库车盆地早始新世成盐期卤水温度及其意义

古气候和古卤水温度条件与盐湖成钾有着密切的联系,定量化重建库车盆地早始新世成盐期古卤水温度演化特征对评价盆地成钾潜力具有重要的科学意义.因此,首次以库车盆地西部QL1井下始新统石盐岩为研究对象,在详细的岩相学研究的基础上,开展石盐原生流体包裹体均一温度的定量分析工作.分析结果显示,来自钻孔不同深度的6个样品共有135个均一温度数据,介于21.2~57.8℃,平均值为31.8℃,剖面垂向上自底向顶整体上呈现一个稍微升温的趋势.本研究测定的温度范围、平均温度以及最高温度特征均与同时期特提斯海水温度数据吻合,进一步说明温度数据的可靠性和合理性.另外,高温条件有利于水体发生强烈的蒸发浓缩作用,这点与库车盆地始新世初期沉积的巨厚蒸发岩系和钾盐矿物相符.      

基于3S技术的甘肃省耕地质量等别监测评价研究

为全面掌握甘肃省耕地质量变化情况及其驱动因素,从宏观层面上建立"省-区-县-渐变类型区-地块"监测体系,以甘肃省标准耕作制度三级区为单位选取监测县,运用"重点分等因素划定"方法划分监测县耕地等别渐变类型分区、确定驱动因素,通过在县域范围内布设监测单元,对监测单元耕地质量渐变的驱动因素进行监测,并对其引起的耕地质量等别渐变做出趋势性评价。最后,以监测县耕地质量变化情况为基础,运用克里金空间插值方法对甘肃省耕地质量进行空间局部估计,对耕地质量变化空间分布进行特征分析。结果表明：（1）相比2015年耕地质量评价成果,全省监测县耕地等别平均提高了0.14等。河西走廊区中部、陇南山区南部等别有较大幅度提高;晋陵丘陵沟谷区、陇东黄土旱塬区东部、甘南高原区中部等别有较大幅度降低;南部地区变化的幅度整体高于北部地区。（2）甘肃省耕地土壤有机质含量差异较大,且整体偏低;全省耕地类型以旱地为主,耕地灌溉保证率多为一般满足和不满足,但得益于近年来全省修建大型引、供水工程,全省耕地灌溉保证率有了提高;耕地质量分布区域性特征明显。     

Classification,formation, and transport mechanisms of mud clasts

Mud clasts are common in non-marine to marine sedimentary records, however, why lack a widely accepted classification scheme? We propose that it is the relative balance of volumetric abundance, sorting, roundness, and grain size that controls the texture and fabric of mud clasts. Nine distinct types of mud clasts are identified in the study based on quantitatified properties, and fall into two groups coarse-grained and fine-grained. The generation of mud clasts can be assigned to failure, erosion, and/or bioturbation of muddy sediment. These clasts are transported within fluid flows including Newtonian fluids, non-Newtonian fluids, and Bingham plastics (gravity flow and turbidity flow), showing various physical characteristics depended upon the density and viscosity of flows. Newtonian flows with less density and viscosity commonly form mud clasts with mature textures. In non-Newtonian (gravity-driven) flows, mud clasts are normally transported in laminar flows with high density and viscosity, developing matrix-supported mud clasts with immature textures. The study of classification, formation, and transport mechanisms of mud clasts has implications for identifying and interpreting sedimentary environments.     

A Cretaceous Desert-Playa Sedimentary System Controlled the Potash Formation in the Simao Basin

<正>Objective The Simao Basin in Yunnan Province has developed Cretaceous evaporite-bearing clastic deposits,including the Mangang and Mengyejing Formations which were originally interpreted as fluvial and lacustrine deposits.The Mangang Fm.composed of well-rounded quartz sandstones,were commonly considered as the bottom part of the Mengyejing salt series.During last decades,drilling projects targeting to prospect solid potash deposits in the Mengyejing salt series consequently ceased when encountering these sandstones.The poor understanding of sedimentary environments leads to no breakthrough of prospecting solid potash deposits in the Simao Basin.Our     

柴达木盆地东部上泥盆统—下石炭统沉积分异特征及其主控因素讨论

泥盆系/石炭系是广泛的不整合界面.在我国柴达木盆地东部,上泥盆统至下石炭统呈现明显的沉积分异,这种差异代表着晚泥盆世以来沉积环境巨大变迁.为探究二者之间的差异和内在联系,本次利用岩石学研究手段,通过柴达木盆地东部上泥盆统与下石炭统的岩石组合、分布及岩相对比,刻画晚泥盆世至早石炭世沉积物质空间分布特征,并结合地质背景讨论...     

Hydrological Variations and the Ancient Silk Road in the Northern Tarim Basin between Han and Sui Dynasties

The fluctuation pattern of China's civilization can be ascribed to climate change and historical geopolitical variations. The ancient Silk Road served as the most prosperous route connecting East Asia and Europe during Han Dynasty(206 BC–220 AD) and Sui-Tang Dynasties(581–907 AD), but was deserted in Wei, Jin, Northern and Southern dynasties(220–580 AD), of which the Tarim Basin was a key area. However, our understanding about the decline of the route during this period remains limited. Here, we present an ～7-year resolution record based on optically stimulated luminescence(OSL) age-depth model(ca. 120 BC–750 AD) from Luntai(LT) profile, about 5 km from the modern Tarim River, which fed the ancient oases, to assess the potential causes on the documented decline of the ancient Silk Road between Late Han and Sui dynasties. In this study, five episodes of hydrological change were identified by combining grain size, magnetic susceptibility, geochemistry and TOC/TN contents. Our reconstruction reveals that cold and wet climate dominated at 120 BC–50 AD and 550–750 AD, respectively, indicated by strong hydrodynamic conditions. Relatively warm and humid climate occurred at 120–550 AD, between Eastern Han and Sui-Tang dynasties, indicating a better and more suitable local environment. A comparison between the studied region and other areas of China demonstrates that the paleoclimatic variations in eastern and western China exhibit rough discrepancies, and the hydrological conditions in arid region is inconsistent with the decline of ancient Silk Road in the northern Tarim Basin. We suggest that political and societal factors are the key issues that caused the interruption of Silk Road during Wei, Jin, Northern and Southern dynasties, such as the co-occurrence of societal crises, turmoil and division in eastern China, rather than the deteriorating climatic condition in the northern Tarim basin.     

四川盆地富顺-永川地区五峰组—龙马溪组应力场模拟及裂缝发育区预测

岩石中构造裂缝主要受控于地层所处的区域构造应力场,地应力对油气的运移、成藏和分布有着重要的作用。通过应用ANSYS有限元数值模拟方法对四川盆地富顺-永川区块的五峰组-龙马溪组进行应力场模拟及分析研究、应用构造曲率法中的三点法对该层段页岩进行张裂缝发育情况预测研究、综合模拟结果与曲率计算数据对目的区域目的层段进行裂缝发育强度综合预测研究,结果表明富顺-永川区块五峰组-龙马溪组应力高值沿背斜走向分布的规律明显,研究区的东部及西南部的背斜应力值较其他区域背斜高;曲率高值沿背斜走向分布的规律明显,研究区东部及西南部背斜曲率值较其他区域背斜高;在现今应力的作用下,研究区背斜处裂缝发育程度较高,向斜处裂缝发育程度较低,研究区东部及西南部背斜裂缝发育程度较其他区域高。      

Thermal History since the Paleozoic in the Eastern Qaidam Basin,Northwest China

The Qaidam Basin is the one of the three major petroliferous basins in northeastern Tibetan Plateau, which has experienced multiphase superimposition and transformation. The study of thermal history not only plays an important role on revealing the tectonic origin of the Qaidam Basin and the forming mechanism and uplift history of the Tibetan Plateau,but also can provide scientific evidence for the assessment of oil and gas resources. This work used balanced cross-section technique and apatite fission track ages with modeling of fission track length distribution to infer that the eastern Qaidam Basin has experienced significant tectonic movement in the Early Jurassic movement(～200 Ma), which caused the carboniferous uplift and denudation, the geological movement in the Late Cretaceous, characterized by early stretching and late northeast-southwest extrusion; the Himalayan movement in multi-stage development in eastern Qaidam Basin, which can be divided into the early Himalayan movement(41.1–33.6 Ma) and the late Himalayan movement(9.6–7.1 Ma, 2.9–1.8 Ma), and large-scale orogeny caused pre-existing faults reactivated in late Himalayan movement. On the basis of burial history reconstruction, the thermal history of eastern Qaidam Basin was restored. The result shows that the thermal history in eastern Qaidam Basin shows slow cooling characteristics; the paleo-geothermal gradient of eastern Qaidam Basin was 38–41.5℃/km, with an average value of 39.0℃/km in the Late Paleozoic, 29–35.2℃/km, with an average value of 33.0℃/km in the Early Paleogene; the geothermal gradient of the Qaidam Basin increased in the Late Paleogene, which was similar to the present geothermal gradient in the Late Neogene. The characteristics of the tectono-thermal evolution since Paleozoic in the eastern Qaidam Basin are mainly controlled by magmatic thermal events in the study area.     

基于岩体结构特征和未确知测度评价模型的岩质开挖边坡稳定性研究

综合黔西地区层状岩质开挖边坡研究成果发现:岩体结构特征是分析评价层状边坡变形失稳模式、机制和稳定性的重要基础。因此,结合该地区层状边坡地质条件的差异性,针对性地划分岩体结构类型对边坡的分析评价尤为重要。考虑地层岩性组合、地质构造、软弱夹层（结构面）因素,系统地将边坡岩体结构类型分为4个大类（近水平-缓倾边坡岩体,倾斜层状边坡岩体,陡倾、直立、倒转层状岩体,地质构造作用强烈或含有溶蚀洞穴、沟壑的边坡岩体）和10个亚类,并针对相应类型的边坡进行工程地质综合评价,分别阐述了失稳模式和机制。以边坡岩体结构类型为基础,甄选影响开挖边坡稳定性的6个定性指标和6个定量指标;对指标组合赋权,用未确知测度理论对边坡进行稳定性预测评价,建立了“岩体结构-指标组合赋权-未确知测度理论”的新评价体系。实例预测结果表明预测结果与实际情况具有较好的一致性,说明该方法是一种可靠性高、科学合理的稳定性预测新方法,可在相关工程领域中应用推广。     

湖北江陵凹陷古新统沙市组四段硫酸盐硫同位素组成及其地质意义

江汉盆地江陵凹陷古新统沙市组四段硬石膏和钙芒硝中硫同位素组成为25.2‰~32.6‰,远远高于同时期海水硫同位素(20‰)。结合研究区古新统沙四段蒸发岩⁸⁷Sr/⁸⁶Sr研究,借助Mg、Ca、Sr、Ba等元素及其Mg/Ca、Sr/Ba,认为江陵凹陷沙四段时期湖盆为封闭的陆相盐湖。根据典型暖相盐类矿物(原生钙芒硝)的广泛发育和指示气候干旱程度的Fe₂O₃/FeO特征,可以推断研究区在沙市组四段沉积晚期的古气候属于暖旱型气候。在温暖干旱的气候环境下,硫酸盐沉积物供给率较低,因此当时的沉积环境对硫酸盐是封闭的。通过Fe、Mn、Al、 Mg、Ca、Ni、V 、Co、Cu等主微量元素以及Fe/Mn、(Fe+Al)/(Ca+Mg)、w(V+Ni+Mn)、V/(V + Ni)、Ni /Co、Cu/Zn的研究表明,研究区沙市组四段环境为湖盆浪基面之下的缺氧还原环境,为常年性较深水分层湖泊。上述缺氧沉积环境下存在大量的厌氧细菌,表生（≤50 ℃）条件下,厌氧细菌使硫酸盐SO^2-₄还原成H₂S,后者与金属离子结合形成硫化物或直接从体系中逸出,再加上当时的内陆环境对硫酸盐是相对封闭的,这种硫循环过程是造成研究区硬石膏和钙芒硝硫同位素值较高的原因,也是研究区最重要的硫同位素分馏过程。