LAST GLACIATION AND MAXIMUM GLACIATION IN THE QINGHAI-XIZANG (TIBET) PLATEAU: A CONTROVERSY TO M. KUHLE,S ICE SHEET HYPOTHESIS

Since the late 1950's, many Chinese scientists have explored the remains of the Quaternary glaciation in the Qinghai-Xizang (Tibet) Plateau and its surrounding mountains. In the main, 3-4 glaciations have been recognized. The largest one occurred in the Late Middle Pleistocene with piedmont glaciers, ice caps and trellis valley glaciers in many high peak regions. But here is no evidence of a unified ice sheet covering the whole plateau as described by M. Kuhle. Due to the further uplifting of the Himalayas and Qinghai-Xizang Plateau the climate became progressively drier, diminishing the extension of glaciers during the Late Pleistocene. The elevation of the snow line during the Last Glaciation was about 4,000 m on the south, east and northeast edges of the plateau and ascended to 5500 m on the hinder northwest of the plateau. The thermal effect of the big plateau massif, the sharp increase of aridity from the southeast rim to the northwest inland area and the abrupt decrease of precipitation during the     

Coalification in Carboniferous sediments from the Lötschberg base tunnel

Vitrinite reflectance (Rr), proximate analysis and carbon isotope composition (δ¹³C) have been used to characterise coal samples from two zones of Late Carboniferous sediments (Gastern and Ferden) in the Aar massif where they are penetrated by the Lötschberg base tunnel (constructed between 1999 and 2005). Samples are characterised by variable ash yields (21.7–93.9%; dry basis); those with ash yields of less than ~50% and with volatile matter content (V;dry ash-free basis) within the limits 2 < V% ≤ 8 are anthracite. Values of Rr range from 3.89% to 5.17% and indicate coalification to the rank of anthracite and meta-anthracite in both Gastern and Ferden Carboniferous zones. Samples of anthracite and shale from the Gastern Carboniferous exhibit a relatively small range in δ¹³C values (–24.52‰ to –23.38‰; mean: –23.86‰) and are lighter than anthracite samples from the Ferden Carboniferous (mean: –22.20‰). The degree of coalification in the Gastern and Ferden Carboniferous zones primarily depends on the maximum rock temperature (T) attained as a result of burial heating. Vitrinite reflectance based estimates of T range from ~290° –360 °C. For a proposed palaeogeothemal gradient of 25 ° C/km at the time of maximum coalification the required overburden is attributable to relatively thin autochtonous Mesozoic/Cenozoic sedimentary cover of the Aar massif and Gastern granite and deep tectonic burial beneath advancing Helvetic, Ultrahelvetic and Prealpine (Penninic) nappes in Early Oligocene to Miocene.     

应用生烃动力学法研究川东上二叠统烃源岩生烃史

现今川东上二叠统烃源岩生烃史研究具有局限性.首先,没有对上二叠统Ⅰ-Ⅱ1型灰岩生油、Ⅲ型泥岩的生气史分开评价;其次,海相镜质组反射率通过拟合公式换算成镜质体反射率评价烃源岩成熟度具有局限性.针对上述不足,笔者通过热模拟实验,利用化学动力学方法,标定出两类源岩生油、生气的动力学参数,并结合川东地区的埋藏史及热史,模拟出源岩有机质的成烃转化率曲线.研究表明:上二叠统灰岩、泥岩有机质在距今200 Ma和190 Ma分别进入了生油、生气门限,而在距今170 Ma和140 Ma生烃结束.     

煤岩显微组分热解气相色谱特征与化学结构剖析

煤结构是目前地球化学研究领域中的一个难点，但却具有极其重要的理论及实际意义，本文采用分步热解气相色谱技术将树皮体，镜质体和丝质体分解为分子量较小的可测定的有机化合物，在此基础上，据不同温度下热解产物的组成特征来还原显微组分的化学结构，实验结果表明，煤显微组分主要由四大类官能团组成，一是热稳定性较低的NOS杂原子官能团；二是脂族（脂链、脂环）结构；三是苯、烷基苯（甲苯、二甲苯）、萘等芳香族化合物，四是热稳定性很高的难以分解的稠环芳烃。上述四类化合物集中于显微组分的不同结构简单中，树皮体和镜质体结构单元外侧主要由热稳定性较低的杂原子化合物以及分子量较小的苯和烷基苯组成，而丝质体结构单元外侧则主要以短链脂族结构为主，三组分结构核部由热稳定性很高的难以分解的稠环芳烃组成。连结核部稠环芳烃与结构单元外侧杂原子等官能团的主要是热稳定性较高的脂链结构，煤显微组分热成烃主要按结构中各官能团键的强弱随热演化程度的加深依次脱除，生成油气，基本上属平行独立依次反应机制，亦“官能团脱除型”，此外，还包括少量的长链脂族结构裂解为短链脂肪烃的“解聚”过程。     

The Influence of CO on the Carbon Isotopic Composition of CH_4 in Closed Pyrolysis Experiment With Coal

1IntroductionThecarbonisotopiccompositionofnaturalgasesisregardedasacontanttracerusedinthegeochemicalresearchofnaturalgases .Basedonthecarbonisotopiccomposition ,thegenetictypesofnaturalgasesarebasicallydividedtodeterminethematurationofnaturalgasesandmakegas sourcecorrelations (Stahl,1 973;StahlandCarey ,1 975;Stahletal.,1 977;James ,1 983;Schoell,1 983,1 988;DaiJinxingetal.,1 992 ;FuJiamoetal.,1 992 ;XuYongchang ,1 994 ) .Theformationofnaturalgasescouldbededucedintermsofcarbonisotopicvar…     

广西百色水电站边坡治理工程

文章通过广西右江百色水利枢纽地下发电厂房进水口与尾水洞高边坡的治理，介绍在此工程中具有特殊性的一些施工方法。该工程地质体为弱风化硅质泥岩夹泥化夹层、强风化含洞穴硅质泥岩石、强风化硅质岩及全强风化辉绿岩，地质条件非常复杂，对坡体的稳定极其不利。根据三维有限元的分析计算和国内有关权威专家的调查研究需施工1500kN、1000kN的锚索方能保证坡体的永久稳定。大吨位的锚索需锚固在强风化岩土体上，锚索设计采用能提高锚固力的防腐型压力分散锚索。通过现场锚索基本试验，其锚固力完全能满足工程需要。为保证进水口总体施工的进度，在施工进水口约30m高的垂直壁上的锚索时，笔者采用了通常施工中较少采用的垂直壁悬吊式施工法，满足了水电站的整体施工进度和要求。     

云南个（旧）-冷（墩）公路K22＋336回头湾段边坡治理工程研究

目前，在我国地质灾害防治及道路建设工程中，岩土锚固施工大多采用单一的拉力型锚索工法。一般锚索索体的长效防腐问题没有得到应有的重视。文章对云南省个旧-冷墩公路边坡工程中所采用的压力分散型锚索工法从设计、试验及成功应用等多方面进行了详细介绍。①在一些复杂地形条件下，锚索防护方案有其独特的经济实用性。②在地基承载力较低的软弱地层中，常用的拉力型锚索无法提供防护工程所需的大吨位锚固力。而有多个受力体的压力分散型锚索则因其对锚固段全长范围内地基承载力的充分利用来提供较大吨位的锚固力；③永久锚索防护工程作为一项具有隐蔽性强特点的结构工程，为保证在其报务年限内锚索能够可靠地工作，在设计阶段，锚索体的长效防腐应为不能忽略的主要考虑因素。在该工程中首次应用了新型高强材料——环氧全喷涂无粘结钢绞线作为锚索体的杆材，较好地解决了永久锚固工程中的锚索防腐问题。     

云南会泽铅锌矿床分散元素的富集机制——兼论浅色闪锌矿富集Cd的原因

文章对云南会泽铅锌矿床的黄铁矿、方铅矿和闪锌矿中的分散元素进行了电子探针分析(EMPA),探讨了分散元素的富集机制.结果表明,分散元素含量已达到综合利用指标,且富集规律为:分散元素以类质同象的形式赋存,黄铁矿中分散元素含量较低,而方铅矿中分散元素的含量稍高于闪锌矿.闪锌矿中:Cd富集顺序为红色＞杂色＞黑色,在高温阶段Cd置换Fe,低温阶段Cd置换Zn;Ga通过置换Zn进入闪锌矿,Ge可能主要替代Fe而进入闪锌矿晶格.方铅矿中:Cd和Ga元素置换Fe或Pb先进入方铅矿晶格内,Ge则富集较晚,具体表现为:当Ga含量较低时,元素进入方铅矿品格顺序为Fe,Zn→Cd→Ga,Ge,当Ga含量较高时,元素进入方铅矿品格的顺序依次为Cd,Ga→Ge.     

徐湾—石头岗花岗闪长岩体对围岩的热影响

对徐海—石头岗花岗闪长岩体围岩中黑云母及有机质变质程度的研究发现:距岩体580m范围内的接触带岩石皆具有角岩化现象。黑云母含量受原岩成分影响,其鳞片粒径与岩体距离密切有关。围岩中镜质组反射率,(R_(mas))值与岩体距离之间有十分明显的规律。     

Quantitative chemical characterization of vitrinite concentrates using pyrolysis-gas chromatography. Rank variation of pyrolysis products

A series of hand-picked vitrinite samples from the Lower Kittanning Seam, Pennsylvania have been examined using quantitative pyrolysis-gas chromatography. These vitrinites ranged in rank from 0.59 to 1.71% reflectance, a rank range from high volatile C bituminous to low volatile bituminous. High molecular weight pyrolysis products included alkyl aromatic and phenolic compounds. Attempts have been made to correlate the pyrolysis product composition to rank parameters including vitrinite reflectance, volatile matter yield, carbon content, atomic H/C ratio and Rock-Eval determined T_max. Total yield of phenols was found to be strongly and inversely rank related. A clear relationship between C₈ alkyl-benzene yield and rank was not found for the sample set.