Chemo- and Biostratigraphy of the Jurassic Oil Shales from the Qiangtang Basin, Northern Tibet, China: A Case Study of the Toarcian Oceanic Anoxic Event

The marine oil shales of the Qiangtang Basin, northern Tibet, exposed in the Biluo Co, Tuonamu, Shenglihe and Changsheshan areas are believed to be important petroleum source rocks. This work comprehensively analyzed the carbon isotopes, trace elements, and calcareous nannofosills, ammonites and bivalves of the Biluo Co section in the Qiangtang Basin. The organic carbon isotopes show a positive excursion close to 2.17‰(relative to PDB), which, albeit significantly smaller, may also be associated with other Early Toarcian Oceanic Anoxic Events(T-OAE) in the European epicontinental seas and the Tethyan continental margins. Coinciding with the Early Toarcian transgression, the oxygen deficiency in bottom water had led to dysoxic-anoxic conditions and deposition of black shales lacking benthic fauna. Under such condition, the redox-sensitive trace metals such as Mo, V, Ni, Cr, and U were enriched, in conjunction with high planktonic productivity of Watznaueriaceae calcareous nannofossils. Comparison of the results with the records of chemo-and biostratigraphy, as well as the palaeogeography during the Early Jurassic suggests that the anoxia linked to the Early Toarcian oceanic anoxic event was mainly caused by the high surface water temperature, sea-level rise and an increase of surface water productivity.     

Facies and palaeosol analysis in a progradational distributive fluvial system from the Campanian–Maastrichtian Bauru Group,Brazil

The Upper Cretaceous Bauru Group in south‐east Brazil consists of alluvial strata whose characteristics and distribution indicate a fluvial system developed in a semi‐arid to arid climate. Sections exposed within a 90 000 km² study area in Minas Gerais State (in south‐eastern Brazil) were evaluated using facies and palaeosol analysis to formulate depositional and pedogenic models that may account for geomorphic and climate features. From east to west, the study succession records a gradual decrease in grain size, an increase in the width/thickness ratio in channels, a decrease in the lateral and vertical connectivity of channel deposits, and an increase in overbank deposits. The fluvial architecture indicates a braided channel belt, ephemeral ribbon–channels, and an unconfined fluvial facies from east to west in the study area. The lateral and vertical distribution of facies, stratigraphic architecture and palaeocurrent data suggest proximal, medial and distal portions of a progradational distributive fluvial system. The sedimentary dynamics were marked by the building and abandonment of channels related to processes of aggradation, vegetation growth and palaeosol generation. Macromorphological and micromorphological analyses have identified pedological and mineralogical features that indicate an arid to semi‐arid climate with a provenance from the north‐eastern part of the basin (Alto Paranaiba Uplift). From the proximal to the distal portions of the distributive fluvial system, the palaeosol development is different. In the proximal portion, the palaeosols are absent or poorly developed, allowing a possible general comparison with the present soil order: Inceptisols and Aridisols. In the medial portion of the fluvial system, the palaeosols are well‐developed and characterized by Bt, Btk, C and Ck horizons (Alfisols, Aridisols, Inceptisols and Entisols). Poorly drained to well‐drained palaeosols from the base to the top in the distal plain (Aridisols and Inceptisols) are associated with geomorphic and hydromorphic changes in the fluvial system due to progradational evolution. The genetic relationship between the fluvial architecture and the palaeosols enhances the understanding that the sedimentation and pedogenesis that occurs in different portions of the distributive fluvial system are related to the tectonic and climatic evolution of the basin.     

塔里木地块库车坳陷早白垩世古地磁结果及磁倾角偏低的成因探讨

运用主成分分离及线性区段等方法 ,使早白垩世样品明显分离出二组磁组分 .叠加剩磁为喜山期重磁化 ,特征剩磁明显偏离现代地磁场方向 ,经倾斜校正后 ,有很好的一致性并通过了倒转检验 ,给出塔里木地块库车坳陷早白垩世巴西盖组古地磁新数据 .综合已有的古地磁结果 ,获得了塔里木地块早白垩世平均剩磁方向及平均古地磁极 ,阐明了塔里木地块早白垩世磁倾角明显偏低这一现象 .分析导致磁倾角偏低的诸多因素 ,认为压实作用可能是导致磁倾角偏低的重要因素之一 .     

江山铅锌金矿选矿试验研究

针对江山铅锌金矿品位低,矿物组成复杂的特点,采用"铅-锌-硫优先浮选,硫(金)精矿氧化焙烧预处理-焙砂氰化浸金"的工艺,金在铅(金)精矿、锌精矿、硫(金)精矿中的总回收率为81.25%。可使硫(金)精矿中96.89%的硫以二氧化硫的形式得到回收,对原矿的回收率为73.25%;金的作业浸出率达84.76%,对原矿的回收率为31.91%;浸渣中的铁品位达57.99%,对原矿的回收率为26.71%。通过试验研究与分析,确定适宜的选矿工艺及药剂制度,为今后合理开发该区矿石提供技术依据。     

Characteristics and landcover of estuarine boundaries: implications for the delineation of the South African estuarine functional zone

This study investigated whether the current lateral boundary for estuaries in South Africa, i.e. the estuarine functional zone (EFZ), includes all estuarine habitats. The EFZ covers 173 930 ha in 304 estuaries/outlets nationally. Field surveys and analysis of available aerial images showed that 82 (12 956.70 ha) of these estuaries (26%) had estuarine habitats occurring outside of this boundary. As a result of mapping scale, the National Vegetation Map does not represent habitats that are associated with small estuaries (approximately 50% of South Africa's estuaries). For estuaries in the Western and Eastern Cape provinces, most habitats have been lost due to urban development, whereas in subtropical areas (northern Eastern Cape and KwaZulu-Natal), cultivation has removed estuarine habitat. Although delineation of boundaries can be complicated by landcover changes, the estuarine lateral boundary in Cape estuaries could be identified based on sediment characteristics (moisture content, organic content, electrical conductivity), groundwater characteristics (salinity, conductivity and depth) and plant species. The delineation of the EFZ needs to be consistent, inclusive of all estuarine physical and biological processes, and cost-effective to identify so that it can protect estuarine habitats.     

CORS基准站周跳探测与修复方法研究

在高精度GNSS测量中,周跳的存在直接影响到整周模糊度的解算及最终定位精度。针对目前各省市连续运行基准站网多系统观测数据的获取导致周跳探测工作量增加,该文基于甘肃省卫星定位连续运行基准站网(GSCORS)双频观测值提出了一种满足普遍条件的多系统周跳探测方法。采用相位减伪距结合电离层残差法分别对GPS和BDS原始观测值进行周跳探测与修复,通过对相应载波的模拟周跳探测发现,BDS较大的卫星钟差和伪距噪声影响了数据质量,其周跳检测量时间序列波动大于GPS,对7周以上周跳探测的精度较GPS会有1周的偏差,但电离层残差法能对BDS相位减伪距法探测残留的1周小周跳进行二次探测并修复。实验最终证实该方法能够有效探测并且正确分离GPS和BDS每个频率1周以上的周跳。     

面向信息化测绘的网络化测图系统研究与应用

随着信息化测绘生产体系构建的不断深入,利用先进的信息技术对数字化测绘流程升级改造迫在眉睫,传统航测生产单机作业模式已难以满足网络化、信息化的高效生产需求。本文以武汉长江新城房屋测图为例,借助MapMatrix Grid软件进行网络化测图系统的研究和应用,论述了网络化测图生产的关键技术和生产流程,并对系统性能进行了评价。