Growth behavior and resource potential evaluation of gas hydrate in core fractures in Qilian Mountain permafrost area,Qinghai-Tibet Plateau

The Qilian Mountain permafrost area located in the northern of Qinghai-Tibet Plateau is a favorable place for natural gas hydrate formation and enrichment, due to its well-developed fractures and abundant gas sources. Understanding the formation and distribution of multi-component gas hydrates in fractures is crucial in accurately evaluating the hydrate reservoir resources in this area. The hydrate formation experiments were carried out using the core samples drilled from hydrate-bearing sediments in Qilian Mountain permafrost area and the multi-component gas with similar composition to natural gas hydrates in Qilian Mountain permafrost area. The formation and distribution characteristics of multi-component gas hydrates in core samples were observed in situ by X-ray Computed Tomography (X-CT) under high pressure and low temperature conditions. Results show that hydrates are mainly formed and distributed in the fractures with good connectivity. The ratios of volume of hydrates formed in fractures to the volume of fractures are about 96.8% and 60.67% in two different core samples. This indicates that the fracture surface may act as a favorable reaction site for hydrate formation in core samples. Based on the field geological data and the experimental results, it is preliminarily estimated that the inventory of methane stored in the fractured gas hydrate in Qilian Mountain permafrost area is about 8.67×10¹³ m³, with a resource abundance of 8.67×10⁸ m³/km². This study demonstrates the great resource potential of fractured gas hydrate and also provides a new way to further understand the prospect of natural gas hydrate and other oil and gas resources in Qilian Mountain permafrost area.©2023 China Geology Editorial Office.     

马氏珠母贝两个与生长性状相关QTL 的验证

利用2个马氏珠母贝群体对遗传连锁图谱已经定位的,与马氏珠母贝生长性状相关的数量性状位点(Quantitative trait locus,QTL)中的两个进行验证。结果显示:m59标记在2个群体中与壳高、壳长、壳宽和总重具有显著的相关性(P0.05),其GT基因型的个体壳高、壳长、壳宽和总重均显著高于GG基因型的个体;154165标记在湛江群体中与壳高具有显著相关性(P0.05),而在深圳群体中与壳宽具有显著相关性(P0.05);表明QTL标记m59在2个群体中是共享QTL,而154165标记在群体中是特异QTL。基于这两个QTL在这2个群体中分别构建二倍型,发现在湛江群体中二倍型C_1(AAGT)和深圳群体中D_1(AGGT)型和D_2(AAGT)型对马氏珠母贝生长最为有利,可作为优先的基因型组合。     

Enclosing the land: Cotton,population growth and tenure in Mali

On-going tenure changes in the cotton zone in southern Mali are discussed. Land tenure in the area is changing and adapting to the rapid agricultural development taking place. This adaptation supports the main tenets of Property Rights Theory (PRT). The driving forces behind enclosure of land rights as described by PRT, such as population pressure and increased market access, are acknowledged. Enclosure takes two forms in the study area. First, some customary authorities in villages where population pressure is relatively high attempt to restrict access to pastures and woods on village land to create exclusive village commons. Second, holdings are being subdivided and farmers are increasingly confining their fields through tree planting. Except around the towns, where semi-formal land sales are becoming increasingly frequent, this individualisation does not imply exclusive and absolute private property to land. Bundles of overlapping rights still exist where various individuals or groups control access to different resources on the same piece of land.     

平原湖区抑螺防病林池杉生长规律的研究

通过对血吸虫病重疫区江汉平原池杉抑螺防病林进行观测调查和树干解析,研究探讨了平原湖区池杉的树高、胸径和材积生长规律,并建立了随年龄变化的数学模型。池杉树高早期生长快,20a之后增长速度明显下降,连年生长量和平均生长量在15a左右相交。胸径生长以4～14a最为迅速,连年生长量和平均生长量均呈先升后降趋势并在12～14a相交。材积平均生长量在前24a一直呈上升趋势,连年生长量在22a时达到最大。材积生长率和形数随树龄增加而逐渐减小,形数在6a后趋于稳定。应根据池杉生长规律,科学营建抑螺防病林,实现综合效益最大化。     

稻麦农业气象决策服务系统

RWAMDSS具有作物产量预报、作物气候评价、作物生长模拟、作物田间诊断专家系统等功能，是一个较为完整的农业气象决策服务系统。文章详细介绍了它的设计原理、结构及功能特点。     

论我国区域开发的理论模式*

本文概括和总结了我国区域开发的若干模式的原形.涉及对建设项目进行评估的成本效益分析、各类厂址选择模式(生产接近原料地和消费区线性模式;企业原、燃、材料和产品运输最近便非线性模式,以及第三产业的服务半径或吸引区模式)、区域和区际投入产出模式,以及区域增长模式(新古典区域增长和非均衡增长模式).作者认为,将这些模式付诸于我国的实践时,应视具体情况进行修正和补充.     

大兴安岭南段白音查干Sn-Ag-Zn-Pb矿床电气石矿物学特征及对岩浆-热液演化过程的启示

内蒙古西乌旗白音查干矿床是大兴安岭南段锡矿带内最典型、规模最大的Sn-Ag-Zn-Pb矿床。电气石在成矿岩体花岗斑岩和围岩地层中均广泛发育，依据其产状可分为四类：Ⅰ团斑状电气石；Ⅱ热液角砾岩胶结物中电气石；Ⅲ热液脉状电气石；Ⅳ弥散状电气石。在详细的岩相学基础上，利用电子探针点分析和面扫描分析对不同产状和结构的电气石进行了详细的成分分析。结果显示，花岗斑岩体深部的团斑状电气石（Ⅰa类）以自形、环带发育为特征，至少可见三期生长环带：核部电气石（Ⅰa-1）极高的Fe/（Fe+Mg）和Al值暗示其岩浆成因；边部电气石（Ⅰa-3）较富Mg，且与热液矿物共生，是从早期热液流体中沉淀形成的；幔部电气石（Ⅰa-2）的结构和成分显示其形成可能与不混溶的富B-Fe-Na的熔体或流体有关。因此，电气石从核部到边部的生长记录了从晚期岩浆到早期热液阶段的演变过程。花岗斑岩体中上部的团斑状电气石（Ⅰb类）环带不发育，其与热液矿物共生的组合及成分暗示其形成更倾向于与热液过程相关，可能是岩浆顶部聚集的早期流体释放之后被固结岩浆"圈闭"的残余流体结晶的产物。随后，大规模释放的富B流体形成了大量以电气石为主要胶结物的热液角砾岩（Ⅱ类）、成矿前电气石-石英阶段脉系（Ⅲa类）及伴随围岩蚀变而形成的弥散状电气石（Ⅳ类）。对Ⅱ类和Ⅲa类电气石内存在的生长环带分析显示，成矿前可能存在多个脉冲期次且成分有差异的流体的叠加作用。同时，电气石从早期到晚期向富Mg方向的演化，及成分明显受围岩地层影响的现象，暗示岩浆热液流体与围岩地层发生的水岩反应可能在金属成矿过程中起了重要作用。此外，本研究显示，不同产状电气石的结构和成分信息能够有效记录矿床内岩浆-热液转变及热液演化过程的众多细节信息，为深入理解成矿过程提供了依据。     

Effects of copper exposure on the scope for growth of the clam Ruditapes decussatus from southern Portugal

The clam Ruditapes decussatus L. was collected from Ria Formosa, Faro, southern Portugal, and exposed to a sublethal copper concentration of 0.01 mg l⁻¹ for 20 days. Physiological measurements, respiration rates, clearance rates and absorption efficiency, were undertaken initially and after 2, 5, 9, 14 and 20 days and used to calculate Scope for Growth. Copper accumulation rate was calculated through the analysis of copper in the tissues at the same sampling times. The experiment showed two phases. Initially, copper was rapidly accumulated (1.95 μg Cu g⁻¹ dw day⁻¹ in the first 48 h), clearance rates declined markedly (lowest value 13.5% of control) and respiration rates increased (116% of control), resulting in a rapid decline of Scope for Growth, which showed a negative value after 5 days. In the second phase, (from day 9 on), the rate of copper uptake declined to 0.55 μg Cu g⁻¹ day⁻¹ and physiological responses were more stable. After 20 days, copper concentration in the tissues was 38.4 μg Cu g⁻¹ dw (bioconcentration factor 3840). Clearance rates were 50% of control rates and respiration rates were still high, 145% of control rates. Therefore, Scope for Growth and performance of the clams was still greatly affected (ca. 23% of the control values), indicating that though animals partially recovered through detoxifying mechanisms, excess copper caused sustained impairment of physiological functions. This experiment confirms that the physiological energetics approach and the integrated Scope for Growth measurement is a sensitive methodology to detect deviations from normal performance and assess stress at environmental realistic copper concentrations.     

Radiaxial fibrous calcites as low-magnesian calcite cement precipitated in a marine-meteoric mixing zone

Abstract Radiaxial fibrous calcite (RFC) has previously been interpreted as a marine or replacive cement. Study of the Dongjeom Formation (Early Ordovician), Korea, shows that RFC can form in marine‐meteoric mixing zones as a low‐magnesian calcite (LMC) cement. RFC in the shallow‐marine Dongjeom Formation occurs in arenaceous limestones at the top of a transgressive facies overlying a regressive facies. It shows well‐developed growth zonation, and lighter oxygen isotope values and more radiogenic strontium isotope ratios than those of Early Ordovician marine calcite. Such petrographic and chemical evidence indicates that the RFC was precipitated as a primary LMC cement in a marine and meteoric mixing zone. Owing to the unique environment of formation, the Dongjeom RFC is characterized by growth zonal fabric comprising alternating subzones, which may indicate precipitation from varying fluids. In addition, this study documents the importance of substrate for development of RFC. Early ‘nucleation’ for RFC occurred mainly on microcrystalline skeletal grains and internal sediments, whereas on homogeneously altered substrates, thin‐coated banding structure developed, ultimately forming coarse crystalline spar. This suggests that microcrystalline substrates are preferred sites for nucleation of RFC.     

Nutrient control of the global occurrence of isolated carbonate banks

The growth and origin of the world's isolated carbonate banks are as yet not completely understood. This paper presents a comparison of the areas, depths, and latitudinal distribution of the world's carbonate banks. These are then compared with chemical parameters of seawater in the upper mixed zone of the oceans and at depth. The results allow large-scale inferences to be made on the interacting controls on bank growth and distribution. The data support the hypothesis that nutrient-rich waters commonly control bank depth and size.