两高分辨率黄土剖面末次冰消期气候事件的差异探讨

高分辨率黄土剖面的获取使我们对亚轨道时间尺度上的气候事件的研究成为可能。通过对六盘山东、西部两个高分辨率黄土剖面与GRIP冰芯记录的对比研究,我们发现两剖面都捕捉到了末次冰消期内的Younger Dryas 事件与Heinrich-1事件及Blling和Allerd事件,并且它们在时间上与冰芯的结果较为一致。更为重要的是,这些亚轨道时间尺度上的气候事件在东西两剖面内存在较大差异:Heinrich-1事件在西面沙沟剖面的烙印较东面的王官剖面要深;对于Blling和Allerd事件,沙沟剖面较王官剖面的波动要多;在沙沟剖面,Younger Dryas 的结束是一种突变行为,而在王官剖面中则是一种渐变行为;此外,沙沟剖面比王官剖面表现出更大的波动幅度和更多千年尺度上的快速波动。初步推测上述差异是由高、低纬地区对它们影响的不同所造成的。     

海南文昌涣文村老红砂剖面的磁化率测量及意义

通过对海南文昌县涣文村老红砂剖面的野外调查和磁化率测量, 绘制了该剖面磁化率曲线; 分析了剖面磁化率特征与剖面颜色及红化过程的关系。指出剖面磁化率可以作为反映老红砂堆积过程中(及以后)气候变化的物理参数。开展老红砂堆积连续剖面的磁化率测量, 以此进行气候地层的划分与对比, 对华南沿海乃至更大范围环境变化的研究具有重要意义     

施用不同畜禽粪便土壤剖面中重金属分布特征

针对不同粪便集中施用情况, 选取禹城市3 个畜禽养殖区, 通过采集不同旱地农田土壤剖面样品, 研究典型重金属元素随粪便施用程度的变化、土壤剖面中重金属垂直分布特征以及施用不同畜禽粪便土壤剖面中重金属分布的差异。结果发现,长期施用畜禽粪便土壤剖面中重金属Cu、Zn、Pb、Cr、As的含量要高于未施用畜禽粪便的对照土壤剖面, 其中Cu、Zn 超过对照组较大;偶尔施用畜禽粪便土壤剖面Cu、Zn、Pb、Cr、As 的含量低于长期施用畜禽粪便土壤剖面, 且与未施用畜禽粪便的对照土壤剖面相差不大。牛粪集中施用区土壤剖面中Cu、Pb、Cr、Cd、Ni 等重金属存在较为明显的淋溶下移性, Hg、As两元素存在较为明显的表层或亚表层聚集现象;猪粪集中施用区土壤剖面各重金属除Cr、Ni 外, 都显示出较为明显的表层或亚表层聚集现象;鸡粪集中施用区的土壤剖面Cu、Pb、Cd、Cr、Ni 存在一定的淋溶下移性, 而Zn、Hg、As等3 种元素存在显著表层亚表层聚集现象。长期施用不同畜禽粪便的不同土壤剖面Cr、Ni、Cd、Pb 等含量变化差异明显, 而As、Hg差异性不显著;施牛粪与施鸡粪剖面中的Zn, 施猪粪与施鸡粪剖面中的Cu差异也不显著。     

长白山圆池泥炭氮元素分布特征及其影响因素分析

通过对长白山圆池4个泥炭剖面样品的分析,揭示了其氮元素分布规律。在圆池选取4个具有代表性的采样点,利用泥炭采样器采取新鲜泥炭样品。分析结果表明,4个泥炭剖面氮元素含量在0.014%~3.353%之间;剖面间相比较,其中贫营养泥炭整体含氮量较低;4个泥炭剖面的氮元素分布呈现明显规律,受泥炭上层不同植物、泥炭水分和有机质含量等因素的影响,泥炭剖面中氮元素累积峰可能出现在剖面的表层(0~5cm)或中间层(10~20cm);泥炭剖面氮元素与有机质呈极显著的正相关;泥炭剖面C/N比值变化在9.51~66.98之间,部分剖面层位C/N比值异常高,表明该层位碳的累积速度显著高于氮元素。     

红色风化壳地球化学特征及对古气候演变的响应——以辽南石槽剖面为例

以辽南地区石槽剖面红色风化壳为研究对象,通过研究剖面的常量元素和地球化学指标,揭示剖面的地球化学特征,探讨剖面化学风化过程以及对古气候环境演变过程的响应。结果表明：石槽剖面红色风化壳中Ca元素重度亏损,其他常量元素均出现了相对富集;石槽剖面风化强度总体上低于南方红色风化壳,属于中等风化阶段;多个地球化学指标的垂向变化表明石槽剖面风化强度表现为风化很强-风化减弱-风化加强-风化较弱4个阶段的变化,指示辽南地区在石槽剖面发育期内古气候环境经历了湿热-暖湿-回暖-相对暖湿的演变过程。     

基于ArcGIS的条带剖面提取方法在地貌分析中的应用

条带剖面提取方法是利用数理统计原理,获得垂直于剖面线方向上一定缓冲区范围的高程信息,计算最大、最小和平均高程以及地形起伏度,把地形剖面图对线状地形起伏特征的描述转化为对面状地形起伏特征的描述。该文基于ArcGIS 9.3对三峡地区SRTM-DEM数据进行了条带剖面提取方法研究,实现了基于ArcGIS的条带剖面提取技术流程。应用条带剖面对三峡地区地形地貌进行了定量分析,该方法可快速提取条带剖面,能准确获取高程属性的相关统计参数,对地形地貌信息提取和定量分析具有一定价值。     

三维含拓扑地质剖面三角剖分可视化研究

三维剖面是地质对象表达和地质问题分析中最基本和最常用的数据。该文分析三维复杂地质折剖面可视化存在的问题,并提出展开剖分算法。该方法保证了各点之间的水平距离与剖面拓扑关系不变,能够对由"多边形-弧段-结点"矢量结构构成的三维折剖面进行有效剖分。在此基础上实现了三维剖面的可视化,尤其合理解决了纹理映射中的纹理变形与重复接缝等问题。     

澧阳平原晚冰期短尺度气候变化的风成沉积物稀土元素和粒度记录

对澧阳平原SL剖面的系统采样和室内稀土元素分析、粒度分析和AMS14C年代测定,揭示了澧阳平原岗地黄土剖面成因特征,探讨了澧阳平原晚冰期短尺度的气候变化过程。结果表明,澧阳平原岗地黄土在稀土元素配分模式上与黄土高原黄土-古土壤、镇江下蜀黄土具有高度的一致性,而且岗地剖面沉积物无任何水流作用痕迹,因此表明,澧阳平原岗地黄土剖面为风成成因。粒度结果表明,SL剖面较好地记录了晚冰期短尺度的气候变化过程,SL遗址剖面自然沉积物记录了晚冰期千年尺度的气候事件,如BL事件、OlderYD事件、AL事件、YD事件。SL剖面全新世早期表现为升温阶段,9.0～8.00kaBP的彭头山文化在此区兴起,表明此时气候相当适宜,适合人类生存。     

我国地质遗迹有哪些类型?

<正>地质遗迹依其形成原因、自然属性等可分为下列6种类型:(1)标准地质剖面:如中国最古老的岩石——鞍山白家坟花岗岩;陕西小秦岭元古界剖面;天津蓟县中、上元古界层型剖面;云南晋宁梅树村剖面;吉林浑江大阳岔寒武——奥陶系界线剖面;宁夏中宁陆相泥盆系及生物群保护遗址;云南曲靖陆相泥盆系剖面;广西桂     

天津地区典型土壤剖面饱和烃分布特征 及环境意义

分析了天津地区不同环境功能区7 条土壤剖面中饱和烃含量、组成及部分地球化学参数 的变化规律, 比较了不同土壤剖面饱和烃在纵向上的变化特征。结果表明, 市区( 南开区) 及近郊 区( 武清区, 北辰区和宁河县交界处) 表层土饱和烃含量最高, 其他剖面含量较低; 随深度增大, 饱 和烃含量均有所降低, 但不同剖面变化幅度不同, 表层含量较高的剖面随深度增大, 饱和烃含量 降低幅度较大, 反之则较小。根据部分典型地球化学参数的纵向变化特征, 推测表层土壤饱和烃 主要为石油源和植物源的混合源, 且市区和郊区主要受石油源控制。不同土壤剖面表层土污染源 存在差别。同一剖面表层土壤( <30cm) 不同层次的样品的饱和烃污染源较为接近; 剖面深部( > 30cm) 不同层次样品中正构烷烃不同于表层, 且成因复杂, 既受来源于土壤中有机质降解产物的 影响, 又受表层土中饱和烃纵向迁移作用的影响。对于甾、萜类化合物, 表层土壤中饱和烃含量较 高的剖面, 深层土壤受表层土壤甾、萜类污染物迁移作用的影响; 表层土壤中饱和烃含量较低的 剖面, 深层土壤受表层土壤甾、萜类污染物影响较小。     

萨拉乌苏河地区粘土矿物组合分析与古气候的关系

萨拉乌苏河嘀哨沟湾剖面中晚更新统下部萨拉乌苏组,晚更新统上部的城川组中部,全新统中下部河湖沉积或黑垆土中的粘土矿物组合以伊利石为主,但伴有少量的高岭石类矿物;而晚更新统上部的城川组上下部,全新统上部嘀哨沟湾组以风成沙为主的粘土矿物组合均以伊利石-绿泥石为主,并有少量的蒙脱石。萨拉乌苏河雷家咀子、马达渠以北西北部梁地的第四纪地层中的粘土矿物组合与萨拉乌苏河嘀哨沟湾剖面的结果基本吻合。这表明本区第四纪风成沙与黄土是在相对干冷气候下沉积的,而河湖相、湖沼相及古土壤是在相对暖湿的气候下形成的。由本区第四纪地层中的粘土矿物组合,反映自晚更新世以来,本区气候曾经历暖湿→干冷→温湿→干冷→暖湿→干冷的多次更替,大体与北半球的玉木——里斯间冰期、前玉木冰期、玉木间冰阶、玉木主冰期、冰后转暖期和新冰期气候变化趋势一致。     

Sedimentary cycles of trace elements in Salawusu River Valley since 150 ka BP

The paper makes some analyses on 11 trace elements in the Milanggouwan stratigraphical section in the Salawusu River valley, which is regarded as a prototype geology-palaeoclimate record since 150 ka BP. The results show that the content and variation of trace elements has experienced remarkably regular changes in the pace with coarse and fine sedimentary cycles of palaeo-aeolian sands to its overlying fluvio-lacustrine facies or/and palaeosols. The trace elements with chemical properties of relatively active (V, Sr, Cu, Ni, As) and relatively stable (P, Pb, Rb, Mn, Nb, Zr) are a manifestation of the corresponding 27 changeable cycles between peak and valley values, appearing a multi-fluctuational process line of relative gathering and migration since then. The low numerical value distribution of these two types of trace elements in the aeolian sand facies represents erosion and accumulation under wind force during the cold-dry climate. Whereas their enrichments in both fluvio-lacustrine facies and palaeosols are related to the valley’s special low-lying physiognomic position between the Ordos Plateau and the Loess Plateau under the warm and humid climate conditions. The above relatively migrated and gathered change of the trace elements is the result of 27 climatic cycles of cold-dry and warm-humid, which is probably caused by repeated alternations of winter monsoon and summer monsoon in the Mu Us Sandy Land influenced by the climate vicissitudes in northern hemisphere during glacial and interglacial periods since 150 ka BP.     

Sedimentary cycles of trace elements in Salawusu River Valley since 150 ka BP

The paper makes some analyses on 11 trace elements in the Milanggouwan stratigraphical section in the Salawusu River valley, which is regarded as a prototype geology-palaeoclimate record since 150 ka BP. The results show that the content and variation of trace elements has experienced remarkably regular changes in the pace with coarse and fine sedimentary cycles of palaeo-aeolian sands to its overlying fluvio-lacustrine facies or/and palaeosols. The trace elements with chemical properties of relatively active (V, Sr, Cu, Ni, As) and relatively stable (P, Pb, Rb, Mn, Nb, Zr) are a manifestation of the corresponding 27 changeable cycles between peak and valley values, appearing a multi-fiuctuational process line of relative gathering and migration since then. The low numerical value distribution of these two types of trace elements in the aeolian sand facies represents erosion and accumulation under wind force during the cold-dry climate. Whereas their enrichments in both fluvio-lacustrine facies and palaeosols are related to the valley’s special low-lying physiognomic position between the Ordos Plateau and the Loess Plateau under the warm and humid climate conditions. The above relatively migrated and gathered change of the trace elements is the result of 27 climatic cycles of cold-dry and warm-humid, which is probably caused by repeated alternations of winter monsoon and summer monsoon in the Mu Us Sandy Land influenced by the climate vicissitudes in northern hemisphere during glacial and interglacial periods since 150 ka BP.     

地表物质组成与土地沙漠化

土地沙漠化是在干旱、半干旱地区,由于特定的自然条件和人类不合理地利用自然资源,所引起的环境退化过程。随着这个过程的进一步发展对人类的不利影响越来越大。因此,对土地沙漠化的问题,也越来越得到人们的普遍重视。在内蒙伊克昭盟及宁夏、陕北地区,沙漠化的土地面积,分别占总土地面积的32%、25.2%和45.9%。这说明了在上述地区土地沙漠化是相当严重的。造成土地沙漠化的自然因素,除气候的干旱、多风外,地表物质的组成是其物质基础。而地表物质组成与沉积条件密切相关,因此,不同的沉积环境形成不同的沉积物,其质地性质差异很大。这些不同的沉积物,对土地沙漠化的发生及发展速度、类型和治理措施都有直接关系。因此,研究地表物质组成与土地沙漠化之间的关系是极为重要。     

An early Holocene erosion phase on the loess tablelands in the southern Loess Plateau of China

A Holocene loess profile to the west of Xi'an China was studied multi-disciplinarily to investigate the relationships between soil erosion and monsoonal climatic change. The proxy data obtained from this aeolian loess and palaeosol sequence indicate large-scale variations of climate in the southern Loess Plateau since the last glaciation. A rainwash bed, indicative of a wetter climate, excessive runoff and erosion on the loess tablelands, was identified relating to the early Holocene before the onset of the “climatic optimum”. This is synchronous with the early Holocene physiographic erosional stage identified in the valleys in North China. It means that severe erosion took place when the region was undergoing climatic amelioration during the early Holocene. The evidence presented in this paper shows that the erosion occurred as a regional response to a monsoonal climatic shift in the southern Loess Plateau. During the last glaciation, prior to the erosion phase, the land surface on the tablelands had been largely stable except for the rapid accumulation of aeolian dust and the resultant increase in its elevation. Relatively slow dust accumulation and intensive bio-pedogenesis responding to the Holocene “climatic optimum” followed the erosion phase. The loess tablelands were most vulnerable to erosion during the large-scale monsoonal climatic shift from dry-cold glacial to humid-warm post-glacial conditions in the southern Loess Plateau.     

陕西五里铺黄土微量元素组成与全新世气候不稳定性研究

通过对岐山黄土剖面Pb、Cu、Zn、Cd、Mn元素含量、磁化率及粒度的研究表明,这些元素含量变化实质是气候变化的直接结果,其含量高指示风化成壤作用强烈的湿润环境,含量低指示寒冷的干旱环境。揭示出黄土高原南部全新世气候在总体温暖的情况下有明显波动变化,在5000~6000 a BP出现一次明显气候干旱期,使全新世"大暖期"分裂形成两个主要的成壤期S₀¹和S₀²。在S₀¹、S₀²成壤时期仍存在次一级的气候变化事件。全新世时期该地区经历了黄土沉积(L_t)→古土壤发育(S₀²)→黄土覆盖(L₀²)→土壤再度发育(S₀¹)→黄土堆积及现代表土(L10)的发展演化阶段。     

对黄土高原风尘搬运动力与沉积控制因素的新认识

风尘是地球表层系统的重要组成部分,广泛参与地球系统中不同时空尺度的物理、化学和生物过程,对全球气候和生态环境产生重要的影响。中国北方地区发育了世界最广、最厚的风尘沉积,记录了至少22 Ma以来东亚季风演化和亚洲内陆干旱化历史。半个多世纪以来对风尘沉积的气候记录和黄土高原的成因进行了大量研究并取得了丰硕成果,然而对黄土高原风尘物质沉积过程的认识还存在很多问题。例如,近年来基于物源示踪研究对传统的风尘搬运过程提出了新认识,认为虽然黄土主体是风成的,但以前忽略了河流对于碎屑物质的搬运贡献。我们在前人研究基础上从沉积学角度分析风尘沉积过程,发现青藏高原两期抬升与区域构造运动对粉尘沉积起着不亚于气候变化的重要控制作用;同时从沉积-侵蚀和地貌发育过程探讨风力与流水这两种最常见的外动力方式在黄土沉积和黄土高原发育过程中所起的作用,认为风尘的沉积和黄土高原的形成是侵蚀与搬运沉积作用的长期动态平衡过程,风力和流水在其中所起的作用都不是单一不变的,在不同时期和不同区域有可能会同时充当建设者和破坏者的角色。     

常量元素氧化物含量及其比值揭示的中晚全新世以来玛曲高原的环境演变

对玛曲高原具有代表性的黄土-古土壤-风成砂剖面(OL剖面)常量元素氧化物含量及其比值的地球化学特征分析表明:(1)常量元素氧化物总含量为91.93%且SiO₂(67.93%) >Al₂O₃(11.2%) >Fe₂O₃(3.97%) >CaO(3.76%)>K₂O(2.16%) >Na₂O(1.81%) >MgO(1.1%);(2)玛曲高原处于较弱的脱Ca、Na初级风化阶段,并伴有碳酸盐的淋失;(3)玛曲高原的气候经历了冷干-凉润-温湿-凉干的冷暖旋回。依据常量元素氧化物含量及其比值揭示的环境特征并结合¹⁴C测年将玛曲高原中晚全新世以来的环境演变划分为4.6 ka BP以前的风沙活动强烈期、4.6～4.3 ka BP的风沙活动较弱期、4.3～0.3 ka BP的固结成壤期和0.3 ka BP至今的风沙活动增强期4个阶段。     

Aeolian influences on the soils and landforms of the southern Yilgarn Craton of semi-arid, southwestern Australia

Within a landscape developed on the deeply weathered, dominantly granitic rocks of the Yilgarn Craton in southwestern Australia, there is strong evidence of prior aeolian activity. Multiple arrays of clayey saltation deposits occur as clay dunes or lunettes extending up to 5 km to the southeast of playas, and quartzose sand dunes and sheets occur in a 2-km wide band that extends 10 km southeast of an ephemeral creek line. Parabolic dunes occur within some clayey lunettes. The parallel orientation of these diverse features and the elliptical shape of the playas suggest that the winds that have created these geomorphic entities have been from the northwest. Multiple lunette arrays with up to seven members have not been previously reported in this region.There is evidence for a more widespread, but more subtle, aeolian influence on the soils. Dust deposits appear to mantle parts of the landscape and are inferred to be coeval with the clayey saltation deposits. Although these do not occur as a discrete layer, evidence includes a plume of calcareous and illitic soils southeast of the major playa, in a landscape otherwise characterised by acidic, kaolinitic soils. Similarly, the occurrence of deep sandy soils on many slopes with a southeasterly aspect may indicate the interference of topography on the transport of saltating sands during an arid climatic phase. The presence of such aeolian deposits has implications for agricultural management, mineral exploration and the interpretation of ecological gradients in similar undisturbed landscapes.Current desertification, in the form of salinization and wind erosion, has precedence in this landscape. The aeolian deposits provide a means of interpreting landscape-scale responses to previous climate change and a key to predicting possible outcomes of both desertification and future climate change. Assuming that Bowler's theory that clay dunes require an adjacent salinized playa bed to form is correct, the arrays of clayey lunettes together with vegetated former playas indicate that the landscape has undergone multiple cycles of salinization and recovery. The lunettes may thus provide a means of predicting landscape hydrological responses to the widespread removal of natural vegetation for farming. Dating of the various sequences is required to provide a time scale for these landscape processes.     

禹门口南黄河东岸沙丘初步研究

在禹门口南山西省河津、万荣县境内黄河阶地上发育了一些固定、半固定沙丘,注入黄河的汾河将这些沙丘分成了南北两部分。北部的沙丘多在海拔400m左右,高出现代黄河约35m,位于黄河的第二级阶地上,由两条南北向的沙垄和两垄之间分布的抛物线形沙丘构成特殊的景观。这些抛物线形沙丘一般高度约7~8m,背风面突出,迎风坡坡度一般为15°~20°,背风坡坡度一般大于40°。风沙堆积下伏的河流堆积物的¹⁴C年龄为26.40±0.8kaBP,表明沙丘形成于距今26ka以来。南部沙丘海拔高度近500m,高出现代黄河水面150m,覆盖于黄河第三级阶地之上。一个天然剖面揭示,第三阶地的底部为黄色中粗砂与灰绿色粉砂粘土互层,中部为灰黄色黄土,顶部为黄色风沙层。在黄土地层中可以识别出S₁古土壤和位于风沙堆积下面的可能为L₁SS₁的弱成土层。由此推断风沙堆积于距今3万a以来。黄河阶地上的沙丘是在特殊的地区和特定的时期;强大的风力、丰富的沙源和气候变干条件下形成的。虽然东岸沙丘已是固定、半固定沙丘,但沙化仍然是该地区的一个问题。由于3~4a前开始在丘前洼地栽种苹果树,破坏了下风向沙丘迎风面的植被,造成了原来已固定沙丘的活化,在沙丘顶部生成了新的小抛物线形沙丘,高度大于1 m。沙丘上裸露的树根指示表土已被侵蚀0.3 m。南部沙丘区的风蚀作用也很强,例如,万荣县裴庄乡西范村北一片柿树林的树根由于风蚀已经裸露1.2 m。