A preliminary discussion on the bio-metallogenesis of Tl deposits in the low-temperature minerogenetic province of southwestern China

Starting with the research status of bio-metallogenesis of Tl deposits and their geology, this work deals with the geological background of Tl enrichment and mineralization and the mechanism of bio- metal-logenesis of Tl deposits, as exemplified by Tl deposits in the low-temperature minerogenetic province. This research on the bio-metallogenesis of Tl deposits is focused on the correlations between bio-enrichment and Tl, the enrichment of Tl in micro-paleo-animals in rocks and ores, bio-fossil casts in Tl-rich ores, the involvement of bio-sulfur in minerogenesis and the enrichment of bio-genetic organic carbon in Tl ores. Thallium deposits have experienced two ore-forming stages: syngenetic bio- en-richment and epigenetic hydrothermal reworking (or transformation). Owing to the intense epigenetic hydrothermal reworking, almost no bio-residues remain in syngenetically bio-enriched Tl ores, thereby the Tl deposits display the characteristics of hydrothermally reoworked deposits.     

A study on relation between acoustic emission and characteristic displacement field on the sample with multi en echelon structures——The theoretic and experimental explorations of strain gap

Introduction ZHOU, et al (1994) collected and investigated periods of level deformation data from 1954 to 1992, and gained sequence of a picture per year (or several years) that vividly showed the varia-tion of the deformation field of Tangshan earthquake source area around the Tangshan diamond block which was 21.3. They indicated that the Tangshan earthquake source area showed de-formation gap and the hard solid characteristic of relative stabilization or relative closedown. In the investig…     

Experimental investigation of the elastic modulus of a fractal system—A model of fractured rocks

The elastic properties of a physical model representing a damaged rock matrix were studied using a square lattice deformed under tensile stress. The elastic modulusM of such a system varies in agreement with percolation theory as|x–x _c | ^f , wherex is the damage parameter andx _c the threshold value of the damage parameter,f3.6. Atxx _c the scale dependence ofM can be expressed asML ^–f/v , whereL is the size of the sample andv the correlation exponent in percolation theory.The experimental results are of interest in assessing elastic properties in earthquake focal zones and fault zones in general.     

Experimental study on the relation between the water content of surface soil and theacoustic wave

Introduction Earthquake is not an isolated event. The focal region is not a closed system either. It is able to exchange energy or material with the medium outside this region. These kinds of exchange may cause various physical and chemical effects, so it is possible to get precursory signals by using space remote sensing technology. Many scholars (QIANG, et al, 1990; GENG, et al, 1992; XU, et al, 1995) have carried out some preliminary researches and experiments on the mechanism of therm…     

A preliminary research establishing the present-time intraplate blocks movement model on the Chinese

Ａｐｒｅｌｉｍｉｎａｒｙｒｅｓｅａｒｃｈｅｓｔａｂｌｉｓｈｉｎｇｔｈｅｐｒｅｓｅｎｔ－ｔｉｍｅｉｎｔｒａｐｌａｔｅｂｌｏｃｋｓｍｏｖｅｍｅｎｔｍｏｄｅｌｏｎｔｈｅＣｈｉｎｅｓｅｍａｉｎｌａｎｄｂａｓｅｄｏｎＧＰＳｄａｔａＳＨＵＯ－ＹＵＺＨＯＵ１）（周...     

Temporal variations in the fractal properties of seismicity in the North Anatolian Fault Zone between 31°E and 41°E

We investigate the nature of temporal variations in the statistical properties of seismicity associated with the North Anatolian Fault Zone between longitudes 31°–41°E during the instrumental period 1900–1992. Temporal variations in the seismicb value and the fractal (correlation) dimensionD _c of earthquake epicenters are examined for earthquakes of magnitudeM _S 4.5, using sliding windows of 100 consecutive events.b varies temporally between 0.6 and 1.0, andD _c between 0.6 and 1.4, both representing significant fluctuations above the errors in measurement technique. A strong negative correlation (r=–0.85) is observed betweenb andD _c , consistent with previous observation of seismicity in Japan and southern California. Major events early in this century (M _S 7) are associated with lowb and highD _c , respectively consistent with greater stress intensity and greater spatial clustering of epicenters—both implying a greater degree of stress concentration at this time.     

A discussion on the application of b-value to the prediction of seismic tendency

It has been recognized for a long time that the b-value in the Gutenberg-Richters fre-quency-magnitude relation (Gutenberg, Richter, 1954) tends to decrease before some of the earth-quakes (LI, et al, 1979, and the references therein). Since the 1980s, study on b-value has caused much attention among seismologists and physicists when b-value was related to the fractal dimen-sion of an earthquake fault (Aki, 1981; King, 1983) and/or the scaling constant in the model of self-organized critical…     

Seismic intensity investigation of the 2001 M=6.0 Yajiang-Kangding earthquake and discussion on its background of seismogenic structures

Introduction According to the determination of the state seismic station network, a strong earthquake with magnitude of 6.0 occurred at 08h09min, February 23, 2001 (Beijing Time) in the mountainous area of Garze, Sichuan Province in southwest China. The epicenter is at 101?6E, 29?4N. The seismic region is just located on combining part among six counties. After the occurrence of the earthquake, an investigating team from the Seismological Bureau of Sichuan Province started off to the sei…     

Deep electrical anomaly in the M7.5 Qiongzhou earthquake region and its relation with future seismicity

From the magnetotelluric detection in the epicentral region and the adjacent areas of the 1605 M7.5 Qiongzhou earthquake, we have discovered there is a low resistive body in the deep crust of the epicentral region. The low resistive body extends straightly from the depth of about 13 km to the upper mantle, which is supposed as an up-rising mantle pole. We therefore consider it is just the existing mantle pole and its upwelling thermal material that result in the faulting and stick-slipping activities of the upper crust, which is an important factor for the M7.5 Qiongzhou great earthquake occurrence. The postseismic faulting activity is characterized by creep, which shows that the risk is greatly decreased for the occurrence of a great earthquake with similar intensity in the future.     

Investigation on the relation between the gravity anomaly，crustal deformation and underground water

Ｉｎｖｅｓｔｉｇａｔｉｏｎｏｎｔｈｅｒｅｌａｔｉｏｎｂｅｔｗｅｅｎｔｈｅｇｒａｖｉｔｙａｎｏｍａｌｙ，ｃｒｕｓｔａｌｄｅｆｏｒｍａｔｉｏｎａｎｄｕｎｄｅｒｇｒｏｕｎｄｗａｔｅｒＸｕｅ－ＦａｎｇＷＵ（吴雪芳），Ｓｈｉ－ＨｕａＴＩＡＮ（田世华）ａｎｄＧｕ...     

Analysis of future seismicity of Jing－Jin－Tang region and seven major seismic zones with the extreme－value theory

ＡｎａｌｙｓｉｓｏｆｆｕｔｕｒｅｓｅｉｓｍｉｃｉｔｙｏｆＪｉｎｇ－Ｊｉｎ－Ｔａｎｇｒｅｇｉｏｎａｎｄｓｅｖｅｎｍａｊｏｒｓｅｉｓｍｉｃｚｏｎｅｓ　ｗｉｔｈｔｈｅｅｘｔｒｅｍｅ－ｖａｌｕｅｔｈｅｏｒｙＲａｎＺＨＯＵ（周冉）ａｎｄＢａｎｇ－ＨｕｔＬＩＮ（...     

Lg coda Q0 value and its relation with the tectonics in Chinese mainland and adjacent regions

We have collected 432 vertical component records from 45 stations of new CENC （China Earthquake Network Center） in Chinese mainland and adjacent regions. These records were used to calculate Q0 （Q at 1Hz） and η values of Lg coda from each station by the stack spectral ratio （SSR） method. Then the tomography method was applied to obtaining lateral variation of Q0 and η values in Chinese mainland and adjacent regions. The result indicates that Q0 value varies between 150 and 600 in the studied areas. Yunnan, southwest Sichuan, and northwest Myanmar show the lowest Q0 value （Q0〈240） and the crust of these regions is characterized by complicated crack and strong hydrothermal activity. The highest Q0 value （Qo〉510） exists in the border of southern Mongolia, Alxa and Ordos block. The η value varies between 0.45 and 0.75 in Chinese mainland and its adjacent regions.     

A preliminary study on the heat storage fluxes of a tropical seasonal rain forest in Xishuangbanna

In order to discuss the values and daily variation characteristics of heat storage fluxes in a tropical seasonal rain forest in Xishuangbanna, the sensible and latent heat storage flux within air column, canopy heat storage flux, energy storage by photosynthesis and ground heat storage above the soil heat flux plate, as well as the ratios of these heat storage fluxes to the net radiation in the cool-dry, hot-dry and rainy season were compared and analyzed based on the observation data of carbon fluxes, meteorological factors and biomass within this tropical seasonal rain forest from January 2003 to December 2004. The findings showed that heat storage terms ranged significantly in the daytime and weakly in the nighttime, and the absolute values of sensible and latent heat storage fluxes were obviously greater than other heat storage terms in all seasons. In addition, the absolute values of total heat storage fluxes reached the peak in the hot-dry season, then were higher in the rainy season, and reached the minimum in the cool-dry season. The ratios of heat storage fluxes to net radiation generally decreased with time in the daytime, moreover, the sensible and latent heat storage dominated a considerable fraction of net radiation, while other heat storage contents occupied a smaller fraction of the net radiation and the peak value was not above 3.5%. In the daytime, the ratios of the total heat storage to net radiation were greater and differences in these ratios were distinct among seasons before 12:00, and then they became lower and differences were small among seasons after 12:00. The energy closure was improved when the storage terms were considered in the energy balance, which indicated that heat storage terms should not been neglected. The energy closure of tropical seasonal rain forest was not very well due to effects of many factors. The results would help us to further understand energy transfer and mass exchange between tropical forest and atmosphere. Moreover, they would supply a research basis for studying energy closure at other places.     

The seismicity research in the sub-regions of Chinese mainland using strain accumula-ting and releasing model

Introduction Lots of researches suggest that the seismicity is irregular in the space and unsteady on the time. The former behaves as that the earthquakes usually are distributed in bands or zones, the latter behaves as that the seismicity has the active and placid alternant stages (high and low). Analyzing the seismicity of Chinese mainland shows that the distribution of strong earthquakes indicates different distributing pictures in space in different periods. According to strain releasing …     

Seismicity research in the subregions of Chinese mainland using strain accumulating and releasing model based on G-R relation

Introduction Earthquake activity analysis in different sub-regions in Chinese mainland shows that the dis- tribution of strong earthquakes exhibits the different spatial patterns in different periods. Seismic activity in the same earthquake area or seismic belt is self-similar to some extent, and the charac- teristic in time is some ″periodicity-like″. It shows that the frequency and intensity are quite dif- ferent in different periods (SHI et al, 1997). For a seismic region, strain is one…     

A tentative model for the explanation of Båth law using the order parameter of seismicity in natural time

Using the order parameter of seismicity defined in natural time, we suggest a simple model for the explanation of Båth law, according to which a mainshock differs in magnitude from its largest aftershock by approximately 1.2 regardless of the mainshock magnitude. In addition, the validity of Båth law is studied in the Global Centroid Moment Tensor catalogue by using two different aftershock definitions. It is found that the mean of this difference, when considering all the pairs mainshock-largest aftershock, does not markedly differ from 1.2 and the corresponding distributions do not depend on the mainshock’s magnitude threshold in a statistically significant manner. Finally, the analysis of the cumulative distribution functions provides evidence in favour of the proposed model.     

An aquifer model with a parameter characterizing the inhomogeneity of media

Ａｎ　ａｑｕｉｆｅｒ　ｍｏｄｅｌ　ｗｉｔｈ　ａ　ｐａｒａｍｅｔｅｒ　ｃｈａｒａｃｔｅｒｉｚｉｎｇ　ｔｈｅ　ｉｎｈｏｍｏｇｅｎｅｉｔｙ　ｏｆ　ｍｅｄｉａ（王六桥）（李善因）Ａｎａｑｕｉｆｅｒｍｏｄｅｌｗｉｔｈａｐａｒａｍｅｔｅｒｃｈａｒａｃｔｅｒｉｚｉ...     

An experimental study on variation of b value during deformation of rock samples with different structural models

Introduction Analyses of the b value in the frequency-magnitude relation (Gutenberg & Richter curve, G-R curve), lgN=a?bM, is one of important methods for earthquake prediction. It is often used to study the state of tectonic deformation and regional stress field. Many studies on the b value have been made in aspects of seismicity, experimental modeling (acoustic emission) and theory (Mogi, 1962; Scholz, 1968; LI et al, 1978; MA, 1978; CHEN, 1977; GENG, 1986; DU and MA, 1986; CAI et…