广西明山微细粒型金矿床地质特征及找矿标志

明山金矿是广西发现的微细粒型金矿之一,文章概述了其矿床地质特征,分析了矿床成因,提出了找矿标志。     

震源破裂类型的划分及预报意义

对地表有反映震源破裂方式构造形迹的强震,提出按倾向滑动分量（Ｓ１）与走向滑动分量（Ｓ２）的比值ｒ（ｒ＝Ｓ１／Ｓ２）大小的分类原则,命名时次要成份在前,主要成份在后,研究还表明,不同震源破裂类型,其中短期前兆特征无明显区别。对Ｍ≥７．５级大震余震序列的研究表明,最大余震强度、主震与最大余震震级差以及Ｍｓ≥５．０级地震累计频次等方面,与震源破裂方式有关。一般是走滑型破裂最大余震的强度小,与主震震级差大     

Variations of δ~(18)O in Precipitation along Vapor Transport Paths

Three sampling cross sections along the south path starting from the Tropics through the vapor passage in the Yunnan-Guizhou Plateau to the middle-low reaches of the Yangtze River, the north path from West China, via North China, to Japan under the westerlies, and the plateau path from South Asia over the Himalayas to the northern Tibetan Plateau, are set up, based on the IAEA (International Atomic Energy Agency)/WMO global survey network and sampling sites on the Tibetan Plateau. The variations, and the relationship with precipitation and temperature, of the δ18 O in precipitation along the three cross sections are analyzed and compared. Along the south path, the seasonal differences of mean δ18O in precipitation are small at the stations located in the Tropics, but increase markedly from Bangkok towards the north, with the δ18O in the rainy season smaller than in,the dry season. The δ18O values in precipitation fluctuate on the whole, which shows that there are different vapor sources. Along the n     

Influence of moisture transport on stable isotope in precipitation in Yarlungzangbo River basin

The relationship between the variation of δ ¹⁸O in precipitation in Yarlungzangbo River basin and the moisture flux was analyzed with NCEP/NCAR reanalysis grid data and δ ¹⁸O in precipitation at four stations (Lazi, Nugesha, Yangcun and Nuxia) of the region investigated. In terms of spatial variations, there is obviously a positive correlation between them for the entire basin. With the decrease in moisture flux from the downstream to the upstream area, δ ¹⁸O in precipitation became gradually decreased. However, in terms of temporal variations, higher δ ¹⁸O in precipitation during spring is linked to small moisture flux while low δ ¹⁸O in precipitation during summer is linked to large moisture flux. A model involving meteorological data from NCEP/NCAR was subsequently set up which successfully traced the moisture transport trajectories at Yangcun station. Based on the traced moisture transport trajectories and the δ ¹⁸O in precipitation at Yangcun station, the relationship between δ¹⁸O in precipitation in Yarlungzangbo River basin and the moisture transport history was discussed. We found that the humid marine air mass from the Indian Ocean in general has significantly lower δ ¹⁸O values than the continental air mass from the north or local re-evaporation. The fluctuation of δ ¹⁸O in precipitation during the monsoon season is very pronounced; the lower values are usually related to farther distance and multilayer moisture transport, as well as moisture crossing the Himalaya Mountains. __________ Translated from Advances in Earth Science, 2007, 22(8): 842–850 [译自: 地球科学进展]     

1635—2019年通辽地区聚落变迁研究

以通辽地区为研究区,统计3 943个聚落并作矢量点数据,利用GIS空间分析及数理统计分析法对研究区聚落1635年以来的空间分布模式及空间分布格局的演变进行了分析。结果发现：① 通辽地区聚落从1795年开始增长速度不断加快,莫兰指数的计算结果表明,分布模式在整体上从1723年开始从随机分布越来越趋于显著的集聚分布。从不同年份的Ripley’s K函数看出,局部上1635—1723年一直处于集聚与离散不均衡的情况,所有距离段内从1795年呈现出显著集聚分布模式。② 1635—1840年,聚落点的几何中心呈现出西南-东北-西北的演变轨迹。核密度分析表明,聚落点在1635年是南部离散分布,1723—1840年南部密度最高。1840—1912年中部出现大量聚落,分布格局变为中部密度最高,1947年至今,西南部和中部都有大量的增长,北部也有一定增长,分布格局变为中部与西南部河流流域最密集。③ 聚落空间格局的演变是人地关系规律、宏观与微观的人文社会因素共同作用的结果,自然条件中地形、水文、气候等因素都直接或间接影响人类生产和居住,进而影响聚落的分布格局。聚落的增长速度及空间演变与不同历史时期的土地政策、人口迁入规模关系密切,土地政策及行政区划调整、人口迁徙等因素是主要的人为因素。     

Evidence for pre-seismic crustal movement in China and Japan

Some recent Chinese observations on precursory crustal movements detected by geodetic measurements such as short-range levelling or base-line survey across the active fault corroborate the three gamma phases model of Fujita and Fujii: Gamma 1 phase is pre-slip along the imminent faulting, gamma 2 is coseismic slip and gamma 3 is post-slip along the main or subsidiary faulting after an earthquake. Typical of these are the results of short-range levelling across the earthquake fault that ruptured during the 1976 Tangshan earthquake (M_s= 7.8). Associated with the occurrence of the Tangshan earthquake or the subsequent Ninghe earthquake (M_s= 6.9), remarkable gamma 2 phases were observed. At this same location abnormal gamma 1 or gamma 3 phases were detected from the Lulong 1982 earthquake (M_s= 6.2) that originated from the north end of the Tangshan Fault and was one of the aftershocks of the Tangshan earthquake. These phases are interpreted by analogy with the recent experimental results of stick-slip motion of the frictional sliding of rock.     

Humidity Effect and Its Influence on the Seasonal Distribution of Precipitation δ~(18)O in Monsoon Regions

The humidity effect, namely the markedly positive correlation between the stable isotopic ratio in precipitation and the dew-point deficit ATd in the atmosphere, is put forward firstly and the relationships between the δ18O in precipitation and ATd are analyzed for the Urumqi and Kunming stations, which have completely different climatic characteristics. Although the seasonal variations in δ18O and △Td exhibit differences between the two stations, their humidity effect is notable. The correlation coefficient and its confidence level of the humidity effect are higher than those of the amount effect at Kunming, showing the marked influence of the humidity conditions in the atmosphere on stable isotopes in precipitation. Using a kinetic model for stable isotopic fractionation, and according to the seasonal distribution of mean monthly temperature at 500 hPa at Kunming, the variations of the δ18O in condensate in cloud are simulated. A very good agreement between the seasonal variations of the simulated     

Humidity Effect and Its Influence on the Seasonal Distribution of Precipitation δ18O in Monsoon Regions

The humidity effect, namely the markedly positive correlation between the stable isotopic ratio in precipitation and the dew-point deficit △Td in the atmosphere, is put forward firstly and the relationships between the δ18O in precipitation and △Td are analyzed for the Urumqi and Kunming stations, which have completely different climatic characteristics. Although the seasonal variations in δ18O and △Td exhibit differences between the two stations, their humidity effect is notable. The correlation coefficient and its confidence level of the humidity effect are higher than those of the amount effect at Kunming, showing the marked influence of the humidity conditions in the atmosphere on stable isotopes in precipitation.Using a kinetic model for stable isotopic fractionation, and according to the seasonal distribution of meanmonthly temperature at 500 hPa at Kunming, the variations of the δ18O in condensate in cloud aresimulated. A very good agreement between the seasonal variations of the simulated mean δ18O and themean monthly temperature at 500 hPa is obtained, showing that the oxygen stable isotope in condensateof cloud experiences a temperature effect. Such a result is markedly different from the amount effect atthe ground. Based on the simulations of seasonal variations of δ18O in falling raindrops, it can be foundthat, in the dry season from November to April, the increasing trend with falling distance of δ18O in fallingraindrops corresponds remarkably to the great ATd, showing a strong evaporation enrichment function infalling raindrops; however, in the wet season from May to October, the δ18O in falling raindrops displaysan unapparent increase corresponding to the small ATd, except in May. By comparing the simulated meanδ18O at the ground with the actual monthly δ18O in precipitation, we see distinctly that the two monthlyδ18O variations agree very well. On average, the δ18O values are relatively lower because of the highlymoist air, heavy rainfall, small △Td and weak evaporation enrichment function of stable isotopes in thefalling raindrops, under the influence of vapor from the oceans; but they are relatively higher because of the dry air, light rainfall, great △Td and strong evaporation enrichment function in falling raindrops, under the control of the continental air mass. Therefore, the δ18O in precipitation at Kunming can be used to indicate the humidity situation in the atmosphere to a certain degree, and thus indicate the intensity of the precipitation and the strength of the monsoon indirectly. The humidity effect changes not only the magnitude of the stable isotopic ratio in precipitation but also its seasonal distribution due to its influence on the strength of the evaporation enrichment of stable isotopes in falling raindrops and the direction of the net mass transfer of stable isotopes between the atmosphere and the raindrops. Consequently, it is inferred that the humidity effect is probably one of the foremost causes generating the amount effect.     

Glaciochemical records from Naimona’Nyi ice core in the Himalayas

A 6-m ice core was recovered in 2004 from the Naimona’Nyi Glacier, the middle Himalayas. Empirical orthogonal function (EOF) analysis on the major ion reveals that EOF1 represents the variations of majority of ions which may be originated from crustal aerosols. Comparing the calcium concentrations from the Naimona’Nyi with these from Dasuopu, East Rongbuk and Guliya ice cores, it is observed that calcium, a good indicator of the input of crustal aerosol in snow, concentrates mostly in the Guliya ice core located on the northern Tibetan Plateau, and gradually decreases from west to east in the Himalayas.     

Glaciochemical records from Naimona’Nyi ice core in the Himalayas

Chemical records in ice and snow from polar ice sheets or mountain glacier can provide information about atmospheric composition, climate and environmental changes. Using glaciochemical records, the source of dust and moisture, and changes of atmospheric …