Petrology and structure of the Palaeoproterozoic (1.9 Ga) Rytky nickel sulphide deposit,Central Finland: a comparison with the Kotalahti nickel deposit

The Palaeoproterozoic (1.9 Ga) Rytky and Kotalahti mafic-ultramafic intrusions are located in the contact zone between the Archaean craton and Proterozoic supracrustal rocks. During the second deformation event (D₂) the surrounding country rocks were subjected to intensive metamorphism and deformation associated with the Svecofennian orogeny; the Archaean/Proterozoic boundary controlled both D₂ thrusting and magma ascent. Emplacement of the Rytky and Kotalahti intrusions took place at the culmination of D₂, as shown by the gneiss inclusions with S₂ schistosity within the intrusions. Overthrusting continued after emplacement, with detached fragments of the bodies incorporated into the Archaean gneisses. During the third deformation event (D₃) the originally subhorizontal intrusions were rotated into a subvertical position, so that they now have their stratigraphic top towards the west. The Rytky intrusion is composed mainly of medium- and coarse-grained lherzolite, websterite and gabbronorite. The nickel deposit with pentlandite as the main nickel mineral is associated with the lherzolite and websterite. The coarse-grained lherzolite, websterite and melagabbro represent the first rocks to form, and they contain the nickel sulphide mineralisation. Country rock contamination, as indicated by high TiO₂, P₂O₅, Rb, Zr and light rare earth element contents (LREE), is most pronounced in the marginal part of the intrusion, which was the first to form. The variation in olivine composition (Fo 78.6-84.77 mole %; Ni 630–2386 ppm) and the metal ratio of the sulphide (Ni/Co 19.3 – 50.3) along with the internal stratigraphy of the intrusion indicate an in-situ process of sulphide ore formation.Editorial handling: P. LightfootAn erratum to this article can be found at     

Food and feeding habits of juvenile flounder Platichthys flesus (L.), abd turbot Scophthalmus maximus L. in the åland archipelago, northern Baltic Sea

The food choice of juvenile flounder (Platichthys flesus) and turbot (Scophthalmus maximus) was studied in the northern Baltic Sea during the years 1988, 1989, 1994 and 1995. The diet included organisms from 30 species/taxa in flounder (n = 306) and 10 species/taxa in turbot (n = 41). Flounder 45 mm mainly consumed meiofauna (dominating taxon: Harpacticoida, Copepoda) and larger fish (46–101 mm) consumed macrofauna (dominating taxa: Oligochaeta, Amphipoda and Chironomidae). In terms of biomass, macrofauna dominated for all sizes of flounders, and meiofauna was important only for the smallest fish. A strong seasonal variation could be detected in the diet. In spring, macrofauna dominated for all size classes of fish (only fish > 30 mm were caught in spring), while in summer and autumn meiofauna dominated the diets for fish 45 mm in size. Juvenile turbot (22–88 mm) consumed macrofauna and small fish. Turbot 30 mm consumed mainly amphipods, while > 30 mm turbot consumed mysid shrimps, amphipods and fish.The ontogenetic shift from meio- to macrofauna-sized prey in flounders occurs at a larger fish size in the northern Baltic Sea than reported in other areas, possibly depending on the increased relative importance of meiofauna in the northern Baltic. The seasonal variation in the diet could be due to seasonally changing abundances in the zoobenthos, or for the small fish (1-group, spring), to switching from meio- to macrofauna in order to optimize their energy gain. The 0-group flounders consumed meiofauna for a long period, possibly due to a learning-process or simply due to easy availability of meiofauna. Turbot has a much larger mouth gap than flounders, thus allowing them to consume macrofauna from the beginning of their benthic life.     

Two-Dimensional Magnetotelluric Modelling of Ore Deposits: Improvements in Model Constraints by Inclusion of Borehole Measurements

A combination of magnetotelluric (MT) measurements on the surface and in boreholes (without metal casing) can be expected to enhance resolution and reduce the ambiguity in models of electrical resistivity derived from MT surface measurements alone. In order to quantify potential improvement in inversion models and to aid design of electromagnetic (EM) borehole sensors, we considered two synthetic 2D models containing ore bodies down to 3000 m depth (the first with two dipping conductors in resistive crystalline host rock and the second with three mineralisation zones in a sedimentary succession exhibiting only moderate resistivity contrasts). We computed 2D inversion models from the forward responses based on combinations of surface impedance measurements and borehole measurements such as (1) skin-effect transfer functions relating horizontal magnetic fields at depth to those on the surface, (2) vertical magnetic transfer functions relating vertical magnetic fields at depth to horizontal magnetic fields on the surface and (3) vertical electric transfer functions relating vertical electric fields at depth to horizontal magnetic fields on the surface. Whereas skin-effect transfer functions are sensitive to the resistivity of the background medium and 2D anomalies, the vertical magnetic and electric field transfer functions have the disadvantage that they are comparatively insensitive to the resistivity of the layered background medium. This insensitivity introduces convergence problems in the inversion of data from structures with strong 2D resistivity contrasts. Hence, we adjusted the inversion approach to a three-step procedure, where (1) an initial inversion model is computed from surface impedance measurements, (2) this inversion model from surface impedances is used as the initial model for a joint inversion of surface impedances and skin-effect transfer functions and (3) the joint inversion model derived from the surface impedances and skin-effect transfer functions is used as the initial model for the inversion of the surface impedances, skin-effect transfer functions and vertical magnetic and electric transfer functions. For both synthetic examples, the inversion models resulting from surface and borehole measurements have higher similarity to the true models than models computed exclusively from surface measurements. However, the most prominent improvements were obtained for the first example, in which a deep small-sized ore body is more easily distinguished from a shallow main ore body penetrated by a borehole and the extent of the shadow zone (a conductive artefact) underneath the main conductor is strongly reduced. Formal model error and resolution analysis demonstrated that predominantly the skin-effect transfer functions improve model resolution at depth below the sensors and at distance of \(\sim \) 300–1000 m laterally off a borehole, whereas the vertical electric and magnetic transfer functions improve resolution along the borehole and in its immediate vicinity. Furthermore, we studied the signal levels at depth and provided specifications of borehole magnetic and electric field sensors to be developed in a future project. Our results suggest that three-component SQUID and fluxgate magnetometers should be developed to facilitate borehole MT measurements at signal frequencies above and below 1 Hz, respectively.     

Developing survey metrics for analysing cross-border proximity

Cross-border innovation cooperation (CBIC) has been heralded as one of the corner stones of innovation-driven growth opportunities for firms located in cross-border regions (CBRs). The success of this cooperation is affected by varying types of proximities identified in the literature as geographical, institutional, cultural, cognitive, technological, organizational and social. Although the topic has been widely discussed, the validation of the concept of proximity vis-à-vis CBIC has been persistently hindered by a lack of readily available empirical metrics. Therefore, this research note attempts to operationalize the varying types of proximity – in relation to CBIC – in the form of a questionnaire tested through pilot studies of two CBRs, at the Finnish–Swedish and Danish–German border, and for two contrasting service industries, namely knowledge-intensive business services and tourism. The findings indicate that the developed survey metrics are effective in depicting the phenomenon of proximity. The foundational work undertaken in this research note provides a platform, and catalyst, for more extensive investigations of the topic.     

"拓展亚洲国际河流跨境水与生态安全合作"国际学术研讨会在大理召开

The International Workshop on "Expanding Transboundary Cooperation for Water and Environment Security in Asia's International Rivers" was held on December 10-14, 2005, Dali, Yunnan, China. It was organized by Tsinghua University, the World Bank Institute (WBI), the United Nations University (UNU) and Asian International Rivers Center (AIRC). A total of over 60 scholars from the USA, Canada, Australia, Finland, Japan, Thailand, Vietnam, Laos, India, Sri Lanka, Iran and China participated in this workshop. The topics include seeking reasonable utilization and sustainable conflict resolutions related to transboundary water resources, and transboundary eco-security maintenance; expanding cooperation between Asia and the rest of the world on international river issues, identifying potential opportunities; and possibility of a common research agenda for addressing environment changes in Mekong River Basin.     

Parameterization of ammonia and water content of atmospheric droplets with fixed number of sulfuric acid molecules

We present a parameterization for numbers of water and ammonia molecules in an equilibrium droplet with fixed number of sulfuric acid molecules at known relative humidity, ammonia mixing ratio and temperature. The radius of the droplet is also parameterized. The parameterizations are based on macroscopic model of solution droplets and up-to-date thermodynamics. The binary parameterizations are valid for temperatures 190–330 K and relative humidities 1–99%. The ternary parameterization can be used at temperatures 240–300 K, relative humidities 5–95%, and ammonia mixing ratios 10^− 4–100 ppt. In both cases the parameterizations are valid for droplets containing up to 10¹¹ sulfuric acid molecules. The droplet composition is always between the limits of pure ammonium bisulfate and pure ammonium sulfate.     

Understanding tourists' travel behavior before,during, and after the trip with data from social media platforms

Analyzing tourists' travel behavior at different stages of a trip can help to better understand their travel demands, providing valuable suggestions for destination management. In this article, we propose a research framework that can help in comprehensively analyzing tourists' travel behavior from the perspective of the three main stages: before, during, and after the trip. A case study was conducted based on user-generated content data from the Old Town of Lijiang to verify the feasibility of the proposed research framework. The results show that: (1) before the trip, tourists inquire about destinations and optimal stay; (2) during the trip, tourists are attracted to natural sceneries; (3) after the trip, tourists discuss experience and services. Travel behavior in stages provide detailed (inter-, intra-, and individual attractions) guidance (from tourists) for destinations. The proposed framework provides a novel perspective for exploring the spatiotemporal behavioral features of tourists at different stages of their trips.