乌石凹陷流沙港组成岩作用及其孔隙演化

通过铸体薄片鉴定、X射线衍射、扫描电镜以及镜煤等多种实验手段对乌石凹陷流沙港组砂岩成岩作用及孔隙演化做了详细研究.结果表明:乌石凹陷流沙港组二段、三段岩石类型主要为石英砂岩,少量长石石英砂岩,粒级分选中等偏差.砂岩的成岩强度均已达到中成岩阶段A期.孔隙类型以原生粒间孔和次生溶蚀孔隙为主,压实作用、胶结作用等减少原生粒间孔隙,溶蚀作用产生大量的次生溶孔,改善储集层物性.     

新疆博格达-哈尔里克-带金矿类型及找矿方向研究

结合新疆博格达-哈尔里克一带金矿的成矿特点,将区内已发现的金矿划分为4个主要类型：韧性剪切带型金矿、火山热液型金矿、岩浆热液型金矿以及沉积型金矿。通过分析大地构造环境、地层建造、断裂构造、侵入岩及化探异常等因素对该地区金矿的控矿作用,总结区域金矿的成矿条件以及在时间和空间上的成矿规律和演化过程,指明各类型金矿的控矿因素以及找矿标志,为研究区今后的金矿勘查工作指明方向。     

A Review of: “Remote Sensing of Soils and Vegetation in the USSR”. By P. J. CURRAN,G. M. FOODY,K. YA. KONDRATYEV,V. V. KOZODEROV and P. P. FEDCHENKO. (London: Taylor & Francis, 1990.) [Pp. 200.] Price £30·00. ISBN 085066 4020.

As they increase in popularity, social media are regarded as important sources of information on geographical phenomena. Studies have also shown that people rely on social media to communicate during disasters and emergency situation, and that the exchanged messages can be used to get an insight into the situation. Spatial data mining techniques are one way to extract relevant information from social media. In this article, our aim is to contribute to this field by investigating how graph clustering can be applied to support the detection of geo-located communities in Twitter in disaster situations. For this purpose, we have enhanced the fast-greedy optimization of modularity (FGM) clustering algorithm with semantic similarity so that it can deal with the complex social graphs extracted from Twitter. Then, we have coupled the enhanced FGM with the varied density-based spatial clustering of applications with noise spatial clustering algorithm to obtain spatial clusters at different temporal snapshots. The method was experimented with a case study on typhoon Haiyan in the Philippines, and Twitter’s different interaction modes were compared to create the graph of users and to detect communities. The experiments show that communities that are relevant to identify areas where disaster-related incidents were reported can be extracted, and that the enhanced algorithm outperforms the generic one in this task.     

Formation and evolution of petroliferous basins in African continent and their hydrocarbon distribution

There are eighty sedimentary basins in five different types in African continent,i.e.craton sag basin,foreland basin,intermountain basin,passive margin basin and rift basin,which underwent the stress environment of stable depression-compression-extension.The first three types of basins had been intensely influenced by Hercynian and Alpine tectonic movement,while the later two types of basins always exist in a stable extension environment.Different basin evolution caused the obviously hydrocarbon distributio...     

Retrieving capillary-gravity wave spectrum from polarimetric microwave radiation of ocean surface

A new simple two-scale model on the polarimetric microwave emission of ocean surface is derived at first, which can be ex-pressed as an integral of weighting functions (M0 and M2) and ocean surface curvature spectrum coefficients (C0 and C2). This provides a simple way to investigate the effect of curvature spectrum on ocean emission. It is found that ocean waves with wavelengths both comparable to and much greater than the electromagnetic wavelength can contribute to the harmonics of ocean surface microwav...     

A one-dimensional heat transfer model of the Antarctic Ice Sheet and modeling of snow temperatures at Dome A, the summit of Antarctic Plateau

A vertical one-dimensional numerical model for heat transferring within the near-surface snow layer of the Antarctic Ice Sheet was developed based on simplified parameterizations of associated physical processes for the atmosphere, radiation, and snow/ice systems. Using the meteorological data of an automatic weather station (AWS) at Dome A (80°22′S, 70°22′E), we applied the model to simulate the seasonal temperature variation within a depth of 20 m. Comparison of modeled results with observed snow temperat...     

Processes and modes of permafrost degradation on the Qinghai-Tibet Plateau

Climate warming must lead the mainly air temperature controlled permafrost to degrade.Based on the numerical simulation,the process of permafrost degradation can be divided into five stages,i.e.,starting stage,temperature rising stage,zero geothermal gradient stage,talic layers stage,and disappearing stage,according to the shape of ground temperature profile.Permafrost on the Qinghai-Tibet Plateau (QTP) is generally considered a relic from late Pleistocene,and has been degenerating as a whole during Holocen...     

A comparative study of boron isotopes and trace elements of the marine foraminifers during the last glacial maximum and Holocene

Boron isotopic compositions in marine planktonic foraminifers can record changes in seawater pH and hence provide a new tool to reconstruct the changes of paleo-atmospheric PCO2.Here a comparative study was done on boron isotopes and trace element abundances of planktonic foraminifers,Globigerinoides sacculifer and Globigerinoides ruber from three tropical ODP sites,Site 806B,Site 664C and Site 999A.It is demonstrated here that G.ruber is a better species to be used for downcore boron isotope analyses on gl...     

The spatio-temporal distribution of thermodynamic forces at the land-atmosphere interface in China

Correlation analysis and the complementary relationship model are used to indirectly measure and characterize the dynamic and thermodynamic properties at the land-atmosphere interface in China.Results show that thermodynamic forces driving the exchange fluxes of energy,water and carbon between the land surface and the overlying atmosphere are significantly enhanced along the mid-upper reaches of the Yangtze River basin around Sichuan Basin and the northern region of Heilongjiang.The thermodynamic forces exh...     

东秦岭金堆城花岗斑岩体的锆石U-Pb年龄、物质来源及成矿机制

通过LA-ICP-MS方法测得金堆城和老牛山花岗岩体中锆石U-Pb年龄分别为143.7±3 Ma和144.5±4.4 Ma,与金堆城钼矿床中辉钼矿的Re-Os年龄139±3.0 Ma在误差范围内一致,界定了金堆城成岩成矿时代为侏罗纪末-白垩纪初,2个岩体为同期岩浆事件的产物,与燕山运动有关.金堆城岩体较老牛山岩体富SiO₂、K₂O,岩石地球化学数据显示2个岩体都具有一致的高硅、富碱、过铝质系列和钙碱性岩石系列特征;高的ε_Sr(t)、低的ε_Nd(t)及Pb同位素图解证明2个岩体主要来自下地壳物质部分熔融,可能有少量地幔物质加入.年代学与岩石地球化学数据证实老牛山岩体和金堆城岩体的岩浆源区与岩石成因相同,推测老牛山岩体在深部发生分异演化,为金堆城小岩体提供了大量的热液和矿物质,从而出现了金堆城小岩体成大矿现象.