Stage-progressive distribution pattern of the Lungmachi black graptolitic shales from Guizhou to Chongqing,Central China

The Lungmachi Formation is widely distributed in Guizhou, Chongqing and the adjacent area. It is important for the study of Silurian biostratigraphy and shale-gas investigation. Based on those biostratigraphically well-studied sections from Guiyang to Huayingshan, we reveal the stage-progressive distribution pattern of the Lungmachi black shales. The distribution of the Lungmachi black shales in the studying area can be subdivided into four geographic belts from the south to the north,reflecting the joint effect of regional and global environmental changes. The graptolite depth zonation model was adopted herein to infer the water depth of major graptolite assemblages from the black shales. The changes in the water depth indicate two major stages. The first stage is named the transgressive distribution stage which ranged from the Persculptograptus persculptus Biozone(LM1, upper Hirnantian) to the Coronograptus cyphus Biozone(LM5, upper Rhuddanian), an interval mostly controlled by global sea-level rise. The second stage, ranging from the Demirastrites triangulatus Biozone(LM6, lower Aeronian) to the Spirograptus guerichi Biozone(LM9, lower Telychian), is named the regressive shrinking stage, during which the black shales were gradually replaced by mixed-facies or carbonate sediments from the south to the north, representing the effects of the persistent uplifting of the Central Guizhou Oldland.     

Rhuddanian to Aeronian (Llandovery,early Silurian) carbon isotope stratigraphy throughout carbonate sequences in the upper Yangtze region,South China block

The Xiangshuyuan Formation (middle Rhuddanian to middle Aeronian stages of the Llandovery Series, lower Silurian) records a shelly fauna representing recovery after the end-Ordovician mass extinction in a well-oxygenated shallow carbonate platform of the Upper Yangtze region, South China Block. Carbon isotope stratigraphy is documented from limestone sequences of the formation at the Qiankou section, northeast Guizhou. The early Aeronian carbon isotope excursion (EACIE, with an amplitude of about 2 ‰ and peak value of 2.44 ‰) is identified in the middle and upper parts of the formation (Ozarkodina obesa conodont Biozone). The EACIE recorded herein correlates well with those in Baltica, Canada, and the United States; together with its records from organic material (δ¹³C_org) the data verify that the EACIE is a global event. The beginning of the EACIE can be used as a chemostratigraphic marker defining the Rhuddanian/Aeronian boundary in strata that lack high-resolution biostratigraphic constraints.     

Geochemistry of black shale at the bottom of the Lower Cambrian in Tarim Basin and its significance for lithosphere evolution

At the bottom of the Lower Cambrian, there widely develops a suit of rock association com-posed of black shales interbedded with thin silicalite in the India, northern Pakistan, Iran, southern France, England, northern Oman, the former USSR, southern Kaza…     

黑龙江省及其邻区地震序列时期特征研究

通过对中国大陆１０３个地震序列（自１９６６年以来）显地震发生在６小时内的资料进行分析表明,中国东部地区地震序列的数量明显低于西部地区,而黑龙江省及其邻区地震序列的数量则更少,地震累积频度拟合函数主要呈指数函数、幂函数分布,其中双震型或多震型序列以指数函数分布为主,主余震型则以幂函数分布为主。ｈ值、ｋ值与地震数量及主余震时间差等无线性关系。显地震有前震的序列,其地震频度拟合函数、ｈ值与前震至显     

黑龙江省及其邻区地震序列早期特征研究

通过对中国大陆103个地震序列（自1966年以来）显著地震发生后6小时内的资料进行分析表明,中国东部地区地震序列的数量明显低于西部地区,而黑龙江省及其邻区地震序列的数量则更少。地震累积频度拟合函数主要呈指数函数、幂函数分布,其中双震型或多震型序列以指数函数分布为主,主余震型则以幂函数分布为主。 h 值、k 值与地震数量及主余震时间差等无线性关系。显著地震有前震的序列,其地震频度拟合函数、h 值与前震至显著地震的时间间隔有关,当时间间隔大于7小时,地震累积频度拟合函数多呈指数函数分布,h 值<0.5。     

The impact of environmental factors on the distribution pattern of aquatic plants along the Danube River corridor (Slovakia)

The aim of the study was to evaluate pattern of the aquatic macrophyte species distribution along the Danube fluvial corridor in Slovakia, and to identify the impact of environmental abiotic parameters on macrophyte species diversity. Field sampling was performed in the period 1999–2005 from the boat. Aquatic habitats were divided into 365 survey unit (SU). The survey of aquatic macrophytes and abiotic parameters followed the European standard approach EN 144184 2003. The plant mass estimate (PME – a semi-quantitative estimation of the amount of individual species in a SU, which takes into account three-dimensional development of plant stands) was estimated according to a five-point-scale in each SU; environmental pattern, were assessed over six abiotic parameters (river km, bank type, sediment type, flow velocity class, land-use type, and heavily man-modified water bodies). Altogether, four hydrologic connectivity types of aquatic habitats were distinguished: the Danube River, Open Arms, Separated Arms, and Seepage Water-bodies.

In total, 54 aquatic macrophytes were recorded for the whole data set of the Danube fluvial corridor. The PME data of true aquatic macrophytes and the length of SUs created a basis for numerical derivates, relative plant mass (RPM), mean mass indices (MMT, MMO) and the distribution ratio (d).

The results correspond with comparable studies on this topic: the highest macrophytes species diversity occurred in Separated Arms. On the contrary, macrophytes had the lowest richness in the Danube River main channel, although their diversity was slightly higher in heavily man-modified water bodies (such as the hydropower plant's reservoir and the abandoned main channel of the so-called Old Danube). Our results suggest that the lateral connectivity types of the river water bodies, primarily characterised by different hydrologic dynamics and human impact expressed as land-use types are responsible for the variability of aquatic macrophyte assemblages along the Danube corridor in Slovakia.     

Aboveground biomass and its spatial distribution pattern of herbaceous marsh vegetation in China

Herbaceous marsh is the most widely distributed type of marsh wetland ecosystem, and has important ecological functions such as water conservation, climate regulation, carbon storage and fixation, and sheltering rare species. The carbon sequestration function of herbaceous marsh plays a key role in slowing climate warming and maintaining regional environmental stability. Vegetation biomass is an important index reflecting the carbon sequestration capacity of wetlands. Investigating the biomass of marsh vegetation can provide a scientific basis for estimating the carbon storage and carbon sequestration capacity of marshes. Based on field survey data of aboveground biomass of herbaceous marsh vegetation and the distribution data set of marsh in China, we analyzed the aboveground biomass and its spatial distribution pattern of herbaceous marsh on a national scale for the first time. The results showed that in China the total area of herbaceous marsh was 9.7×104 km2, the average density of aboveground biomass of herbaceous marsh vegetation was 227.5±23.0 g C m-2(95% confidence interval, the same below), and the total aboveground biomass was 22.2±2.2 Tg C(1 Tg=1012 g). The aboveground biomass density of herbaceous marsh vegetation is generally low in Northeast China and the Tibetan Plateau, and high in central North China and coastal regions in China. In different marsh distribution regions of China, the average biomass density of herbaceous marsh vegetation from small to large was as follows: temperate humid and semi-humid marsh region(182.3±49.3 g C m-2)Tibetan Plateau marsh region(243.9±26.6 g C m-2)temperate arid and semi-arid marsh region(300.5±73.2 g C m-2)subtropical humid marsh region(348.4±59.0 g C m-2)coastal marsh region(675.4±73.8 g C m-2). Due to the different area of herbaceous marsh, the total aboveground biomass of herbaceous marsh vegetation in different marsh distribution regions was the largest in the temperate humid and semi-humid marsh region(9.6±2.6 Tg C), and was the smallest in the coastal marsh region(1.1±0.1 Tg C). The spatial distribution of aboveground biomass of herbaceous marsh vegetation in China has obvious non-zonality characteristics, but also presents certain zonality in some regions. The aboveground biomass of herbaceous marsh vegetation in the Tibetan Plateau decreased with the increase of altitude. With the aggravation of drought, the aboveground biomass of herbaceous marsh vegetation in temperate humid and semi-humid regions and temperate arid and semi-arid regions decreased first and then did not obviously change. The aboveground biomass of herbaceous marsh vegetation in temperate humid and semi-humid regions was relatively larger in the regions with higher average annual temperature. The results can provide scientific basis for accurately evaluating the adjustment action of wetland ecosystems on climate, and provide decision support for adaptive management of wetland ecosystems.     

On an earthquake early warning system (EEW) and its applications

It is clear that the basic countermeasure against earthquake strong motion is to reinforce buildings and other structures. Realtime earthquake disaster prevention is a countermeasure during the earthquake itself and is different from realtime seismology. An EEW, earthquake early warning system, is required to trigger realtime earthquake disaster prevention. It is important to avoid too much trust in EEW for the disaster prevention. This paper describes the concept of an EEW and gives a brief history, which eventually led to the development of the UrEDAS, the urgent earthquake detection and alarm system, the first operational P-wave early warning system. A real-world example of disaster prevention by this system is described. Finally, the role of national or public organizations in earthquake disaster prevention will be discussed, with special emphasis on the situation in Japan.     

我国城市湖泊空间分布格局特征分析及影响因素探讨

城市湖泊作为城市与自然之间进行水气交换的蓝色空间,具有供水、防洪、休闲、气候调节以及改善城市生态环境等诸多生态服务功能。中国地域辽阔、城市众多,不同区域的城市湖泊受自然地理环境和社会经济发展等因素的影响而具有显著的空间差异特征。目前已有研究对我国省会城市和个别大型城市的湖泊空间分布及变化特征等开展研究,但全国范围内各行政等级单元内城市湖泊分布的空间格局及其影响因素仍缺乏综合分析。本研究基于中国城市湖泊数据集,从城市分布的地域单元、行政等级、城市规模3个方面对城市湖泊分布特征进行统计分析和比较,并结合自然和人类活动要素,初步探讨影响城市湖泊分布规模和丰度的主控因子。结果表明,2020年全国共有约11万个面积大于0.001km²城市湖泊(不包括太湖、滇池等大型湖泊),总面积约2112 km²,约占全国城市(遥感城市不透水层区域)面积的1.1%。城市湖泊的分布具有显著的集聚和分异特征,数量超过70%的城市湖泊分布在约20%的县(区)级行政单元,约21%的县(区)级行政单元基本没有(<10 m遥感影像分辨率下10个像元)城市湖泊分布。城市湖泊数...     

Sand veins and MISS from the Mesoproterozoic black shale (ca. 1.7 Ga) in North China: Implication for methane degassing from microbial mats

The Mesoproterozoic Chuanlinggou Formation (ca. 1.7 Ga) consists mainly of dark-gray to black shales that are widespread in the North China Platform. Abundant centimeter-scale sand veins are present within the shale layers of this unit, particularly in the middle part. Sand veins display ptygmatic shapes, perpendicular or with a high angle to bedding planes. They penetrate the black shale layers but are often terminated by thin, lenticular sandstone beds, forming small-scale ‘tepee-like’ structures. On bedding planes, sand veins are expressed as small ridges with 1–3 mm positive relief. Lack of polygonal shapes and their occurrence in thinly laminated, relatively deep-water shales preclude an origin from sand-filled desiccation cracks. Instead, their close association with microbially induced sedimentary structures (MISS) such as micro-wrinkles and gas blisters, putative bacterial fossils (possibly coccoidal cyanobacteria) and framboidal pyrites, suggests that they were formed by degassing of methane from microbial mat decay. Methane gas disrupted overlying sedimentary layers, creating fractures open to seawater. Fine-grained quartz sands, which were transported into the depositional environment by strong winds, filled the fractures. Sand-filled fractures were shortened and folded during burial compaction, forming ptygmatic shapes. The presence of dispersed dolomite and siderite in these sand veins suggests authigenic carbonate precipitation from anaerobic oxidation of methane (AOM). Sand veins are intensely distributed within the Chuanlinggou Formation and are spatially widespread in the North China Platform. If their methane origin is confirmed, they may have important implications for the Mesoproterozoic paleoclimate. With anoxic oceans and low seawater sulfate concentration during the Mesoproterozoic, methane release from microbial mat decay and/or microbial methanogenesis during shallow burial may have been proportionally higher than that of the modern marine environments, with resultant increase in the relative importance of methane in maintaining the Mesoproterozoic greenhouse climate.     

Neotectonic Crustal Uplift on the Continents and its Possible Mechanisms. The Case of Southern Africa

According to a large volume of data an intensive crustal uplift began in the Oligocene over most of the continental areas after a long period of relative tectonic stability. This Neotectonic uplift formed most of the present positive topographic features on the continents, and its strong acceleration took place during the last several million years. In many regions the uplift was associated with magmatism. The main methods of studying the Neotectonic uplift are considered together with the data on the uplift of Southern Africa. In this area the uplift took place in the Early Miocene (up to 300 m) and in the Late Pliocene and Pleistocene (up to 900 m). It occurred without stretching or shortening of the crust. Rapid erosion of the lower part of mantle lithosphere by a plume material is proposed as a mechanism of the uplift. This material ascended from below and rapidly spread along the base of the lithosphere. Its spreading for 1000 km during a few million years is possible only under a low viscosity of normal asthenosphere (1019 Pa s) and a much lower viscosity of a plume material (2 × 1016 Pa s). As in Southern Africa, in most of the regions the Neotectonic uplift was associated with insignificant shortening or stretching of the crust. This indicates that in some regions a plume material ascended from below and rapidly spread along the base of the lithosphere and eroded the mantle lithosphere in vast areas beneath the continents. In regions with a hot asthenosphere a strong weakening of the mantle lithosphere which allows its erosion can be associated with a high temperature of the plume material. In regions where the asthenosphere is at moderate temperature weakening of the mantle lithosphere can result from infiltration of volatiles from the plume material.     

Earthquake early warning feasibility in the Campania region (southern Italy) and demonstration system for public school buildings

We present the results of a feasibility study of an earthquake early warning system (EEWS) for the Campania region (southern Italy) using schools as specific targets. The study considered the seismogenic zones as sources of potential earthquakes for the area, the Italian accelerometric network as the recording network for seismic event occurrence, and the performances of the software platform PRESTo ^Plus for data analysis and processing. We analyze the distribution of lead-times for all possible threatening seismic sources for each municipality in the region under study by extracting the lead-time value corresponding to the 5th, 10th and 25th percentiles of the distributions. We discuss the results for the 5th percentile in order to analyze the worst-case scenario: in the case of a single site, the lead-time is expected to be larger than this value in the 95 % of the cases. Since the population distribution in Campania is uneven and most of the people live nearby the coast, whilst the most destructive earthquakes occur along the Apennine chain, we can conclude that an efficient EEWS can allow most of the schools in the area to undertake some mitigating actions. The testing of the EEWS was carried out in the high school ITIS ‘E. Majorana’, located at Somma Vesuviana, about 80 km from the seismogenic Irpinia region. For this purpose, the Sentinel, an actuator made up of low-cost hardware (i.e., Arduino^®), was developed in close cooperation with students and teachers of the school to receive alert messages from the PRESTo ^Plus platform and warn the school users in case of a seismic event. The EEWS and the Sentinel were successfully tested during some blind drills performed during normal school activities.     

The occurrence and distribution of freshwater snails in a heavily industrialised region of Poland (Upper Silesia)

Anthropogenic water bodies namely fish ponds, clay pits, sand pits, dam reservoirs or mining subsidence pools are the characteristic feature of Upper Silesian landscape. In the study, the gastropod communities occurring in 296 anthropogenic water bodies were discussed in relation to their distribution in macroregions of Upper Silesia, role in industrialised and urbanised environment and the significance for regional biodiversity.In period 1998–2002, 31 freshwater gastropod species were found in the study area. It is noteworthy, that the anthropogenic water habitats of Upper Silesia provide a refuge for several rare and vulnerable species, among them e.g. Anisus leucostoma (Millet, 1813), Gyraulus rossmaessleri (V. Auerswald, 1852) and Hippeutis complanatus (Linnaeus, 1758).     

Geodynamic pattern of the West Bohemia region based on permanent GPS measurements

In West Bohemia in the period of 2003–2005 five permanent GPS stations were established to detect local movement trends. Their mutual position changes were determined from time series of GPS observations and were associated with seismic, gravity, and geo-scientific data related to the geodynamics of the West Bohemian region. Knowledge of local physical processes based on spatial and time earthquake occurrences, focal mechanisms of main events, stress and strain fields set up a tool for recent seismotectonic analyses. The permanent GPS measurements bring independent effective phenomenon, direct monitoring of site movements. The movements detected by our GPS stations evidenced WSW-ENE extension with subsiding trends in the western part of the Cheb Basin and the Smrčiny Mts. Besides, there were monitored dextral movements along the Mariánské Lázně tectonic fault zone (MLF). A comparison of results with previous data formed a presumption that an antithetic stress pattern has to exist inside the inner part of the MLF tectonic zone. This antithetic stress can explain the coexistence of dextral and sinistral movements on individual tectonic elements in the West Bohemian area.     

淠河流域河源溪流鱼类空间分布格局及主要影响因素

淠河是安徽省内淮河右岸最大的支流,也是淮河中游重要的水源地.为了解淠河流域河源溪流鱼类的空间分布格局及其主要影响因素,本研究于2015年4—5月对6条河源溪流鱼类及其环境因子进行了调查.研究结果表明,6条溪流共采集鱼类19种,其中杂食性种类占57.9%,肉食性和植食性种类分别占26.3%和15.8%.所有种类中,宽鳍鱲(Zacco platypus)是主要优势种,绿太阳鱼(Lepomis cyanellus)为研究区域首次报道的外来入侵种.就6条溪流各样点的平均值而言,淠河西部3条溪流鱼类种类数及个体数均明显高于东部3条溪流,但重量却并没有类似趋势.Sorensen相似性分析表明,6条溪流鱼类组成具有较高相似性,且相对较小值主要位于高、低海拔溪流之间.除趋势对应分析二维空间排序与相似性分析结果一致.Pearson相关分析表明,影响鱼类种类数的主要是局域栖息地参数(包括海拔、流速、底质、水深、河宽和电导率)和溪流的空间位置参数(溪流级别、流量量级和下游量级);影响鱼类个体数和重量的均仅有局域栖息地参数中的底质因素.本研究结果可为淠河流域鱼类的保护和管理提供重要的基础资料.     

龙门山和青藏高原的隆起与2008年汶川(M=7.9)地震

龙门山山脉,即2008年5月12日汶川（M=7．9）毁灭性地震的发生地,界定了喜马拉雅造山带的东缘,并显现出比青藏高原任何地方都大的地形起伏。然而,在这次地震之前,大地测量与地质调查工作都没有测到横跨该山系前缘有明显的缩短变形（Shenetal,2005;Meade,2007;Chenetal,2000）,从而引起了关于该山岳带地形的形成与发展过程的激烈争论。现已提出两个端元模型：（1）脆性地壳增厚,即具有大量滑动的逆冲断层切穿岩石层并引起隆起（Ta—pponnieretal,2001）;（2）地壳流动,即青藏高原下地壳的低粘度物质向外挤出,抬升了喜马拉雅山东北部的地壳（Roydenetal,1997;Burehfiel,2004;Bird,1991）。在此,我们使用平衡地质剖面来说明该山系前缘的地壳缩短、构造起伏与地形地貌是密切相关的。这表明,地壳缩短是位于青藏高原东缘的龙门山的隆起及其地形形成的主要驱动力。致使沿该山系前缘大型逆冲断层发生破裂,并造成数万人死亡和大范围破坏的2008年汶川地震（M=7．9）就是这种地壳缩短过程的作用表现。     

太湖水体交换周期变化(1986-2018年)及对水质空间格局的影响

针对太湖水体交换周期近十余年发生的变化,本文收集整理了1986-2018年太湖水文巡测、汛期水文巡测数据以及太湖流域沿江城市引水量、流域降雨量变化数据,基于太湖出入湖水量的变化研究了太湖水体交换周期的变化及原因,并对交换周期变化对水质空间格局的影响进行分析.结果 表明:太湖入湖水量有显著上升,2007年以来平均每年入湖...     

黔东页岩复电阻率各向异性及其与页岩气储层参数关系研究

电法勘探因其成本低、效率高的优势,常被作为寻找页岩气储层的辅助手段.然而,到目前为止,页岩的电性特征,特别是复电阻率各向异性特征,以及其与页岩气储层参数的关系研究甚少,这在一定程度上阻碍了电法勘探在页岩气勘探中的应用.基于此,本文采集了黔东地区几种典型黑色页岩岩样,并测量了 6块黑色页岩在走向、倾向和垂直层理方向的复电...     

非迁移潮作用下的电离层赤道异常区单峰现象及其经度分布

当喷泉效应较弱而双峰结构发展不充分的时候,可能在赤道异常区仅能够观测到一个电子密度的峰值,称之为单峰现象.本文利用CHAllenging Minisatellite Payload卫星在2001-2010年的电子密度数据给出了单峰的发生规律,单峰在地方时早上08：00-10：00和下午16：00-19：00发生率高,发生位置在经度上呈现多波数分布,尤其在10：00-18：00明显：在分季时多呈现四波,而在冬至季时以三波为主.单峰发生多的经度,正好对应着双峰的结构特征较弱之处.究其原因,是非迁移潮的DE2和DE3分量调制了背景风场和大气发电机电场,在电场和喷泉效应减弱的经度,双峰结构难以形成时,就会表现为单峰结构.本文扩展了对单峰现象的地方时、季节和经度分布等规律的了解,明确了非迁移潮在其中施加的影响,由此,单峰同双峰现象一样可以用于研究非迁移潮对热层-电离层的作用.

     

泥岩、页岩声速各向异性及其影响因素分析

在实验室超声波频率下(纵波主频为700kHz、横波为250kHz)对层理发育的页岩和泥岩的各向异性进行了研究,给出了在干燥和油饱和条件下,样品不同方向上纵、横波速度以及各向异性参数随压力的变化规律. 用X 射线衍射和扫描电镜分析了样品中引起各向异性的原因,指出平行于层理定向排列的粘土矿物和微裂隙是使样品显示出强弹性各向异性的内在原因. 随着压力的增高微裂隙逐渐闭合,样品的各向异性程度减弱. 孔隙流体的存在增强了孔隙（裂隙）的刚度,减弱了各向异性随压力增大而减小的趋势.