Cosmogenic isotope (Cl) surface exposure dating of the Norber erratics, Yorkshire Dales: Further constraints on the timing of the LGM deglaciation in Britain

Cosmogenic isotope (³⁶Cl) surface exposure dating of four of the erratic boulders at Norber in the Yorkshire Dales National Park, northwest England, yielded mean ages of ∼22.2 ± 2.0 ka BP and ∼18.0 ± 1.6 ka BP for their emplacement. These two mean values derive from different ³⁶Cl production rates used for exposure age calculation. The ages are uncorrected for temporal variations in production rates and may underestimate the true ages by 5-7%. The former age, although implying early deglaciation for this area of the British ice sheet, is not incompatible with minimum deglaciation ages from other contexts and locations in northwest England. However, the latter age is more consistent with the same minimum deglaciation ages and geochronological evidence for ice-free conditions in parts of the northern sector of the Irish Sea. Within uncertainties, the younger of the mean ages from Norber may indicate that boulder emplacement was associated with North Atlantic Heinrich event 1. The limited spatial (downvalley) extent of the Norber boulders implies that at the time of their deposition the ice margin was coincident with the distal margin of the erratic train. Loss of ice cover at Norber was followed by persistent stadial conditions until the abrupt opening of the Lateglacial Interstadial when large carnivorous mammals colonised the area. The ³⁶Cl ages are between ∼3.0 ka and ∼13.0 ka older than previous estimates based on rates of limestone dissolution derived from the heights of pedestals beneath the erratics.     

Anthropogenic hillslope terraces and swidden agriculture in Jiuzhaigou National Park, northern Sichuan, China

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.     

福建沿岸当地平均海面的高程研究与应用

通过对福建沿岸多年来已有的当地平均海面高程资料和与1985国家高程基准的水准点联测成果,分析并研究了福建沿岸主要验潮站的当地平均海面的高程情况和变化趋势,对福建沿岸当地平均海面的高程（1985国家高程基准）进行了比较深入的研究和探讨,阐述了福建沿岸与浙江、广东沿海平均海面高程的连续性和与我国海区平均海面高程的一致性,论述了当地平均海面高程的应用方法,以解决福建沿海海岸地形图和水深图的基准统一及高度衔接问题。     

降水量对连古城自然保护区荒漠植被凋落物分解和氮状态的影响

对连古城自然保护区不同降雨梯度(不截留和分别截留30％、50％、80％)下荒漠典型植被土壤无机氮和原位净氮矿化的凋落物分解和养分释放进行了连续的观测分析.结果表明:(1)随着水分输入减少,凋落物的分解速率减小,凋落物分解速率与年降水量正相关.与此相反,净氮矿化与降水量无关.(2)土壤NO3-浓度随着降水输入的增加而显著...     

Glacial change in the vicinity of Mt. Qomolangma （Everest）, central high Himalayas since 1976

Glaciers are one of the most important land covers in alpine regions and especially sensitive to global climate change. Remote sensing has proved to be the best method of investigating the extent of glacial variations in remote mountainous areas. Using Landsat thematic mapping (TM) and multi-spectral-scanner (MSS) images from Mt. Qomolangma (Everest) National Nature Preserve (QNNP), central high Himalayas for 1976, 1988 and 2006, we derived glacial extent for these three periods. A combination of object-oriented image interpretation methods, expert knowledge rules and field surveys were employed. Results showed that (1) the glacial area in 2006 was 2710.17 ± 0.011 km² (about 7.41% of the whole study area), and located mainly to the south and between 4700 m to 6800 m above sea level; (2) from 1976 to 2006, glaciers reduced by 501.91 ± 0.035 km² and glacial lakes expanded by 36.88 ± 0.035 km²; the rate of glacier retreat was higher in sub-basins on the southern slopes (16.79%) of the Himalayas than on the northern slopes (14.40%); most glaciers retreated, and mainly occurred at an elevation of 4700–6400 m, and the estimated upper limit of the retreat zone is between 6600 m and 6700 m; (3) increase in temperature and decrease in precipitation over the study period are the key factors driving retreat.     

利用国家数字地震台网记录计算汶川地震余震峰值加速度分布图

数字地震台网可实时获取地震记录,因此可据此快速计算地震动参数,如峰值加速度、峰值速度的分布图,为震后救灾提供参考依据。本文对国家数字地震台网的地震记录,采用插值型求导公式中的两点公式计算加速度时程,并通过计算原始记录和仿真加速度时程的幅值谱,检验了结果的可靠性。最后对汶川大地震后的两个强余震进行了计算和分析,作出了峰值加速度分布图。     

Characteristics and changes of permafrost along the engineering corridor of National Highway 214 in the eastern Qinghai-Tibet Plateau

Due to a series of linear projects built along National Highway 214, the second "Permafrost Engineering Corridor" on the Qinghai-Tibet Plateau has formed. In this paper, by overcoming the problems of data decentralization and standard inconsistency, permafrost characteristics and changes along the engineering corridor are systematically summarized based on the survey and monitoring data. The results show that: 1) Being controlled by elevation, the permafrost is distributed in flake discontinuity with mountains as the center along the line. The total length of the road section in permafrost regions is 365 km, of which the total length of the permafrost section of National Highway 214 is 216.7 km, and the total length of the permafrost section of Gong-Yu Expressway is 197.3 km. The mean annual ground temperature (MAGT) is higher than -1.5 °C, and permafrost with MAGT lower than -1.5 °C is only distributed in the sections at Bayan Har Mountain and E'la Mountain. There are obvious differences in the distribution of ground ice in the different sections along the engineering corridor. The sections with high ice content are mainly located in Zuimatan, Duogerong Plain and the top of north and south slope of Bayan Har Mountain. The permafrost thickness is controlled by the ground temperature, and permafrost thickness increases with the decrease of the ground temperature, with the change rate of about 37 m/°C. 2) Local factors (topography, landform, vegetation and lithology) affect the degradation process of permafrost, and then affect the distribution, ground temperature, thickness and ice content of permafrost. Asphalt pavement has greatly changed the heat exchange balance of the original ground, resulting in serious degradation of the permafrost. Due to the influence of roadbed direction trend, the phenomenon of shady-sunny slope is very significant in most sections along the line. The warming range of permafrost under the roadbed is gradually smaller with the increase of depth, so the thawing settlement of the shallow section with high ice-content permafrost is more significant.     

地质环境的地球化学研究——贺"环境地质学的出现"发表30周年暨中国科学院地球化学研究所环境地球化学国家重点实验室成立10周年

1972年刘东生院土撰文发表了“环境地质学的出现”。中国科学院地球化学研究所环境地球化学国家重点实验室于1992年正式成立,刘东生院士的环境地质学学术观点聚焦于：环境地质学发展的动力源于社会需要,地球环境系统的整体性及其与人类关系的相互依存性。30年来,地质环境的地球化学研究以区域环境质量和全球环境变化两大科学问题作了基本目标,经历了调查评价,区域综合和界面机理3个发展阶段,研究重点是典型区域环境演化的发生学原理,谱系特征以及健康和生态效应,云贵高原地质环境的特殊性显示出青藏隆起对周边现代环境的影响。环境地质学以“地质学与人类”为宗旨,将在21世纪为人类谋求更多的福利。     

黄河源区多年冻土温度及厚度研究新进展

利用新布设的冻土孔及原有冻土资料,分析黄河源区冻土温度和厚度的空间分布。源区实测多年冻土年均地温最低为-1.81℃,冻土最厚74 m,均位于巴颜喀拉山北坡的查拉坪。214国道(K445-K604段)沿线多为高温多年冻土(年均地温>-1℃),但巴山北坡海拔4 520 m、布青山海拔4 300 m以上,年均地温低于-0.5℃。巴山北坡海拔4 610 m、布青山海拔4 420 m以上,年均地温低于-1℃。巴山北坡海拔每升高100 m,年均地温减少0.47~0.75℃,冻土厚度增加16~25 m;纬度向北增加1°,年均地温减少0.85℃,冻土厚度增加20~30 m。     

江西东江源国家湿地公园的湿地保护技术与措施设计

湿地保护保育措施设计是江西东江源国家湿地公园规划与建设的核心。对河流湿地进行保护和保育、修复和恢复,构建良好的河流廊道生态系统,恢复其生态功能和湿地生物多样性,营造优美的湿地景观,是把东江源国家湿地公园打造成＂健康的湿地、洁净的水源、原生态的河流＂的关键。通过设计河道保洁工程、河流湿地修复与恢复工程、生态河岸带建设工程、水生生物多样性恢复工程、湿地生态滤场构建、生态缓冲控制区6大工程14个项目,对东江源国家湿地公园的湿地进行科学、系统与有效的保护。