Dynamics Behind Cycles and Co-movements in Metal Prices: An Empirical Study Using Band-Pass Filters

After living one of the most intense metal price cycles, several ongoing macroeconomic phenomena with the potential of structurally redefining the long-run supply and demand for metals, and raising divergency regarding where the metal prices are trending, it is suitable to evaluate the dynamics in the metal prices, especially focus on the long cyclical components. This article studies in detail the cyclical components of the real prices of base metals, iron ore, and gold, applying band-pass filters and a novel decomposition over time series with length as far as 1800. The main findings are: (1) the long cyclical components in real prices are highly correlated among them and with the proposed long economic cycles, (2) short and medium cyclical components are more relevant in explaining the price deviations from their trend, but the long cyclical component is not negligible, (3) co-movement in base metals is strong for all the cyclical components, but decreasing as cyclical frequency increases, and (4) prices are either sideways or upward-trending depending on the assumptions for correction of the US Consumer Price Index, which suggests that the supply side of these industries, in the best case, only offset the cost increases by depletion.

     

Mineralogy and Geochemistry of Sedimentary Huntite Deposits in the Egirdir-Hoyran Lake Basin of Southern Turkey

The sediment-hosted huntite-magnesite deposits are located in the Egirdir-Hoyran lake basin in the Isparta Angle (southern Turkey). The deposits occur at two different localities in the region: (1) Kemersirti huntite deposit, (2) Köytepe huntite-magnesite deposit. The huntite-magnesite occurrences are found in shallow lacustrine rocks of the Miocene-Pliocene Kizilcik Formation and formed as a result of Neogene tectonic activity. Based on X-ray diffraction and scanning electron microscopic studies, the mineral assemblage of huntite deposits contains mostly huntite, less magnesite, dolomite, very little calcite, illite, simectite, brucite, and quartz in the Kemersirti area but contain huntite, magnesite, dolomite, and calcite in the Köytepe area.In the huntite and magnesite-bearing huntite samples, MgO varies from 32.70 to 37.95 wt. %, CaO from 7.83 to 15.10 w.t. %, and SiO₂ from 0.99 to 10.60 w.t. %. Ba and Sr are dominant minor elements in the deposits. Ba and Sr for huntite and magnesite bearing huntite in the study area vary from 11 to 233 ppm and from 325 to 765 ppm, respectively. As, U, Zr, V and Ce contents ranged from 11.5-146 ppm, 0.5-3.7 ppm, 1.4-13.2 ppm, 7-34 ppm, and 0.9-2.7 ppm respectively. The huntite-magnesite is characterized by relatively lower Ni (0.5-2.4 ppm) and Co (0.5-1.1 ppm) contents. The huntite and magnesite-bearing huntite occurrences have higher Ba, Sr, As, Zr, V, and U contents than those of the other elements. The d13C isotope values vary between 7.8‰ to 8.8‰ PDB for huntite+magnesite, 8.2‰ PDB for huntite, 1.4‰ PDB for magnesite+dolomite, and 4.0‰ PDB for limestone from deposits in the study area. The δ¹⁸O isotope values of the huntite deposits ranged from 30.4 to 35.5‰ SMOW for huntite+magnesite, 32.4‰ SMOW for huntite, 29.8‰ SMOW for magnesite+ dolomite, and 26.9‰ SMOW for limestone.The presence of nodular huntite and the abundance of gastropod, ostracoda and Chura shells in the carbonate units indicate that the huntite occurrences are precipitated at shallow, alkaline (8.5-9.5 pH) and lower temperature (approximately 25°C) lake conditions. The Mg⁺⁺, Ca⁺⁺ and Si⁺⁺ ions for the huntite formation were derived from the surrounding rocks such as ultrabasic rocks, dolomite, dolomitic limestone, and limestone in the Egirdir-Hoyran lake basin. Also, the C isotope ratios indicate that the CO₂ source for the huntite formations results to sedimentary basin from metamorphic CO₂, carbonate rocks, fresh water carbonates, and ground water. The source of oxygen for the huntite formation may come from marine limestone, fresh water carbonates and meteoric water.     

Prediction of pore-water pressure response to rainfall using support vector regression

Nonlinear complex behavior of pore-water pressure responses to rainfall was modelled using support vector regression (SVR). Pore-water pressure can rise to disturbing levels that may result in slope failure during or after rainfall. Traditionally, monitoring slope pore-water pressure responses to rainfall is tedious and expensive, in that the slope must be instrumented with necessary monitors. Data on rainfall and corresponding responses of pore-water pressure were collected from such a monitoring program at a slope site in Malaysia and used to develop SVR models to predict pore-water pressure fluctuations. Three models, based on their different input configurations, were developed. SVR optimum meta-parameters were obtained using k-fold cross validation and a grid search. Model type 3 was adjudged the best among the models and was used to predict three other points on the slope. For each point, lag intervals of 30 min, 1 h and 2 h were used to make the predictions. The SVR model predictions were compared with predictions made by an artificial neural network model; overall, the SVR model showed slightly better results. Uncertainty quantification analysis was also performed for further model assessment. The uncertainty components were found to be low and tolerable, with d-factor of 0.14 and 74 % of observed data falling within the 95 % confidence bound. The study demonstrated that the SVR model is effective in providing an accurate and quick means of obtaining pore-water pressure response, which may be vital in systems where response information is urgently needed.     

Mixing processes in hydrothermal spring systems and implications for interpreting geochemical data: a case study in the Cappadocia region of Turkey

Mixing is a dominant hydrogeological process in the hydrothermal spring system in the Cappadocia region of Turkey. All springs emerge along faults, which have the potential to transmit waters rapidly from great depths. However, mixing with shallow meteoric waters within the flow system results in uncertainty in the interpretation of geochemical results. The chemical compositions of cold and warm springs and geothermal waters are varied, but overall there is a trend from Ca–HCO₃ dominated to Na–Cl dominated. There is little difference in the seasonal ionic compositions of the hot springs, suggesting the waters are sourced from a well-mixed reservoir. Based on δ¹⁸O and δ²H concentrations, all waters are of meteoric origin with evidence of temperature equilibration with carbonate rocks and evaporation. Seasonal isotopic variability indicates that only a small proportion of late spring and summer precipitation forms recharge and that fresh meteoric waters move rapidly into the flow system and mix with thermal waters at depth. ³H and percent modern carbon (pmC) values reflect progressively longer groundwater pathways from cold to geothermal waters; however, mixing processes and the very high dissolved inorganic carbon (DIC) of the water samples preclude the use of either isotope to gain any insight on actual groundwater ages.     

Influences of human activities and agriculture on groundwater quality of Kayseri-Incesu-Dokuzpınar springs,central Anatolian part of Turkey

Human activities and agriculture have had direct and indirect effects on the rates of contamination of groundwater in the Incesu-Dokuzp inar spring area. Direct effects include dissolution and transport of excess quantities of fertilizers with associated materials and hydrological alterations related to irrigation and drainage. Indirect effects may include changes in water–rock reactions in soils and aquifers caused by increased concentrations of dissolved oxidants, protons, and major ions. Agricultural activities have directly or indirectly affected the concentrations of a large number of inorganic chemicals in groundwater, for example NO ₃, N ₂, Cl, SO ₄ ², H ⁺, K, Mg, Ca, Fe, Cu, B, Pb, and Zn, as well as a wide variety of pesticides and other organic compounds. For reactive contaminants like NO ₃, it is recommended that a combination of hydrochemical and environmental-tracer analytical approaches might be required to resolve changing inputs from subsequent alterations as causes of concentration gradients in groundwater. The water type of Dokuzp inar springs is mainly Na–Mg–Ca–Cl–HCO ₃. Note that the water types of the springs were directly related to the hydrogeochemical properties of outcrops at the study area. Thus, the high concentration of Ca ²⁺ and HCO ₃ is mainly related to the high CO ₂ contents in the marbles, whereas the high Na concentration arises from the existing syenite, volcanic ash, basalt, and clay units, although the Incesu-Dokuzp inar springs cover most of the drinking and irrigation water demands of this area. The high concentrations of NO ₃ and NaCl show that the area around the springs is continuously being contaminated by untreated sewage and agricultural wastes, especially during dry periods. Therefore, this approach is based on the vulnerability studies of the catchment area, determination of the transfer time of the pollutant, and the water-bearing formations of Incesu-Dokuzp inar springs. Vulnerability in this study is defined as the intrinsic hydrogeochemical characteristics of an aquifer, which may show the sensitivity of groundwater to be contaminated by different human activities.     

An empirical attenuation relationship for Northwestern Turkey ground motion using a random effects approach

Using a random effects model that takes into consideration the correlation of data recorded by a single seismic event, a database consisting of 195 recordings from 17 recent events is employed to develop empirical attenuation relationships for the geometric mean of horizontal peak ground acceleration and 5-percent damped spectral acceleration (S_a). The recordings employed are obtained from strong motion stations operating in Northwestern Turkey and resulted from events that include the Kocaeli (M_w=7.4) and the Düzce (M_w=7.1) earthquakes and their aftershocks as well as other events. By studying differences in standard errors, the random effects model is compared with a fixed effects model that does not account for distinctions between intra- and inter-event variability. Effects of local site conditions are included in the empirical relationships developed. The dependence on frequency of the various model parameters is also studied. Frequency-dependent attenuation coefficients for the proposed random effects models developed are summarized in tables to facilitate their use.     

Progressive failure in stratified and jointed rock mass

Summary This paper describes a mathematical model for analyzing progressive failure in a stratified and jointed rock mass dipping parallel to the slope face. The relationship between the necessary support forces and permissible displacement in the rock mass is discussed. An analytical expression is provided for the minimum required support force corresponding to a critical displacement. This expression is used to evaluate the potential of unstable failure propagation. The effect of time on progressive failure is considered by using a simple rheological model for joints. A case study, involving an excavation in a stratified medium, is used to compare model prediction with monitored performance.     

Paleostress analysis of the Cretaceous rocks in the eastern margin of the Dead Sea transform, Jordan

This paper presents the first paleostress results from fault-slip data on Cretaceous limestone at the eastern rim of the Dead Sea transform (DST) in Jordan. Stress inversion of fault-slip data is performed using an improved right dieder method, followed by rotational optimization (Delvaux, TENSOR Program). The orientation of the principal stress axes (σ₁, σ₂ and σ₃) and the ratio of the principal stress differences ( ) show two main paleostress fields marking two main stress regimes, strike-slip and extensional. The first is characterized by NNW–SSE compression and ENE–WSW extension and related to Middle Miocene-Recent sinistral movement along the Dead Sea transform and the opening of the Red Sea. The second paleostress field is a WNW–ESE compression and NNE–SSW extension restricted to the northern part of the investigated area. This stress field could be associated with the development of the Syrian Arc fold belt which started during the Turonian, or it may be due to an anticlockwise rotation of the first stress field.