Prediction of true classes of surficial and deep earth materials using multivariate spatial data is a common challenge for geoscience modelers. Most geological processes leave a footprint that can be explored by geochemical data analysis. These footprints are normally complex statistical and spatial patterns buried deep in the high-dimensional compositional space. This paper proposes a spatial predictive model for classification of surficial and deep earth materials derived from the geochemical composition of surface regolith. The model is based on a combination of geostatistical simulation and machine learning approaches. A random forest predictive model is trained, and features are ranked based on their contribution to the predictive model. To generate potential and uncertainty maps, compositional data are simulated at unsampled locations via a chain of transformations (isometric log-ratio transformation followed by the flow anamorphosis) and geostatistical simulation. The simulated results are subsequently back-transformed to the original compositional space. The trained predictive model is used to estimate the probability of classes for simulated compositions. The proposed approach is illustrated through two case studies. In the first case study, the major crustal blocks of the Australian continent are predicted from the surface regolith geochemistry of the National Geochemical Survey of Australia project. The aim of the second case study is to discover the superficial deposits (peat) from the regional-scale soil geochemical data of the Tellus Project. The accuracy of the results in these two case studies confirms the usefulness of the proposed method for geological class prediction and geological process discovery.
The dynamics of the pseudo-Newtonian restricted four-body problem has been studied in the present paper, where the primaries have equal masses. The parametric variation of the existence as well as the position of the libration points are determined, when the value of the transition parameter ϵ ∈(0, 1]. The stability of these libration points has also been discussed. Our study reveals that the Jacobi constant as well as transition parameter ϵ have substantial effect on the regions of possible motion, where the fourth body is free to move. The multivariate version of Newton-Raphson iterative scheme is introduced for determining the basins of attraction in the configuration (x, y) plane. A systematic numerical investigation is executed to reveal the influence of the transition parameter on the topology of the basins of convergence. In parallel, the required number of iterations is also noted to show its correlations to the corresponding basins of convergence. It is unveiled that the evolution of the attracting regions in the pseudo-Newtonian restricted four-body problem is a highly complicated yet worth studying problem. 相似文献
The practical (Sp) and reference (SR) salinities do not account for variations in physical properties such as density and enthalpy. Trace and minor components of seawater, such as nutrients or inorganic carbon affect these properties. This limitation has been recognized and several studies have been made to estimate the effect of these compositional changes on the conductivity–density relationship. These studies have been limited in number and geographic scope. Here, we combine the measurements of previous studies with new measurements for a total of 2857 conductivity–density measurements, covering all of the world׳s major oceans, to derive empirical equations for the effect of silica and total alkalinity on the density and absolute salinity of the global oceans and to recommend an equation applicable to most of the world׳s oceans. The potential impact on salinity as a result of uptake of anthropogenic CO2 is also discussed. 相似文献
Quantifying the variability and allocation patterns of aboveground carbon stocks across plantation forests is central in deriving accurate and reliable knowledge and understanding of the extent to which these species contribute to the global carbon cycle and towards minimizing climate change effects. The principal objective of this study was to quantify the variability and allocation patterns of aboveground carbon stocks across Pinus and Eucalyptus plantation forests, tree-structural attributes (i.e. stems, barks, branches and leaves) and age groups, using models developed based on remotely sensed data. The results of this study demonstrate that aboveground carbon stocks significantly (α = 0.05) vary across different plantation forest species types, structural attributes and age. Pinus taeda and Eucalyptus grandis species contained aboveground carbon stocks above 110 t C ha−1, and Eucalyptus dunii had 20 t C ha−1. Across plantation forest tree structural attributes, stems contained the highest aboveground carbon stocks, when compared to barks, branches and leaves. Aboveground carbon stock estimates also varied significantly (α = 0.05) with stand age. Mature plantation forest species (i.e. between 7 and 20 years) contained the highest aboveground carbon stock estimates of approximately 120 t C ha−1, when compared to younger species (i.e. between 3 and 6 years), which had approximately 20 t C ha−1. The map of aboveground carbon stocks showed distinct spatial patterns across the entire study area. The findings of this study are important for understanding the contribution of different plantation forest species, structural attributes and age in the global carbon cycle and possible climate change moderation measures. Also, this study demonstrates that data on vital tree structural attributes, previously difficult to obtain, can now be easily derived from cheap and readily-available satellite data for inventorying carbon stocks variability. 相似文献
This paper investigates the spaces for participation that have been created by readiness preparations launched in connection with the international initiative “Reduced Emissions from Deforestation and Forest Degradation” (REDD+) in Colombia and Costa Rica. I analyse the emergence of these spaces and who is leading the process in each country. My findings indicate that in Costa Rica, the public sector is leading preparation activities and creating the public spaces for participation in REDD to which private actors are invited. In Colombia on the other hand, NGOs, development assistance agencies and other private actors are leading the process and the state is the invited actor. I identify four factors that determine the scope of different actors’ possibilities to participate in the REDD+ spaces. These are (a) control of key resources, (b) ideological affinity, (c) the creation and dissemination of information and knowledge, and (d) the creation of norms to validate REDD+ pilot initiatives. The separation between these factors is not clear-cut and consequently they reinforce each other at different levels. The research presented here contributes to a better understanding of the implications that national REDD+ politics may have in the future functioning of the programme. 相似文献
Proponents of payments for ecosystem services (PES) schemes advocate targeting payments to geographical areas that can: (a) maintain or enhance ecosystem services, (b) permit economically efficient arrangements and (c) address poverty objectives. The location of these efficient, effective and equitable (or triple-win) solutions is viewed as the ‘holy grail’ of PES and is often sought in isolation to broader socio-economic pressures, political relationships, or local cultural conditions. While the plethora of PES design perspectives often follow the concepts of efficiency and effectiveness, they seldom relate to pluralistic value systems and may disparage local self-determination for influencing the form and terms of negotiation. This paper critically analyses the assumptions underpinning the design of PES schemes which seek to optimise or target efficient, effective and poverty objectives. Using a case study for a proposed PES initiative in the Kathmandu Valley of Nepal, we employ spatial analysis to geographically visualise the discrepancy between the location for a typology of targeted objectives and actual preferences which support local perceptions of natural resource use and conservation. The case study highlights the inequity inherent in targeting payments under a neoliberal framing. Instead, spatially differentiating incentives according to socially determined priorities and collective management is suggested. 相似文献