蚀变带元素地球化学成矿预测法——以金龙山微细浸染型金矿为例

金矿化作用伴随围岩蚀变,且多受断裂控制,反映在地球化学上出现某些元素的异常晕.在已发现一定矿(化)体并掌握一般控矿特征的地区,利用已有工程,经科学的组合采样(主要在蚀变带范围内连续拣块采样),分析有关指示元素,总结有关的地球化学指标,建立地球化学预测模式(从元素异常特征或线金属量、地球化学指标或元素比值、逐步回归方程估值等三方面),对已知矿(化)体及外围异常进行地球化学评价研究.这就是蚀变带元素地球化学成矿预测法.该方法在秦岭南坡金龙山微细浸染型金矿上的应用有较好的效果.本方法的预测是半定量或定性的,回归分析估值是近似定量的,同时也是有效的,低成本的.     

贵州都匀下泥盆统蟒山群Zosterophyllum australianum(澳大利亚工蕨)新材料及其古地理意义*

Zosterophyllum(工蕨属)是早期陆生植物的代表性类群之一,全球广泛分布。Z.australianum(澳大利亚工蕨)产自华南和澳大利亚,是东北冈瓦纳古植物地理区系的典型分子。文中描述了产自贵州都匀包阳剖面蟒山群中的Z.australianum新材料。该标本的孢子囊具短柄,呈椭圆形或扇形,宽2.6~4.1 mm,高可达3.9 mm,加厚带宽约0.6 mm,紧密螺旋排列形成孢子囊穗,与云南文山早泥盆世坡松冲植物群中的Z. australiaunum极为相似。依据目前对Z. australianum时代延限的认识,并结合蟒山群其他植物属种的发现(如Adoketophyton subverticillatum),推断该群下段的时代为早泥盆世布拉格期。Z. australianum在蟒山群中的发现,扩展了该植物的地理分布范围,反映出蟒山群中的植物组合与坡松冲植物群存在一定联系。     

生活垃圾淋滤液组分的变化特征及其污染机理分析──以长春市为例

利用室内模拟试验成果对长春市生活垃圾淋滤液的组分特征、变化规律及其对土壤、地下水的污染机理进行了分析；结合野外监测资料运用非确定性模型方法建立模拟模型，对淋滤液的污染组分进行趋势预测，为垃圾堆放场地的设计和垃圾污染的治理提供理论上的依据。同时为解决城市生活垃圾污染问题和寻找垃圾场地奠定了基础     

U–Pb and Hf isotopic study of zircons from migmatised amphibolites in the Cathaysia Block: Implications for the early Paleozoic peak tectonothermal event in Southeastern China

Amphibolites occur in a number of localities in the Cathaysia Block, some of them have been migmatised and their protoliths represent basaltic magmas erupted in various tectonic settings. Four migmatised amphibolites were collected from Jiangxi and Fujian Provinces. Cathodo-luminescence images of zircons extracted from the representative amphibolites show unzoned or sector-zoned structure. LA-ICP-MS analysis indicates that most zircons have high Th/U ratios and yield U–Pb zircon ages of 446 ± 5, 435 ± 2, 434 ± 4 and 423 ± 2 Ma, respectively. Lu–Hf isotopic analysis on these zircons gives Hf model ages ranging from 900 to 1200 Ma. Based on lithological observations and previously published geochronological data, we interpret that these U–Pb ages record an important tectonothermal event that led to the migmatization. This early Paleozoic (Caledonian) tectonothermal event in the Southeastern China has a great tectonic implication for the evolutionary history of the Cathaysia Block.     

East Asia: Seismotectonics,magmatism and mantle dynamics

In this article, we review the significant recent results of geophysical studies and discuss their implications on seismotectonics, magmatism, and mantle dynamics in East Asia. High-resolution geophysical imaging revealed structural heterogeneities in the source areas of large crustal earthquakes, which may reflect magma and fluids that affected the rupture nucleation of large earthquakes. In subduction zone regions, the crustal fluids originate from the dehydration of the subducting slab. Magmatism in arc and back-arc areas is caused by the corner flow in the mantle wedge and dehydration of the subducting slab. The intraplate magmatism has different origins. The continental volcanoes in Northeast Asia (such as Changbai and Wudalianchi) seem to be caused by the corner flow in the big mantle wedge (BMW) above the stagnant slab in the mantle transition zone and the deep dehydration of the stagnant slab as well. The Tengchong volcano in Southwest China is possibly caused by a similar process in BMW above the subducting Burma microplate (or Indian plate). The Hainan volcano in southernmost China seems to be a hotspot fed by a lower-mantle plume associated with the Pacific and Philippine Sea slabs’ deep subduction in the east and the Indian slab’s deep subduction in the west down to the lower mantle. The occurrence of deep earthquakes under the Japan Sea and the East Asia margin may be related to a metastable olivine wedge in the subducting Pacific slab. The stagnant slab finally collapses down to the bottom of the mantle, which may trigger upwelling of hot mantle materials from the lower mantle to the shallow mantle beneath the subducting slabs and cause the slab–plume interactions. Some of these issues, such as the origin of intraplate magmatism, are still controversial, and so further detailed studies are needed from now.     

Characteristics analysis of spatial and temporal variation on extreme weather events in Anhui Province for recent 50 years

To mitigate the impact of natural or man-made hazards on the services of an infrastructure facility, it is important to quantitatively assess its available capacity. For example, in a post-disaster scenario, critical infrastructure is likely to experience (i) excessive demand for the service of an infrastructure and/or (ii) compromised capacity because of damage to the infrastructure and the failure of infrastructure interdependencies. As the demand grows and nears the capacity limit of an infrastructure facility, a shortage of services required for the community’s recovery will occur. The development of mitigation strategies and an assessment of their effectiveness require a systematic approach. In this paper, a functional stress–strain principle for infrastructure facilities is proposed to quantitatively assess their serviceability in post-disaster scenarios. Functional stress in infrastructure management represents a service-related demand on an infrastructure facility, while strain indicates its coping capacity. The dynamic nature of infrastructure services will be considered depending on the relationship between demand and available capacity. The allowable range of functional stress is then defined, considering plastic and elastic patterns of responses of a facility during recovery to explore strain capacity variations. The proposed principle facilitates a systematic understanding of how infrastructure facilities can adapt themselves to growing stress and the maximum level of stress they can handle. The application of the proposed functional stress–strain principle is demonstrated through case studies of two infrastructure facilities in a post-earthquake scenario: a medical facility and a power facility.     

A modified normalized model for predicting effective soil thermal conductivity

Effective soil thermal conductivity (λ _eff) describes the ability of a multiphase soil to transmit heat by conduction under unit temperature gradient. It is a critical parameter for environmental science, earth and planetary science, and engineering applications. Numerous models are available in the literature, but their applicability is generally restricted to certain soil types or water contents (θ). The objective of this study was to develop a new model in the similar form of the Johansen 1975 model to simulate the λ _eff(θ) relationship of soils of various soil textures and water contents. An exponential type model with two parameters is developed and a new function for calculating dry soil thermal conductivity is presented. Performance of the new model and six other normalized models were evaluated with published datasets. The results show that the new model is able to well mimic λ _eff(θ) relationship of soils from sand to silt loam and from oven dry to full saturation. In addition, it has the best performance among the seven models under test (with root-mean-square error of 0.059 W m^?1 °C^?1, average deviations of 0.0009 W m^?1 °C^?1, and Nash–Sutcliffe efficiency of 0.994). The new model has potential to improve the reliability of soil thermal conductivity estimation and be incorporated into numerical modeling for environmental, earth and engineering studies.     

Temporal and spatial characteristics of dissolved organic carbon in the Wujiang River,Southwest China

River systems play an important role in the global carbon cycle. Rivers transport carbon to the ocean and also affect the carbon cycle in the coastal ocean. The flux from land to the ocean is thought to be a very important part of the land carbon budget. To investigate the effect of dam-building on dissolved organic carbon (DOC) in rivers, three reservoirs of different trophic states in the Wujiang basin, Guizhou Province, were sampled twice per month between May 2011 and May 2012. Temporal and spatial distributions of DOC in the reservoirs and their released waters were studied. It was found that different factors controlled DOC in river water, reservoir water, and released water. DOC in the rivers tended to be affected by primary production. For reservoirs, the main controlling factors of DOC concentration varied by trophic state. For the mesotrophic Hongjiadu Reservoir, the effect of primary production on DOC concentration was obvious. For the eutrophic Dongfengdu Reservoir and the hypereutrophic Wujiangdu Reservoir, primary production was not significant and DOC came instead from soil and plant litter.     

Dating megafaunal extinction on the Pleistocene Darling Downs,eastern Australia: the promise and pitfalls of dating as a test of extinction hypotheses

A key to understanding Late Pleistocene megafaunal extinction dynamics is knowledge of megafaunal ecological response(s) to long-term environmental perturbations. Strategically, that requires targeting fossil deposits that accumulated during glacial and interglacial intervals both before and after human arrival, with subsequent palaeoecological models underpinned by robust and reliable chronologies. Late Pleistocene vertebrate fossil localities from the Darling Downs, eastern Australia, provide stratigraphically-intact, abundant megafaunal sequences, which allows for testing of anthropogenic versus climate change megafauna extinction hypotheses. Each stratigraphic unit at site QML796, Kings Creek Catchment, was previously shown to have had similar sampling potential, and the basal units contain both small-sized taxa (e.g., land snails, frogs, bandicoots, rodents) and megafauna. Importantly, sequential faunal horizons show stepwise decrease in taxonomic diversity with the loss of some, but not all, megafauna in the geographically-small palaeocatchment. The purpose of this paper is to present the results of our intensive, multidisciplinary dating study of the deposits (>40 dates). Dating by means of accelerator mass spectrometry (AMS) ¹⁴C (targeting bone, freshwater molluscs, and charcoal) and thermal ionisation mass spectrometry U/Th (targeting teeth and freshwater molluscs) do not agree with each other and, in the case of AMS ¹⁴C dating, lack internal consistency. Scanning electron microscopy and rare earth element analyses demonstrate that the dated molluscs are diagenetically altered and contain aragonite cements that incorporated secondary young C, suggesting that such dates should be regarded as minimum ages. AMS ¹⁴C dated charcoals provide ages that occur out of stratigraphic order, and cluster in the upper chronological limits of the technique (～40–48 ka). Again, we suggest that such results should be regarded as suspicious and only minimum ages. Subsequent OSL and U/Th (teeth) dating provide complimentary results and demonstrate that the faunal sequences actually span ～120–83 ka, thus occurring beyond the AMS ¹⁴C dating window. Importantly, the dates suggest that the local decline in biological diversity was initiated ～75,000 years before the colonisation of humans on the continent. Collectively, the data are most parsimoniously consistent with a pre-human climate change model for local habitat change and megafauna extinction, but not with a nearly simultaneous extinction of megafauna as required by the human-induced blitzkrieg extinction hypothesis. This study demonstrates the problems inherent in dating deposits that lie near the chronological limits of the radiocarbon dating technique, and highlights the need to cross-check previously-dated archaeological and megafauna deposits within the timeframe of earliest human colonisation and latest megafaunal survival.     

基于流域尺度的地下水可持续开采量的确定——以饮马河流域为例

地下水可持续开采量的确定与评价既是合理开发地下水资源的基础,又是水文地质学研究中的难点。为克服没有统一的评价标准以及对众多约束条件难以定量化计算的难点,本文从提高流域内整体水资源的利用率出发,综合考虑了流域水资源整体开发利用效益和生态环境需水,以及人工调蓄作用对地下水系统的影响作用,提出了流域地下水可持续开采量的概念; 论述了所提出概念的内涵;建立了由流域水循环模拟模型、水资源开发综合效益模型和可持续开采量优化模型组成的流域地下水可持续开采量的评价体系,将流域水循环模拟模型作为研究平台,以水资源开发的综合效益模型作为选优依据,以不同生态环境需水条件为约束条件,对施加其上的各种不同调控措施进行模拟,最后通过性价比的综合分析与评估,得到可持续开发方案下的流域地下水可持续开采量。以吉林省饮马河流域为例展开实例应用,确定饮马河流域最满意的开发模式下,即水库高比例供水(水库供水4.850×108m3),保证河道适宜生态需水时,饮马河流域地下水可持续开采量为2.516×108m3/a。