Resolvability of the interval between inversions using marine magnetic anomalies based on the Rao-Cramer inequality

It has been indicated that the Rao-Cramer inequality can be used to estimate the resolvability of intervals with opposite geomagnetic field polarity based on marine anomalies and for measurement planning. Specifically, it has been elucidated that the width of a detected interval of one polarity is determined more exactly than its center.     

Mineralogy,chemistry and crystallization sequence of clay minerals in altered tholeiitic basalts from the Peru Trench

Petrographic examination of amygdules and veins associated with moderately altered pillow basalts dredged from the Peru Trench has revealed that a consistent pattern of mineral crystallization has occurred. This sequence is: (1) green, weakly pleochroic clay (R.I. > 1.56); (2) dark yellowish brown, non-pleochroic clay (R.I. > 1.56); (3) light yellowish brown to colorless, fibrous, weakly pleochroic clay (R.I. < 1.56); and (4) calcite or celadonite. Chemical and X-ray diffraction analyses suggest that all clay mineral amygdule and vein fillings are dominated by intimate mixtures of an Fe-rich saponite and nontronite with very small admixtures of serpentine and illite. It is argued that sequential mineral fillings of fractures and vesicles may provide significant information about the chemistry of circulating interstitial fluids. For the pillow basalts studied the first-formed clays were enriched in nontronite, thereby suggesting Fe-rich fluids. These in turn were followed by saponite-rich clays and calcite. The change from Fe-and Mg-rich fluids to dominantly Ca-rich fluids is thought to correspond to a change from mafic mineral alteration to plagioclase alteration in the pillow basalts. An increase in the Fe³⁺/Fe²⁺ ratio of clays toward the centers of vesicles may indicate a change toward a more oxidizing environment of alteration.     

Karst groundwater protection in the Kupa River catchment area and sustainable development

One of the most significant water resources in the Republic of Croatia is the catchment area of the Kupa River, located in the region bordering the Republic of Slovenia. About 88% of the total amount of water in this catchment originates in Croatia and just 12% from Slovenia; therefore, the largest part of the catchment area (about 1000 km²) is on the Croatian side of the border. It is a typical karst area of the Dinarides with aquifers characterized by a relatively rapid water exchange, high groundwater flow velocities and aquifers open to human impact from the surface. Consequently, the aquifers are highly vulnerable and at risk. Due to the availability of large quantities of high-quality spring water (about 6 m³/s), the entire area has a strategic importance within the context of any future development strategy pertaining to the western part of Croatia. The catchment area on the Croatian side was investigated using a wide range of research methods that included a classical hydrogeological approach, the detailed hydrologic calculation of water balance to the hydrogeochemical analyses and modelling. The objective was to determine protection zones and protection measures for the whole area. The difficulties are increased due to the fact that the karst catchment area is crossed by major traffic corridors, oil pipelines and a railway and that many settlements and a highly developed wood industry are present. The combination of protecting water resources with adequate prevention measures and necessary remedial activities that should satisfy the very strict requirements necessary for the protection of the karst aquifers while still allowing for present and future human activities is difficult – but not impossible – to achieve. One good example is the present highway with a closed dewatering system and waste water treatment before the water passes into the karst underground system.     

New radiolarian biostratigraphic age constraints on Middle Triassic basalts and radiolarites from the Inner Hellenides (Northern Pindos and Othris Mountains, Northern Greece) and their implications for the geodynamic evolution of the early Mesozoic Neotethys

The Avdella Mélange in the northern Pindos Mountains and its equivalent formation, the Loggitsion Unit in the Othris Mountains expose early Mesozoic (Mid-Late Triassic) oceanic fragments beneath the Western Greek Ophiolite Belt of the Inner Hellenides, Northern Greece. The mélange consists of locally interfingering blocks and slices of ribbon radiolarite, radiolarian chert and pillow basalt and is usually overthrust by Jurassic ophiolites. New Middle and Upper Triassic radiolarian biostratigraphic data are presented from radiolarites and basalt-radiolarite sequences within mélange blocks. Pillow basalts associated with the radiolarites provide clues to the opening of the Neotethyan ocean basin. The radiolarians indicate a Middle Triassic age (latest Anisian, probably early Illyrian), which is documented for the first time in the northern Pindos Mountains. The new radiolarian biostratigraphic data suggest that rift-type basalt volcanism already began in pre-Ladinian time (late Scythian?—Anisian). These basalts were then overlain by Upper Anisian to Carnian (?Norian) radiolarites.     

Artificial Neural Network as a Tool for Backbreak Prediction

Backbreak is one of the destructive side effects of the blasting operation. Reducing of this event is very important for economic of a mining project. Involvement of various parameters has made the backbreak analyzing difficult. Currently there is no any specific method to predict or control the phenomenon considering all the effective parameters. In this paper, artificial neural network (ANN) as a powerful tool for solving such complicated problems is used to predict backbreak in blasting operation of the Sangan iron mine, Iran. Network training was fulfilled using a collected database of the practiced operation including blast design details and rock condition. Trying various types of the networks, a network with two hidden layers was found to be optimum. Performance of the ANN model was compared with statistical analysis using datasets which were kept apart from the original database. According to the obtained results, for the ANN model there existed a higher correlation (R² = 0.868) and lesser error (RMSE = 0.495) between the predicted and measured backbreak as compared to the regression model. Also, sensitivity analysis revealed that the inputs rock factor and number of rows are the most and the least sensitive parameters on the output backbreak, respectively.     

Siltation analysis in the Neyyar reservoir and forest degradation in its catchment: a study from Kerala state, India

 Impact of catchment erosion and the resultant reservoir siltation from a tropical environment is reported here to discuss the effect of a reservoir in the natural degradation of an evergreen-forested segment. While an area of 8.01 km² has been affected by direct inundation at the full reservoir level, another 2.6 km² area once under thick forest cover, had also lost its identity over the last 38 years by indirect degradation. This zone mainly falls in the confluence of tributaries, namely Neyyar and Mullayar, with the reservoir. The capacity of the reservoir was found to be reduced by 28.8 Mm³ during this period and the annual average loss is calculated as 0.75 Mm³ (0.71%), indicating the intensity of erosion from the catchment zone. In case the proposed upper dam in the reservoir comes into existence, an additional area of 2.4 km² from the virgin forest would be submerged and more area would face degradation around the inundated zone. Received: 29 July 1998 · Accepted: 16 November 1998