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1.
大兴安岭南部—松辽盆地西斜坡晚二叠世古沉积环境一直以来备受争议,关于该地区中—晚二叠世古环境演化方面的研究也鲜见报道。本文采用元素地球化学和有机地球化学相结合的研究方法,对松辽盆地西斜坡蒙科地1井中—晚二叠世古沉积环境演化特征进行综合研究。结果表明,中二叠世为明显的海相沉积,沉积水体相对较深,期间可能存在多次干热—暖湿波动,其中中二叠世ZSI晚期—ZSII早期较为明显,水体性质体现为咸水—微咸水—半咸水,水体还原性—偏氧化性—还原性,气候干热—温湿—干热。晚二叠世早期为微咸水—半咸水海相沉积,至晚二叠世晚期转变为淡水—微咸水海陆过渡相沉积,期间存在两次明显的气候环境波动,与中二叠世哲斯组沉积中期气候环境变化相似,表现为水体变浅、咸度降低、还原性减弱,气候由干热转向温湿。晚二叠世以来气候逐渐向温暖湿热转变,水体逐渐变浅,可能与二叠纪—三叠纪之交气候变暖有关。至三叠纪、侏罗纪时期,区域处于构造抬升阶段,沉积环境由海陆过渡相环境转变为陆相沉积。结合TOC、古生产力指标分析得出,中二叠世ZSI晚期—ZSII2早期、晚二叠世LXI晚期、晚二叠世LXII中期、晚二叠世LXIII沉积期偏湿润的气候条件和低咸度、弱还原—偏氧化性的沉积水体环境,是形成厚度较大、富有机质烃源岩的有利的气候环境条件。  相似文献   
2.
Marine ferromanganese nodules and crusts containing Mn, Cu, Ni and Co in the most promising resource-grade concentrations and quantities, together with Fe and Zn (all elements of biogeochemical importance) are found far from land on the deep seafloor of the Pacific Ocean. The biogeochemical, chemical and physical mechanisms contributing to their formation, distribution, abundance and – for these six elements – variability in their concentrations in these deposits, are the main focus of the present review. The mechanisms addressed include biological productivity, sedimentation types and rates, bottom water characteristics, the Calcium Carbonate Compensation Depth, the depth and intensity of the oxygen minimum zone, and biogeochemical characteristics of the six focal elements. Particular attention is given to comparisons between the deposits found in the north and the south Pacific, in order to present an overarching view of our current understanding of the mechanisms that apply to both nodules and crusts in both oceanic hemispheres, including examination of the possible existence of a marine ferromanganese oxide continuum. The renewed interest in the commercial exploitation of these deposits has stimulated a welcome increase in scientific research that is essential to informing the public discourse on seabed mining. We briefly reflect on the work addressed in this review in that context.  相似文献   
3.
利用机器学习方法对地震活动大数据进行挖掘,识别出一些过去认识不到的异常,提高地震预测的准确性,是一个非常具有挑战性的科学问题.本文基于川滇部分地区(24°N—32°N,98°E—106°E)地震目录,采用滑动的时空窗口,选取16个反映地震时空强度分布特征的地震预测因子,建立了长短时记忆(LSTM)神经网络,对研究区域9个子区块未来一年的最大地震震级进行预测.通过设置训练集∶测试集=8∶2和训练集∶测试集=7∶3两个不同的训练测试模型,对过往发生的地震进行了回溯性预报.结果表明:训练集∶测试集=7∶3模型能够利用1970年1月至2004年9月的地震目录进行学习,成功回溯性预报2008年汶川地震;训练集∶测试集=8∶2模型利用1970年1月至2009年5月资料进行训练,回溯性预报2010—2019年间6级以上地震的R评分为0.407,回溯性7级地震预报时准确率高达92.31%.本文还探讨性给出预测意见:2022年2月前研究区西部、中部、东部、西南部存在发生5.1~5.3级地震的潜在危险性.  相似文献   
4.
Large rock slope failures play a pivotal role in long-term landscape evolution and are a major concern in land use planning and hazard aspects. While the failure phase and the time immediately prior to failure are increasingly well studied, the nature of the preparation phase remains enigmatic. This knowledge gap is due, to a large degree, to difficulties associated with instrumenting high mountain terrain and the local nature of classic monitoring methods, which does not allow integral observation of large rock volumes. Here, we analyse data from a small network of up to seven seismic sensors installed during July–October 2018 (with 43 days of data loss) at the summit of the Hochvogel, a 2592 m high Alpine peak. We develop proxy time series indicative of cyclic and progressive changes of the summit. Modal analysis, horizontal-to-vertical spectral ratio data and end-member modelling analysis reveal diurnal cycles of increasing and decreasing coupling stiffness of a 260,000 m3 large, instable rock volume, due to thermal forcing. Relative seismic wave velocity changes also indicate diurnal accumulation and release of stress within the rock mass. At longer time scales, there is a systematic superimposed pattern of stress increased over multiple days and episodic stress release within a few days, expressed in an increased emission of short seismic pulses indicative of rock cracking. Our data provide essential first order information on the development of large-scale slope instabilities towards catastrophic failure. © 2020 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd.  相似文献   
5.
The passive, ambient sound above the water from a river has previously untapped potential for determining flow characteristics such as stage. Measuring sub-aerial sound could provide a new, efficient way to continuously monitor river stage, without the need for in-stream infrastructure. Previous published work has suggested that there might be a relationship between sound and river stage, but the analysis has been restricted to a narrow range of flow conditions and river morphologies. We present a method to determine site suitability and the process of how to record and analyse sound. Data collected along a 500 m length of the River Washburn during July 2019 is used to determine what makes a site suitable for sound monitoring. We found that sound is controlled by roughness elements in the channel, such as a boulder or weir, which influences the sound produced. On the basis of these findings, we collect audio recordings from six sites around the northeast of England, covering a range of flow conditions and different roughness elements, since 2019. We use data from those sites collected during storms Ciara and Dennis to produce a relationship between this sound and river stage. Our analysis has shown a positive relationship between an R2 of 0.73 and 0.99 in all rivers, but requires careful site selection and data processing to achieve the best results. We introduce a filter that is capable of isolating a river's sound from other environmental sound. Future work in examining the role of these roughness elements is required to understand the full extent of this technique. By demonstrating that sound can operate as a hydrometric tool, we suggest that sound monitoring could be used to provide cost-effective monitoring devices, either to detect relative change in a river or, after more research, a reliable stage measurement.  相似文献   
6.
This study presents a meta-analysis of radiocarbon ages for the environs of Göbekli Tepe – one of the oldest monumental structures worldwide – using cumulative probability functions to diachronically assess phases of geomorphodynamic activity as controlled by natural or anthropogenic drivers. We employ sediment cascades as a heuristic framework to study the complex responses of the geomorphological system to various triggers at local to supra-regional scales. Possible triggers include climatic variability as documented by supra-regional hydroclimatic proxy data, regional demographic trends, and local to regional socioeconomic developments such as the emergence of sedentism or the introduction and dispersal of livestock herding. Our results show that phases of intensified geomorphodynamic activity occurred between ca. 7.4–7.0 and 5.8–3.3 ka BP. These phases roughly coincide with phases of population growth in southern Turkey and climatic variations in Turkey and the Levant. The phase between ca. 5.8–3.3 ka BP also corresponds to the time when organized agriculture and the seeder plough were introduced. Also, the identified phases are in agreement with the general trend of varying geomorphodynamic activity in the Eastern Mediterranean as driven by human impact and climatic change. However, neither the Younger Dryas–Holocene transition nor the development of herding during the Pre-Pottery Neolithic left a clear signature. We demonstrate how the different depositional environments in the studied landscape compartments vary with respect to their spatiotemporal coverage and discuss challenges when trying to understand processes that once shaped landscapes of past societies. © 2020 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd  相似文献   
7.
自然资源调查是实现自然资源统一管理的重要前提和基础性工作。本文通过对自然资源分类体系、调查方案和数据库组织的研究,构建了以第三次国土调查和各类专项调查数据为基础的自然资源调查监测体系,提出了新的数据库组织和更新方法,并在江苏省徐州市进行了实践验证,形成了地市级调查成果,旨在为全国范围内地级市自然资源调查工作提供参考,构建可复制、可推广的调查体系。  相似文献   
8.
《China Geology》2021,4(3):421-432
The Badain Jaran Desert is the third largest desert in China, covering an area of 50000 km2. It lies in Northwest China, where the arid and rainless natural environment has a great impact on the climate, environment, and human living conditions. Based on the results of 1∶250000 regional hydrogeological surveys and previous researches, this study systematically investigates the circulation characteristics and resource properties of the groundwater as well as the evolution of the climate and ecological environment since the Quaternary in the Badain Jaran Desert by means of geophysical exploration, hydrogeological drilling, hydrogeochemistry, and isotopic tracing. The results are as follows. (1) The groundwater in the Badain Jaran Desert is mainly recharged through the infiltration of local precipitation and has poor renewability. The groundwater recharge in the desert was calculated to be 1.8684×108 m3/a using the water balance method. (2) The Badain Jaran Desert has experienced four humid stages since the Quaternary, namely MIS 13-15, MIS 5, MIS 3, and the Early–Middle Holocene, but the climate in the desert has shown a trend towards aridity overall. The average annual temperature in the Badain Jaran Desert has significantly increased in the past 50 years. In detail, it has increased by about 2.5°C, with a higher rate in the south than in the north. Meanwhile, the precipitation amount has shown high spatial variability and the climate has shown a warming-drying trend in the past 50 years. (3) The lakes in the hinterland of the Badain Jaran Desert continuously shrank during 1973–2015. However, the vegetation communities maintained a highly natural distribution during 2000–2016, with the vegetation cover has increased overall. Accordingly, the Badain Jaran Desert did not show any notable expansion in that period. This study deepens the understanding of groundwater circulation and the climate and ecological evolution in the Badain Jaran Desert. It will provide a scientific basis for the rational exploitation of the groundwater resources and the ecological protection and restoration in the Badain Jaran Desert.© 2021 China Geology Editorial Office.  相似文献   
9.
安徽宣城地区上二叠统龙潭组海陆过渡相页岩不仅是我国下扬子区重要的烃源岩,也是目前我国页岩气勘探的重要层位之一。为研究海陆过渡相页岩沉积环境与有机质富集的关系,以港地1井和两个露头剖面为研究对象,系统开展了有机地球化学测试、有机岩石学研究、氩离子抛光—扫面电镜观察、元素地球化学分析等工作。结果表明:下扬子宣城地区龙潭组页岩沉积时期处于暖湿型气候,沉积水体处于氧化—贫氧状态,具有高的生物生产力和沉积速率。海陆过渡相富有机质页岩的形成,不是由单一因素所决定的,而是由古气候、水体氧化还原性质、古生产力、沉积速率等多个要素相互配置与耦合的结果,这些因素都会直接或者间接地影响有机质的供给或者有机质的埋藏和保存。其中,温湿型气候不仅有利于陆源高等植物的生长,而且会促进生物地球化学作用,使得母岩化学风化程度加大,向水体输入的营养物质增多,有利于菌藻类等低等水生生物勃发,高等植物碎屑和低等水生生物共同为富有机质页岩沉积提供了丰富的有机质来源。宣城地区晚二叠世沉积时期,较高的古生产力为海陆过渡相富有机质页岩的形成提供了良好的物质基础,有机质产生后进一步埋藏和保存,虽然富氧水体环境不利于有机质保存,但高的沉积速率可以缩短有机质在富氧水体中暴露的时间,使得有机质来不及被氧化或分解,也可造成有机质的富集。  相似文献   
10.
随着现代工业的发展,城市黑臭河道问题日趋严重,严重影响了城市形象、生态环境和居民身心健康。利用多水塘活水链人工湿地技术净化江苏常州永胜河河水水质。监测结果显示:该技术使水体总氮浓度削减了92.0%、总磷浓度削减了82.9%,处理后的水体总氮、总磷含量达到地表IV类水标准。项目年处理水量约30万t,每年以较低的成本(平均水处理费用约为0.03元/t),削减总氮、总磷和氨氮量分别为1496.6 kg、176.0 kg和1408.6 kg。通过引植多种浮叶植物、挺水植物、沉水植物,该湿地修复工程为当地营造了优美的湿地景观。多水塘活水链人工湿地是集经济效益、生态效益、环境效益于一体的新型水体生态治理技术,为我国城镇黑臭河道治理提供了一条新的途径。  相似文献   
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