中国已查明的铁矿资源的结构特征

以中国2005年的铁储量库为基础,总结了中国铁矿查明资源的矿床类型、矿石类型、矿石品级、矿产组合、勘查程度、矿体埋深等的结构特征。结果表明：中国铁矿床类型以沉积变质型、岩浆型、接触交代-热液型及火山岩型为主,查明铁矿资源绝大多数为单一矿产和主要矿产,虽然品位低,但以易选的磁铁矿石和钒钛磁铁矿石为主;勘查程度高,开发利用的风险较小;勘查深度浅,开采技术和经济条件有利,深部找矿潜力大。     

Toxicities of antifouling biocide Irgarol 1051 and its major degraded product to marine primary producers

Irgarol 1051 (2-methythiol-4-tert-butylamino-6-cyclopropylamino-s-triazine) is an algaecide commonly used in antifouling paints. It undergoes photodegradation which yields M1 (2-methylthio-4-tert-butylamino-6-amino-s-triazine) as its major and most stable degradant. Elevated levels of both Irgarol and M1 have been detected in coastal waters worldwide; however, ecotoxicity effects of M1 to various marine autotrophs such as cyanobacteria are still largely unknown. This study firstly examined and compared the 96 h toxicities of Irgarol and M1 to the cyanobacterium Chroococcus minor and two marine diatom species, Skeletonema costatum and Thalassiosira pseudonana. Our results suggested that Irgarol was consistently more toxic to all of the three species than M1 (96 h EC50 values: C. minor, 7.71 microug L(-1) Irgarol vs. > 200 microg L(-1) M1; S. costatum, 0.29 microg L(-1) Irgarol vs. 11.32 microg L(-1)M1; and T. pseudonana, 0.41 microg L(-1) Irgarol vs. 16.50 microg L(-1)M1). Secondly, we conducted a meta-analysis of currently available data on toxicities of Irgarol and M1 to both freshwater and marine primary producers based on species sensitivity distributions (SSDs). Interestingly, freshwater autotrophs are more sensitive to Irgarol than their marine counterparts. For marine autotrophs, microalgae are generally more sensitive to Irgarol than macroalgae and cyanobacteria. With very limited available data on M1 (i.e. five species), M1 might be less toxic than Irgarol; nonetheless this finding warrants further confirmation with additional data on other autotrophic species.     

A hypothesis of the Senoumi submarine megaslide in Suruga Bay in Japan—based on the undrained dynamic-loading ring shear tests and computer simulation

The distinctive bathymetric feature exists in the Suruga Bay, Japan. It has been called as Senoumi (Stone flower sea) from old times. Senoumi is a 30?km wide and 20?km long concave feature. Its origin has not been explained yet; however, the feature might be a combined consequence of intensive tectonic activity in the plate border, landslides, and a submarine flow coming from the Oi River. If the Senoumi was caused by a landslide, the latter would be larger than any on-land landslide in Japan. The downshelf “exit” from this feature is much narrower than its central part. This is not usual shape of landslides, but it is similar to the liquefied landslides such as those in quick clays which mobilize great strength reduction after failure. To study Senoumi as a landslide, the shear behaviors of the following three soil samples were investigated by the cyclic and seismic undrained stress control ring shear tests. One sample is volcanic ash taken from the base of landslide deposits (mass transport deposits), from 130 to 190?m deep layer below the submarine floor which was drilled and cored by the Integrated Ocean Drilling Program Expedition 333. Another two samples are the Neogene silty–sand and silt taken from the Omaezaki hill adjacent to the Senoumi, because the shear zone might have been formed in Neogene layers extending from on-land to the continental shelf. The largest strength reduction from peak to steady-state shear resistance in the undrained cyclic loading test was found in volcanic ash. The strength reduction in Neogene silty–sand was smaller than volcanic ash, while the Neogene silt mobilized the least post-failure strength reduction. An integrated model simulating the initiation and motion of earthquake-induced rapid landslides (landslide simulation (LS)-RAPID, Sassa et al. Landslides 7–3:219–236, 2010) was applied to this study. The steady-state shear resistance and other geotechnical parameters measured by the undrained ring shear tests and the greatest strong motion record in the 2011 off-the-Pacific Coast of Tohoku earthquake (M _w 9.0), also known as “2011 Tohoku Earthquake” at the observation point MYG004 (2,933?gal) were input to this model. As the result, it was found that landslides would be triggered by 0.30–1.0 times of MYG004 in volcanic ash, 0.4–1.0 times of MYG004 in Neogene silty–sand and Neogene silt, though the depth and area of triggered landslides were different in soils and intensity of shaking. Feature, created by LS-RAPID using the parameters of volcanic ash, was most similar to the Senoumi in depth and extent. The result obtained from this study includes a hypothesis to be proved, but presents the strong need to investigate the risk of the large-scale submarine landslides which could enhance tsunami wave and possibly enlarge the submarine landslide retrogressively into the adjacent coastal plain by the upcoming mega earthquake in the Nankai Trough.     

Rocky desertification and its causes in karst areas: a case study in Yongshun County,Hunan Province,China

Rocky desertification, a process of land degradation characterized by soil erosion and bedrock exposure, is one of the most serious land degradation problems in karst areas, and is regarded as an obstacle to local sustainable development. It is well known that human activities can accelerate rocky desertification; however, the effects of climate change on rocky desertification in karst areas are still unclear. This study focused on the effects of temperature and precipitation changes and human activities on rocky desertification in karst areas to determine the impacts of climate change and human disturbances on rocky desertification. Areas of different level of rocky desertification were obtained from Landsat TM (1987) and Landsat ETM+ (2000) images. The results show that, although the total desertification area increased by only 1.27% between 1987 and 2000, 17.73% of the slightly desertified land had degraded to a moderate or intense level, 2.01 and 15.71%, respectively. Meanwhile, between 1987 and 2000, the air temperature increased by 0.7°C, and precipitation increased by 170 mm. Statistical results indicate that the increase in precipitation was caused by heavy rainfall. In addition, under the interactive influences of heavy rainfall and temperature, the average karst dissolution rate was about 87 m³ km⁻² a⁻¹ during the 14 years in the study area. Further analysis indicated that rocky desertification was positively related with the increase in temperature and precipitation and especially with the heavy rainfall events. Climate change accelerated rocky desertification in the karst areas. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

生态景观与城市形态整合研究

早在19世纪末生态思想就开始用于指导城市空间结构的研究,如今景观生态学关于格局与过程的生物空间理论,已成为城市自然景观组织和生态景观建设的主要理论支撑。本文探讨了生态景观的含义及建设途径,以南京为例运用景观生态学原理研究城市形态可持续格局,分析高密度开发条件下城市自然或近自然景观与人工建筑环境整合方法,并提出了在大都市区、主城区、街区三个不同尺度上由表及里、由内而外的生态景观与城市形态整合模式：绿楔与星形放射状城市相嵌、绿径网络与街区路网纹理相伴、须状绿色延伸与邻里环境相融。为城市景观生态重建和城市化地区生态安全格局构建提供参照。     

Maximum-likelihood ambiguity resolution based on Bayesian principle

 Based on the Bayesian principle and the fact that GPS carrier-phase ambiguities are integers, the posterior distribution of the ambiguities and the position parameters is derived. This is then used to derive the maximum posterior likelihood solution of the ambiguities. The accuracy of the integer ambiguity solution and the position parameters is also studied according to the posterior distribution. It is found that the accuracy of the integer solution depends not only on the variance of the corresponding float ambiguity solution but also on its values. Received: 27 July 1999 / Accepted: 22 November 2000     

Variation of mineral composition,fabric and oxygen fugacity from massive to foliated eclogites during exhumation of subducted ocean crust in the North Qilian suture zone,NW China

Eclogites from the North Qilian suture zone are high‐pressure low‐temperature metamorphic rocks of ocean crust protolith, and occur in both massive and foliated varieties as individual blocks of tens to hundreds of metres in size. The massive type is weakly deformed and shows granoblastic texture characterized by a coarse‐grained peak mineral assemblage of Grt¹ + Omp¹ + Ph + Rt ± Lws (or retrograde Cz). In contrast, the foliated type is strongly deformed and shows a fine‐grained retrograde mineral assemblage of Grt² + Omp² + Cz + Gln + Ph. Both total FeO and aegirine contents in omphacite, as well as X_Fe[=Fe³⁺/(Fe³⁺ + Al^VI)] in clinozoisite/epidote, increase significantly from massive to foliated eclogites. Lattice preferred orientation (LPO) of omphacite, determined by electron back‐scatter diffraction analysis, is characterized by weak and strong SL‐type fabrics for massive and foliated eclogites, respectively. Clinozoisite/epidote also developed SL‐type fabric, but different from the LPOs of omphacite in <010> and <001> axes, owing to their opposite crystallographic long and short axis definitions. The transition of deformation mechanism from dislocation creep to diffusive mass transfer (DMT) creep in omphacite and the concomitant retrograde metamorphism both are efficiently facilitated when the original coarse‐grained Omp¹ + Grt¹ + Lws assemblage is dynamically recrystallized and retrogressed into the fine‐grained Fe³⁺‐rich assemblage of Omp² + Grt² + Cz + Gln. The DMT process with concomitant anisotropic growth assisted by fluids is considered to be an important deformation mechanism for most minerals in the foliated eclogite. P–T estimates yielded 2.3–2.6 GPa and 485?510 °C for the massive eclogite and 1.8–2.2 GPa and 450?480 °C for the foliated eclogite. The significant increase in total Fe and Fe³⁺ contents in omphacite and clinozoisite/epidote from massive to foliated eclogite suggests changes in mineral compositions accompanied by an increase in oxygen fugacity during ductile deformation associated with exhumation. The LPO transition of omphacite, clinozoisite and rutile from weak SL‐type in massive eclogites to strong SL‐type in foliated eclogites is interpreted to represent the increment of shear strain during exhumation along the ‘subduction channel’.