Age and genesis of the Myanmar jadeite: Constraints from U-Pb ages and Hf isotopes of zircon inclusions

Myanmar jadeite (jadeitite) is well known for its economical value and distinctive tectonic locality within the collisional belt between India and Eurasian plates. However, it is less studied for its genesis and geodynamic implications due to precipitous topography, adverse weather and local military conflicts in the area. By means of combined ICP-MS and LA-MC-ICPMS techniques, we have carried out in-situ trace elements, U-Pb and Lu-Hf isotopes for zircon inclusions in a piece of jadeite gem sample. CL imaging suggests that the zircons are metasomatic in origin, and contain mineral inclusions of jadeite and omphacite. Seventy-five analyses on 16 grains of the zircons yield a U-Pb age of 158 ± 2 Ma. The Myanmar zircons differ from other types in that they have no significant Eu anomalies despite high HREE concentrations. Measured ¹⁷⁶Hf/¹⁷⁷Hf ratios range from 0.282976 to 0.283122, with an average value of 0.283066 ± 7; ε_Hf(t) value of 13.8 ± 0.3 (n=75). These results indicate that the Myanmar jadeite was formed in the Late Jurassic, probably by interaction of fluid released from subducted oceanic slab with mantle wedge. Therefore, its formation has no genetic relationship to the continental collision between Indian and Euroasian plates. Supported by National Natural Science Foundation of China (Grant No. 40673039) and the Science Plan Foundation of Guangdong (Grant No. 2007B031200005)     

The fluid inclusions in jadeitite from Pharkant area, Myanmar

A lot of liquid-gas and liquid-gas-solid inclusions were found in Pharkant jadeitites, northwestern Myanmar and their characteristics, geological setting and porphyroclastic jadeites with inclusions in them were described in detail. The results analyzed by Raman spectrometer showed that the component of liquid-gas phase and solid phase (daughter minerals) in fluid inclusions is H₂O + CH₄ and jadeite separately. The results indicated that Pharkant jadeitites were crystallized from H₂O + CH₄ bearing jadeitic melt which may originate from mantle. The P-T conditions in which the jadeitites were crystallized were speculated to be T ＞650℃, P ＞1.5 GPa.     

缅甸板瓦矽卡岩型铅锌矿床成矿作用及找矿方向浅析

本文介绍了缅甸板瓦矿区矿床地质背景、矿床地质特征,分析了矿床的形成条件及成矿作用,并指明了该区找矿方向。     

重开史迪威公路的战略意义

二战时期的史迪威公路,又称中印公路,被誉为远东抗战生命线,为中国抗战和世界远东地区的反法西斯战争发挥了重要作用。但二战之后,由于种种原因,这条辉煌一时的战略公路大部分处于废弃状态,直到上个世纪80年代末,缅甸政府宣布对外开放,这才为史迪威公路的重开创造了条件。目前,从区域经济合作的视角看,重开这一积淀着悠久历史的通道,变生命线为经济线,不论对中国西南地区来说,还是对缅甸北部和印度东北部地区的经济社会发展来看,都具有非常重要的战略意义和现实意义。     

缅甸D区块非渗透性防塌钻井液研究

 针对缅甸D区块钻井过程中存在的井壁失稳问题,系统分析了缅甸D区块易塌井段泥页岩黏土矿物组分、岩石微观结构、泥页岩水化性能,结合现场实际对前期钻井液存在的问题进行分析,优化出适宜缅甸D区块特点的非渗透性防塌钻井液配方。室内性能评价表明,该非渗透性防塌钻井液具有较强的抗污染能力、抗温能力,泥页岩抑制能力以及封堵能力。在现场应用4口井过程中,该钻井液取得了较好的井眼稳定效果,可有效解决缅甸D区块井眼坍塌和井径扩大率的问题,显著降低了井下复杂事故的发生。     

缅甸C Y油田构造特征及其与油气成藏关系研究

关于缅甸C Y油田构造特征及其与油气成藏关系研究,国内外研究相对较少。本文以新地层统层划分对比结果为基础,充分利用已有井及新钻井、测井资料、取芯资料、二维地震资料等,通过井震结合分析,对缅甸C Y油田浅层至深层地层构造特征进行了研究,包括：断裂特征、构造样式分析、构造格局及构造带分布、圈闭类型及特征分析研究等,总结了构造与油气运移聚集成藏的关系,指出了未来勘探重点潜力方向。     

Two new species of the subgenus Cacoxenus (Nankangomyia) from the Oriental Region (Diptera,Drosophilidae)

Two new species of the subgenus Cacoxenus (Nankangomyia) Máca and Lin, 1993 Máca, J. and Lin, F. J. 1993. The Drosophilidae of Taiwan: genera Amiota (excluding subgenus Phortica) and Leucophenga (Nankangomyia subg. nov.).. Bulletin of the Institute of Zoology, Academia Sinica, 32: 1–11.  [Google Scholar] are described: C. (N.) gani sp. nov. from southwest China and C. (N.) unipaxillus sp. nov. from Myanmar. The diagnosis of Nankangomyia is revised.     

缅甸的平衡外交及其对中缅关系的影响

为了应对西方的制裁,缅甸选择了平衡外交,密切的中缅关系以及缅甸自身的优势也是促使缅甸实施平衡外交的因素。缅甸的平衡外交使中缅关系受到了一定程度的冲击,但从缅甸面临的国际形势和平衡外交的实施效果来看,中缅关系不会受到实质性的影响。而且,平衡外交的实施对中缅关系的健康发展还起到了一定的积极作用。     

The freshwater medusa Limnocnida and associated plankton in the floodplain of the Ayeyarwaddy River,Myanmar

Freshwater medusae of the genus Limnocnida were found in a shallow lake in the floodplain of the Ayeyarwaddy River. The medusae are described and identified as a small form of L. indica. Single immature specimens were found in two other localities in Myanmar, within the Ayeyarwaddy catchment. These records are an eastward extension of the known range of Limnocnida, and indicate that it is probably widespread in the Ayeyarwaddy catchment. The associated phytoplankton and zooplankton are listed, and the zooplankters are compared to those found with Limnocnida in a floodplain lake of the River Sokoto in West Africa. In both situations there was a marked preponderance of rotifers and cyclopoid copepods. This indicates that Limnocnida influences the zooplankton in a manner similar to that found in various studies on the freshwater medusa Craspedacusta in Europe and North America.