Controlling factors of groundwater hydrochemistry in a small island’s aquifer

Factor analysis was applied to the hydrochemical data set of Manukan Island in order to extract the principal factors corresponding to the different sources of variation in the hydrochemistry. The application of varimax rotation was to ensure the clear definition of the main sources of variation in the hydrochemistry. The geochemical data of dissolved major, minor and trace constituents in the groundwater samples indicates the main processes responsible for the geochemistry evolution. By using Kaiser normalization, principal factors were extracted from the data for each location. The analysis reveals that there are four sources of solutes: (1) seawater intrusion; (2) leaching process of underlying rock mediated by pH; (3) minerals weathering process and (4) dissolution of carbonate minerals characterized by high loadings of Ca, Zn and Mg. Such processes are dominated by the significant role of anthropogenic impact from the over abstraction of fresh water from the aquifer. Those factors contributed to the changes of the groundwater geochemistry behavior explain the effect of rising extraction of freshwater from the aquifer.     

Eocene tonalite–granodiorite from the Havza (Samsun) area,northern Turkey: adakite-like melts of lithospheric mantle and crust generated in a post-collisional setting

ABSTRACT

Eocene intermediate to felsic plutons of different sizes and compositions are widespread in the Eastern Pontides Orogenic Belt in northern Turkey. Of these, the Ta?l?k Tepe pluton in the Havza (Samsun) area is fine-to-medium-grained, with granular, porphyritic, and micrographic textures, and include mafic microgranular enclaves (MMEs). LA-ICP-MS U-Pb zircon dating yielded emplacement ages of 42.9 (± 1.4) and 40.5 (± 1.3) Ma for the host granodioritic pluton and the dioritic MMEs, respectively. Petrochemically, the host pluton has I-type, high-K calc-alkaline, and metaluminous-to-slightly peraluminous features (A/CNK = 0.95–1.06). The host pluton also shows geochemical features of adakite-like rocks with high SiO₂ (67–68 wt%) and Al₂O₃ (15.5–16.0 wt%) content and Ba/La (17–23), Sr/Y (40.7–61.6), and La_N/Yb_N (14.4–23.7) ratios and low Y (8.2–9.9 ppm) and Yb_N (3.1–4.4) contents. Whole-rock major and trace element variations suggest that fractional crystallisation played a significant role in the pluton evolution. The N-MORB normalised trace element patterns of the pluton are similar to those of MMEs with enrichment in large-ion lithophile elements, Th and Ce, and negative Nb and Ti anomalies. Chondrite-normalised rare earth element plots show moderate-to-highly enriched concave patterns (La_N/Lu_N = 14.2–21.6) with insignificant negative Eu anomalies (Eu_N/Eu* = 0.86–1.14), all of which imply hornblende fractionation during magmatic evolution. The pluton samples have ⁸⁷Sr/⁸⁶Sr ratios of 0.704767 to 0.704927, ¹⁴³Nd/¹⁴⁴Nd ratios of 0.512767–0.512774, εNd values of (+2.52) – (+2.65), and δ¹⁸O values of 7.9–9.7‰. The isotopic compositions of the host pluton and MMEs are similar to I-type granitoids derived from mantle sources. The MMEs show incomplete magma mixing/mingling, representing small bodies of mafic parental magma. Combined with regional studies, these new data suggest that the parental magma of the studied adakite-like pluton was generated from the lithospheric mantle and then modified by fractional crystallisation and assimilation in a post-collisional setting.     

The Filament Disappearance of 7 May 1992 (the Ebi)

The 7 May 1992 filament disappearance in the low corona is analyzed. The cool and hot components of this event are studied, using H, soft X-ray and radio data. We first show the general effect of the disparition brusque (DB) on the life of the filament, which was a quiescent filament in the vicinity of an active region, and then give the history of the development of the 7 May event. The main stages of the event are: (i) the formation of hot arches spanning the cool filament; (ii) rise of the filament, with plasma ejection into the corona, in which we note some spreading of loops from the main body, with two distinct rising velocity phases of the H filament; (iii) formation of X-ray arches below the filament, the foot points of the arcades being two-ribbon H flare patches. The dynamics of H and X-rays features are given.     

Swelling Behaviour of Expansive Shales from the Middle Region of Saudi Arabia

Severe and widespread damage in residential buildings, sidewalks and pavements in various parts of the middle region of Saudi Arabia is caused by the development of heave and swelling pressure in the expansive shales in the region. This paper presents the problems and the geotechnical and physicochemical properties of the tested shales. The swelling potential was determined using various methods. Swell tests were conducted under different loading conditions and following different procedures to quantify the amount of vertical swell and swelling pressure. The conventional one-dimensional oedometer swell tests were performed using three different procedures, namely, free swell, constant volume swell and swell overburden. In addition, swell tests were performed in the stress path triaxial apparatus. Tests under different vertical stresses and confinements were conducted. Vertical swell and swelling pressure obtained from the various methods were compared. The reliability of the different methods for estimation of swelling potential is discussed.     

Young magmatism in Afghanistan as the consequence of the neocene-quaternary tectonic movements

A considerable portion of the territory of Afghanistan, having structures of the Mediterranean folded belt, has been subjected to a general tectonomagmatic activization over the Miocene through to the present, resulting in different (predominantly oscillating) tectonic movements, intrusive magmatism, terrestrial volcanism, mineral occurrences, and springs of carbonated and nitrous thermal water.Three types of young magmatism and volcanism products have been recognized in Afghanistan:

1. (1) Miocene alkaline granite intrusions, described as the Share—Arman Complex, resulted from the early orogenic stage of the Late Alpine geosynclinal troughs development and were restricted to transversal uplifts, in both the geosynclinal structures and on their extension, in the surrounding median masses. These transversal uplifts also play the role of mineralization-controlling structures.

2. (2) Late orogenic—Early Quaternary volcanics (the Dash-i-Nawar Complex) cropping out by the periphery of median masses and at the marginal uplifts of the Late Alpine folded area and also restricted to the transversal uplifts with the confined fault zones to them.

3. (3) Alkaline carbonatitic (the Khanneshin Complex) and trachybasaltic (the SarLogh Complex) Early—Middle Quaternary volcanics in the inner parts of the Central Afghanistan Median Mass and in the southeastern segment of the Turan Plateau.

Areas with products of Middle Quaternary volcanism are restricted to knot areas of the major subcrustal faults which are currently active.     

Macrobenthic composition of the southeast continental shelf of India

Macrobenthic faunal composition was studied at six different depth ranges (30–50, 51–75, 76–100, 101–150, 151–175 and >176 m) in five transects (off Karaikkal, Parangipettai, Cuddalore‐SIPCOT, Cheyyur and Chennai) in the continental shelf of southeast coast of India. Eleven diverse taxa were found, comprising 113 species of polychaetes, 14 species of bivalves, 10 species of amphipods and ‘others’ (five tanaids, five crabs, four isopods, three echinoderms, two shrimps, two cnidarians, two fishes and one cephalochordate). Polychaetes were the dominant taxa, constituting 88.5% of the total abundance and 30.7% of the total biomass. The number of species (seven per 0.2 m² at >176 m depth range in Chennai to 46 per 0.2 m² at 30–50 m in Cheyyur), abundance (216 per 0.2 m² at >176 m in Karaikkal to 353 per 0.2 m² at 30–50 m in Cheyyur) and biomass (0.09 g per 0.2 m² at 151–175 m in Karaikkal and 4.6 g per 0.2 m² at 30–50 m in Cheyyur) of macrobenthos decreased with increase in depth. DO decreased gradually from 30 m depth; beyond 150 m, the decrease was pronounced due to the presence of the oxygen minimum zone. Using the distance based linear model (DISTLM), it was found that the environmental variables explained about 73.3% of the total variability in macrofaunal distribution. The heavy metals cobalt and mercury, as well as water pressure (proxy for depth), showed a significant relationship with macrofauna, explaining respectively 9, 7.3 and 7% of the total variability. The contribution of other variables was smaller.     

Evaluation of the intermediate-term periodicities in solar and cosmic ray activities during cycle 23

In this paper we investigate the presence and temporal evolution of galactic cosmic rays (GCRs) time-series and three solar parameters, namely the daily sunspot number, the coronal green line and the 10.7 cm solar radio flux over the period 1996–2003 by the wavelet technique. A number of short- and intermediate-term quasi-periodicities were also detected in both GCR and solar parameters. For the short-term range, we have identified quasi-periods of 16–30 days, 40–55 days, 60–70 days, 80–90 days and 80–100 days. In the case of intermediate range, the significant periods were 120–140 days, 150–170 days, 190–210 days, 240–260 days, ≈1.09 yr. and ≈1.23 yr. The wavelet power spectra show that all the above-mentioned periods are intermittent in nature and occurred in different time-series in different intervals. The result exhibits that the well-known “Rieger period” of (150–160 days) was prominent in both GCR and solar data sets during the ascending phase of cycle 23. Possible reasons behind the observed periods were discussed with the help of previous results and existing numerical models.