species's southern limit of distribution, showed, in the field, the strongest deviations for the ecophysiological traits measured, and were in the experiments the most sensitive to stress.     

Zircon U–Pb and pyrite Re–Os age constraints on pyrite mineralization in the Yinjiagou deposit,China

We report new zircon U–Pb and pyrite Re–Os geochronological studies of the Yinjiagou poly-metallic deposit, sited along the southern margin of the North China Craton (SMNCC). In this deposit, pyrite, the most important economic mineral, is intergrown/associated with Mo, Cu, Au, Pb, Zn, and Ag. Prior to our new work, the age of chalcopyrite–pyrite mineralization was known only from its spatial relationship with molybdenite mineralization and with intrusions of known ages. The U–Pb and Re–Os isotope systems provide an excellent means of dating the mineralization itself and additionally place constraints on the ore genesis and metal source. Zircons separated from the quartz–chalcopyrite–pyrite veins include both detrital and magmatic groups. The magmatic zircons confine the maximum age of chalcopyrite–pyrite mineralization to 142.0 ± 1.5 Ma. The Re–Os results yield an age of 141.1 ± 1.1 Ma, which represents the age of the chalcopyrite–pyrite mineralization quite well. The common Os contents are notably low (0.5–20.1 ppt) in all samples. In contrast, the Re contents vary considerably (3.0–199.2 ppb), most likely depending on intensive boiling, which resulted in an increase of Re within the pyrite. This study demonstrates that the main chalcopyrite–pyrite mineralization occurred late in the magmatic history and was linked to a deeper intrusion involving dominant mantle-derived materials. This mineralization event might be related to the Early Cretaceous lithospheric destruction and thinning of the SMNCC.     

珠江河口及近海水体中铜的水平和形态分布

对夏季(2002-07)和冬季(2003-01)航次中珠江河口及近海水域样品中金属铜的总含量以及总溶解态、颗粒态、游离态铜含量进行对比分析。结果发现,夏季铜的总浓度水平分布并非完全体现陆源性规律,而是随河口向外海递增。而在冬季,总铜浓度的空间变化呈现和夏季完全相反的趋势,即随河口向外海逐渐降低。说明研究水域中金属铜可能具有其他来源,同时在很大程度上受到夏季沿岸上升流的影响。但是,游离态铜的分布在冬季和夏季却呈现相同的趋势,即自河口向外海逐渐降低。说明铜的形态分布在更大程度上取决于水体的理化性质。