Mesozoic radiolarian faunas from the northwest Ilocos Region,Luzon, Philippines and their tectonic significance

Northwestern Ilocos Norte in Luzon, Philippines, exposes cherts, peridotite and a variety of metamorphic rocks including chlorite schist, quartzo‐feldspathic schist, muscovite schist and actinolite schist. These rocks are incorporated within a tectonic mélange, the Dos Hermanos Mélange, which is thrust onto the turbidite succession of the Eocene Bangui Formation and capped by the Upper Miocene Pasuquin Limestone. The radiolarian assemblages constrain the stratigraphic range of the cherts to the uppermost Jurassic to Lower Cretaceous. Stratigraphically important species include Eucyrtidiellum pyramis (Aita), Hiscocapsa acuta (Hull), Protunuma japonicus (Matsuoka & Yao), Archeodictyomitra montisserei (Squinabol), Hiscocapsa asseni (Tan), Cryptamphorella conara (Foreman) and Pseudodictyomitra carpatica (Lozyniak). The radiolarian biostratigraphic data provide evidence for the existence of a Mesozoic basinal source from which the cherts and associated rocks were derived. Crucial to determining the origin of these rocks is their distribution and resemblance with known mélange outcrops in Central Philippines. The mélange in the northwestern Ilocos region bears similarities in terms of age and composition with those noted in the western part of the Central Philippines, particularly in the islands of Romblon, Mindoro and Panay. The existence of tectonic mélanges in the Central Philippines has been attributed to the Early to Middle Miocene arc–continent collision. This event involved the Philippine Mobile Belt and the Palawan Microcontinental Block, a terrane that drifted from the southeastern margin of mainland Asia following the opening of the South China Sea. Such arc–continent collision event could also well explain the existence of a tectonic mélange in northwestern Luzon.     

Engineering geological characterisation of the rock masses at Tannur Dam site,South Jordan

This paper highlights the geomechanical characterisation of the rock masses exposed at the dam abutments and reservoir area at the Tannur Dam site, South Jordan. The right abutment rock masses are characterised by closely to widely spaced joints. The rock-mass qualities were assigned using the rock-mass rating (RMR) and Q-tunnelling index. Both systems assigned a poor quality for foundation rocks because of the presence of weak rocks. The rock masses constituting the dam abutments exhibit fair quality. The results of packer tests indicate that the hydraulic conductivity of the rock masses of Fuheis-Hummar-Shueib (FHS) and Wadi es Sir (A7) formations range from 10 to 150 Lugeon units (LU). The FHS was characterised by lower LU values compared with A7; this reflects the fracturing characteristics of A7. However, the A7 should be grouted especially the right abutment. However, the FHS needs less grouting because the spacing between joints seems to be tight. The estimated shear strength envelopes relevant to the rock masses of both abutments as well as the foundation rocks were quite similar and, therefore, present similar shear strength characteristics. The shear strength for jointed rock masses showed curvilinear failure planes with average cohesion values of 0.67 and 0.64 MPa and friction angles of 36.5 and 35.5° for dam abutments and the foundation area, respectively.     

Characteristics of lipid tracer compounds transported to the Arabian Gulf by runoff from rivers and atmospheric dust transport

River runoff and atmospheric fallout (dust and air particulate matter) are major input sources of natural and anthropogenic terrestrial organic and inorganic components to the Arabian seas. In this study, we report on the various lipid tracer compounds that might be transported to the Arabian Gulf by rivers, dust, and air particulate matter. These are based on geochemical analysis of sediment, dust, and particulate samples collected from Iraq, Kuwait, and Saudi Arabia. The samples were extracted with a dichloromethane/methanol mixture and analyzed by gas chromatography-mass spectrometry. The extractable organic compounds (lipids) in the samples include n-alkanes, n-alkanoic acids, n-alkanols, methyl n-alkanoates, steroids, triterpenoids, carbohydrates, and petroleum hydrocarbons. The steroids and triterpenoids were major components in river and wetland samples. The major sources of these lipids were from natural vegetation, microbial (plankton and bacteria) residues in the sediments, sand, and soils, with some contribution from anthropogenic sources. Accordingly, these sources could be major inputs to the Arabian seas besides the autochthonous marine products. Future studies of the organic and inorganic biogeochemistry on river, dust, and coastal areas are needed to characterize the various regional sources, transformation, and diagenetic processes of the organic matter en route to the marine environment.     

On lattice reduction algorithms for solving weighted integer least squares problems: comparative study

Decorrelation or reduction theory deals with identifying appropriate lattice bases that aid in accelerating integer search to find the optimal integer solution of the weighted integer least squares problem. Orthogonality defect has been widely used to measure the degree of orthogonality of the reduced lattice bases for many years. This contribution presents an upper bound for the number of integer candidates in the integer search process. This upper bound is shown to be a product of three factors: (1) the orthogonality defect, (2) the absolute value of the determinant of the inverse of the generator matrix of the lattice, and (3) the radius of the search space raised to the power of the dimension of the integer ambiguity vector. Four well-known decorrelation algorithms, namely LLL, LAMBDA, MLAMBDA, and Seysen, are compared. Many simulated data with varying condition numbers and dimensions as well as real GPS data show that the Seysen reduction algorithm reduces the condition number much better than the other algorithms. Also, the number of integer candidates, before and after the reduction process, is counted for all algorithms. Comparing the number of integer candidates, condition numbers, and orthogonality defect reveals that reducing the condition number and the orthogonality defect may not necessarily result in decreasing the number of integer candidates in the search process. Therefore, contrary to the common belief, reducing the orthogonality defect and condition number do not always result in faster integer least squares estimation. The results indicate that LAMBDA and MLAMBDA perform much better in reducing the number of integer candidates than the other two algorithms, despite having a larger orthogonality defect and condition number in some cases. Therefore, these two algorithms can speed up the integer least squares estimation problem in general and the integer ambiguity resolution problem in particular.     

Effects of atmospheric stability conditions on heat fluxes from small water surfaces in (semi-)arid regions

Atmospheric stability conditions over the water surface can affect the evaporative and convective heat fluxes from the water surface. Atmospheric instability occurred 72.5% of the time and resulted in 44.7 and 89.2% increases in the average and maximum estimated evaporation, respectively, when compared to the neutral condition for a small shallow lake (Binaba) in Ghana. The proposed approach is based on the bulk-aerodynamic transfer method and the Monin-Obukhov similarity theory (MOST) using standard meteorological parameters measured over the surrounding land. For water surface temperature, a crucial parameter in heat flux estimation from water surfaces, an applicable method is proposed. This method was used to compute heat fluxes and compare them with observed heat fluxes. The heat flux model was validated using sensible heat fluxes measured with a 3-D sonic anemometer. The results show that an unstable atmospheric condition has a significant effect in enhancing evaporation alongside the sensible heat flux from water surfaces.     

Health risk assessment of trace elements in drinking water from Najran City,southwestern Saudi Arabia

The concentrations of 16 trace elements (Ag, Al, As, B, Ba, Cd, Cr, Cu, Hg, Mn, Ni, Pb, Se, Ti, U, and Zn) in drinking water from Najran City, Saudi Arabia, were determined by inductively coupled plasma-mass spectrometry (ICP-MS) and compared with local, regional, and international guidelines. Water samples from 22 water treatment plants and 13 commercial bottled water brands were analyzed. Except for B and U, the trace element concentrations were below the permitted limits defined in SASO, GSO, and WHO drinking water quality guidelines. The B concentrations in three brands of bottled water were 533.19, 602.29, and 1471.96 μg/L, which were all higher than the GSO and SASO limit (500 μg/L). The U concentrations were higher than the SASO limits for drinking water in two samples; one in treatment plant (2.39 μg/L) and another in foreign bottled water (2.17 μg/L). The median As, Ba, Cu, Ni, U, and Zn concentrations were statistically significantly higher in the treatment plant water samples than those in the bottled water samples, and conversely, the B concentrations were higher in the bottled water samples. The Cd, Hg, and Ti concentrations were below the detection limits of ICP-MS in all of the water samples. Apart from few exceptions, trace element concentrations in drinking water of Najran City were all within limits permitted in the national, regional, and international drinking water quality guideline values.     

Assessment of the Stability of Rock Slopes by the Slope Stability Rating Classification System

Given the lack of suitable systems in the characterization of slope stability of heavily jointed rock masses, a new rock mass classification system called Slope Stability Rating (SSR) is proposed. In addition to the so-called modified Geological Strength Index, the proposed system considers five additional parameters whose relative effects on the stability of fractured rock slopes were precisely examined based on data retrieved from eight different rock slope sites in Iran. An overall rating for the rock mass is obtained from the summation of the individual ratings of each parameter. A number of design charts are provided as illustration. The new system was then validated based on 46 slope case histories from Iran and Australia. For this, by means of the design charts previously mentioned, a recommended stable angle for each slope was given and compared with the current slope conditions. As a result, SSR design charts for maximum excavation angle (FS = 1.0) and also for other more conservative excavation angles (FS = 1.2, 1.3, 1.5) were presented.