云南境内澜沧江流域土地利用时空变化特征及动因分析

    澜沧江-湄公河是一条集内河、界河、国际河流为一体的河流。云南境内澜沧江流域涉及云南西部 7个地州39个县市。复杂的地形地貌结构和多种气候带,形成植被垂直分布和地域分布的特点,呈现出多样性变化特征;域内94％为山区;占流域人口83％的民族（18个少数民族）大分散小聚居立体分布在山区,土地资源一直是他们赖以生存的最主要的生产生活资料,不同民族土地利用习俗,使流域内土地利用格局呈现出多元化特征。在这样一个边疆山区民族地区,寻求一条多元民族文化下土地资源合理利用和可持续发展战略,是加强民族团结,寻求均等发展机会脱贫致富,实现各民族共同繁荣和富裕的关键。
    采用遥感（RS）、地理信息系统（GIS）、全球卫星定位系统（GPS）高新技术,典型地区启用了快速农村评估（PRA,RapidRuralAppraise）方法,对流域1990年、1998年土地利用现状及空间结构演变进行了时空动态叠合研究、森林土地时空动态的整体演变研究以及变化动因分析,在此基础上,就多元民族文化下土地利用人地系统演变和流域发展的关联问题,提出一些看法,仅供商榷。     

青藏高原东北部新近纪古流向与物源分布对隆升的响应

通过对青藏高原东北部11个新近纪沉积盆地的沉积相演化、古流向和物源演变的详细对比研究,揭示了研究区新近纪4次沉积演变与构造隆升的响应.①中新世早期(23～19.5Ma):阿牙克库木湖、柴达木、德令哈和酒泉盆地的古流向和物源分析表明东昆仑和阿尔金已经抬升成剥蚀区.循化、贵德和临夏等盆地物源和古流向指示西秦岭和拉脊山也已成为隆起区.区域上整体地势差异不显著.②中新世早中期(17.5～15Ma):区域湖盆面积扩大,阿牙克库木湖、索尔库里、柴达木和酒泉盆地的资料反映东昆仑、阿尔金和祁连山已经全面隆升,贵德循化、临夏盆地的古流向反映为盆地周缘型,指示西秦岭和拉脊山明显抬升,区域差异隆升造成盆地凹陷扩张进入湖泛期.③中新世中晚期(10～7Ma):阿牙克库木湖、索尔库里、柴达木和酒泉盆地沉积物的粒径和沉积速率增大,与热年代学证据一致,揭示出阿尔金山和祁连山进一步快速隆升.贵德、循化和临夏盆地古流向和物源反映为显著的多源性,除西秦岭和拉脊山外,位于循化和临夏两盆地间的积石山也开始隆起.④上新世(5.3Ma以来):索尔库里、柴达木和酒泉盆地古流向没有明显变化,沉积速率和粒径继续增大,阿尔金和祁连山加速隆升为高海拔地貌.贵德盆地主物源区是拉脊山.区域上,地势差异加强,湖盆被肢解后逐步萎缩消亡.     

Major element geochemistry of purple soils/rocks in the red Sichuan Basin, China: implications of their diagenesis and pedogenesis

Major element compositions and chemical weathering features of the purple soils and their corresponding rocks in the Red Sichuan Basin, China were studied in this paper to infer the diagenetic features of the purple rocks and the pedogenetic features of the purple soils. The results showed that all of the rock and soil samples, except those from Yibin, have strongly similar major element compositions and the distribution patterns of their major element compositions are similar to those of the upper continental crust. Chemical index of alteration, chemical index of weathering and Na₂O/K₂O indicate that the purple soils and rocks have similar chemical weathering intensities, whereas the Al₂O₃–CaO* + Na₂O–K₂O (A–CN–K) relationship, suggests that chemical weathering was strong during diagenesis of the purple rocks, but weak during pedogenesis of the purple soils. Variations in major element compositions of the purplish rock samples, except that from Yibin, do not primarily reflect differences in compositions of the sediment source, sediment recycling and potassium metasomatism, and therefore the effects of chemical weathering on the major element compositions were mainly dependent on climate condition and the residence time of material exposed to chemical weathering. Chemical weathering of the purple rocks reached only moderate degrees under the general influence of warm and humid climate during Jurassic and Cretaceous. Warmer and more humid climate conditions partly resulted in stronger chemical weathering of rocks in the southern region of the basin than in the central and western region, whereas shorter residence time of material in upslope position partly resulted in weaker chemical weathering of rocks in the eastern region than in the central and western region. The same climate and stable tectonic setting led to comparable chemical weathering intensities of rocks in the Ziliujing and Jiaguan Formations. Gradually colder and dryer climate from Early Jurassic to Middle Jurassic then to Late Jurassic and shorter residence time in tectonically active setting of Middle Jurassic and late Late Jurassic resulted in the following order of chemical weathering intensity of the purple Jurassic rocks: Ziliujing Formation ? Shaximiao Formation ≈ Suining Formation > Penglaizhen Formation.     

利用ArcGIS提取CAD中分离式标注水深

海底的地形地貌是海洋地质调查的重要部分.自动提取CAD海图中数字分离式标注水深操作相对复杂,往往需要自编程序处理.本文基于ArcGIS平台,提供了一种自动提取数字分离式标注水深的简便方法,并给出了实例操作.本方法能有效提取CAD海图中数字分离标注式水深,无需自编程序,具有操作简单、提取准确、自动化程度高的特点.提取成果能直接应用于GIS平台进行三维和空间分析,具有重要的应用意义.     

Evaluation of oxygen isotopes in carbonate as an indicator of lake evolution in arid areas: The modern Qinghai Lake, Qinghai–Tibet Plateau

The oxygen isotopic composition of carbonate in lakes has been used as a useful indicator in Palaeolimnological research, and has made some important contributions to our understanding of lacustrine systems. For modern lakes in arid or cold areas, however, there are few data available to test the effect of lake salinity and temperature on the oxygen isotopic composition of various carbonate sources such as ostracod, bulk carbonate, and fine-grained carbonate (< 60 μm). Here we examined the oxygen isotopic composition of ostracods, bulk carbonate, and fine-grained carbonates, as well as that of coexisting water from Lake Qinghai and the smaller surrounding lakes and ponds on the Qinghai–Tibet Plateau. Our investigation highlights three key effects. First, the oxygen isotopic composition of ostracods, bulk carbonate, and fine-grained carbonate in the lakes and ponds shows a clear response to lake water δ¹⁸O values, and these vary with water salinity. The relationship between lake water δ¹⁸O and salinity is not only dominated by the evaporation/freshwater input ratios, but is also controlled by the distance to the mouth of the major rivers supplying to the lake. Second, the ostracod, bulk carbonate, and fine-grained carbonate show similar isotopic change trends in the study area, and oxygen isotopic differences between ostracods and authigenic carbonate may be explained by the different water temperatures and very small ‘vital offsets’ of ostracods. Finally, the effect of water depth on temperature leads to increasing δ¹⁸O values in carbonates as water depth increases, both in benthic ostracods living on the lake bottom, as well as in bulk carbonate precipitated at the water surface.For arid, high-altitude Lake Qinghai, our results suggest that variations in the δ¹⁸O values of carbonate in Lake Qinghai are mainly controlled by the oxygen-isotope ratio of the lake water changing with water salinity. As a secondary effect, increasing water depth leads to cooler bottom and surface water, which may result in more positive δ¹⁸O values of ostracod and bulk carbonate.     

Silurian collisional suturing onto the southern margin of the North China craton: Detrital zircon geochronology constraints from the Qilian Orogen

The Qilian Orogen of north western China records mid-Paleozoic collisional suturing of arc and continental blocks onto the south western margin of the North China craton. Silurian strata from the retroarc foreland basin mark the transition from ocean closure and northward subduction to the initiation of collision suturing. Detrital zircons were analysed from the western and eastern parts of the basin and show a spectrum of ages from Archean to Paleozoic with major age concentrations at around 2.5 Ga, 1.6 Ga, 1.2 Ga, 0.98 Ga, 0.7 Ga and 0.45 Ga. Archean age grains are derived from the North China craton, whereas the Central Qilian Bloc, which lies to the south provides the likely source for the bulk of the Proterozoic detritus. Paleozoic grains are restricted to Early Silurian samples from the western part of the basin and are considered to have been derived from the magmatic arc related to ocean closure and ultimate collision of the Central Qilian Belt with the North China craton.     

秦岭终南山地质公园地质遗迹保护与旅游资源开发

秦岭终南山地质公园地处西安市南,总面积1074．85km^2。素有“中国人的中央公园”之称的秦岭造山带,是全球典型的复合型大陆造山带之一,是形成统一中国大陆的主要结合带,是中国南北天然的地质、地理、生态、气候、环境乃至人文的分界线。秦岭终南山地质公园地处秦岭造山带的主体部位,是中央造山带的经典地段。依次分布有：翠华山山崩地貌与佛教文化园区、骊山裂谷地垒构造园区、冰晶顶韧性剪切带与构造混合岩化园区、玉山岛弧型花岗岩峰岭地貌园区、南太自板块碰撞缝合带与第四纪冰川园区等五个各具特色主题又互相联系的园区和黑河、沣峪两条科学考察路线。是至今为止距大都市最近的地质公园。     

柏树岗金红石矿床矿石类型及金红石特征

柏树岗金红石矿床含矿岩石主要为下元古界宽坪组角闪片岩等,矿体呈（似）层状,产状与地层一致。矿石可划分为角闪石型片状（或块状）、绿帘石型片状（或块状）、斜长石型块状、云母（或绿帘石）石英型片状、绿帘黑云斜长石型片状、白云母型片状、黑云母型片状（或块状）及石英脉型块状等类型。金红石早于、同时或晚于主变质期脉石矿物形成,以前两种为主,其杂质含量不超过5％,主要为FeO、Cr2O3及SiO2等;决定金红石杂质含量的因素主要为杂质元素离子半径,次为杂质元素在矿石中含量。矿床是下元古界富钛火山-沉积岩系经泥盆纪的区域变质作用形成的。     

中国古生界海相地层油气勘探

影响中国古生界海相油气勘探并且需要加强研究的主要问题是:保存条件的认识与有利区预测;有效烃源岩与资源潜力;储层的复杂性及其对非构造圈闭的影响。保存条件分为三个层次:含油气盆地的保存、含油气系统的保存、油气藏的保存。塔里木、四川、鄂尔多斯三大克拉通盆地是中国古生界保存较好的盆地,是海相油气勘探的战略目标区,另外还有准噶尔、楚雄等盆地。盆地斜坡相泥岩及泥状灰岩是海相油气勘探的主要烃源;海陆过渡相烃源岩发育区是重要战略方向;陆表海碳酸盐岩烃源岩区是中小油气田勘探领域。从储层条件来说,下古生界应以非砂岩岩溶储层为主要勘探对象,溶蚀不整合面广泛发育,已发现的下古生界大中型油气田仅见于碳酸盐岩溶储层;上古生界以孔隙性碎屑岩及碳酸盐岩储层为主要勘探对象,晚古生代的构造一古地理演化为这两类储层的广泛发育提供了条件。     

小波变换在饶阳凹陷层序地层格架建立中的应用

小波变换提供了一种研究层序地层格架的新方法,它将测井信号从一维深度域转换到二维深度—尺度域,从多尺度识别不同级次的地层旋回界面。根据小波变换的原理,确定了测井数据小波变换在层序地层划分中的地质意义,建立了四种小波变换中的地层旋回模型。在饶阳凹陷的实际应用中,选取自然伽马曲线进行小波变换,应用时频色谱图分析和快速傅里叶变换多种方法选取尺度因子。通过对时频色谱图和不同尺度下小波系数曲线的综合分析,对饶阳凹陷古近系G104井层序地层进行了划分,并以2 198.625m位置为突变界面,划分出两个较大尺度旋回,以2142.375m、2 163.875m、2 198.625m、2 238.625m位置为界面,划分出5个较小尺度旋回。实际结果应用表明,小波多尺度变换划分层序地层的结果和传统方法划分基本一致。