Coupled Process Models as a Tool for Analysing Hydrothermal Systems

Hydrothermal systems are characterised by complex interactions between heat transfer, fluid flow, deformation, species transport and chemical reactions. Numerical models can provide quantitatively constrained information in regions where acquisition of new data is difficult or expensive thus providing a means for reducing risks, costs, and effort during targeting, production, and management of resources linked to hydrothermal systems. Here we show how numerical simulations of hydrothermal processes can be used to better understand coupled reactive transport in modern geothermal systems and in ancient hydrothermal ore deposits. We give examples based on the Enhanced Geothermal System at Soultz-sous-Forêts in France, hydrothermal mineralisation at Mount Isa in Australia, and the geothermal resource at Hamburg-Allermöhe in Germany.     

Taxonomy and biogenicity of Archaean spheroidal microfossils (ca. 3.0 Ga) from the Mount Goldsworthy–Mount Grant area in the northeastern Pilbara Craton, Western Australia

Microstructures recently reported from an Archaean sedimentary succession (ca. 3.0 Ga) in the Mount Goldsworthy–Mount Grant area in the northeastern Pilbara Craton meet the criteria for compelling evidence of biogenicity [Sugitani, K., Grey, K., Allwood, A., Nagaoka, T., Mimura, K., Minami, M., Marshall, C.P., Van Kranendonk, M.J., Walter, M.R., 2007. Diverse microstructures from Archaean chert from the Mount Goldsworthy–Mount Grant area, Pilbara Craton, Western Australia: microfossils, dubiofossil, or pseudofossils. Precambrian Res. 158, 228–262]. The structures are morphologically diverse. Although they were tentatively classified into five major morphological types (thread-like, film-like, small (<15 μm) and large (>15 μm) spheroidal, and spindle-like), the possible taxonomic significance of these groups was not discussed. Building on our earlier analysis, we focus on the morphology of the larger spheroids, as well as presenting further evidence relating spindles and several bizarre forms, and attempt to group them taxonomically and adduce additional evidence for their biogenicity.Taphonomic features were identified in each of the various morphological groups, but the range of morphological diversity of the spheroids cannot be attributed solely to taphonomic alteration. Four subdivisions of spheroids are proposed: (1) simple single-walled spheroids, (2) thin-walled spheroids having a diffuse envelope, (3) thick-walled spheroids, and (4) spheroids having an extensively folded wall. Simple single-walled spheroids, 15–60 μm in diameter, with various wall textures but commonly lacking envelopes or appendages form the dominant subgroup. Other complex morphologies are present and include aligned or associated bodies of thin-walled spheroids with diffuse envelopes, and spindle-like structures containing inner spheroidal bodies. The degree of morphological complexity and associations between structures suggest the presence of reproductive phases. If correct, this implies that the early Earth (ca. 3.0 Ga) showed a higher level of biodiversity than is currently postulated.     

First discovery of Holocene Alaskan and Icelandic tephra in Polish peatlands

Despite the discovery of cryptotephra layers in over 100 peatlands across northern Europe, Holocene cryptotephra layers have not previously been reported from Polish peatlands. Here we present the first Holocene tephra findings from two peatlands in northern Poland. At Bagno Kusowo peatland we identify the most easterly occurrence of the AD 860 B tephra, recently correlated to the White River Ash (WRAe) derived from Mount Churchill, Alaska. A shorter core from Linje peatland contains tephra from the Askja 1875 eruption, extending the spatial distribution and regional importance of this Icelandic tephra in Eastern Europe. Our research indicates the potential of cryptotephra layers to date and correlate the growing number of palaeoenvironmental studies being conducted on Polish peatlands and contributes towards the development of a regional Holocene tephrostratigraphy for Poland. Copyright © 2017 The Authors. Journal of Quaternary Science Published by John Wiley & Sons, Ltd.

     

第四纪冰川遗迹的判别标准与方法问题——兼论蒙山巨砾堆积堤之成因

判断中国东部中低山地冰川作用遗迹的真伪,只能通过科学实践检验和学术争鸣加以解决。利用实地考察所测数据资料,证明山东蒙山确无第四纪冰川遗迹。包括蒙山在内的山东中低山丘陵,迄今为止没有发现符合判别标准的末次冰期冰川地貌三要素组合。蒙山兰溪峡谷的谷形指数（0.07~0.24）与世界各地真正的冰川槽谷不符,被当作冰川证据的蒙山兰溪峡谷谷壁擦痕和拦马墙巨砾堆积堤砾石擦痕,不具有作为冰川地貌证据的唯一性或专属性,而是砾石沿河谷滚动、拖拽摩擦和撞击的结果。不连续、不对称分布于兰溪下游凹岸的拦马墙巨砾堆积堤,沿流向延伸或呈流线构造,具有平行主流的平顶、陡坡砾石堆和立石等景观,砾石的圆度、分选和砾组构造均指向泥石流堆积堤或特大洪水巨石边滩。它可能是1668年7月25日郯城大地震保存下来的群发性灾害遗迹。     

Pyroclastic density currents resulting from the interaction of basaltic magma with hydrothermally altered rock: an example from the 2006 summit eruptions of Mount Etna,Italy

After 16 months of quiescence, Mount Etna began to erupt again in mid-July 2006. The activity was concentrated at and around the Southeast Crater (SEC), one of the four craters on the summit of Etna, and eruptive activity continued intermittently for 5 months. During this period, numerous vents displayed a wide range of eruptive styles at different times. Virtually all explosive activities took place at vents at the summit of the SEC and on its flanks. Eruptive episodes, which lasted from 1 day to 2 weeks, became shorter and more violent with time. Volcanic activity at these vents was often accompanied by dramatic mass-wasting processes such as collapse of parts of the cone, highly unusual flowage processes involving both old rocks and fresh magmatic material, and magma–water interaction. The most dramatic events took place on 16 November, when numerous rockfalls and pyroclastic density currents (PDCs) were generated during the opening of a large fracture on the SE flank of the SEC cone. The largest PDCs were clearly triggered explosively, and there is evidence that much of the energy was generated during the interaction of intruding magma with wet rocks on the cone’s flanks. The most mobile PDCs traveled up to 1 km from their source. This previously unknown process on Etna may not be unique on this volcano and is likely to have taken place on other volcanoes. It represents a newly recognized hazard to those who visit and work in the vicinity of the summit of Etna.     

Elemental composition of PM2.5 and PM10 at Mount Gongga in China during 2006

In order to investigate the chemical characteristics of atmospheric aerosols in a regional background site, PM_2.5 and PM₁₀ were collected at Mount Gongga Station once a week in 2006. The concentrations of fifteen elements including Na, Mg, Al, K, Ca, V, Fe, Ni, Cu, Zn, As, Ag, Ba, Tl, and Pb were detected by Inductively Coupled Plasma Mass Spectrometer (ICP-MS). The results showed that Na, Mg, Al, K, Ca, Fe were the major components of elements detected in PM_2.5 and PM₁₀, occupied 89.5% and 91.3% of all the elements. Crustal enrichment factor (EF) calculation indicated that several anthropogenic heavy metals (Ni, Cu, Zn, As, Ag, Tl, Pb) were transported long distances atmospherically. The concentrations of all elements (except Na) measured in PM_2.5 and PM₁₀ in spring and winter were higher than those in summer and autumn. The backward air mass trajectory analysis suggests that northeast India may be the source region of those pollutants.     

珠峰地区雨季对流层大气的特征分析

利用2007年7月中国科学院珠穆朗玛峰综合观测站的边界层塔、无线电探空和风温廓线仪观测资料,分析了珠穆朗玛峰地区雨季低层大气风温湿等特征.珠峰地区雨季近地层风速、风向、温度等有明显的日变化.近地层风的日变化有两个很明显的阶段,00:00～14:30受谷风的影响而刮偏北风,14:30～24:00受冰川风的影响以偏南风为主.白天的冰川风比夜间的谷风要强些.中午13:30在600m以下存在强水平风速垂直切变,这可能是珠峰地区发生降雨的重要原因之一.低空急流在夏季比较常见.对流层平均降温率为0.685K/100m.低层大气的相对湿度一般有两个峰值高度,最大值在4000m以下,第二峰值高度不固定,到16000m以后相对湿度超不过10%.各层大气的风速风向差别较大.     

旅游活动对九华山风景区大型土壤动物群落影响

土壤动物是旅游活动对风景区生态系统影响最敏感的环境因素之一,也是旅游生态环境影响研究的重点。在九华山风景区6条主要游道附近选取了8条取样样带,样带设置与游道相垂直。每条样带按照距游道距离的不同设置4个取样样方,每个样方取枯枝落叶层并以5cm为一个层垂直向下取4层土样,用手拣法和网筛法拾取大型土壤动物。共捕获大型土壤动物2076头,隶属于3门8纲27个类群。运用多样性H′指数、集聚度等指标对不同样带和样方的不同土层中捕获的大型土壤动物类群和数量进行对比分析,结果表明:(1)九华山风景区大型土壤动物受到旅游活动的影响明显,旅游活动量越大土壤动物捕获量越少;(2)由近游道向远离游道的水平方向上大型土壤动物的类群和数量呈现递增规律;(3)在垂直分布上土壤动物向表层集聚明显,游憩活动的影响导致大型土壤动物类群和数量的表层聚集度由近游道样方向远离游道样方逐渐增大;(4)旅游活动量与各游道不同样方的捕获量呈现出不同的相关性。     

Environmental Hazard of Capable Faults: The Case of the Pernicana Fault (Mt. Etna,Sicily

When dealing with hazard, the concept of fault capability (the probability of significant surface displacement in the near future) is more useful than the generic and often misleading concept of fault activity. The example of the Pernicana fault, located in the north-eastern flank of the Mt. Etna volcano is used here to illustrate the damage which can be expected in an urbanised area from a capable fault, in this case characterized by 'aseismic creep along part of its length. Along this fault, buildings, roads and other essential lifelines are being affected by slow, left-lateral displacement. The Pernicana fault is only one of a set of structures in the area whose movement, either connected to seismicity or not, is producing severe damage. First identified at the end of the last century, this source of hazard is, nevertheless, still poorly considered by planners and technicians. In Italy fault creep is quite rare outside the Etna region, but fault capability associated with strong earthquakes is relatively frequent, based on historical and palaeoseismological data, and is a feature that should be taken into account for hazard reduction programs.