升金湖沉积物1000年以来的元素地球化学记录及其水文意义

中国东部季风区过去千年的水文变化已有大量研究并取得重要进展,但水文环境变化的起止时间、空间特征、温湿配置研究仍存在显著的区域差异,水文环境变化的驱动机制研究相对较少且不明确。以安徽升金湖沉积岩心为研究对象,分析元素地球化学指标的水文指示意义,结合总有机碳(TOC)、碳氮比(C/N)、无机碳(IC)等环境代用指标,讨论升金湖过去1 000年的水文变化。结果表明:1)在1 000～1 350 A.D.,Ti、Rb/Sr、Cr、SiO₂含量呈波动下降,Sr、CaO含量呈低值波动,指示中世纪暖期水文环境向干旱化变化。2)在1 350～1 850 A.D.内可分为两个阶段;第一阶段(1 350～1 600 A.D.),Ti、Rb/Sr、Cr、SiO₂含量波动变化,但总体在高值水平,Sr、CaO含量为低值,指示流域降水较多;第二阶段(1 600～1 850 A.D.),Ti、Rb/Sr、Cr、SiO₂含量下降,总体呈低值水平,Sr、CaO含量为高值呈上升趋势,指示降水减少,说明小冰期水文环境由湿润转向干旱。3)1 850～2 000...     

南海西部54万年以来元素地球化学记录及其反映的古环境演变

通过对南海西部上升流区MD05-2899孔开展高分辨率碳酸盐地层学和XRF岩芯扫描元素地球化学分析,重建了晚第四纪54万来以来东亚夏季风的演化历史,探讨海平面升降对南海西部陆源碎屑供应量的影响。研究选用了ln(Ba/Al)作为该海区古生产力的指标,ln(Br/Al)作为有机物的指标,ln(Ti/Al)作为陆源碎屑供应量的指标。研究结果显示,东亚夏季风在过去54万年以来强度不断增强,具有明显的冰期—间冰期旋回特征,在间冰期强盛和冰期减弱,是控制该海区有机物含量变化的主要因素。东亚夏季风不断强盛可能直接导致了南海周边陆地降雨增强,河流径流量加大,使得南海西部上升流区域的陆源碎屑供应量在间冰期明显高于冰期。研究发现,当相对海平面低于-60 m的时候,大面积暴露的巽他陆架可能向南海西部深水区输入大量陆源碎屑物质,造成研究站位的陆源碎屑供应量在冰盛期出现高值。因此,晚第四纪的东亚夏季风演化和海平面升降共同控制了南海西部上升流区陆源碎屑物质供应量的变化。     

30 ka以来东阿拉伯海U1456站位粘土粒级碎屑沉积物来源及其古环境意义

通过对国际大洋发现计划U1456站位沉积物AMS 14C年代、粘土矿物、常量元素及粒度组成的综合分析,探讨了东阿拉伯海粘土粒级碎屑沉积物的源-汇过程及其古环境指示意义.30 ka以来U1456站位的粘土矿物组合以蒙脱石和伊利石为主,并含有少量的绿泥石和高岭石.物源分析结果表明粘土粒级碎屑沉积物主要来自于印度河与德干高原.30 ka以来西南季风很可能是影响喜马拉雅山脉以及印度大陆风化剥蚀的重要因素.在西南季风减弱的阶段,印度河物源端元对研究区的输入量减少,这可能与此时热带辐合带的南移及末次冰盛期喜马拉雅山脉冰川覆盖面积的增加有关,从而导致印度河径流量及喜马拉雅山脉可供风化剥蚀的区域减少.K/Al比值指示的源区大陆化学风化作用强度与前人重建的西南季风记录间较为同步,在东阿拉伯海可以作为晚第四纪以来西南季风演化的有效重建指标.      

西藏佩枯错早全新世以来湖泊退缩过程及其古环境意义

湖泊的扩张或收缩与冰川融水、大气降水及蒸发量等水文气候因素密切相关。晚第四纪以来,青藏高原许多湖泊经历了显著的水位波动与面积变化,记录了诸多古环境信息并为青藏高原古气候研究提供了重要载体。水位与面积是湖泊演化的关键指标之一。湖泊水位的下降通常会导致入湖河流下切,从而发育河流阶地并出露下伏河湖相地层,因此这些沉积物的年龄和高度为反演湖泊水面的波动历史提供了间接证据。本研究对青藏高原南部佩枯错入湖河流下切的河湖相沉积物进行了光释光定年,结果表明:①约10.0±0.8~11.0±1.3 ka,佩枯错出现拔湖高度大于53 m的高水位,可能与希夏邦马冰川强盛的融水补给有关;②在6.4±0.6~7.4±0.5 ka前后,佩枯错水位出现明显下降,可能反映了季风降水及冰川融水的减少;③在全新世中晚期(约2.1±0.1~3.4±0.2 ka),湖泊水位再次快速下降,可能与季风降水的减弱有关。综上所述,冰川融水与季风降水的协同作用,共同塑造了佩枯错约11 ka以来湖泊的演化历史。     

南海北部东沙海区11.3 ka BP以来甲烷渗漏的沉积记录及其环境意义

南海北部东沙海区是天然气水合物有利远景区,关于其甲烷厌氧氧化作用（AOM）的沉积记录研究相对较少,不利于探讨东沙海区甲烷渗漏与该海区气候环境演化的耦合关系。本研究通过对南海北部东沙海区D7和DSF两根沉积柱的总硫含量（TS）、硫碳比值（S/C）、正构烷烃、甘油二烷基甘油四醚（GDGTs）类化合物的分析,重建了东沙海区自11.3 ka BP以来甲烷厌氧氧化作用的沉积记录和海水表层温度（SST）。两根沉积柱的TS、S/C值、GDGT-0、古菌醇和甲烷指数值（MI）的剖面变化表明东沙海区在6.4～7.5 ka BP和0.75～1.3 ka BP时发生了AOM作用,在4.0～4.2kaBP时可能发生了AOM作用,存在甲烷渗漏现象。由TEX^H ₈₆重建的SST显示该海区早全新世SST持续上升,晚全新世SST呈下降趋势,推测自11.3 ka BP以来东沙海区存在小范围的甲烷渗漏,但释放的甲烷并没有导致该海区表层水体温度显著升高。     

浙江古代青瓷(1127～1279年)的化学组成及其意义

本文用ENGLE-型微探针能量色散X荧光光谱(EDXRF)技术测定了一批青釉瓷残片中的16种元素氧化物的含量,其残片来自浙江杭州地区的南宋郊坛窑和老虎洞窑。由主量元素判别方程的Q值表明,两类青釉瓷均属官窑制品。主成分统计分析看出,郊坛官窑与老虎洞官窑的瓷釉成分有明显不同,但其胎质成分的分布,却有部分的重叠,这显示了当时两处官窑的工匠们在使用胎料中的交往。从釉层、过渡层、和胎层的Al2O3和CaO的含量数据表明,郊坛官窑和老虎洞官窑的青釉瓷制品,分别存有厚度为120～140μm和230～240μm的过渡层,表明两处使用釉料和烧制工艺上的…     

硫化物矿物的主微(痕)量元素分析进展

金属或半金属元素(Fe、Mo、As、Cu、Co、Ni、Zn、Pb等)、贵金属元素(Au、Ag)和铂族元素(PGE)、稀有分散元素(Re、Ga、In等)以高浓度富集或微量赋存于硫化物矿物中,常形成具有工业意义和经济价值的大型矿床,对研究矿床成因、经济地质、环境地球化学具有重要意义。因此,对硫化物组成的精确分析是了解上述方向的重要途径。硫化物矿物的主微(痕)量元素的快速、精确定量分析一直以来备受关注,本文就近几十年来对硫化物矿物的定量分析进展作了详细介绍,重点评述了电子探针(EPMA)、X射线荧光光谱(XRF)、电感耦合等离子体质谱(ICP-MS和LA-ICPMS)和电感耦合等离子体发射光谱(ICP-AES)在硫化物矿物主微(痕)量分析中的应用。     

马达加斯加索菲亚省BINARA地区铬铁矿遥感找矿预测

马达加斯加北部地区地广人稀、交通不便、植被稀疏、矿产资源丰富,利用遥感技术提取矿化蚀变信息具有独特的优势和较好的效果。为了对BINARA地区铬铁矿进行遥感找矿预测,文章首先利用Landsat 8遥感数据2、4、5、6波段进行主成分分析提取研究区内基性-超基性岩信息;然后基于实测高光谱数据,采用偏最小二乘回归法建立Fe含量定量反演模型,并利用该模型对Hyperion高光谱遥感数据进行计算,提取研究区内Fe含量异常信息;最后根据综合遥感异常信息以及野外调查验证结果,确定研究区内的Fe含量为一级异常的区域作为预测区。     

秦皇岛石门寨亮甲山奥陶系剖面化学地层和旋回地层研究

根据秦皇岛石门寨亮甲山奥陶系剖面的化学地层和岩石地层特征,将亮甲山组(O1l)细分为下、中、上段。选取Fe/Ca、Ti/Ca作为古气候替代指标,开展时间序列分析。通过多窗谱法(MTM)和傅里叶变换法(FT),从Fe/Ca、Ti/Ca比值中共提取出两个明显的米兰科维奇旋回：长偏心率405 ka和短偏心率90 ka。基于长偏心率周期建立的天文年代标尺表明,亮甲山组沉积时长为6.2 Ma,平均沉积速率为14.68 m/Ma,其中亮甲山组下段(0.00~48.00 m)和中上段(48.00~91.00 m)的沉积速率分别为12.00 m/Ma和19.55 m/Ma;马家沟组下部的沉积速率为18.00 m/Ma。奥陶纪生物大辐射可能直接导致碳酸盐生产模式由以灰泥生产为主转变为以生物碎屑生产为主,并使亮甲山组下段与中上段之交碳酸盐沉积速率大幅增加。旋回地层分析显示,早、中奥陶世之交天文轨道周期变化引起的地球气候改变可能对奥陶纪生物大辐射有重要的调控作用。     

南海南部120ka以来元素地球化学记录的东亚夏季风变迁

利用XRF岩芯元素扫描仪对南海南部MD05-2896孔岩芯样品进行1 cm间隔的元素测试。该孔底部年龄约为120ka。研究表明,南海南部间冰期夏季风活动增强,上升流发育;夏季风和降雨带来的陆源有机物输入增加,提高了表层的生产力;冰期夏季风减弱,陆源有机物输入减少,表层生产力降低。海洋表层生产力在MIS3早期(60~40 ka)较高,指示该时有特强的夏季风,上升流作用增强。Ba/Ti值表明东亚夏季风的强弱变化,并与北半球夏季日射量基本呈线性关系,体现了东亚夏季风演化的天文驱动机制。     

The Mid-Miocene Pollen Record of the Xunhua Basin, NE Tibetan Plateau: Implications for Global Climate Change

The northeastern Tibetan Plateau is located at the convergence of the Asian winter and summer monsoons and westerlies; thus, this area has witnessed historic climate changes.The Xunhua basin is an intermontane basin on the northeastern margin of the Tibetan Plateau.The basin contains more than 2000 m of Cenozoic fluvial–lacustrine sediments, recording a long history of climate and environmental changes.We collected the mid-Miocene sediments from the Xunhua basin and used palynological methods to discuss the relationship between aridification in the interior of Asia, global cooling, and uplift of the Tibetan Plateau.Based on the palynological analysis of the Xigou section, Xunhua basin, the palynological diagram is subdivided into three pollen zones and past vegetation and climate are reconstructed.Zone I, Ephedripites–Nitraridites–Chenopodipollis–Quercoidites(14.0–12.5 Ma), represents mixed shrub–steppe vegetation with a dry and cold climate.In zone II, Pinaceae–Betulaepollenites–Ephedripites–Chenopodipollis–Graminidites(12.5–8.0 Ma), the vegetation and climate conditions improved, even though the vegetation was still dominated by shrub–steppe taxa.Zone III, Ephedripites–Nitrariadites–Chenopodipollis(8.0–5.0 Ma), represents desert steppe vegetation with drier and colder climate.The palynological records suggest that shrub–steppe dominated the whole Xigou section and the content gradually increased, implying a protracted aridification process, although there was an obvious climate improvement during 12.5–8.0 Ma.The aridification in the Xunhua basin and surrounding mountains during 14.0–12.5 Ma was probably related to global cooling induced by the rapid expansion of the East Antarctic ice-sheets and the relatively higher evaporation rate.During the 12.5–8.0 Ma period, although topographic changes(uplift of Jishi Shan) decreased precipitation and strengthened aridification in the Xunhua basin on leeward slopes, the improved vegetation and climate conditions were probably controlled by the decrease in evaporation rates as a result of continuous cooling.From 8.0 to 5.0 Ma, the rapid development of the desert steppe can be attributed to global cooling and uplift of the Tibetan Plateau.     

青藏高原Pb同位素地球化学及其意义

根据青藏高原不同构造单元基底片麻岩、花岗岩类和火山岩等不同类型岩石的486套Pb同位素数据的整理和分析,发现青藏高原岩石圈存在3种主要类型,即亏损Pb同位素的特提斯洋地幔域端元、富集Pb同位素的喜马拉雅成熟大陆地壳端元和青藏高原北部的过渡型Pb同位素的地幔端元。这3类地球化学端元与前人通过Sr-Nd同位素研究获得的3类端元一致。拉萨地块内部不同类型岩石的Pb同位素地球化学特征指示出两类岩浆作用,一类是特提斯洋岩石圈俯冲消减再循环和亏损地幔物质注入导致的亲特提斯洋型岩浆作用,另一类是与类似于喜马拉雅大陆地壳物质加入导致的富集地幔源区有关的超钾质岩浆作用。岩浆作用的Pb同位素地球化学记录了特提斯洋俯冲消减作用和随后发生的印度大陆向北拼合、碰撞和俯冲过程,也记录了大规模的壳幔相互作用对高原岩石圈演化与隆升的贡献。     

青藏高原纳木错湖阶沉积的发生特征及环境指示意义

选取的21个湖相沉积物样品分别采自纳木错湖西岸塔吉古日（剖面Nam Co 1）和纳木错湖东北岸的干玛弄附近（剖面Nam Co 2）。按照其发生特征分别将剖面从顶部到底部划分为12个和9个层次,通过分析各个层次沉积物的粒径分布特征、质地组成特点、总有机碳（TOC）、总无机碳（TIC）、总碳（TC）的百分含量、酸度值（pH）、电导率（EC）、含水量等若干环境指示因子。结果显示:无论在比较两个剖面的发生特征,还是环境指示因子特征,剖面Nam Co 1发育程度较剖面Nam Co 2更加发育;通过对测年数据结果分析,两个剖面均形成于晚更新世,并且通过比较各自剖面在垂直方向上的各项环境指示因子的变化趋势,可知纳木错湖流域在晚更新世（约40 ka BP）阶段发生过3次相对明显的冷暖交替过程.     

Major Ion Geochemistry of Nam Co Lake and its Sources, Tibetan Plateau

The major cations and anions from lake water samples and its sources, including glacier snow, precipitation, stream, and swamp water in the Nam Co basin, central Tibetan Plateau, were studied. The concentrations of the major ions varied significantly in the five environmental matrices. Generally, the mean concentrations of most ions are in the order of lake water > swamp water > stream water > precipitation > snow. Rock weathering is the dominant process controlling the chemical compositions of the stream and swamp waters, with carbonate weathering being the primary source of the dissolved ions. The Nam Co lake water is characterized by high Na⁺ concentration and extremely low Ca²⁺ concentration relative to other ions, resulting from evapoconcentration and chemical precipitation within the lake. Comparison with the water chemistry of other lakes over the Tibetan Plateau indicated that Nam Co is located in a transition area between non-saline lakes and highly saline lakes. The relatively low concentration of total dissolved solids is possibly due to the abundant inflow of glacial meltwater and relatively high annual precipitation.     

西藏高原扎布耶盐湖128ka以来沉积特征与古环境记录

本文首次披露青藏高原腹地扎布耶盐湖约128ka以来高分辨率湖芯研究记录,据连续采取1346件样品,通过多种综合测试方法研究,取得了较为良好的14C年龄和铀系不平衡法与ESR数据,揭示SZK02孔0～83.63m湖芯年龄为约800a至128ka。文中对湖芯沉积特征(包括岩性、矿物组合)作了较详细分析,并与介形类Ⅰ～ⅩⅩ组合、孢粉A—I带作了对比;而在湖芯自生钙镁碳酸盐δ18O与矿物、孢粉、微体古生物环境标志综合分析基础上,与格陵兰、古里雅冰芯等氧同位素变化作了对比,将扎布耶盐湖128ka以来划分出:阶段5末次间冰期(包括e、d、c、b、a5个亚阶段)、阶段4末次冰期早冰阶、阶段3末次冰期间冰阶、阶段2末次冰期晚冰阶或称末次盛冰期、阶段1冰后期;还辨认出6个Heinrich(H6—H1)事件、新仙女木事件(YD)和8.2ka冷事件等。     

Sedimentary Characteristics and Paleoenvironmental Records of Zabuye Salt Lake, Tibetan Plateau, since 128 ka BP

This paper for the first time reveals high-resolution core records of Zabuye Salt Lake in the interior of the Qinghai-Tibet Plateau. According to 1346 samples taken continuously, relatively accurate 14^C, U-series disequilibrium and ESR ages have been obtained, thus revealing that the lake core ages from 0 to 83.63 m of hole SZK02 are -800 to over 128 ka. In the paper, the lake core sedimentary characteristics （including the lithologies and mineral assemblages） are analyzed in detail and correlated with ostracod assemblages I to XX and sporopollen zones A to I, and on the basis of an integrated analysis of the δ^18O values of authigenic calcium-magnesium carbonate and environmental proxies of minerals, sporopollen and microfossils in the lake core, a correlation has been made of oxygen isotope change between this lake core and the Greenland GISP2 and GRIP and Guliya ice cores, and the climate of Zabuye Salt Lake since 128 ka BP is divided into the last interglacial stage （including substages e, d, c, b and a） of oxygen isotope stage （OIS） 5, early glacial stadial of the last glacial stage of OIS 4, interglacial stadial of the last glacial stage of OIS 3, late glacial stadial of the last glacial stage or Last Glacial Maximum of OIS 2 and postglacial state of OIS 1; in addition, 6 Heinrich （H6-H1） events, Younger Dryas event and 8.2 ka BP cold event have been recognized.     

南海沉积物漫反射光谱反映的220ka以来东亚夏季风变迁

对南海越南岸外“太阳号”95航次17954孔220ka以来的沉积样品进行了漫反射光谱分析, 并从中提取F1和F2两个主因子及亮度和红度等漫反射光谱特征值, 发现漫反射光谱F1值和亮度反映了沉积物中的碳酸盐含量, 而漫反射光谱F2值和红度反映了沉积物中的铁氧化物含量, 后者可用作东亚夏季风的替代性指标.17954孔沉积物的漫反射光谱F2值显示, 倒数第二次冰消期东亚夏季风快速增长时间约在129ka; 本次工作还发现东亚夏季风在两次冰消期前的氧同位素2阶段和6阶段晚期各有一个异常强盛的时期.漫反射分析结果显示东亚夏季风主要受控于太阳辐射强度变化, 并明显地受低纬地区气候的影响.      

Sources and flux of trace elements in river water collected from the Lake Qinghai catchment,NE Tibetan Plateau

River waters play a significant role in supplying naturally- and anthropogenically-derived materials to Lake Qinghai, northeastern Tibetan Plateau. To define the sources and controlling processes for river water chemistry within the Lake Qinghai catchment, high precision ICP-MS trace element concentrations were measured in water samples collected from the Buha River weekly in 2007, and from other major rivers in the post-monsoon (late October 2006) and monsoon (late July 2007) seasons. The distributions of trace elements vary in time and space with distinct seasonal patterns. The primary flux in the Buha River is higher TDS and dissolved Al, B, Cr, Li, Mo, Rb, Sr and U during springtime than those during other seasons and is attributed to the inputs derived from both rock weathering and atmospheric processes. Among these elements, the fluxes of dissolved Cr, B and Rb are strongly influenced by eolian dust input. The fluxes of dissolved Li, Mo, Sr and U are also influenced by weathering processes, reflecting the sensitivity of chemical weathering to monsoon conditions. The anthropogenic sources appear to be the dominant contribution to potentially harmful metals (Ni, Cu, Co, Zn and Pb), with high fluxes at onset of the main discharge pulses due, at least partially, to a runoff washout effect. For other major rivers, except for Ba, concentrations of trace elements are higher in the monsoon than in the post-monsoon season. A total of 38.5 ± 3.1 tons of potentially harmful elements are transported into the lake annually, despite human activities within the catchment being limited. Nearly all river water samples contain dissolved trace elements below the World Health Organization guidelines for drinking water, with the exception of As and B in the Daotang River water samples collected in late July probably mobilized from underlying lacustrine sediments.     

GDGTs揭示的西宁盆地中中新世环境变化

西宁盆地关家山剖面微生物细胞膜脂的生物标志化合物甘油二烷基甘油四醚类脂物（Glycerol Dialkyl Glycerol Tetraethers,简称GDGTs）古温度指标MAT_mr记录了从16.8 Ma到13.4 Ma的持续降温过程（下降约5.1℃）,与全球深海氧同位素记录的中中新世气候适宜期（MMCO）及其后的中中新世气候转型（MMCT）事件一致,揭示了西宁盆地古温度在此期间受全球温度变化控制。其环化参数CBT'重建的古pH值（CBT'-pH）平均为6.56±0.50,且80%样点的干旱指标R_i/b（古菌类异戊二烯型isoprenoid GDGTs（简称iGDGTs）与细菌支链型branched GDGTs（简称bGDGTs）相对含量比值）小于0.5,表明西宁盆地在此期间整体上处于较为湿润的环境,但是在14.0 Ma和14.8 Ma,R_i/b值记录了两次干旱事件。总之,虽然在古温度绝对值计算等问题上仍存在一定困难,GDGTs展现了在西宁盆地乃至青藏高原东北部在新近系甚至更老地层中应用的潜力。