Middle Eocene‐Oligocene broken‐foreland evolution in the Andean Calchaqui Valley,NW Argentina: insights from stratigraphic,structural and provenance studies

Two end‐member models have been proposed for the Paleogene Andean foreland: a simple W‐E migrating foreland model and a broken‐foreland model. We present new stratigraphic, sedimentological and structural data from the Paleogene Quebrada de los Colorados (QLC) Formation, in the Eastern Cordillera, with which to test these two different models. Basin‐wide unconformities, growthstrata and changes in provenance indicate deposition of the QLC Formation in a tectonically active basin. Both west‐ and east‐vergent structures, rooted in the basement, controlled the deposition and distribution of the QLC Formation from the Middle Eocene to the Early Miocene. The provenance analysis indicates that the main source areas were basement blocks, like the Paleozoic Oire Eruptive Complex, uplifted during Paleogene shortening, and that delimits the eastern boundary of the present‐day intraorogenic Puna plateau. A comparison of the QLC sedimentary basin‐fill pattern with those of adjacent Paleogene basins in the Puna plateau and in the Santa Bárbara System highlights the presence of discrete depozones. These reflect the early compartmentalization of the foreland, rather than a stepwise advance of the deformation front of a thrust belt. The early Tertiary foreland of the southern central Andes is represented by a ca. 250‐km‐wide area comprising several deformation zones (Arizaro, Macón, Copalayo and Calchaquí) in which doubly vergent or asymmetric structures, rooted in the basement, were generated. Hence, classical foreland model is difficult to apply in this Paleogene basin; and our data and interpretation agree with a broken‐foreland model.     

An analysis of coastal erosion in the tropical rapid accretion delta of the Red River, Vietnam

The largest plain in the North Vietnam has formed by the redundant sediment of the Red River system. Sediment supply is not equally distributed, causing erosion in some places. The paper analyzes the evolvement and physical mechanism of the erosion. The overlay of five recent topographical maps (1930, 1965, 1985, 1995, and 2001) shows that sediment redundantly deposits at some big river mouths (Ba Lat, Lach, and Day), leading to rapid accretion (up to 100 m/y). Typical mechanism of delta propagation is forming and connecting sand bars in front of the mouths. Erosion coasts are distributed either between the river mouths (Hai Hau) or nearby them (Giao Long, Giao Phong, and Nghia Phuc). The evolvement of erosion is caused by wave-induced longshore southwestward sediment transport. Meanwhile sediment from the river mouths is not directed to deposit nearshore. The development of sand bars can intensively reduce the erosion rate nearby river mouths. Erosion in Hai Hau is accelerated by sea level rise and upstream dams. Sea dike stability is seriously threatened by erosion-induced lowering of beach profiles, sea level rise, typhoon, and storm surge.     

Image smoothing of multispectral imagery based on the HNN and geo-statistics

A new method for image down-scaling using geostatistical interpolation or smoothing based on the Hopfi eld Neural Network (HNN) and zero semivariance value is introduced. The method utilises the smoothing effect of the semivariogram matching process to produce the smoothened sub-pixel multispectral (MS) image with smaller RMSEs in comparison with the bilinear interpolation. In fact, the zero semivariograms increase the spatial correlation between the adjacent sub-pixels of the superresolution image. Containing higher spatial correlation, the resulting super-resolution MS image has smaller RMSEs compared with the original coarse image.     

Investigating Correlations and Variations of Air Pollutant Concentrations under Conditions of Rapid Industrialization – Kocaeli (1987–2009)

In this study, it was aimed to characterize temporal variations of air pollutants for determining contribution to pollution episodes and to obtain correlations between these pollutants. With this aim we used data analysis for measured sulfur dioxide (SO₂), particulate matter (PM, black fume and PM10), nitrogen oxides (NO_x), ozone (O₃), carbon monoxide (CO), methane (CH₄), and non‐methane hydrocarbons (NMHC) recorded in Kocaeli, one of the most industrilizated cities of Turkey. Pollutant concentrations were the results of continuous and semi‐automatic measurements. Semi‐automatic measurements of SO₂ and PM (black fume) were enclosing period from 1987 to 2008 whereas continuous monitoring of all pollutants included years of 2007–2009. In the first stage of the study daily, monthly, annual, and seasonal variations of pollution were researched. Annual average concentrations were compared with limits set by Air Quality Protection Regulation (AQPR), Air Quality Evaluation and Management Regulation (AQEMR), World Health Organization (WHO), European Union (EU), and National Ambient Air Quality Standards (USEPA). In the following stage relationships between pollutants such as NO₂–O₃, NO_x–CO, NO_x–NMHC, and NO_x–SO₂ were investigated and correlation coefficients were determined as 0.87, 0.56, 0.51, and 0.69, respectively. R² values of regression models developed from these correlations were 0.78, 0.56, 0.34, and 0.72, respectively. Vehicle density of the traffic was evaluated with NO_x–O₃ emissions and decrease was seen in NO_x emissions due to decreasing vehicle density at weekends whereas O₃ concentrations increased. These correlations enable prediction of the parameters that cannot be measured which is important for providing improvement in early warning systems.     

Numerical modeling and experiments of coarsening foam

Numerical and experimental results of drying and wetting foam are presented. Foam can be wetted by wash water delivered on its top boundary, or drained by allowing the liquid to move downward in response to gravity. These processes are governed by nonlinear equations that in special cases accept exact solutions. Here we develop a numerical model that satisfies realistic boundary conditions. Numerical results are presented in conjunction with experiments conducted with coarsening foam. In addition, calculations were carried out modeling the wetting and draining of coarsened foam. From the simulations and experiments, coarsening bubbles were found responsible for accelerating drainage, or vice versa.     

Freshwater stromatolites with the cone-in-cone structure from the Neogene lacustrine sediments of Vietnam

Morphological features of the columnar-stratiform stromatolites, which resemble the cone-in-cone structure, from Neogene lacustrine sediments of northern Vietnam are analyzed. Their structural-textural peculiarities and interrelations with the host terrigenous sediments of a stromatolitic buildup are discussed. It is shown that stages of the growth of columns are recorded in the succession of vertically oriented carbonate plates, which form stromatolites, and in the serrate surface protrusions of the plates at their contacts with host sediments. It is established that replacement of the columnar stromatolites by the stratiform varieties in the section can be related to variations in the intensity of terrigenous material influx to the sedimentation basin. Stratiform stromatolites were formed during relatively slow accumulation of sedimentary material. Appearance of the columnar varieties is attributed to intensification of sedimentation.     

Phosphorus removal in low alkalinity secondary effluent using alum

The alkalinity plays an important role in phosphorus removal using coagulant. The dosage of coagulant in the low alkalinity wastewater is limited due to rapid pH changes. In the present study, a series of jar test was conducted using low alkalinity wastewater (50 mg/L) to evaluate the optimum pH, dosage and performance parameters (slow mixing and settling time) for the common coagulant alum. From the experiment, it was found that the dosage of coagulant and removal of phosphorus depend upon the pH of the wastewater after adding coagulant. The final optimum pH for efficient P removal was found to be within the range of 5.7–5.9. This range acts as an indicator and it is the maximum tolerable pH range for phosphorus removal for low alkalinity wastewater. The optimum time for slow mix and settling was found to be 20 min. The optimum mole ratio of alum to remove one mole of phosphorous was found to be 2.3. The alum coagulation at pH 7 produced effluent with the total residual phosphorus and reactive phosphorus content of 0.3 and 0.9 mg/L, respectively.     

越南O Quy Ho钼矿床的成矿时代及成矿物质来源探讨

越南西北部O Quy Ho钼矿床为范士版成矿带的典型钼矿床之一,矿体以脉状形式就位于中生代花岗岩中,辉钼矿主要赋存于石英脉及长石石英脉中,与黄铁矿、黄铜矿、磁铁矿等共生。8件样品硫同位素分析结果表明,δ34S介于0.14‰～3.34‰之间,平均值为1.53‰,表明成矿物质具有深源特征。黄铁矿的206Pb/204Pb范围为18.583～22.355,207Pb/204Pb变化于15.632～15.812之间,208Pb/204Pb变化于38.989～39.199;辉钼矿的206Pb/204Pb、207Pb/204Pb、208Pb/204Pb分别为18.686～18.737、15.655～15.660和39.081～39.082,与范士版含角闪石花岗斑岩具有成因联系。辉钼矿Re-Os同位素等时线测年获得了(36±1)Ma的年龄,该年龄与金沙江-红河新生代斑岩铜钼矿成矿带岩浆-成矿活动的年龄一致,提出O Quy Ho钼矿床为金沙江-红河新生代斑岩铜钼矿带的一部分。     

Hydrological characteristics of karstic groundwater in the northeast Viet Nam as studied by isotopic techniques

The stable water isotopic composition (δ²H and δ¹⁸Ο), tritium (³H) activity, dissolved organic carbon, alkalinity, as well as the composition of carbon 13 (δ¹³C) in dissolved inorganic carbon (DIC) of 36 water samples taken from 16 resurgences in the northeast provinces of Viet Nam in the dry (Mar 2008) and rainy (June 2008) seasons were analyzed to elucidate hydrological characteristics of the karstic aquifers in the area. The stable water isotopic composition of the water samples collected clearly demonstrated that the karstic groundwater in the region was recharged from the local meteorological water. The tritium activity in the samples was found to be in between 3 and 4 TU, falling in the range of the ³H activity in the local precipitation and thus meaning that the traveling of recharge water to the resurgences was very short. Concentrated and diffuse allogenic recharges seem to be important sources of karstic groundwater in the study region. Water in the karstic aquifers could be classified into three types as: (a) water from karstic areas with dense vegetation cover that causes DIC be depleted in carbon 13 (¹³δ<?12‰ vs. Pee Dee Belemnite standard of Vienna, VPDB); (b) water from karstic areas with poor vegetation cover that originates DIC with carbon 13 composition ranging from ?11 to ?12‰; and (c) surface water from lakes, springs and rivers that has DIC with enriched carbon 13 (δ¹³C >?10‰). This implies that there are several sources of carbon dioxide contributing to the DIC in water of the karstic aquifers in the study region. Among other potential sources, the atmospheric CO₂, CO₂ from carbonate rock dissolution, biomineralization of soil organic matters and plant roots respiration seem to be important sources of the DIC in the waters of this region. The results show high vulnerability towards anthropogenic contaminants of karstic groundwater in the study region.