云南大理点苍山地区晚更新世以来的古植被和古气候

根据云南大理点苍山地区晚更新世沉积地层中的古植被的孢粉化石鉴定，结合孢粉图示的综合分析以及孢粉组合带的划分，探讨了该地区自晚更新世以来古植被的演替过程，并在此基础之上对古气候的波动过程进行了初步推测，结论显示自122-118Ka.BP的湿热气候期之后，该地区的气候演变经历了7次从冷-湿热的气候波动旋回。     

江淮东部平原晚更新世末植被演替及气候变化

在对位于江淮东部平原的江苏兴化蒋家舍地层剖面进行野外考察采样、AMS14 C年代测定和孢粉分析的基础上,初步探讨了研究区晚更新世末的植被演替及气候变化.结果表明:1)27.9-13.5cal.ka BP,剖面中孢粉含量高,植物的科属也丰富.其中,27.9-26.7cal.ka BP、14.5-14.2 cal.ka BP时段研究区植被为针阔叶混交林,反映气候温暖较湿润,而26.7-14.5 cal.ka BP期间地层出现沉积间断,气候寒冷干燥;14.2-13.5 cal.ka BP时段草本植物含量较高,总体为针阔叶混交林草原植被,气候温凉稍干.2)13.5-12.6cal.ka BP,剖面中孢粉含量较低,植物的科属也较贫乏,木本植物所占百分比较低,草本植物花粉含量相对较高.其中,13.5-12.8 cal.ka BP为覆盖度趋低的针阔叶混交林或草原植被,气候向干冷发展,12.8-12.6 cal.ka BP时段为针阔叶混交林植被,木本植物含量有所上升,反映气候稍暖湿.3)针叶乔木松属花粉和蕨类植物水蕨科植物孢子在剖面中自下而上均有不同程度的分布,常绿阔叶和落叶阔叶类出现率较低,这种现象跟当地现代植被的植物组合略有差异.     

一万年以来陕西富平的植被与气候环境演化

通过对黄土高原中部的陕西富平剖面的地质调查、密集采样和31个样品的孢粉分析,显示了该地区全新世植被和气候环境的演化阶段。将孢粉图式划分为Ⅰ、Ⅱ、Ⅲ三个带分别代表早、中、晚三个时期的孢粉带:Ⅰ带为松—菊—香蒲组合带,以草本植物花粉占优势,针叶树植物花粉含量较高为特征;Ⅱ带为松—栎—蒿—环纹藻组合带,以乔木花粉增加,草本植物花粉减少为特征;Ⅲ带为栎—松—蒿组合带,以草本植物花粉增加,乔木花粉减少为特征。结果表明:早全新世植被为森林草原—干草原,气候干凉—干冷;中全新世植被为森林草原与针阔叶混交林草原,气候温暖半湿润;晚全新世植被为森林草原或疏林草原,气候干旱偏暖—温凉干旱。     

山西省五台山地区晚更新世以来环境演变的研究

五台山属华北中、高山类型,晚更新世以来受新构造运动及气候的影响,垂直地带变化极为明显,在1700m以上山地形成一系列冰缘地貌类型;对山间盆地出露晚更新世以来的沉积物及孢粉分析,可恢复本区环境演变的过程。     

晚更新世以来渤海湾沿岸的海进海退及古气候环境

晚更新世以来渤海湾沿岸的海进海退及动植物的演化与组合关系，反映了当时的古气候环境。     

陕西洛南中晚更新世根田鼠化石

目的研究陕西洛南张坪洞穴群中发现的根田鼠化石M icccrotus oeconomus。方法运用经典古生物学方法,包括化石解剖、系统描述、形态对比、统计归纳。结果M3舌侧3褶沟4褶角;m1有4个封闭的三角,第5个与前帽贯通,后环位于齿列纵轴上;m3唇侧3褶角;M3和m1的长度、宽度从第6层洞到第1层洞逐渐变大,第6齿峡(Is6)的宽度变小。结论化石的主要特征可与周口店第1地点的M.epiratticeps相对比,主要测量值在现生种的变异范围之内,确定为中更新世以来不同时段的根田鼠化石,其颊齿趋于增大,第6齿峡趋于变窄。     

长江三角洲晚更新世末期古土壤与古环境

长江三角洲地区第一暗绿色硬粘土层是上海地区主要建筑持力层之一，也是划分全新统与更新统的标志层，前人已做过大量研究，但尚缺乏古土壤方面的系统研究工作，本文首次从古土壤学的角度系统研究了该层的古土壤特征，通过粒度分析发现有粘粒的生成，微形态研究发现有粘粒及铁锰、碳酸盐等化学组分的迁移与淀积，化学全量分析得出该层的硅铝率为２．８０￣３．３７，说明该层已发生较强的成土作用，可以确认该层为古土壤层，并地一步     

晚更新世以来黄土高原地区的环境变迁

晚更新世以来自然环境的变化直接影响着黄土高原国土资源的开发利用。本文在研究晚更新世以来环境演化过程、人类活动与环境演化、自然环境与地面侵蚀的关系基础上,提出了黄土高原国土整治的战略。     

陕北地区退耕坡地植被恢复技术及效益评价

目的 为了给黄土高原地区生态环境恢复和林业生态工程建设提供技术指导。方法 对该地区“退耕还林”工程中存在的技术问题进行了调查分析。结果 提出了陕北地区退耕坡地植被恢复技术方案，包括适宜优良树草种选择及造林技术、林种树种的水平和垂直配置技术、以蓄水保墒为中心的抗旱造林技术和混交林营建技术等，并对预期达到的生态、社会效益进行了评价。结论 该方案对黄土高原地区生态环境恢复和林业生态工程建设具有指导意义。     

Atlantic overturning responses to Late Pleistocene climate forcings

The factors driving glacial changes in ocean overturning circulation are not well understood. On the basis of a comparison of 20 climate variables over the past four glacial cycles, the SPECMAP project proposed that summer insolation at high northern latitudes (that is, Milankovitch forcing) drives the same sequence of ocean circulation and other climate responses over 100-kyr eccentricity cycles, 41-kyr obliquity cycles and 23-kyr precession cycles. SPECMAP analysed the circulation response at only a few sites in the Atlantic Ocean, however, and the phase of circulation response has been shown to vary by site and orbital band. Here we test the SPECMAP hypothesis by measuring the phase of orbital responses in benthic delta(13)C (a proxy indicator of ocean nutrient content) at 24 sites throughout the Atlantic over the past 425 kyr. On the basis of delta(13)C responses at 3,000-4,010 m water depth, we find that maxima in Milankovitch forcing are associated with greater mid-depth overturning in the obliquity band but less overturning in the precession band. This suggests that Atlantic overturning is strongly sensitive to factors beyond ice volume and summer insolation at high northern latitudes. A better understanding of these processes could lead to improvements in model estimates of overturning rates, which range from a 40 per cent increase to a 40 per cent decrease at the Last Glacial Maximum and a 10-50 per cent decrease over the next 140 yr in response to projected increases in atmospheric CO(2) (ref. 4).     

New evidence for human occupation of the northern Tibetan Plateau, China during the Late Pleistocene

The described stone artifacts are recovered from the 70 m-high terrace (4600 m a.s.l.) at the southeastern shore of the Siling Co on the northern Tibetan Plateau. The terrace was formed during the Interstadial period before the LGM, ca. 40-30 ka B.P. based on paleoenvironmental research. The Paleoliths from the Siling Co provide evidence for early human occupation of the northern Tibetan Plateau. They show technological and typological affinities with the European Middle Paleolithic suggesting that the early human occupation here might relate to migratory waves during the Late Pleistocene that dispersed humans across the Old World.     

New views on age of the Salawusu Formation of Late Pleistocene in northern China

The Salawusu Formation in the Salawusu River basin of Inner Mongolia is a typical sequence of the Upper Pleistocene in northern China. However, there have been some different views about the division and age of stratigraphic facies since the establishment of the Salawusu Formation. According to the stratigraphic subdivision and dating of the Dishaogouwan section, it is thought that the fluviolacustrine-aeolian sand sequence from the Dishaogouwan section can be compared with loess, deep-sea deposit records and climatic fluctuations of glacial period. The Salawusu Formation of fluviolacustrine facies was formed in the last interglacial period from 140 to 70 ka BP, roughly corresponding to the fifth stage of deep-sea oxygen isotope, and developed in the same period as the palaeosol S1 on the Loess Plateau; the aeolian sand of the Chengchuan Formation was formed in the last glacial period from 70 to 10 ka BP, constituting the heteropic geological body along with the Malan Loess on the Loess Plateau; the fluviolacustrine deposit and black soil of the Dagouwan Formation and the Dishaogouwan Formation was formed in the Holocene warm period from 9 700 to 3 000 a BP, or developed in the same period as the plaeosol B1 on the Loess Plateau.     

基于目标规划方法的陕北地区坡耕地种植结构研究

在对陕北地区坡耕地种植现状研究的基础上,采用目标规划方法,建立陕北地区坡耕地种植利润最大的目标规划模型,通过转化为线性规划模型,得出最优解.以横山县土地类型最具代表性的乡镇为例进行实证分析,生成研究范围内的最优种植方案.     

Vegetation and climate change during Marine Isotope Stage 3 in China

Fossil pollen records from 45 sites across China were evaluated and synthesized to document Vegetation and climate change during Marine Isotope Stage 3 （MIS 3） at 60-27 ka and to understand the large-scale controls. During MIS3, vegetation type was dominantly forest in eastern China, forest steppe/meadow in the north and Tibetan Plateau, and steppe desert in northwestern arid China. We developed a semi-quantitative vegetation index to reflect change in plant abundance （by inferring the general climate conditions）, with a vegetation score from 1 to 3 based on the different vegetation types inferred from pollen data at individual sites at intervals of 2,000 years.The reconstructed vegetation index shows higher values during MIS 3, especially during the period 53-40 ka, than at the Last Glacial Maximum. Our results also suggest that climate on the basis of vegetation change was cooler and drier during MIS 3 than during the Holocene optimum; however, MIS 3 vegetation was probably similar to modern vegetation. The close relationship between vegetation change, insolation and Asian summer monsoon strength suggests that climate variations, probably in both temper- ature and precipitation, are the primary drivers of regional vegetation change. Additional well-dated, high-resolution palaeoclimate records from many locations across China will be needed to understand the vegetation change and climate forcings on millennial and centennial scales within MIS 3.     

陕北志丹地区前侏罗纪古地貌及其控制作用

综合运用印模法、残厚法及沉积法等将志丹地区前侏罗纪古地貌划分为侵蚀高地、侵蚀斜坡、侵蚀沟谷以及侵蚀残丘四个基本单元.研究结果表明:前侏罗纪古地貌对印支侵蚀不整合面上下之地层、构造、沉积、储层以及油气成藏特征等都具有重要的控制和影响.侵蚀面之下的长2油层组顶面剥蚀构造特征较好地反映了印支古地貌的基本格局;侵蚀面之上的延安组早期的沉积是前古地貌发育的镜像反映;而延10顶面构造则具有围绕古高地背景集中发育的特点.古高地与斜坡发育区是侵蚀面上下油气富集成藏的有利指向和主要场所,而深切的沟谷则为沟通下部油源以及油气运移提供了主要通道.油藏类型主要为地层-岩性油藏、构造-岩性油藏以及小而局限的构造、岩性油藏等.     

陕北神木北部矿区构造发育规律

根据陕北神木北部矿区的172个钻孔资料,采用趋势分析方法,对矿区主采煤层5-2煤层底板标高进行趋势分析.在此基础上,揭示了矿区内整体构造特征,并对构造发育规律及其成因作了初步分析.矿区内总体构造为一向西倾伏的宽缓向斜,倾角为1～3°;大型次级褶皱共有5条,均为宽缓褶皱,轴向在NWW桸W,平面上呈平行式分布;大中型断层11条,其中查明的有7条,均为张性正断层,走向近NW桽E向,延伸小于16 km,断距10～80 m,倾角55～80°,推测断层有4条,均为张性正断层,平面上呈雁列式分布.这些构造样式是由三期构造运动形成的.     

陕西秦岭以北地区高氟地下水的成因与防治研究

根据陕西秦岭以北地区高氟地下水分布状况，分析了该地区高氟地下水的分布规律．结果表明，高氟地下水的形成原因主要是受地层岩土、地貌、气候、水文地球化学和地质构造等条件的制约．提出了防氟改水措施是以在陕北打窖、关中打井为主，其次伴以理化除氟等方法．