Resource Model Updating For Compositional Geometallurgical Variables

In the field of mineral resources extraction, one main challenge is to meet production targets in terms of geometallurgical properties. These properties influence the processing of the ore and are often represented in resource modeling by coregionalized variables with a complex relationship between them. Valuable data are available about geometalurgical properties and their interaction with the beneficiation process given sensor technologies during production monitoring. The aim of this research is to update resource models as new observations become available. A popular method for updating is the ensemble Kalman filter. This method relies on Gaussian assumptions and uses a set of realizations of the simulated models to derive sample covariances that can propagate the uncertainty between real observations and simulated ones. Hence, the relationship among variables has a compositional nature, such that updating these models while keeping the compositional constraints is a practical requirement in order to improve the accuracy of the updated models. This paper presents an updating framework for compositional data based on ensemble Kalman filter which allows us to work with compositions that are transformed into a multivariate Gaussian space by log-ratio transformation and flow anamorphosis. This flow anamorphosis, transforms the distribution of the variables to joint normality while reasonably keeping the dependencies between components. Furthermore, the positiveness of those variables, after updating the simulated models, is satisfied. The method is implemented in a bauxite deposit, demonstrating the performance of the proposed approach.

     

A Parametric Approach for Dealing with Compositional Rounded Zeros

In this work, a parametric approach for replacing data below the detection limit, also known as rounded zeros, in compositional data sets is proposed. Compositional rounded zeros correspond to small proportions of some whole that cannot be reliably detected by the analytical instruments under given operating conditions. This kind of zeros appear frequently in the data collection process in geosciences. They must be treated in an adequate way before some multivariate analysis can be applied. Our procedure results from a modification of the Expectation-Maximization (EM) algorithm and is based on the additive log-ratio transformation. Its coherence with the nature of compositional data and with basic operations in the simplex sample space is checked. Using real data sets, we find that this approach improves other parametric and non-parametric techniques for compositional rounded zeros.     

不同类型热液金矿床主成矿期黄铁矿成分标型特征

黄铁矿作为成矿热液活动的产物,是热液金矿床中最为重要的载金矿物,其成分标型特征记录了大量矿床成因信息。在分类总结了各类型热液金矿床关键地质特征的基础上,采用比较矿床学的研究思路,较为系统地分析了不同类型热液金矿床中主成矿期或与金矿化同期的黄铁矿的主微量元素及组合特征、(Fe+S)As特征、δFeδS特征、AsCoNi特征以及热电性特征。结果表明,不同类型热液金矿床中的黄铁矿成分特征具有显著差异,彼此显示出特征性的成因标型特征,可作为判别热液金矿床成因的依据。结合各类热液金矿床形成的构造背景,提出热液金矿床是研究大陆动力学的理想对象。通过这些研究,初步建立了不同类型热液金矿床地质与黄铁矿成分标型特征之间的耦合关系,为今后热液金矿床成因的判别和黄铁矿标型特征的进一步研究提供一定的参考。     

Styles of mantle convection and their influence on planetary evolution

Mantle convection is the method of heat elimination for silicate mantles in terrestrial bodies, provided they are not too small or too hot. Bodies that are small (～Moon or smaller, possibly even Mercury) may rely largely on conduction or melt migration, and bodies that are very hot (Io, very early Earth) may use massive melt migration (magma oceans) and heat pipes. In the standard, simple picture, we can use scaling laws to determine the secular cooling of a planet, likelihood and form of volcanism, and the possibility of a core dynamo. Contrary to popular belief, small planets do not cool faster than larger planets (provided they convect) but they do tend to have a slightly lower internal temperature at all times and thus may cease to be volcanically active at an earlier epoch. On the other hand, a larger volume fraction of a small planet may be involved in melt generation. However, our understanding of heat transfer by mantle convection is limited by three very important, largely unsolved problems: The complexities of rheology, the effects of compositional gradients, and the effects of phase transitions, especially melting. The most striking manifestation of the role of rheology lies in the difference between a mobile lid mode (plate tectonics for Earth) and a stagnant lid mode (other large terrestrial bodies). This difference may arise because of the role of water, but perhaps also because of melting, or size (gravity), or the vagaries of history. It has profound effects for the differences in history of Earth, Venus and Mars, including their surface geology, volatile reservoirs and magnetic fields. Since thermal convection is driven by small density differences, it can also be greatly altered or limited by compositional or phase effects. Melt migration introduces additional complications to the heat transport as well as being a source for the irreversible differentiation that might promote layering. Our limited understanding and ability to model these processes continues to limit the development of a predictive framework for the differences among the terrestrial planets.     

Compositional and thermal convection in magma chambers

Magma chambers cool and crystallize at a rate determined by the heat flux from the chamber. The heat is lost predominantly through the roof, whereas crystallization takes place mainly at the floor. Both processes provide destabilizing buoyancy fluxes which drive highly unsteady, chaotic convection in the magma. Even at the lowest cooling rates the thermal Rayleigh number Ra is found to be extremely large for both mafic and granitic magmas. Since the compositional and thermal buoyancy fluxes are directly related it can be shown that the compositional Rayleigh number Rs (and therefore a total Rayleigh number) is very much greater than Ra. In the case of basaltic melt crystallizing olivine Rs is up to 10⁶ times greater than Ra. However compositional and thermal buoyancy fluxes are roughly equal. Therefore thermal and compositional density gradients contribute equally to convection velocities in the interior of the magma. Effects of thermal buoyancy generated by latent heat release at the floor are included.The latent heat boundary layer at the floor of a basaltic chamber is shown to be of the order of 1 m thick with very low thermal gradients whereas the compositional boundary layer is about 1 cm thick with large compositional gradients. As a consequence, the variation in the degree of supercooling in front of the crystal-liquid interface is dominated by compositional effects. The habit and composition of the growing crystals is also controlled by the nature of the compositional boundary layer. Elongate crystals are predicted to form when the thickness of the compositional boundary layer is small compared with the crystal size (as in laboratory experiments with aqueous solutions). In contrast, equant crystals form when the boundary layer is thicker than the crystals (as in most magma chambers). Instability of the boundary layer in the latter case gives rise to zoning within crystals. Diffusion of compatible trace elements through the boundary layer can also explain an inverse correlation, observed in layered intrusions, between Ni concentration in olivine and the proportion of Ni-bearing phases in the crystallizing assemblage.     

Earthquake preparedness: the case of Eastern UAE

During the last 30 years, UAE witnessed earthquakes that ranged from minor to moderate, with maximum magnitude of 5.1 that occurred in the Masafi area (eastern UAE, on March 11, 2002). Recent earthquakes that hit Iran such as on May 11, 2013, caused tremors and mild shaking of buildings in some UAE cities. Although the tremors are small in magnitude, their sequences apparently become an important research topic and deserve more assessment from different perspectives such as geographical, geological, engineering, and social. This is because low risk does not equal no risk. This study is concerned with public perceptions of earthquake preparedness (reduction of disaster impact) that can be measured by various variables such as developing an emergency plan, preparation of disaster supply kits, and training. The methodology consists of a survey of 470 people who live around the Masafi area, near Fujairah city, UAE. GIS and GPS were used for site selection in conducting the survey, and remote sensing was used as an aid in identification of buildings’ ages. Results show that around 90% of the people surveyed have water tanks that can support them up to 3 days, and 60% of them normally buy food that can support them up to 2 days. Thirty percent of the respondents were familiar with storing first-aid kits and tools such as flashlights. The findings point to a need for more research regarding public awareness about earthquakes. The findings of this study may be useful for people who are involved in the four cornerstones of disaster risk reduction: community participation, public policy actions, safer construction and urban development, and development of a culture of prevention.     

Petrogenetic grids for metacarbonate rocks: pressure-temperature phase-diagram projection for mixed-volatile systems

Isothermal or isobaric phase diagram sections as a function of fluid composition (X ^F) are widely used for interpreting the genetic history of metacarbonate rocks. This approach has the disadvantages that: (1) the influence of a key metamorphic variable, either pressure (P) or temperature (T), is obscured; (2) the diagrams are inappropriate for systems that are not fluid-saturated. These problems are avoided by constructing phase-diagram projections in which the volatile composition of the system is projected onto a P-T coordinate frame, i.e., a petrogenetic grid. The univariant curves of such P-T projections trace the conditions of the invariant points of isothermal or isobaric phase-diagram sections, thereby defining the absolute stability of high-variance mineral assemblages, with and without a coexistent fluid phase. Petrogenetic grids for metacarbonate rocks are most useful for the study of regional metamorphism and for systems in which fluid composition has not been externally controlled. A calculated example of a P-T projection for the system CaO−MgO−SiO₂−H₂O−CO₂ suggests that many assemblages (e.g., calcite +tale, enstatite+fluid, magnesite+tremolite, antigorite+diopside+dolomite, and calcite+forsterite+tremolite) in mixed-volatile systems have stability fields that make them useful as P-T indicators. Consideration of the principles governing projection topology demonstrates that the univariant curves around a fluid present invariant point cannot be oriented independently with respect to the direction of compositional variation in the fluid phase. This has the interesting predictive implication that if the direction of compositional variation along one univariant curve around an invariant point is known, then the direction of compositional variation along the remaining curves can be determined solely from topologic constraints. The same constraints can be applied to systems containing simple mineral solutions or melts in order to predict compositional variations.     

太阳活动及其对地球环境的影响

太阳活动及其对地球环境影响的研究至今已发展成一门涉及太阳物理学、空间物理学和地球物理学的边缘学科,它研究三者的关系及相互作用的过程。本文将太阳活动分成缓变型和爆发型两类,分别介绍了它们的主要成员冕洞、总辐射、太阳黑子、太阳耀斑和日冕物质抛射的性质及特征;分别讨论了这两类太阳活动对地球环境的影响,还指出了太阳活动对固体地球的作用。     

Measures of variability for geological data

Diverse global and local measures of variability appear in the geological literature and, along with methods used to apply them, have been subject to some debate. Measures of variability for three data types—replicate, locational, and compositional—are considered; the source and nature of the variability determine the appropriate type of measure. To illustrate the effects of these measures and expose their inadequacy when improperly applied, the variability of a three-column data set is interpreted under three different suppositions. Geologists need to be aware of the confusion and misleading results that can develop from the use of variance as a measure of variability for locational or compositional data.     

Measuring Subcompositional Incoherence

Subcompositional coherence is a fundamental property of Aitchison’s approach to compositional data analysis and is the principal justification for using ratios of components. We maintain, however, that lack of subcompositional coherence (i.e., incoherence) can be measured in an attempt to evaluate whether any given technique is close enough, for all practical purposes, to being subcompositionally coherent. This opens up the field to alternative methods that might be better suited to cope with problems such as data zeros and outliers while being only slightly incoherent. The measure that we propose is based on the distance measure between components. We show that the two-part subcompositions, which appear to be the most sensitive to subcompositional incoherence, can be used to establish a distance matrix that can be directly compared with the pairwise distances in the full composition. The closeness of these two matrices can be quantified using a stress measure that is common in multidimensional scaling, providing a measure of subcompositional incoherence. The approach is illustrated using power-transformed correspondence analysis, which has already been shown to converge to log-ratio analysis as the power transform tends to zero.     

Identification of the Unchanging Reference Component of Compositional Data from the Properties of the Coefficient of Variation

In analyses of compositional data, it is important to select a suitable unchanging component as a reference to detect the behavior of a single variable in isolation. This paper introduces two tests for detecting the unchanging component, based on a new approach that utilizes the coefficient of variation of component ratios. That is, the coefficient of variation of a compositional ratio is subject to change when the unchanging component is switched between the denominator and numerator, and the coefficient of variation tends to be small when the unchanging component occurs as the denominator against any arbitrary components (Test 1). In addition, the ratio of the component pair that gives the lowest coefficient of variation is most likely to represent the two unchanging components (Test 2). However, Tests 1 and 2 are not necessary and sufficient conditions for uniquely finding the unchanging component. To verify the effectiveness of the tests, 500 artificial datasets were analyzed and the results suggest that the tests are able to identify the unchanging component, although Test 1 underperforms when the dataset includes a component with skewness greater than 0.5, and Test 2 fails when the dataset includes components with a correlation coefficient greater than 0.75. These defects can be overcome by interpreting the two test results in a complementary manner. The proposed tests provide powerful yet simple criteria for identifying the unchanging component in compositional data; however, the reliability of this approach needs to be assessed in further studies.     

The bimodal composition of carbonatites: Reality or misconception?

The concept of compositional bimodality in carbonatites has become widely accepted and has been used to impose restrictions on the composition of carbonatite magmas. We agree that mineralogical bimodality exists in carbonatites (most are either calcitic or dolomitic/ankeritic), but we argue that there is no compositional bimodality. The idea of bimodality is based on the interpretation of a variety of element distribution diagrams which were compiled only from chemical analyses in which SiO₂ is < 10 wt.%. All others were rejected. Even with such a restricted data set the case for compositional bimodality is extremely weak, but the inclusion of analyses with higher SiO₂ content destroys it completely. Yet these more siliceous compositions must be included, for many carbonatites contain substantial amounts of Fe–Mg silicates which are an essential part of the magmatic mineralogy of the rocks. They account for much of the Mg in carbonatites that are otherwise calcitic. Many such carbonatites contain well in excess of 10 wt.% SiO₂. Supporters of the bimodality concept argue that liquids having compositions between calcite and dolomite can precipitate neither calcite nor dolomite because the minimum on the solid solution loops in the system calcite–dolomite permits only a carbonate of intermediate composition. Therefore, it is argued, liquids of such intermediate composition cannot be parental to calcitic and dolomitic carbonatites; their parent magmas must be calcitic and dolomitic. This deduction is incorrect. It is well established that dolomitic liquids have calcite as the liquidus phase over substantial temperature intervals, and that this is followed by dolomite precipitation. Mixed calcite–dolomite carbonatites are explicable in this way. Therefore, dolomitic liquids can be parental to calcitic carbonatites. However, dolomitic carbonatites cannot crystallize from a calcitic liquid. We suggest that intermediate composition carbonatite magmas are probably common. Bimodality in carbonatites is solely mineralogical, not compositional.     

Environmental impact assessment of open pit mining in Iran

Mining is widely regarded as having adverse effects on environment of both magnitude and diversity. Some of these effects include erosion, formation of sinkhole, biodiversity loss and contamination of groundwater by chemical from the mining process in general and open-pit mining in particular. As such, a repeatable process to evaluate these effects primarily aims to diminish them. This paper applies Folchi method to evaluate the impact of open-pit mining in four Iranian mines that lacked previous geo-environmental assessment. Having key geologic resources, these mines are: Mouteh gold mine, Gol-e-Gohar and Chogart iron mines, and Sarcheshmeh copper mine. The environmental components can be defined as public health and safety, social relationships, air and water quality, flora and fauna hence, various impacting factors from the mining activities were estimated for each environmental component. For this purpose, each impacting factor was first given a magnitude, based solely on the range of possible scenarios. Thereafter, a matrix of weighted factors was derived to systematically quantify and normalize the effects of each impacting factor. The overall impact upon each individual environmental component was then calculated by summing the weighted rates. Here, Folchi method was applied to evaluate those environmental conditions. Based on the acquired results, the present paper finally concludes that amongst four case histories in Iran, Sarcheshmeh copper mine significantly affects the environment, with critical level of air pollution there.     

Experimental petrology of normal MORB near the Kane Fracture Zone: 22°–25° N,mid-Atlantic ridge

Melting experiments carried out at 1-atm and at 2 kbar on mid-ocean ridge basalts dredged from the mid-Atlantic ridge near the Kane Fracture Zone (KFZ, 22° to 25° N. latitude) provide a basis for evaluating the role of crystal fractionation in generating compositional variability observed in normal mid-ocean ridge basalt. The 1-atm olivine-plagioclase-clinopyroxene saturation boundary for KFZ lavas defines a path in mineral projection schemes and in oxide-oxide diagrams that is displaced from the same experimentally determined boundaries in FAMOUS (Grove and Bryan 1983) and Oceanographer Fracture Zone (Walker et al. 1979) basalts. The glass margins of sparsely phyric KFZ lavas record small amounts of near surface, low pressure fractional crystallization, and their glass and bulk rock compositions are similar. An important signature of low pressure differentiation is recorded in the quenched glass margins of moderately phyric KFZ lavas compared to their bulk rock compositions, and the glass has evolved along low-pressure fractionation paths that are similar to those produced in the 1-atm experiments. Many of the lavas have retained phenocrysts in equilibrium proportions, so that their bulk rock compositions represent liquid compositions. When the effects of near-surface differentiation and crystal accumulation are removed from the Kane data set, and only liquid compositions are considered, a suite of basalt magmas can be identified that forms a trend in mineral component projection schemes parallel to the 1-atm oliv-plag-cpx multiple saturation boundary, but displaced from it toward olivine. These basalts have only olivine and plagioclase as phenocrysts, and are well removed from clinopyroxene saturation at low pressure. The compositional variation can not be generated by mixing any primary liquid composition with a low pressure liquid that has evolved along the oliv-plag-cpx multiple saturation boundary. Major and trace element models of this trend using olivine, plagioclase and clinopyroxene as fractionating phases match the compositional variability. This compositional trend is generated by fractionation at pressures greater than 2 kbar, but within the plagioclase stability field. A review of the data for other normal MORB suites from this part of the mid-Atlantic ridge reveals a similar elevated pressure fractionation signature which persists when the effects of low pressure magma mixing are removed from the data set.     

鄂尔多斯盆地陇东地区延长组砂岩储层岩石学特征

鄂尔多斯盆地陇东地区延长组是该地区的主要产油层,素以“低孔低渗”而闻名。根据岩心观察、薄片鉴定、粒度分析和扫描电镜、阴极发光和X 衍射等分析化验对该地区延长组储层的岩石学特征及其变化规律进行了深入研究。研究表明,陇东地区延长组砂岩储层岩石类型主要为细中粒岩屑质长石砂岩和长石质岩屑砂岩;成分成熟度较低;总体上从西部耿湾-环县向东至合水-塔儿湾,砂岩成分成熟度逐渐增高;下部的长8-长10及上部长1-长4+5较粗,为中细粒砂岩,中部长6、长7较细,多为粉-细砂岩。砂岩岩屑含量高、类型丰富,发育泥岩、白云岩等沉积岩岩屑,喷发岩、花岗岩等岩浆岩岩屑及板岩、千枚岩、片岩等变质岩岩屑,其中长8-长10以喷发岩岩屑为主,含量东西差异小,长1-长7以白云岩岩屑为主,含量西高东低;变质岩岩屑各层段都存在;云母在东部含量较高。按岩屑对成岩作用的影响分为刚性和塑性两大类,其中刚性可再细分为易溶与难溶两类,塑性可细分为易压实变形及易蚀变两类。此项研究成果对于分析延长期的盆地演化、物源类型及储层后期成岩作用及孔隙演化具有重要意义。     

A laboratory study of covers made of low-sulphide tailings to prevent acid mine drainage

Covers with capillary barrier effects (CCBE) are considered to be one of the most effective ways to control acid mine drainage (AMD) production from mine wastes. The use of low-sulphide tailings in CCBE has been proposed recently for cases where other types of material may be unavailable near the mining site. This paper presents leaching column test results showing that CCBEs with a moisture-retaining layer made of slightly reactive tailings, with three different sulphide contents, can effectively limit the production of AMD from the acid-generating tailings placed underneath. With these layered covers, the leachate pH was maintained near neutrality throughout the testing period. When compared to uncovered tailings, the efficiency of the cover systems for reducing the amount of contaminants in the percolated water was determined to be greater than 99% for zinc, copper and iron. This study shows that the use of low-sulphide tailings can improve the ability of a CCBE to limit gas diffusion by consuming a fraction of the migrating oxygen.     

CO<Subscript>2</Subscript> leakage through an abandoned well: problem-oriented benchmarks

The efficiency and sustainability of carbon dioxide (CO₂) storage in deep geological formations crucially depends on the integrity of the overlying cap-rocks. Existing oil and gas wells, which penetrate the formations, are potential leakage pathways. This problem has been discussed in the literature, and a number of investigations using semi-analytical mathematical approaches have been carried out by other authors to quantify leakage rates. The semi-analytical results are based on a number of simplifying assumptions. Thus, it is of great interest to assess the influence of these assumptions. We use a numerical model to compare the results with those of the semi-analytical model. Then we ease the simplifying restrictions and include more complex thermodynamic processes including sub- and supercritical fluid properties of CO₂ and non-isothermal as well as compositional effects. The aim is to set up problem-oriented benchmark examples that allow a comparison of different modeling approaches to the problem of CO₂ leakage.     

Format and philosophy for collecting,compiling, and reporting microprobe monazite ages

Microprobe monazite dating has been increasingly used to constrain the timing of deformation and metamorphism because of the potential to date very small monazite domains (down to 5 μm or less) in structural and petrologic context. This paper presents an analytical strategy, presentation format, and error considerations for microprobe monazite dating. The strategy involves high-resolution compositional mapping to delineate compositional domains within monazite crystals. Then for each compositional domain, a series of Th, U and Pb analyses are made, and a single date and error are calculated. The number of analyses in each domain is determined by the desired statistical precision of the date. Results from several monazite grains are typically combined and, along with textural relationships, are used to build an argument that the dates constrain the age of a deformation or metamorphic event. The total error involves three components: short-term random error (dominated by counting statistical uncertainty), short-term systematic error (uncertainty in background correction, conductive coating variation, and calibration), and long-term systematic error (uncertainty in standard composition, mass absorption factors, decay constants, etc.). In homogeneous compositional domains, short-term random errors (2σ) of less than 10 m.y. can be obtained from five to ten analyses. However, short-term systematic error, mainly background estimation uncertainty, would typically result in a doubling of the magnitude of random error. Microprobe dates are presented as a single Gaussian probability distribution for each domain, along with representative compositional maps. It is recommended that a consistency standard be analyzed during each analytical session and the results be reported along with those from the unknown. This proposed strategy and format are compatible with those of other geochronological techniques; they incorporate analytical limitations associated with trace, as opposed to major element, microprobe analysis, and will allow better comparisons to be made between labs and between different geochronological techniques.     

Sensitivity and uncertainty analysis of mixing and mass balance calculations with standard and PCA-based geochemical codes

One of the most important observations that can be obtained from the study of an aquifer system dominated by mixing is the contribution of each end-member water to the chemical composition of every water parcel in the aquifer. Once the first-order effect of mixing has been taken into account via the mixing proportions, water–rock interaction can be used to explain the remaining variability. There are many sources of uncertainty that can prevent the accurate calculation of the mixing proportions of a mixing-dominated system, but the type and intensity of the chemical reactions that have taken place as a consequence of mixing is one of the most critical. Here the uncertainty in the computed mixing proportions of samples from a “synthetic” aquifer system derived from the actuation of different chemical reactions are assessed (always remembering that the chemical reactions are a second-order effect). These uncertainties are explored using two different geochemical codes in order to infer the limits of both methodological approaches: PHREEQC, as an example of a standard geochemical code; and M3, as an example of a Principal Component-based geochemical code. Several synthetic water samples are created with the direct approach of PHREEQC, both by pure mixing and including different types of chemical reactions. Together with the chemical information of the end-member waters, these samples are then fed into PHREEQC (inverse modelling) and M3 and the mixing proportions and mineral mass transfers are computed. PHREEQC calculations give a reasonable estimate of the real mixing proportions and the chemistry of the groundwaters. However, similar mixing proportions and mass transfers can be obtained using different sets of reactions, indicating a source of uncertainty that should be overcome with additional chemical information. For M3, where synthetic samples have been included in a real data set of groundwater samples from the Scandinavian Shield, mixing proportions are only mildly affected either by the number of compositional variables or the number of samples used for the Principal Component Analysis (PCA). However, the robustness of the output is quite sensitive to whether only conservative compositional variables are used or both conservative and non-conservative compositional variables. Mass balance calculations in M3 are much more sensitive to non-conservative compositional variables and the recommendation here is not to use non-conservative variables with PCA-based codes if any information about reactions is to be obtained.     

Statistical comparisons of heavy metal pollutants between seven regions of the Polish exclusive economic zone

This paper addresses three intractable difficulties associated with the statistical analysis of compositional data, such as percentages or ppm. These are: (1) that such data do not follow multivariate normal distributions thus rendering inappropriate, standard parametric statistical tests and estimation procedures, (2) the covariance/correlation coefficients between specific pairs of components are determined in whole or in part by the presence or absence of other components, and, (3) the negative bias property. That is, at least one covariance and therefore at least one correlation, must be negative, hence the remaining correlations are prevented from ranging freely between ?1 and +1. It follows that correlation coefficients formed from compositional data are not only not absolute, but also frequently spurious. Standard multivariate procedures based on them are unreliable, and intrinsic associations between components inferred from strong positive correlations in particular, are potentially false. In a recent 2009 paper, it was reported that 59 surface sediment samples from 7 regions in the Polish exclusive economic zone had been chemically analyzed for 16 elements. Enrichment factors together with crude correlation coefficients between selected elements were presented. All these quantities were computed from the initial raw compositional data resulting from the chemical analyses In this paper, a statistical procedure is presented which is distinctly different to the enrichment factor computations based on the same raw compositional data. The procedure generates a log-ratio measure of the abundance of each element in each of the seven regions, thus enabling comparisons of relative levels of pollution between the regions. Although the two techniques are quite unrelated, it is shown that in general, extremely high or low measures of the relative abundances in the regions are associated with correspondingly high or low values of the enrichment factors in the same regions that were reported in the 2009 paper. That is, the statistical analysis confirms the results of the enrichment factor data in the identification of the most to the least polluted regions. In an additional analysis, the residue term was excluded from each sediment sample by rescaling the 16 element concentrations to sum to 100%, thus forming 59 residue-free sub-compositions. Crude correlation coefficients were computed for pairs of elements of this sub-compositional data. These revealed that certain correlations based on the initial raw data that were reported in the 2009 paper for the same pairs of elements, were not only inconsistent, but sometimes also contradictory. Such contradictions imply that intrinsic geochemical element associations inferred in that paper from such correlations were false.