洞庭湖区水系格局及连通性优化

江湖关系演变及强烈人类活动改变了洞庭湖区的水系格局与连通性,加剧了湖区水环境与水生态的恶化形势,开展水系格局与连通性研究是洞庭湖区水系综合整治和河湖生态修复的重要内容。基于景观生态学中网络连通度分析方法,建立了水系格局与连通性评价指标体系,包括河频率、河网密度、水系环度（α）、节点连接率（β）和网络连接度（γ）等,分析评价了洞庭湖不同片区现状及规划水系格局与连通性的差异以及合理性,提出了水系连通规划的优化方案。结果表明:现状洞庭湖区水系格局和连通性总体较好,但各个片区存在较大差异,湘-资水尾闾地区的现状水系格局和连通性良好,北部地区和松澧地区的现状水系格局与连通性较差。松澧地区水系规划方案改善了该地区的水系格局与连通性,但北部地区的规划方案并不合理。经过比选与优化,北部地区的α、β、γ指标比现状提高了13.2%、6.9%和4.7%,比原规划方案提高26.0%、9.4%和9.4%。     

安徽省含山县柱山-项家山水泥石灰岩矿床成因及开采技术条件

安徽省含山县柱山—项家山水泥石灰岩矿床矿位扬子准地台与华北地台、大别山造山带的结合部位,属扬子板块西北缘,大别造山带的前陆带,郯庐断裂带的东侧,属丘陵地貌,山体走向为北东向,地形起伏变化较大,区域内矿产主要为沉积矿产,有石膏、水泥用石灰岩、石英砂岩、耐火粘土及陶瓷粘土、砖瓦用粘土等。另外有铜、铅、锌、铁、铀、高岭土、煤等矿(化)点。本文对含山县柱山—项家山水泥石灰岩矿床特征、成因以及开采技术条件进行探讨。     

鄂尔多斯盆地晚古生代以来构造-沉积演化与致密砂岩气成藏

鄂尔多斯盆地上古生界主要发育致密砂岩气藏,已发现地质储量超过5万亿m3,勘探潜力大。文中通过盆地构造演化史分析,结合包裹体测温、锆石U Pb定年、自生伊利石K Ar测年等分析方法,明确了晚古生代以来构造演化对上古生界致密砂岩气藏的控制作用。研究表明：石炭纪-二叠纪沉积古地形平缓,构造沉降缓慢,形成了大面积分布的煤系烃源岩和砂岩储层;三叠纪-中侏罗世快速沉降,压实作用及硅质胶结作用明显,水岩作用强,致密砂岩储层形成;晚侏罗世-早白垩世构造活动强烈,伴随构造热事件的发生,天然气大量生成并运聚成藏,致密气藏形成;早白垩世末-现今地层抬升剥蚀,天然气散失,低压气藏形成。     

四川盆地北部下三叠统飞仙关组层序地层分析

为了探讨礁滩储集岩的分布规律,以层序地层学理论与方法系统研究了四川盆地北部下三叠统飞仙关组地层。通过露头、岩芯、测井、地震数据综合分析,识别出两个三级层序及四个准层序组,确定蒸发台地、局限台地、开阔台地、台地边缘滩、斜坡和盆地相六类沉积类型。层序划分及层序界面的确定,依据陆上暴露和向上变浅两个方面的识别标志。暴露界面表现为泥岩表面干裂,淡水选择性溶蚀、白云化现象,白云岩、石膏,伽玛曲线高值。向上变浅层序有向上变厚、变粗序列,向上变细、变泥、变红序列,向上γ值变低序列。对比发现高水位体系域后期发育台地边缘鲕滩和台地内鲕滩。广泛白云岩化作用的台地边缘鲕滩相,具有很好的孔渗性,成为最有利的储集层。对指导进一步的勘探与开发具有重要意义。     

胶莱盆地K/Pg界线下陆相红层的旋回地层学分析

陆相红层因为其含古生物化石稀少给高精度生物、年代地层的对比带来了较大的困难.旋回地层学可以将地层与地时结合起来,解决地层沉积的时限问题.基于前人在对胶莱盆地K/Pg界线识别的基础上,主要利用了一维连续小波变换尺度分析法与频谱分析法对胶莱盆地胶州组K/Pg界线之下、晚白垩世红土崖组玄武岩夹层之上的陆相红层进行旋回地层分析...     

固体—液体层分界面处的P、SV型面波

针对半无限弹性固体—液体层分界面处 Ｐ、 Ｓ Ｖ 型面波不同的数学表达进行了分析研究,认为在有些著作中将它们统称为瑞利波是不够严密的,指出瑞利波和斯通利波是固体—液体层分界面处 Ｐ、 Ｓ Ｖ 型面波的两种极限情况。     

Ecological risk assessment of Cd and other heavy metals in soil-rice system in the karst areas with high geochemical background of Guangxi,China

Karst areas are widely distributed in China, and the soil derived in these areas is enriched with trace elements and has the typical characteristics of high geochemical background. Therefore, soil ecological risk has gradually attracted extensive attention. In this study, 1090 sets of rice grains and paired rhizosphere soils were collected as research objects from the outcropped karst areas of carbonate rocks in Guangxi, and the concentration characteristics and influencing factors of heavy metals, such as Cd and As, in rice grains and the corresponding soils were studied. According to the Chinese Soil Environmental Quality Standard(GB 15618-2018), the proportion of karstic soil samples in Guangxi with heavy metal(As, Cd, Cr, Cu, Hg, Ni,Pb and Zn) concentrations that exceed the standard risk screening values was generally greater than that of surface soils in China or non-karstic soils in Guangxi. Notably, Cd and As were the most prominently enriched heavy metals in soils. According to the Chinese Food Safety Standard(GB 2762-2017), Pb in rice grains from the studied area did not exceed the standard; the exceedance rates of Cr, Hg, and inorganic As were only about 1%; and the exceedance rate of Cd was 12.5%. Soil Cd concentration increased gradually whereas the concentration and exceedance rate of Cd in rice grains decreased gradually with the increase of soil pH. Specifically, the exceedance rate of Cd in rice grains was only 4% when soil pH6.5. The results indicated that the risk screening values of Cd element in the Chinese Soil Environmental Quality Standard are not satisfactorily applicable to the ecological risk assessment of Cd in karstic soils. Therefore, the recommended threshold values for the safe utilization and risk control of Cd in karstic soils was proposed so as to provide a basis for soil environmental quality hierarchization, pollution risk control and land safety zoning of agricultural land in karst areas in China.     

准噶尔盆地南缘深层侏罗系储层沥青成因及其对油气成藏的启示

准噶尔盆地南缘深层下组合(下白垩统吐谷鲁群泥岩之下的储盖组合)勘探潜力大,但勘探程度较低。独山子背斜位于四棵树凹陷的东部,在该背斜浅层的新近系沙湾组砂岩发现了准南最早的油田,而对其深层油气成藏的潜力尚有待研究。深探井独山1井钻探至上侏罗统齐古组(J₃q)储层,在6410～6418m上侏罗统齐古组岩心发现大量沥青沿着断裂面及其周围裂缝定向分布。通过有机地球化学分析,发现独山1井J₃q储层沥青抽提物的Pr/Ph值主要分布在0.12～3.48之间,δ¹³C值多数集中分布在-29.9‰～-25.3‰之间;部分沥青抽提物的γ-蜡烷谱峰明显且存在异构体;规则甾烷C₂₉明显占优势且重排甾烷丰富;烃类是侏罗系和下白垩统烃源岩产生原油的混合产物。通过储层沥青产状、R_b、拉曼光谱及烃类包裹体GOI指数、储层定量颗粒荧光等实验分析,发现独山1井深层下组合存在两期油气运移,但未形成规模油气聚集。四棵树凹陷侏罗系和下白垩统烃源岩在新近纪开始大量生烃,且构造圈闭发育,有利于晚新生代油气成藏,但独山1井位于...     

Three-dimensional modelling of soil organic carbon density and carbon sequestration potential estimation in a dryland farming region of China

Soil organic carbon density(SOCD) and soil organic carbon sequestration potential(SOCP) play an important role in carbon cycle and mitigation of greenhouse gas emissions. However, the majority of studies focused on a two-dimensional scale, especially lacking of field measured data. We employed the interpolation method with gradient plane nodal function(GPNF) and Shepard(SPD) across a range of parameters to simulate SOCD with a 40 cm soil layer depth in a dryland farming region(DFR) of China. The SOCP was estimated using a carbon saturation model. Results demonstrated the GPNF method was proved to be more effective in simulating the spatial distribution of SOCD at the vertical magnification multiple and search point values of 3.0×10~6 and 25, respectively. The soil organic carbon storage(SOCS) of 40 cm and 20 cm soil layers were estimated as 22.28×10~(11) kg and 13.12×10~(11) kg simulated by GPNF method in DFR. The SOCP was estimated as 0.95×10~(11) kg considered as a carbon sink at the 20–40 cm soil layer. Furthermore, the SOCP was estimated as –2.49×10~(11) kg considered as a carbon source at the 0–20 cm soil layer. This research has important values for the scientific use of soil resources and the mitigation of greenhouse gas emissions.     

Extreme Cold Events in North America and Eurasia in November-December 2022: A Potential Vorticity Gradient Perspective

From 17 November to 27 December 2022, extremely cold snowstorms frequently swept across North America and Eurasia. Diagnostic analysis reveals that these extreme cold events were closely related to the establishment of blocking circulations. Alaska Blocking(AB) and subsequent Ural Blocking(UB) episodes are linked to the phase transition of the North Atlantic Oscillation(NAO) and represent the main atmospheric regimes in the Northern Hemisphere. The downstream dispersion and propagation of Rossby...