生物气CO2还原途径中碳同位素分馏作用研究及应用

地质历史中,CO2/H2还原产甲烷作用对生物气的形成具有十分重要的意义。中国柴达木盆地第四系生物气主要为CO2/H2还原型生物气。笔者以CO2/H2还原生气理论为指导,进行不同初始碳同位素值和不同赋存状态碳源的生物模拟实验,研究CO2/H2还原产气过程中发生的碳同位素分馏作用。实验结果表明,产物中δ13CH4值与底物的δ13C值呈很好的正相关关系;在反应母质过量的情况下,碳源的赋存状态可以影响产物甲烷的碳同位素组成。以游离形式CO2还原产生的甲烷δ13C值,相对于以HCO3-、CO23-离子形式产生的甲烷δ13C值轻。通过柴达木盆地东部第四系生物气田实例分析,探讨了该区生物气的主要底物CO2的来源及赋存状态,对评价盆地生物气资源和有利勘探区预测有重要的参考价值。     

国际南极大地参考框架的构建与进展

回顾了南极大地参考框架发展的历史,总结了由国际南极研究科学委员会(SCAR)组织的历次南极地区大地测量观测活动的成果,并结合2007~2008第四次国际极地年(IPY)对南极大地参考框架的前景进行了展望,其中重点介绍了我国对构建南极大地参考框架的贡献。     

The hydrothermal karstification and its effect on Ordovician carbonate reservoir in Tazhong uplift of Tarim Basin,Northwest China

With a detailed study on petrology, mineralogy and geochemistry of some important Ordovician carbonate well core samples in Tazhong uplift of Tarim Basin, the distinguishing symbols of hydrothermal karstification are first put forward as the phenomena of rock hot depigmentation, hot cataclasm and the appearance of typical hydrothermal minerals such as fluorite, barite, pyrite, quartz and sphalerite. The main homogenization temperatures of primary fluid inclusions in fluorite are from 260 to 310°C, indicating the temperature of hydrothermal fluid. The fluid affected the dissolved rocks and showed typical geochemistry features with low contents of Na and Mg, and high contents of Fe, Mn and Si. The ratio of ³He/⁴He is 0.02R _a, indicating the fluid from the typical continental crust. The hydrothermal fluid karstification pattern may be described as follows: the hot fluid is from the Permian magma, containing dissolving ingredients of CO₂ and H₂S, and shifts along fault, ruptures and unconformity, and dissolves the surrounding carbonates while it flows. The mechanism of hydrothermal karstification is that the mixture of two or more fluids, which have different ion intensity and pH values, becomes a new unsaturated fluid to carbonates. The hydrothermal karstification is an important process to form hypo-dissolved pinholes in Ordovician carbonates of Tazhong uplift of Tarim Basin, and the forming of hydrothermal minerals also has favorable influence on carbonate reservoirs.

     

Heavy-Rain expert-system realized by logical language prolog

This article, on the basis of the expert’s analyses and theories of the forecast of heavy-rain, summarizes a variety of the current instruments and methods of forecast and, according to the train of thought of the high-rank forecasters, distills their experiences in forecasting heavy-rain into an inference-tree of 106 junctures from which 101 rule-bases are derived. The logical calculation is automatically carried out with our introduced and developed PROLOG, one of the intelligent languagas by means of micro-computer. This process adopts the uncertain inferential method based on the theory of fuzzy sets, breaks through the limits of two-value logic and is characteristic of the thinking of human brain.     

江西气候生态产品价值实现的探索与思考

江西省气象部门针对气候生态产品价值实现开展了许多探索,积累了一系列的先进经验。文中从江西气候生态产品价值实现途径、效益、政策等方面进行思考和分析,认为政策先行营造制度环境、创建品牌实现气候价值、试点示范稳步实践创新和搭建平台培育价值理念等手段为挖掘气候好资源做好“两山”转化工作提供了有力支撑。针对发现的问题,提出了建议：理念创新,将气候资源价值转化固化于制;机制创新,用制度保护气候资源价值实现;载体创新,创品牌实现气候生态产品价值。     

现代植物炭屑形态的初步分析及其古环境意义*

通过对23种现代植物炭屑的观察、测量以及对草本、木本炭屑模拟破碎试验后的测量统计发现:现代植物炭屑形态根据其长宽比(L/W)和形态特征可以分为3个类型:1)草本型炭屑,L/W最大,平均为10.2±1.3, 呈长-薄条型、针型、簇纤维型,边缘及断口截然,棱角分明,有些具有气孔构造,很少有不规则的形态出现; 2)木本型炭屑(灌木+乔木),L/W较小,平均3.1±0.2,多呈方~长方型或立方体型,边缘多参差不齐,有些横向断口有粗大木纤维露出,相对致密; 3)阔叶类植物叶片炭屑,L/W最小,平均1.7±0.1,薄片状、网状,絮状,易碎。进一步通过对6个典型草原和森林表土样品的实验室分析,发现现代土壤中的炭屑颗粒大小相对现代植物炭屑颗粒大小总体有所减小,但草原土壤中炭屑长宽比相对森林土壤炭屑仍然较大,土壤中炭屑形态和部分结构鉴别特征仍能保留。表明L/W值与炭屑结构特征可以用来区分多数草本与木本植物炭屑。在此基础上,通过对黄土高原渭南剖面S₁以来不同层位12个地层样品的炭屑形态分析,初步研究了不同草本、木本植物炭屑形态变化的特点和环境意义。     

江西寻乌县葫芦练火山穹隆岩相特征

寻乌县葫芦火山穹隆是一保存较为完好的火山机构，河岭大型轻稀土矿床受控于该火山机构。作者根据１∶５万区调资料及前人的勘查成果，阐明了火山穹隆的空间结构、岩性、岩相特征，并对其演化趋势作了初步分析。     

班怒带西段尕尔穷铜金矿两套侵入岩源区及其地质意义——来自Hf同位素特征的指示

尕尔穷铜金矿位于班公湖—怒江缝合带西段南缘的措勤—申扎火山岩浆弧内,为与侵入岩有关的矽卡岩型-破碎带型铜金(铁)矿床。在已有石英闪长岩LA-ICP-MS锆石U-Pb测年的基础上,进一步对其进行锆石Hf同位素研究,同时对最新勘查成果显示具有一定成矿潜力的花岗斑岩进行LA-ICP-MS锆石U-Pb定年和Hf同位素研究,确定了两套侵入岩的形成顺序;结合前人总结的岩石地球化学特征,利用Hf同位素对其岩浆源区进行示踪。结果显示:花岗斑岩锆石206Pb/238U年龄加权平均值为(83.2±0.7)Ma,较石英闪长岩晚4 Ma左右,其初始176Hf/177Hf值为0.282 235～0.283 073,εHf(t)值为-17.2～12.5;石英闪长岩锆石初始176Hf/177Hf值为0.282 800～0.283 015,εHf(t)值为3.5～10.5。结合二者地球化学特征显示:石英闪长岩和花岗斑岩可能是同一岩浆系统不同分异阶段的产物,前者主要起源于具有幔源印记的初生地壳,而花岗斑岩具有和石英闪长岩相似的岩浆源区,但明显混入上地壳基底物质;暗示晚白垩世班怒带西段南缘内随着南羌塘—三江复合板片与冈底斯—念青唐古拉板片之间的弧-陆碰撞,先成的具有幔源印记的初生地壳重熔形成岩浆,随着碰撞的继续和岩浆的上涌分异,部分上地壳受挤压或热效应进一步重熔并参与岩浆系统中,由早至晚形成了由幔源特征向幔-壳混合源特征源区逐渐转变的花岗岩演化系列。尕尔穷铜金矿是起源于具有幔源印记的初生地壳的花岗岩的成矿专属性表现。