广西田东县那矿金矿区地质与地球化学特征及找矿方向

广西田东县那矿金矿位于滇黔桂金三角,属于卡林型金矿。本文在对那矿金矿区进行1∶10000地质填图的基础上,基本上查明了其成矿地质背景,结合1∶10000土壤地球化学测量,选取Au、As、Sb三种元素为成矿指示元素。通过土壤地球化学数据分析,对矿区内指示元素异常的特征、分布与地质现象进行对比分析,进行异常解释评价。研究结果显示:那矿金矿区中三叠统百逢组中上部粉砂质泥岩、泥岩、泥质粉砂岩是赋矿层位;坡表谷背斜与坡表谷断裂的复合部位为成矿有利部位;硅化、(褐)黄铁矿化、毒砂矿化、高岭石化、绢云母化、碳酸盐岩化等蚀变为金的矿化标志;圈定的Ⅰ号异常带是矿致异常,其Au元素异常规模大、品位高,是该区找矿的重点靶区。     

Laboratory Simulation of the Formation Process of Surface Geochemical Anomalies Applied to Hydrocarbon Exploration

The formation mechanisms and processes of geochemical anomalies used as proxies in surface geochemistry exploration (SGE) have not been well understood. Previous studies cannot realize 3D measurement of microseeping hydrocarbons from reservoirs to the surface, which made it difficult to understand the features and pathways of deep hydrocarbon microseepages. Understanding the processes of hydrocarbon microseepages will contribute to the acceptance and effectiveness of surface geochemistry. Based on a simplified geological model of hydrocarbon microseepages, including hydrocarbon reservoir, direct caprock, overlying strata and Quaternary sediments, this work established a 3D experimental system to simulate the mechanisms and processes of deep hydrocarbon microseepes extending to the surface. The dispersive halos of microseeping hydrocarbons in the subsurface were adequately described by using this 3D experimental system. Results indicate that different migration patterns of hydrocarbons above the point gas source within the simulated caprock and overlying strata can be reflected by the ratio of i-butane to n-butane (i-C4/n-C4), which follow diffusion and infiltration (buoyancy) mechanisms. This is not the case for vertical measurement lines far from the point gas source. A vertical gas flow in the form of a plume was found during hydrocarbon microseepage. For sampling methods, the high-density grid sampling is favorable for delineating prospecting targets. Hydrocarbon infiltration or buoyancy flow occurs in the zones of infiltration clusters, coupling with a diffusion mechanism at the top of the water table and forming surface geochemical anomalies. These results are significant in understanding hydrocarbon microseepage and interpreting SGE data.     

Tectonic Evolution of the Dongbo Ophiolite in Western Yarlung Zangbo Suture Zone,Xizang(Tibet)

正The Dongbo ophiolite in the western part of the Yarlung-Zangbo suture zone in southern Tibet rests tectonically on the middle-late Triassic and Cretaceous flysch units,and consist mainly of peridotites,mafic dikes,     

Pore structure and heterogeneity of shale gas reservoirs and its effect on gas storage capacity in the Qiongzhusi Formation

Fine characterization of pore systems and heterogeneity of shale reservoirs are significant contents of shale gas reservoir physical property research.The research on micro-control factors of low productivity in the Qiongzhusi Formation(Fm.)is still controversial.The lower Cambrian Qiongzhusi Fm.in the Qujing,Yunnan was taken as the object to investigate the influence of mineral compositions on the phys-ical properties of the reservoir and the heterogeneity of shale,using the algorithm to improve the char-acterization ability of Atomic Force Microscopy(AFM).The results showed that:(1)The pores are mainly wedge-shaped pores and V-shaped pores.The pore diameter of the main pore segment ranges from 5 to 10 nm.Mesopores are mainly developed in the Qiongzhusi Fm.shale in Well QD1,with the average pore diameter of 6.08 nm.(2)Microscopic pore structure and shale surface properties show strong hetero-geneity,which complicates the micro-migration of shale gas and increases the difficulty of identifying high-quality reservoirs.(3)The increase of clay mineral content intensifies the compaction and then destroys the pores.Conversely,brittle minerals can protect pores.The support and protection of brittle minerals to pores space depend on their content,mechanical properties and diagenesis.(4)Compression damage to pores,large microscopic roughness and surface fluctuations and strong pore structure heterogeneity are the reasons for the poor gas storage capacity of the Qiongzhusi Fm.,which will lead to poor productivity in the Qiongzhusi Fm.     

Erratum:"The Lyman-alpha Solar Telescope(LST)for the ASO-S mission—I.Scientific objectives and overview"(2019,RAA,19,158)

As a result of an error by the authors,in the paper"The Lyman-alpha Solar Telescope(LST)for the ASO-S Mission.I.Scientific Objectives and Overview"by Hui Li et al.(RAA 2019 Vol.19,No.11,158,doi:10.1088/1674C4527/19/11/158),there is an error occurred in Table 2 about the image size of SCI UV in the'Event'mode:the image size 4608×4608 should be replaced by 2048×2048.This correction is indicated in bold face in the following table.     

The conformity of HI galaxies in ALFALFA-SDSS sample

The conformity effect,indicating the evolution of galaxies is related to its surrounding neighbor galaxies as far as a few Mpc,is an interesting phenomenon in the modeling of galaxy and evolution.Here we study the conformity effect of HI galaxies in a matched galaxy sample between SDSS DR7 and ALFALFA surveys.By checking the probability difference for the detected H i galaxies as a function of distance around a normal or an H i galaxy,we find that this effect is significant out to 5 Mpc.It also shows a dependence on the stellar mass of galaxies,with the strength the strongest in the stellar mass range of 10¹⁰*/M_⊙<10^10.5.However,when the sample is confined to central galaxies in groups with virial radii smaller than 1 Mpc,the 1-halo conformity signal is still evident,while the 2-halo conformity signal is reduced to a very weak amplitude.Our results confirm the previous study in the optical band that the 2-halo term is possibly caused by the bias effect in the sample selection.Furthermore,we confirm the existence of the 1-halo conformity discovered in the optical and radio band in previous investigations.Our results provide another viewpoint on the conformity effect and hope to shed light on the co-evolution of the galaxies and their neighbors in the current galaxy formation models.