Anthropogenic hillslope terraces and swidden agriculture in Jiuzhaigou National Park, northern Sichuan, China   总被引：2，自引：0，他引：2  

Amanda Henck  James Taylor  Yongxian Li  Barbara Grub  Alicia Robbins  Tom Hinckley  Lauren Urgenson  Xinxin Hu  Yaowu Yuan  Xun Liao 《Quaternary Research》2010,73(2):201-207

Small, irregular terraces on hillslopes, or terracettes, are common landscape features throughout west central China. Despite their prevalence, there is limited understanding of the nature of these topographic features, the processes that form them, and the role humans played in their formation. We used an interdisciplinary approach to investigate the geology, ecology, and cultural history of terracette development within Jiuzhaigou National Park, Sichuan Province, China. Terracettes occur on south facing, 20° slopes at 2500 m elevation, which appears to coincide with places people historically preferred to build villages. Ethnographic interviews suggest that traditional swidden agricultural cycles removed tree roots, causing the loess sediments to lose cohesion, slump, and the terrace risers to retreat uphill over time. This evidence is supported by landslide debris at terracette faces. Archaeological analysis of terracette sites reveal remains of rammed spread soil structures, bones, stone tools, and ceramics dating from at least 2200 years before present within a distinct paleosol layer. Radiocarbon and optically stimulated luminescence dating of terracette sediments ranged in age from between 1500 and 2000 ¹⁴C yr BP and between 16 and 0.30 ka, respectively. These multiple lines of evidence indicate a long history of human habitation within Jiuzhaigou National Park and, taken together, suggest strong links between terracette formation and human-landuse interactions.  相似文献   

Ozone profile intercomparison based on simultaneous observations between 20 and 40 km     

P. Aimedieu  A.J. Krueger  D.E. Robbins  P.C. Simon 《Planetary and Space Science》1983,31(7):801-807

The vertical distribution of stratospheric ozone has been simultaneously measured by means of five different instruments carried on the same balloon payload. The launches were performed from Gap during the intercomparison campaign conducted in June 1981 in southern France. Data obtained between altitudes of 20 and 40 km are compared and discussed. Vertical profiles deduced from Electrochemical Concentration Cell sondes launched from the same location by small balloons and from short Umkehr measurements made at Mt Chiran (France) are also included in this comparison. Systematic differences of the order of 20% between ozone profiles deduced from solar u.v. absorption and in situ techniques are found.  相似文献   

Plume Distortion and Apparent Attenuation Due to Concentration Averaging in Monitoring Wells   总被引：6，自引：0，他引：6  

James M. Martin-Hayden  Gary A. Robbins 《Ground water》1997,35(2):339-346

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Book reviews     

Yu. N. Korenkov  Carl W. Cable  Vernon F. Cormier  Vassily Levin  Jacek A. Majorowicz  Yehuda Bock  Waclaw M. Zuberek  Teng-fong Wong  William L. Power  Gary A. Robbins  Piotr Raczka  Krzysztof E. Haman  Katarzyna Chałasinska-Macukow  Ryszard Balcer  Henryk Piwkowski 《Pure and Applied Geophysics》1991,137(3):309-336

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那拉提山北缘寒武纪玄武岩的元素地球化学特征及构造意义   总被引：3，自引：2，他引：3  

钱青徐守礼  何国琦Reiner KLEMD熊贤明  龙灵利高俊 《岩石学报》2007,23(7):1708-1720

我国西南天山地区那拉提北缘断裂北侧出露寒武纪（516.3±7.4Ma）橄榄拉斑玄武岩，其Al2O3（120.71％-14.14％）、P2O5（0.09％-0．21％）含量较低，TiO2（1.39％-2．35％）、MgO（5.35％-8.14％）含量中等，全Fe2O3（11.74％-16．03％）含量较高，球粒陨石标准化稀土分布型式平坦，（La／Sm）.和（Y／Nb）.比值接近1，为过渡型洋脊玄武岩（T-MORB）；并且Th／Ta比值（0．8—1.5）低，高场强元素（Nb，Ta，Zr，Hf，P）没有明显亏损，缺乏陆壳混染或俯冲带流体活动的印迹.部分T-MORB的Fe、Ti含量较高（FeO^T〉12％，TiO2〉2％，FeO^T／MgO〉1．75），Mg^#值（0．40—0.49）和Cr（53×10^-6-110×10^-6）含量较低，属于Fe-Ti玄武岩（ferrobasalt），应为岩浆依Fenner趋势发生较高程度结晶分离演化的产物，很可能形成于洋中脊的扩展型裂谷环境.我们认为，那拉提北缘寒武纪T-MORB和Fe-n玄武岩可能与境外吉尔吉斯斯坦境内北天山南缘的旱古生代Terskey蛇绿岩带相连，为Terskey蛇绿岩的残片；寒武纪我国境内发育Terskey洋.那拉提北缘断裂可能与尼古拉耶夫线相连，代表西南天山地区Terskey洋闭合形成的一条早古生代缝合带.  相似文献   

Adaptive Management of the Global Climate Problem: Bridging the Gap Between Climate Research and Climate Policy     

Joseph Arvai  Gavin Bridge  Nives Dolsak  Robert Franzese  Tomas Koontz  April Luginbuhl  Paul Robbins  Kenneth Richards  Katrina Smith Korfmacher  Brent Sohngen  James Tansey  Alexander Thompson 《Climatic change》2006,78(1):217-225

To date the Intergovernmental Panel on Climate Change (IPCC) has concerned itself with gathering a state of the art review of the science of climate change. While significant progress has been made in enhancing our integrated understanding of the climate system and the dynamics of the social systems that produce an array of potential greenhouse gases, it is also clear from the panel's reports how far the science community is from being able to present a dynamic and synoptic view of the climate system as a whole. Clear evidence of these complexities and uncertainties inherent in the climate system is evident in efforts aimed at designing robust policy interventions. In this paper, we argue that the adaptive management framework in ecosystem management may be a useful model for guiding how the IPCC can continue to be relevant both as a scientific establishment and as a policy-relevant scientific endeavor.  相似文献   

大别山北部饶拔寨超镁铁岩体微量元素地球化学   总被引：3，自引：4，他引：3  

支霞臣  靳永斌孟庆 高天山 《岩石学报》2004,20(3):463-472

本文报道了饶拔寨超镁铁岩体的5个钻孔15个岩心样品的主量元素和微量元素成分。该岩体由上、下两部分构成。岩性以方辉橄榄岩为主，纯橄榄岩和二辉橄榄岩次之。主量元素成分表明岩体由饱满地幔经过不同程度部分熔融，形成了亏损程度不同的大陆岩石圈地幔。总体上下部岩体较上部亏损程度大。原始地幔标准化REE等不相容微量元素丰度模式表明岩体在熔融作用后又经过了地幔交代作用，形成不同程度LREE和LILE的富集。样品中有角闪石和金云母等含水矿物，表明有实性地幔交代作用。对比LREE与LILE的富集特征，表明可能有两类地幔交代作用，有两种不同性质的交代介质，LREE和Sr等的富集可能与硅酸盐熔体有关，而Rb、Ba、K等的富集可能与俯冲带流体活动有关。总体上下部岩体的交代作用较上部岩体的强。  相似文献   

Comparative ²¹⁰Pb, ¹³⁷Cs,and pollen geochronologies of sediments from Lakes Ontario and Erie     

J.A. Robbins  D.N. Edgington  A.L.W. Kemp 《Quaternary Research》1978,10(2):256-278

The distribution of ²¹⁰Pb, ¹³⁷Cs, and Ambrosia (ragweed) pollen in two sediment cores from Lake Ontario and in three cores from Lake Erie provides independent estimates of sediment accumulation rates. Geochronology with ²¹⁰Pb is based on radioactive decay of the isotope following burial in sediments. The method can reveal with precision changes in sedimentation occurring over the past 100 yr or so. Geochronologies with ¹³⁷Cs and Ambrosia are based on the occurrence of a horizon corresponding, respectively, to the onset of nuclear testing 25 yr ago and to regional forest clearance in the middle 1800s. These methods provide estimates of long-term average sediment accumulation rates. In all but one core, the distributions of ¹³⁷Cs and ²¹⁰Pb indicate no physical mixing of near-surface sediments. In two cores, including one from central Lake Erie collected by diver, all three estimates of sedimentation rates are in excellent agreement. In two other cores, rates based on ²¹⁰Pb are significantly higher than those inferred from Ambrosia pollen profiles. Lower average rates appear to result from occasional massive losses of sediments. Such events, apparent in the distribution of ²¹⁰Pb but not in pollen records, correlate with the occurrence of major storm surges on the lakes during this century. In one core from western Lake Erie, exponential distributions of both ²¹⁰Pb and Ambrosia appear to be artifacts which may result from extensive biological or physical reworking of sediments in shallow water (11 m). Previous indications of increased sedimentation in Lake Erie since about 1935 based on Castanea (chestnut) pollen data are not substantiated.  相似文献   

Determination of recent sedimentation rates in Lake Michigan using Pb-210 and Cs-137     

John A. Robbins  D.N. Edgington 《Geochimica et cosmochimica acta》1975,39(3):285-304

This paper describes the use of ²¹⁰Pb and ¹³⁷Cs radioactivity measurements to determine the rates of sedimentation in the Great Lakes. Cores from eight locations in Lake Michigan were chosen for examination to cover as wide as possible a range of sedimentation rates and representative sedimentary environments. The surficial ²¹⁰Pb activity in the sediments varies between 7 and 23 pCi/g dry wt and its profile in each core shows the expected exponential decrease with depth consistent with the assumption of uniform sedimentation rate over the last hundred years and secular equilibrium between supported ²¹⁰Pb and ²²⁶Ra (0.5-1.0 pCi/g dry wt). Companion measurements of ¹³⁷Cs indicate that the coring technique satisfactorily recovered the uppermost levels of the deposit and that the mobility of both radionuclides within the sediment is probably small.Based on the limited number of cores analyzed to date, it appears that modern sedimentation rates are not very different from average rates for the last 7000 yr. The excess ²¹⁰Pb appears to originate primarily from atmospheric fallout, but a further inventory of the ²¹⁰Pb distribution over the lake bottom must be made to properly assess the significance of other sources. The spatial distributions of both ¹³⁷Cs and ²¹⁰Pb at certain stations suggest that the mode of transport of these radionuclides are comparable and involve attachment to settling particles. A mathematical model is developed which accounts for the observed limited mobility of both ²¹⁰Pb and ¹³⁷Cs in several of the cores in terms of post-depositional redistribution by physical or biological mixing processes.  相似文献   

Book reviews     

Allan M. Rubin  Gerardo G. Tango  Jeremy Bloxham  Stanislaw Wybraniec  Adam Łyszkowicz  Gary A. Robbins  Benoit Cushman-Roisin  David S. Gutzler  Carlos Lozano  Hanna Pawłowska 《Pure and Applied Geophysics》1991,137(1-2):147-174

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