Late Holocene relative sea level rise and the Neoglacial history of the Greenland ice sheet     

Antony J. Long  Sarah A. Woodroffe  Sue Dawson  David H. Roberts  Charlotte L. Bryant 《第四纪科学杂志》2009,24(4):345-359

In West Greenland, early and mid Holocene relative sea level (RSL) fall was replaced by late Holocene RSL rise during the Neoglacial, after 4–3 cal. ka BP (thousand calibrated years before present). Here we present the results of an isolation basin RSL study completed near to the coastal town of Sisimiut, in central West Greenland. RSL fell from 14 m above sea level at 5.7 cal. ka BP to reach a lowstand of ?4.0 m at 2.3–1.2 cal. ka BP, before rising by an equivalent amount to present. Differences in the timing and magnitude of the RSL lowstand between this and other sites in West and South Greenland record the varied interplay of local and non‐Greenland RSL processes, notably the reloading of the Earth's crust caused by a Neoglacial expansion of the Greenland Ice Sheet (GIS) and the subsidence associated with the collapse of the Laurentide Ice Sheet forebulge. This means that the timing of the sea level lowstand cannot be used to infer directly when the GIS advanced during the Neoglacial. The rise in Late Holocene RSL is contrary to recently reported bedrock uplift in the Sisimiut area, based on repeat GPS surveys. This indicates that a belt of peripheral subsidence around the current ice sheet margin was more extensive in the late Holocene, and that there has been a switch from subsidence to uplift at some point in the last thousand years or so. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

Coupled surface water–groundwater model and its application in the arid Shiyang River basin,China     

Li‐Tang Hu  Zhong‐Jing Wang  Wei Tian  Jian‐Shi Zhao 《水文研究》2009,23(14):2033-2044

The planning and management of water resources in the Shiyang River basin, China require a tool for assessing the impact of groundwater and stream use on water supply reliabilities and improving many environment‐related problems such as soil desertification induced by recent water‐related human activities. A coupled model, integrating rule‐based lumped surface water model and distributed three‐dimensional groundwater flow model, has been established to investigate surface water and groundwater management scenarios that may be designed to restore the deteriorated ecological environment of the downstream portion of the Shiyang River basin. More than 66% of the water level among 24 observation wells have simulation error less than 1·0 m. The overall trend of the temporal changes of simulated and observed surface runoff at the Caiqi gauging station remains almost the same. The calibration was considered satisfactory. Initial frameworks for water allocation, including agricultural water‐saving projects, water diversion within the basin and inter‐basin water transfer, reducing agricultural irrigation area and surface water use instead of groundwater exploitation at the downstream were figured out that would provide a rational use of water resources throughout the whole basin. Sixteen scenarios were modelled to find out the most appropriate management strategies. The results showed that in the two selected management options, the groundwater budget at the Minqin basin was about 1·4 × 10⁸ m³/a and the ecological environment would be improved significantly, but the deficit existed at the Wuwei basin and the number was about 0·8 × 10⁸ m³/a. Water demand for domestic, industry and urban green area would be met in the next 30 years, but the water shortage for meeting the demand of agricultural water use in the Shiyang River basin was about 2·2 × 10⁸ m³/a. It is suggested that more inter‐basin water transfer should be required to obtain sustainable water resource use in the Shiyang River basin. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

Temporal trends of hydro‐climatic variables and runoff response to climatic variability and vegetation changes in the Yiluo River basin,China     

Qiang Liu  Zhifeng Yang  Baoshan Cui  Tao Sun 《水文研究》2009,23(21):3030-3039

The Yiluo River is the largest tributary for the middle and lower reaches of the Yellow River below Sanmenxia Dam. Changes of the hydrological processes in the Yiluo River basin, influenced by the climatic variability and human activities, can directly affect ecological integrity in the lower reach of the Yellow River. Understanding the impact of the climatic variability and human activities on the hydrological processes in the Yiluo River basin is especially important to maintain the ecosystem integrity and sustain the society development in the lower reach of the Yellow River basin. In this study, the temporal trends of annual precipitation, air temperature, reference evapotranspiration (ET₀) and runoff during 1961–2000 in the Yiluo River basin were explored by the Mann‐Kendall method (M‐K method), Yamamoto method and linear fitted model. The impacts of the climatic variability and vegetation changes on the annual runoff were discussed by the empirical model and simple water balance model and their contribution to change of annual runoff have been estimated. Results indicated that (i) significant upwards trend for air temperature and significant downwards trend both for precipitation and ET₀ were detected by the M‐K method at 95% confidence level. And the consistent trends were obtained by the linear fitted model; (ii) the abrupt change started from 1987 detected by the M‐K method and Yamamoto method, and so the annual runoff during 1961–2000 was divided into two periods: baseline period (1961–1986) and changeable period (1987–2000); and (iii) the vegetation changes were the main cause for change of annual runoff from baseline period to changeable period, and climatic variability contributed a little to the change of annual runoff of the Yiluo River. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

Impact of road‐generated storm runoff on a small catchment response     

Daniel W. Woldie  Roy C. Sidle  Takashi Gomi 《水文研究》2009,23(25):3631-3638

The impact of road‐generated runoff on the hydrological response of a zero‐order basin was monitored for a sequence of 24 storm events. The study was conducted in a zero‐order basin (C1; 0·5ha) with an unpaved mountain road; an adjacent unroaded zero‐order basin (C2; 0·2 ha) with similar topography and lithology was used to evaluate the hydrological behaviour of the affected zero‐order basin prior to construction of the road. The impact of the road at the zero‐order basin scale was highly dependent on the antecedent soil‐moisture conditions, total storm precipitation, and to some extent rainfall intensity. At the beginning of the monitoring period, during dry antecedent conditions, road runoff contributed 50% of the total runoff and 70% of the peak flow from the affected catchment (C1). The response from the unroaded catchment was almost insignificant during dry antecedent conditions. As soil moisture increased, the road exerted less influence on the total runoff from the roaded catchment. For very wet conditions, the influence of road‐generated runoff on total outflow from the roaded catchment diminished to only 5·4%. Both catchments, roaded and unroaded, produced equivalent amount of outflow during very wet antecedent conditions on a unit area basis. The lag time between the rainfall and runoff peaks observed in the unroaded catchment during the monitoring period ranged from 0 to 4 h depending on the amount of precipitation and antecedent conditions, owing mainly to much slower subsurface flow pathways in the unroaded zero‐order basin. In contrast, the lag time in the roaded zero‐order basin was virtually nil during all storms. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

柴达木盆地烃蚀变矿物高光谱遥感识别研究   总被引：2，自引：0，他引：2  

胡畔  田庆久  闫柏琨 《国土资源遥感》2009,(2):54-61

高光谱遥感识别烃蚀变矿物可用于探测油气烃类微渗漏和定位地下油气藏.以有天然气分布的柴达木盆地东部三湖地区为研究区,对Hyperion高光谱数据进行重采样处理,克服了目标识别矿物不明显和传感器低信噪比的影响.通过确定烃蚀变矿物高光谱遥感探测的指示标志,采用线性光谱(SAM)拟合与光谱匹配(SAM)相结合的方法确定了影像端元对应的矿物组分.识别结果表明,合理缩减影像波段数和确定影像端元的方法,能有效提高烃蚀变矿物的高光谱遥感识别精度.  相似文献   

Sediment budget of the Napo River,Amazon basin,Ecuador and Peru     

A. Laraque  C. Bernal  L. Bourrel  J. Darrozes  F. Christophoul  E. Armijos  P. Fraizy  R. Pombosa  J. L. Guyot 《水文研究》2009,23(25):3509-3524

The upstream‐downstream sediment budget along the Napo River (100 520 km², 6300 m³ s^?1) was studied in the Andean foothills of Ecuador, at the west of the Amazon basin. A comparative study was made during four hydrological cycles (2001–2005) for three hydrological stations located upstream, and during one hydrological cycle (2004–2005) for the fourth one located near the mouth of the Napo River (region of Iquitos in Peru). This analysis showed an unusual increase in the concentration of suspended sediment recorded for the western part of the Amazon plain. Like the runoff (81 l s^?1 km²), which is a world's maximum, the erosion rate (1160 t km^?2 year^?1, i.e. 47% of total suspended solid (TSS) export at the exit of Ecuador), one of the highest for a floodplain basin is the result of a stepper slope than in the rest of the Andean foothills, where typically sedimentation phenomena are predominant, and can be explained in part by a greater tectonic activity. Similar phenomenes were evidenced in small mountainous rivers in New Guinea (Milliman and Syvitski, 1992; Milliman, 1995). On the headwaters of the Napo River drainage basin, the tectonic uplift causes the Pastaza Megafan's existence. This progressively diverts the course of Napo River towards north and also provokes the remobilization of fine fluvial deposits. Moreover, this geodynamic trend is completed by the impact of volcanic eruption, earthquakes and landslides. The combination of these phenomena, so common in the region, has provided a large sediment transfer, not only at present but also in the past, as can be confirmed by the presence of incised terraces, mainly formed by volcanic materials. Then, these results were compared with a similar study carried out further south in the Madeira basin at the Bolivian foothills. These studies show the spatio‐temporal variability of the relation between sediment transfer and geodynamic processes at the Andean Piedmont. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

西湖凹陷油气成藏的主控因素     

熊斌辉  张喜林  张锦伟  王春红  杨海长 《海洋地质译丛》2008,(2):14-24

西湖凹陷位于东海大陆架边缘，地壳为相对软弱的过渡壳。西湖凹陷中新世末以前属于萎缩型盆地，上新世伴随冲绳海槽的形成才成为扩张性盆地。受构造控制盆地萎缩期沉积有以下3个特点：第一，整体表现为海退；第二，沉积范围逐次减小；第三，泥岩百分比越来越低，盖层条件越来越差。平湖组存在区域盖层，钻遇断块气藏；花港组存在局部盖层，背斜充满度高，断背斜充满度低，断块未成藏；新近系盖层条件更差，断背斜亦未能成藏。由此可见保存条件是西湖凹陷油气成藏的主控因素，保存条件好的领域是西湖凹陷下一步勘探的方向。  相似文献   

南海北部白云大型海底滑坡的几何形态与变形特征   总被引：9，自引：0，他引：9  

孙运宝  吴时国  王志君  李清平  王秀娟  董冬冬  刘峰 《海洋地质与第四纪地质》2008,28(6)

利用二维、三维地震资料，结合多波束水深测量，在南海北部白云凹陷发现大型海底滑坡。白云大型海底滑坡可分为滑坡根部、滑坡主体和滑坡前缘3个主要部分，广泛发育滑坡陡壁、滑塌沟谷、滑移面、滑坡台阶等典型滑坡地貌。地震相特征表现为楔状弱振幅杂乱地震相，块状平行或渡状弱振幅中连续地震相，席状亚平行／波状弱振幅连续地震相，谷状水平充填中振幅、中连续地震相和丘状／透镜体状前积地震相等5种典型地震相特征。初步估算白云海底滑坡范围约为13000km2，滑坡分布受地形和海底沉积物岩性控制，晚期活动在中更新世。白云大型海底滑坡位于深水油气和天然气水合物的富集区，对油气和天然气水合物成藏作用和勘探开发具有重要的影响。  相似文献   

Distribution and characteristics of volcanic reservoirs in China     

HUANG Yulong  WANG Pujun  CHEN Shuming .College of Earth Sciences  Jilin University  Changchun  China.Daqing Oilfield Corporation  PetroChina  Daqing  Heilongjiang  China 《东北亚地学研究》2009,12(2):64-79

About forty productive oil/gas fields hosted in volcanic reservoirs have been found since 1957 in fourteen basins of China. They can be simply subdivided into two groups, the east and the west. Reservoir volcanic rocks of the east group are predominantly composed of Late Jurassic to Early Cretaceous rhyolite and Tertiary basalt, preferred being considered as rift type volcanics developed in the circum-Pacific tectonic regime. Those of the west are Permo-Carboniferous intermediate/basic volcanic rocks, being island-arc type ones developed in paleo-Asian Ocean tectonic regime.  相似文献   

Ages of sediment-hosted Himalayan Pb–Zn–Cu–Ag polymetallic deposits in the Lanping basin,China: Re–Os geochronology of molybdenite and Sm–Nd dating of calcite     

《Journal of Asian Earth Sciences》2013

The Lanping basin is a significant Pb–Zn–Cu–Ag mineralization belt of the Sanjiang Tethyan metallogenic province in China. Over 100 thrust-controlled, sediment-hosted, Himalayan base metal deposits have been discovered in this basin, including the largest sandstone-hosted Pb–Zn deposit in the world (Jinding), and several Cu ± Ag ± Co deposits (Baiyangping, Baiyangchang and Jinman). These deposits, with total reserves of over 16.0 Mt Pb + Zn, 0.6 Mt Cu, and 7000 t Ag, are mainly hosted in Meso-Cenozoic mottled clastic rocks, and strictly controlled by two Cenozoic thrust systems developed in the western and eastern segments of the Lanping basin.To define the metallogenic history of the study area, we dated nine calcite samples associated with copper sulfides from the Jinman Cu deposit by the Sm–Nd method and five molybdenite samples from the Liancheng Cu–Mo deposit by the Re–Os method. The calcite Sm–Nd age for the Jinman deposit (58 ± 5 Ma) and the molybdenite Re–Os age for the Liancheng deposit (48 ± 2 Ma), together with previously published chronological data, demonstrate (1) the Cu–Ag mineralization in the western Lanping basin mainly occurred in three episodes (i.e., ∼56–54, 51–48, and 31–29 Ma), corresponding to the main- and late-collisional stages of the Indo–Asian orogeny; and (2) the Pb–Zn–Ag (±Cu) mineralization in the eastern Lanping basin lacked precise and direct dating, however, the apatite fission track ages of several representative deposits (21 ± 4 Ma to 32 ± 5 Ma) may offer some constraints on the mineralization age.  相似文献