Variations of the temperatures and volumetric unfrozen water contents of fine-grained soils during a freezing–thawing process

Acta Geotechnica - In this study, the variations of the temperatures and volumetric unfrozen water contents for two fine-grained soils (i.e., silty clay and silt) with high degrees of saturation...     

“Soil arching” for piled embankments: insights from stress redistribution behaviour of DEM modelling

Acta Geotechnica - For piled embankments, it is widely recognised that the majority of embankment load can be transferred to the piles through the “soil arching” mobilised in the...     

Yellow diamonds with colourless cores – evidence for episodic diamond growth beneath Chidliak and the Ekati Mine,Canada

Mineralogy and Petrology - Yellow diamonds from the CH-7 (Chidliak) and the Misery (Ekati Mine) kimberlites in northern Canada are characterised for their nitrogen characteristics, visible light...     

贝壳的傅立叶变换红外光谱和热分析

通过傅立叶变化红外光谱(FT-IR)、X射线衍射(XRD)和差热(DSC)等技术分析了蜘蛛螺贝壳粉末的成分和热行为。XRD和DSC结果表明蜘蛛螺贝壳是由文石型碳酸钙构成,在300℃文石转变为方解石。红外光谱表明在海螺壳的有机质中存在NH,OH和amide等官能团,在文石晶格或有机与晶体的界面处存在HCO3-原子团。加热后的FT-IR特征峰的峰型和峰位表现出明显的变化,这些变化说明在250℃加热1 h后贝壳的有机质部分发生分解;在500℃～600℃时海螺壳中的有机质仍然没有完全分解,揭示出贝壳具有良好的热稳定性。     

山东文登金矿成矿条件及成矿过程─—阴极发光技术在包裹体研究中的应用

使用阴极发光技术可取得一般岩石显微镜无法得到的地质信息，并可将包裹体的研究从原来的“群分析”统计规律研究水平提高到“单包体分析”水平，获得更小时间单位成矿流体的演化特征，因而能更准确地模拟和恢复地质作用过程。运用阴极发光对石英等矿物的研究，发现蚀变带中的石英按不同的形态特征和发光性可以分为三期，和成矿关系密切为第一、二期石英。根据阴极发光下显示的生长微形态，系统地测试三期石英不同生长时期的包裹体物相，从而获取了整个成矿过程流体的ｐ—ｔ—υ—ｘ参数，确定构造作用加热大气降水形成成矿流体，体系开放流体两次减压沸腾导致金矿沉淀的矿体定位机理和成矿动力学机制。     

鄂尔多斯盆地东胜地区地浸砂岩型铀矿成矿模型

地浸砂岩型铀矿床是一种具有重要经济价值的铀矿类型,受到世界各国地质勘探部门的高度关注。近年来,鄂尔多斯盆地在石油和天然气勘查取得重大进展的同时,于盆地东胜地区也发现大规模地浸砂岩型铀矿床,标志着中国该类型铀矿勘查取得重要突破。该文应用地球化学综合分析研究,获得成矿流体的温度、盐度条件和同位素地球化学参数。含铀砂岩中碳酸盐胶结物C-O同位素测试结果表明,胶结物中的碳属于地幔碳、生物有机体和沉积的碳酸盐混合成因。通过流体包裹体H-O同位素分析,表明成矿流体可能是原生的岩浆水上涌和大气降水混合形成的建造水,其中一部分有机质加入到成矿作用中来,这对于铀的还原具有重要的意义。结合盆地的演化特点,建立了这种砂岩型铀矿的成矿地球化学模型。笔者认为,其铀矿的形成机制可以分为两个过程,一是氧化过程,二是还原过程,成矿过程伴随各种微量元素和气液相分子的氧化、还原和迁移过程。该成矿模型的建立对认识盆地铀矿质的沉淀和富集规律以及在类似盆地寻找此类铀矿床,具有理论和现实意义。     

Outflow sediment concentration forecasting by integrating machine learning approaches and time series analysis in reservoir desilting operation

Stochastic Environmental Research and Risk Assessment - During typhoons, outflow sediment concentration at dam outlets should be accurately forecast for increasing the efficiency of turbidity...     

Formation of a giant Zn–Pb deposit from hot brines injecting into a shallow oil–gas reservoir in sandstones,Jinding, southwestern China

The association between mineralisation and hydrocarbons in sedimentary basins is widely recognised, but the nature and significance of their relationships are not fully understood. This paper provides an example of metalliferous brines injecting into a palaeo‐oil–gas reservoir to form a world‐class Zn–Pb deposit (Jinding, China). Petrographic and microthermometric studies of oil inclusions and PVT simulations suggest that oil and gas were charged in a shallow (<1300 m) environment before mineralisation. This environment favoured bacterial sulphate reduction (BSR), which produced large amounts of H₂S that accumulated in the gas cap. Forceful injection of hot brines penetrated the oil zone to reach the H₂S‐rich gas cap and precipitated sulphide ores. Individual fluid injection events were short‐lived, and the reservoir was only partly and briefly heated to beyond the bacterial survival temperature. Episodic injection of metalliferous brines and sustained supply of H₂S through BSR resulted in the formation of a large Zn–Pb deposit.     

Late‐Quaternary history of ‘great lakes’ on the Tibetan Plateau and palaeoclimatic implications – A review

Geomorphic evidence suggests that shorelines of 100–200 m above the modern lake levels were common across the Tibetan Plateau during late Marine Isotope Stage (MIS) 3. The timing of this lake‐level highstand is mainly based on radiocarbon ages. Problems surrounding the ages of lacustrine sediments at or beyond the limit of the radiocarbon‐dating method have created a need for alternative geochronometers. Chronological advances during the last decade have renewed interest in the timing of events beyond the limit of radiocarbon dating. Here, we synthesize published data for elevated lacustrine landforms of 48 lakes on the Tibetan Plateau, in order to provide a thorough perspective on the timing and pattern of lake‐level changes in this alpine area during the late Quaternary. The ages of these elevated shore features reveal a long‐term trend of relative lake‐level fall from at least MIS 5, instead of a peak in MIS 3, as previously thought. Dating lacustrine terrace sequences reveals that the rate of lake‐level fall ranged from ~1 to 3 mm a^?1, comparable with that of related river downcutting across the plateau. Palaeoclimatic proxy records point to a sustained drying since the Last Interglacial, suggesting that long‐term aridification might be the culprit for this widespread and progressive lake‐level fall.     

中全新世黄河流域耕地格局重建及对原生植被的影响(英文)

Yangshao culture is the most important mid-Holocene Neolithic culture in the Yellow River catchment,and thus,a study on the impact of human activities on the environment is important.In the current study,the distribution pattern of the cultivated land in late Yangshao culture is reconstructed using GIS tool and site domain analysis(SDA).The results show that the cultivated land during 5.5-5.0 ka BP was mainly distributed in the Weihe River valley,Luohe River valley,northwestern Henan Plain,Fenhe River valley and eastern Gansu region,especially concentrated in the Xi’an-Baoji line of the Weihe River valley.At that time,at least 37,000 km 2 of lands were reclaimed in the middle and lower reaches of the Yellow River,and 132,000 km 2 of lands were affected by agricultural activities.Human activities had become the driving force of land use/land coverage.Charcoal records indicate that the ancestors of Yangshao culture burnt forests for reclamation,leading to the decrease of arbor pollen at 5 ka BP in core areas of the Yangshao culture.The areas that were significantly affected by human activities accounted for 3.2% of the Yangshao culture influenced area,while the moderately affected areas accounted for 20.1% of Yangshao culture influenced area.Meanwhile,92% of the land areas on the edge and outside of the Yangshao culture influenced area were not affected by human activities.The arbor pollen in these areas did not decrease until 4.0 ka BP.