利用分布式光纤声传感设备开展青藏高原易贡湖浅层结构探测     

张衡  徐团伟  裴顺平  赵俊猛 《地学前缘》2021,28(6):227-234

地震数据是利用地震学方法探测地下结构的基础条件,然而传统地震仪器难以获得极端环境地区(水下、高原等)的长时间、高密度连续数据。较之国际仪器厂商,国内的DAS研制相对较晚。自2016年起,国产DAS逐步应用于石油测井和城市区域地下结构探测,而运用在极端环境下的探测工作尚未见报道。中国科学院半导体研究所与青藏高原研究所经过多年合作研究,于2021年4月将自主研发的DAS系统首次应用于青藏高原的野外数据采集。本次试验同时记录了地面和水下的连续背景噪声和重锤数据。该研究利用背景噪声成像技术,获得了西藏易贡湖地区地表70 m以内的横波速度结构。本次研究为极端环境下的低成本、高密度数据采集和地下结构探测提供了理论和试验依据。  相似文献   

金沙江“11·3”白格堰塞湖溃决洪水事件在奔子栏—石鼓段的地貌作用和沉积特征     

苏怀  史正涛  董铭  叶燎原  叶蕾 《地学前缘》2021,28(2):202-210

古堰塞湖溃决洪水事件的重建是当前地学研究的热点问题之一,寻找足够的可参考的现代溃决洪水事件案例是顺利开展这项工作的基础。2018年11月13日发生在金沙江干流的白格堰塞湖超万年一遇的溃决洪水事件(学术界称之为“11·3”白格堰塞湖溃决洪水事件)就是一个难得的样本。这次溃决事件发生在枯水期,洪峰完全由溃决洪水产生,没有叠加其他来源,对评估流域地貌和沉积体系对堰塞溃决事件的响应有很好的参考价值。本文以溃决洪水事件受灾最为严重的奔子栏—石鼓段为研究区,通过详细的野外调查和初步的水力学估算发现“11·3”白格堰塞湖溃决洪水事件在奔子栏—石鼓段的地貌作用主要表现为洪水淹没区的岸坡塌岸和沉积物堆积,未发现明显的基岩侵蚀。沉积物主要由分选良好的具水平纹层的砂组成。受金沙江较低的河床比降影响,洪水产生的基底剪切应力较弱在27~142 N/m²,不能悬浮和搬运直径5 cm以上的砾石,也不能产生明显的磨蚀和冲(撞)击作用。在发生塌岸的部分段落,洪水沉积物中有砾石坠入,甚至会出现类似浊流沉积的层序。这些现象的发现对深入理解堰塞湖溃决洪水的复杂地貌过程和沉积特征有重要参考意义。  相似文献   

Geoarchaeological evidence on a Late Bronze Age earthquake,Ohrid Basin (North Macedonia)     

J. Hošek  M. Verčík  P. Pokorný  J. Beneš  V. Komárková  T. Radoměřský  N. Atanasoska  V. Todoroska  P. Ardjanliev 《第四纪科学杂志》2021,36(6):1003-1012

Geoarchaeological investigations on the northeastern shore of Lake Ohrid revealed 3.5 m thick deepwater lacustrine sediments overlying terrestrial vegetation macrofossils, worked wood and abundant potsherds dated to the Late Bronze Age (LBA). Distinct contact of deepwater sediment with the sub-aerial weathered limestone bedrock point to a sudden increase in lake level. According to radiocarbon data, catastrophic flooding occurred shortly after 1214 yr bc. Because the area is located in a highly active seismic zone, we propose that this event was caused by tectonically induced, metre-scale coseismic subsidence related to faults bordering the Ohrid alluvial plain. Moreover, this event coincides well with a dramatic switch in the habitation and settlement strategy in the region. More important, however, is the finding that the age of the proposed massive tectonic event and change in habitation lies within the interval of the proposed ‘earthquake storm’ in the eastern Mediterranean dated to 1225–1175 bc. As the Ohrid-Korça zone belongs to the same tectonic province, a relationship between the abovementioned earthquakes and the proposed event can be expected. This research therefore might provide the first direct evidence of a large-scale earthquake event linkable to the LBA collapse of Europe's first urban civilisation in the Aegean.  相似文献   

西藏班戈错水菱镁矿藻类成矿实验及其成因分析     

蒋天明  姬连敏  程怀德  李斌凯  李刚  马海州  张西营  李长忠  马学海  张鹏程 《地质论评》2021,67(5):67060004-67060004

目前关于天然水菱镁矿的形成认识主要有蒸发沉积成因和生物成因两类。前人在室内成功制备出水菱镁矿矿物,证实了该矿物的无机成因理论,但是实验结晶条件明显高于西藏班戈错的寒冷气候条件和水化学条件,并且班戈错湖水通过自然蒸发结晶也难以形成水菱镁矿矿物,而这一认识与周边阶地上正在形成水菱镁矿的现象相矛盾。因此,自然蒸发沉积可能不是现阶段班戈错水菱镁矿的主要形成过程,而已有研究表明,藻类具备诱导形成碳酸盐矿物的能力,本文利用西藏班戈错Ⅲ湖湖水及其藻类开展室内模拟实验,并与无藻类的湖水自然结晶结果相对照,探讨藻类生命活动与班戈错水菱镁矿的成因联系。研究发现,藻类不仅能够适应高盐度盐水环境（矿化度117.3 g/L）,并且在其光合作用过程中还能显著提高周围水体pH值（最高可达10.564）,诱导并促进球碳镁石在藻类网状节点处结晶沉淀,该矿物进一步脱水即能够形成水菱镁矿矿物;而人为提高班戈错Ⅲ湖湖水Mg2+浓度也仅能结晶形成三水菱镁矿矿物,无球碳镁石或水菱镁矿结晶析出。因此,西藏班戈错水菱镁矿的形成过程与藻类生物成矿作用密切相关,但是有关球碳镁石向水菱镁矿转变的具体条件以及藻类成矿作用的具体分子机制仍不清楚,有待于进一步研究。  相似文献   

太湖流域降雨与太湖水位关系分析   总被引：1，自引：0，他引：1  

章杭惠  刘曙光  季同德 《水文》2021,41(1):85-89,41

太湖流域快速城镇化、水利工程建设等人类活动对流域水文过程产生了较大影响。基于1981~2018年太湖流域日降雨、太湖水位实测资料,分析了流域降雨与太湖水位涨幅关系,旨在揭示变化环境下该地区降雨与水位关系的变化特征及可能的驱动因素。研究表明,2000年以来太湖水位抬高趋势明显,但同等时段降雨量条件下对应的太湖水位涨幅有所下降,且降雨量越大,太湖水位涨幅减小的越明显;流域各时段降雨与太湖水位涨幅相关关系约0.9,流域10d雨强每增加50mm,太湖水位涨幅约16cm。该研究成果可为太湖水位的中长期预报,尤其是对入汛前、入梅前等关键时间节点的太湖水位调控、雨洪资源利用等流域管理工作提供参考。  相似文献   

寒武纪生物大爆发之后的底栖生态系统工程建造者:以河南地区为例          下载免费PDF全文

刘炳辰  齐永安  代明月  白万备  樊钰超  庆国帅 《地球科学》2021,46(1):148-161

扰动生物作为生态系统工程建造者,通过对沉积底质的改造直接影响沉积物和水体之间的相互作用（营养物质的循环、迁移和存储）,对底栖生态系统工程有重要的影响.遗迹化石作为底栖生物活动的载体,为研究寒武纪大爆发之后底栖生态系统工程建造者的演化规律,并评价底栖生态系统工程建造者对生态系统工程产生的影响提供了依据.对河南地区8个寒武系剖面的遗迹化石数据进行统计,应用现代生物学中生态系统工程影响值的概念,从功能群、阶层、生物灌溉3个方面对底栖生态系统工程建造者进行研究.研究结果表明,寒武系第三阶至鼓山阶底栖生态系统工程建造者功能群类型由生物扩散型扰动者往向上/下运输者转变,阶层逐渐加深,生物灌溉越来越普及,生态系统工程影响值不断增大.鼓山阶至第十阶,遗迹化石类型及结构变化不大,生态系统工程影响值趋于稳定.这表明从寒武纪生物大爆发至鼓山阶,底栖生态系统工程建造者的行为策略发生着明显的进化与创新,生态系统工程建造者不仅开拓了重要的生态空间,而且为其他底栖生物和微生物创造了新的生境,在寒武纪海洋生态系统中扮演着重要的角色.   相似文献   

Holocene environmental evolution recorded by core sediments of Judian Lake in the east of Lubei Plain,Shandong Province          下载免费PDF全文

Zou Chun-Hui  Zhao Qiang  Mao Long-Jiang 《古地理学报》2021,22(6):1209-1220

Judian Lake in the east of Lubei Plain is located in the monsoon area of northern China,which is sensitive to global climate change and provides abundant lake sedimentary data for the study of the past climate and environment evolution in the land-sea interaction area. Based on the sporopollen identification,grain size analysis and AMS¹⁴C dating of core sediments from the drilling hole of the Judian Lake,the evolutional process of climate and environment since 8900 cal a BP in the northern Lubei Plain was discussed. The results show that: 8900-7625cal a BP,the temperature and precipitation increased and the climate changed from cold-dry to warm-wet;7625—6810 cal a BP,the overall climate was becoming cooler and drier;6810—4435cal a BP,the temperature rose and the precipitation increased,showing an overall warm and humid climate in the middle Holocene;4435—3150cal a BP,the climate was generally cold and humid with some low-amplitude fluctuations of cold and warm. During the middle Holocene,there were two obvious cold and dry events in 5450—5280cal a BP and 4160—4090cal a BP,which was consistent with the geological and climatic records in China and even in the world. It may be due to the southward movement of the equatorial convergence zone caused by the change of solar radiation,the change of ocean surface temperature and the feedback of surface vegetation.  相似文献   

黑龙江省兴凯湖自然保护区生态系统固碳服务功能评价     

肖红叶  戴慧敏  杨泽  刘国栋  高铁  杨佳佳  张一鹤 《地质与资源》2021,29(6):570-573

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Cross-site analysis of perceived ecosystem service benefits in multifunctional landscapes     

《Global Environmental Change》2019

Rural development policies in many Organization for Economic Co-operation and Development (OECD) member countries promote sustainable landscape management with the intention of providing multiple ecosystem services (ES). Yet, it remains unclear which ES benefits are perceived in different landscapes and by different people. We present an assessment of ES benefits perceived and mapped by residents (n = 2,301) across 13 multifunctional (deep rural to peri-urban) landscapes in Europe. We identify the most intensively perceived ES benefits, their spatial patterns, and the respondent and landscape characteristics that determine ES benefit perception. We find outdoor recreation, aesthetic values and social interactions are the key ES benefits at local scales. Settlement areas are ES benefit hotspots but many benefits are also related to forests, waters and mosaic landscapes. We find some ES benefits (e.g. culture and heritage values) are spatially clustered, while many others (e.g. aesthetic values) are dispersed. ES benefit perception is linked to people’s relationship with and accessibility to a landscape. Our study discusses how a local perspective can contribute to the development of contextualized and socially acceptable policies for sustainable ES management. We also address conceptual confusion in ES framework and present argumentation regarding the links from services to benefits, and from benefits to different types of values.  相似文献   

太湖蓝藻水华形成的适宜气象指标     

杭鑫  罗晓春  谢小萍  李亚春 《气象科技》2019,47(1):171-178

根据2005—2017年卫星遥感反演的太湖蓝藻水华信息,利用区域气象观测数据分析各类气象因子对太湖蓝藻深水华形成的影响,结果表明:①在日平均气温为0～35℃区间内会出现蓝藻聚集现象,其中最适宜气温区间为15.1～35℃,该区间内累计出现蓝藻水华的面积占比达90%、出现大面积蓝藻水华占比达93%;②在卫星观测到蓝藻前6h,平均风速为0.2～4.8m/s区间内能观测到蓝藻水华,其中最适宜的平均风速区间为0.5～3.4m/s,该区间内蓝藻水华累计出现次数占比达94.7%,大面积蓝藻水华主要出现在平均风速2.0m/s的情况下,占比89%;③降水总体上呈负效应,但在观测到有大面积蓝藻水华的情况下,前24h有小雨(10mm)的情形与总降水次数之比达88%,说明小雨的适度扰动有利于形成大面积蓝藻水华;④日照充足有利于蓝藻生长,但并非蓝藻水华形成的必要条件。在此基础上建立的多元回归综合气象指数模型,拟合结果较好,通过了0.001的显著性检验。  相似文献