Tectonically driven fluid flow and associated low-grade metamorphism during the Alpine compression in the eastern Iberian Chain (Spain)

Fluid inclusions and clay mineralogy of the Permo-Triassic rocks from the Espina and Espadà Ranges (SE Iberian Chain, Spain) have been investigated to establish their relationship with hydrothermal fluid circulation during the Alpine Orogeny. Primary fluid inclusions in quartz-filled tension gashes in Permo-Triassic sandstones reveal maximum temperatures around 230 °C and very constant salinities of 8.5% wt. eq. NaCl. Secondary fluid inclusions found in quartz from the Santonian Ba–Cu–Hg deposits show similar compositional and thermodynamic characteristics, denoting an Alpine recrystallization. Clay mineral composition of Permo-Triassic mudrocks is characterized by pyrophyillite, indicating low-grade metamorphic conditions. Field observations and experimental data suggest that the crystallization of quartz in tension gashes, the formation of secondary fluid inclusions and the development of the metamorphism are contemporaneous and related to fluid circulation during the Alpine compression. Fluid flow took place along the Hercynian fault system that was reactivated during the Mesozoic rift stage and inverted during the Alpine deformation.     

几种非线性滤波算法的性能比较与分析

在非线性状态估计中,传统的扩展卡尔曼滤波通过线性化来实现高斯近似,由于截断误差的存在很难保证估计精度;而基本粒子滤波容易出现粒子退化,导致滤波发散。针对粒子滤波的两个基本假设：蒙特卡罗假设和重要采样假设,采用蒙特卡罗随机链的方法来提高粒子的多样性,并利用无味卡尔曼滤波来产生更高精度的替代分布,发展了无味粒子滤波。通过仿真实验证明,相比较扩展卡尔曼滤波和基本粒子滤波,改进后的无味粒子滤波算法性能更优越,对含有非线性非高斯的状态估计问题有更好的滤波效果。     

Assessing uncertainties in a conceptual water balance model using Bayesian methodology / Estimation bayésienne des incertitudes au sein d’une modélisation conceptuelle de bilan hydrologique

Abstract

Abstract The aim of this study was to estimate the uncertainties in the streamflow simulated by a rainfall–runoff model. Two sources of uncertainties in hydrological modelling were considered: the uncertainties in model parameters and those in model structure. The uncertainties were calculated by Bayesian statistics, and the Metropolis-Hastings algorithm was used to simulate the posterior parameter distribution. The parameter uncertainty calculated by the Metropolis-Hastings algorithm was compared to maximum likelihood estimates which assume that both the parameters and model residuals are normally distributed. The study was performed using the model WASMOD on 25 basins in central Sweden. Confidence intervals in the simulated discharge due to the parameter uncertainty and the total uncertainty were calculated. The results indicate that (a) the Metropolis-Hastings algorithm and the maximum likelihood method give almost identical estimates concerning the parameter uncertainty, and (b) the uncertainties in the simulated streamflow due to the parameter uncertainty are less important than uncertainties originating from other sources for this simple model with fewer parameters.     

环流分解及其在沉积地层旋回分析中的应用

本文应用马尔柯夫链进行地层序列分析。当一个地层序列形成一个具有马尔柯夫性质和极限概率分布的马尔柯夫链时,它的转移概率矩阵可分解为细致平衡部分和环流部分。根据环流矩阵可确定该序列中的主要沉积旋回趋势,为地层序列分析提供重要依据。本文给出了两个研究实例。     

阴山山链隆起机制及有关问题探讨

阴山隆起为异常地幔发育区，软流层上凸、岩石圈变薄、幔汁上侵、地幔底辟，垂直运动激烈；阴山隆起又处在南北两大板块夹击挤压构造带上，水平运动强烈。所以，阴山隆起是中新生代垂直运动和水平运动共同作用的结果。随着阴山山链的隆起，在其南缘形成了呼包、临河等地堑式盆地。     

Case history of the disastrous debris flows of Tianmo Watershed in Bomi County,Tibet, China: Some mitigation suggestions

Debris flows and landslides, extensively developing and frequently occurring along Parlung Zangbo, seriously damage the Highway from Sichuan to Tiebt(G318) at Bomi County. The disastrous debris flows of the Tianmo Watershed on Sept. 4, 2007, July 25, 2010 and Sept. 4, 2010, blocked Parlung Zangbo River and produced dammed lakes, whose outburst flow made 50 m high terrace collapse at the opposite bank due to intense scouring on the foot of the terrace. As a result, the traffic was interrupted for 16 days in 2010 because that 900 m highway base was destructed and 430 m ruined. These debris flows were initiated by the glacial melting which was induced by continuous higher temperature and the following intensive rainfall, and expanded by moraines along channels and then blocked Parlung Zangbo. At the outlet of watershed,the density, velocity and peak discharge of debris flow was 2.06 t/m3, 12.7 m/s and 3334 m3/s, respectively. When the discharge at the outlet and the deposition volume into river exceeds 2125 m3/s and 126×103 m3, respectively, debris flow will completely blocked Parlung Zangbo. Moreover,if the shear stress of river flow on the foot of terrace and the inclination angel of terrace overruns 0. 377 N/m2 and 26°, respectively, the unconsolidated terrace will be eroded by outburst flow and collapse. It was strongly recommended for mitigation that identify and evade disastrous debris flows, reduce the junction angel of channels between river and watershed, build protecting wall for highway base and keep appropriate distance between highway and the edge of unconsolidated terrace.     

Modelling river water temperature using deterministic,empirical, and hybrid formulations in a Mediterranean stream

River water temperature is a common target of water quality models at the watershed scale, owing to its principal role in shaping biogeochemical processes and in stream ecology. Usually, models include physically‐based, deterministic formulations to calculate water temperatures from detailed meteorological information, which usually comes from meteorological stations located far from the river reaches. However, alternative empirical approaches have been proposed, that usually depend on air temperature as master variable. This study explored the performance of a semidistributed water quality application modelling river water temperature in a Mediterranean watershed, using three different approaches. First, a deterministic approach was used accounting for the different heat exchange components usually considered in water temperature models. Second, an empirical approximation was applied using the equilibrium temperature concept, assuming a linear relationship with air temperature. And third, a hybrid approach was constructed, in which the temperature equilibrium concept and the deterministic approach were combined. Results showed that the hybrid approach gave the best results, followed by the empirical approximation. The deterministic formulation gave the worst results. The hybrid approach not only fitted daily river water temperatures, but also adequately modelled the daily temperature range (maximum–minimum daily temperature). Other river water features directly dependent on water temperature, such as river intrusion depth in lentic systems (i.e. the depth at which the river inflow plunges to equilibrate density differences with lake water), were also correctly modelled even at hourly time steps. However, results for the different heat fluxes between river and atmosphere were very unrealistic. Although direct evidence of discrepancies between meteorological drivers measured at the meteorological stations and the actual river microclimate was not found, the use of models including empirical or hybrid formulations depending mainly on air temperature is recommended if only meteorological data from locations far from the river reaches are available. Copyright © 2008 John Wiley & Sons, Ltd.     

Sequence stratigraphy and architecture of a late Early–Middle Aptian carbonate platform succession from the western Maestrat Basin (Iberian Chain, Spain)

The attributes of a ‘four-systems-tract’ sequence are at times difficult to identify in outcrop-scale carbonate successions. Poor exposure conditions, variable rates of sediment production, erosion and/or superposition of surfaces that are intrinsic to the nature of carbonate systems frequently conceal or remove its physical features. The late Early–Middle Aptian platform carbonates of the western Maestrat Basin (Iberian Chain, Spain) display facies heterogeneity enabling platform, platform-margin and slope geometries to be identified, and provide a case study that shows all the characteristics of a quintessential four systems tract-based sequence. Five differentiated systems tracts belonging to two distinct depositional sequences can be recognized: the Highstand Systems Tract (HST) and Forced Regressive Wedge Systems Tract (FRWST) of Depositional Sequence A; and the Lowstand Prograding Wedge Systems Tract (LPWST), Transgressive Systems Tract (TST) and subsequent return to a highstand stage of sea-level (HST) of Depositional Sequence B. An extensive carbonate platform of rudists and corals stacked in a prograding pattern marks the first HST. The FRWST is constituted by a detached, slightly cross-bedded calcarenite situated at the toe of the slope in a basinal position. The LPWST is characterized by a small carbonate platform of rudists and corals downlapping over the FRWST and onlapping landwards. The TST exhibits platform backstepping and marly sedimentation. Resumed carbonate production in shelf and slope settings characterizes the second HST. A basal surface of forced regression, a subaerial unconformity, a correlative conformity, a transgressive surface and a maximum flooding surface bound these systems tracts, and are well documented and widely mappable across the platform-to-basin transition area analyzed. Moreover, the sedimentary succession studied is made up of four types of parasequence that constitute stratigraphic units deposited within a higher-frequency sea-level cyclicity. Ten lithofacies associations form these basic accretional units. Each facies assemblage can be ascribed to an inferred depositional environment in terms of bathymetry, hydrodynamic conditions and trophic level. The architecture of the carbonate platform systems reflects a flat-topped non-rimmed depositional profile. Furthermore, these carbonate shelves are interpreted as having been formed in low hydrodynamic conditions. The long-term relative fall in sea-level occurred during the uppermost Early Aptian, which subaerially exposed the carbonate platform established during the first HST and resulted in the deposition of the FRWST, is interpreted as one of global significance. Moreover, a possible relationship between this widespread sea-level drop and glacio-eustasy seems plausible, and could be linked to the cooling event proposed in the literature for the late Early Aptian. Because of the important implications in sequence stratigraphy of this study, the sedimentary succession analyzed herein could serve as an analogue for the application of the four-systems-tract sequence stratigraphic methodology to carbonate systems.     

文化消费者对黄梅戏展演空间感知的模式与价值寻求：方法−目的链理论的应用

以安庆黄梅戏会馆和再芬黄梅公馆为例,基于方法?目的链理论模型,解读文化消费者对黄梅戏展演空间属性的感知评价、层次处理和价值导向的转变。研究发现：不同层次的空间属性在文化消费者的感知与体验中实现着新的组合与重构,由此形成了基于舞台展演内容、文化呈现形式以及演出环境氛围为主体的3种空间感知模式。结合文化消费者感知的心理结构与路径,黄梅戏展演空间被消费者建构为娱乐空间、情感空间和社交空间,空间的多元化意义和价值得到彰显。方法?目的链理论从消费者的感知与需求出发,探索文化空间意义生成路径,实现了文化空间与消费者之间的双向信息交换。     

基于局部采样MCMC方法的时移探地雷达反演

马尔科夫链蒙特卡洛方法(MCMC)是一种启发式的全局寻优算法,可以用来解决概率反演的问题.基于MCMC方法的反演不依赖于准确的初始模型,可以引入任意复杂的先验信息,通过对先验概率密度函数的采样来获得大量的后验概率分布样本,在寻找最优解的过程中可以跳出局部最优得到全局最优解.MCMC方法由于计算量巨大,应用难度较高,在地...