New Relations of Water Saturation’s Calculus from Well Logs

The saturation in water or hydrocarbon is an important petrophysical parameter used for the evaluation of oil and gas reservoirs. It represents the amount of hydrocarbons in a reservoir. There are many relations to determine the water saturation from well logs by using the physical properties of rocks. The accurate determination of the hydrocarbon formation or the water saturation is given by the accuracy of the parameters used for calculating and by the relations used.     

Downstream variation in bed sediment size along the East Carpathian rivers: evidence of the role of sediment sources

Taking as an example six main rivers that drain the western flank of the Eastern Carpathians, a conceptual model has been developed, according to which fluvial bed sediment bimodality can be explained by the overlapping of two grain size distribution curves of different origins. Thus, for Carpathian tributaries of the Siret, coarse gravel joins an unimodal distribution presenting a right skewness with enhanced downstream fining. The source of the coarse material distributions is autohtonous (by abrasion and hydraulic sorting mechanisms). A second distribution with a sandy mode is, in general, skewed to the left. The source of the second distribution is allohtonous (the quantity of sand that reaches the river‐bed through the erosion of the hillslope basin terrains). The intersection of the two distributions occurs in the area of the 0·5–8 mm fractions, where, in fact, the right skewness (for gravel) and left skewness (for sand) histogram tails meet. This also explains the lack of particles in the 0·5–8 mm interval. For rivers where fine sediment sources are low, the 0·5–8 mm fractions have a higher proportion than the fractions under 1 mm. For the Siret River itself, bed sediment bimodality is greatly enhanced due to the fact that the second mode is more than 25% of the full sample. As opposed to its tributaries, the source of the first mode, of gravel, is allohtonous to the Siret river, generated by the massive input of coarse sediment through the Carpathian tributaries, while the second mode, of the sands, is local. In this case we can also observe that the two distributions of particles of different origins overlap in the 0·5–8 mm fraction domain, creating the illusion of ‘particle lack’ in the fluvial bed sediments. Copyright © 2007 John Wiley & Sons, Ltd.     

Tame and chaotic behavior in the planar isosceles 3-body problem

We show that every planar isosceles solution of the three-body problem encounters a collision of the symmetric particles, either forwards or backwards in time. Regularizing analytically this collision, the solution has at least a syzygy configuration and/or leads to a total collapse. Some further simple results support the intuitive image on the tame local behavior of the motion as long as it does not lead to a triple collision. As a main result we prove that total collapse singularities, can be regularized in aC ¹-fashion with respect to time, for all values of the masses. Using symbolic dynamics, the chaotic character of theC ¹-regularized solutions is pointed out.     

Pb isotopic variability in the modern-Pleistocene Indus River system measured by ion microprobe in detrital K-feldspar grains

The western Himalaya, Karakoram and Tibet are known to be heterogeneous with regard to Pb isotope compositions in K-feldspars, which allows this system to be used as a sediment provenance tool. We used secondary ion mass spectrometry to measure the isotopic character of silt and sand-sized grains from the modern Sutlej and Chenab Rivers, together with Thar Desert sands, in order to constrain their origin. The rivers show a clear Himalayan provenance, contrasting with grains from the Indus Suture Zone, but with overlap to known Karakoram compositions. The desert dunes commonly show ²⁰⁷Pb/²⁰⁴Pb and ²⁰⁶Pb/²⁰⁴Pb values that are much higher than those seen in the rivers, most consistent with erosion from Nanga Parbat. This implies at least some origin from the trunk Indus, probably reworked by summer monsoon winds from the SW, a hypothesis supported by bulk Nd and U-Pb zircon dating. Further data collected from Holocene and Pleistocene sands shows that filled and abandoned channels on the western edge of the Thar Desert were sourced from Himalayan rivers before and at 6-8 ka, but that after that time the proportion of high isotopic ratio grains rose, indicating increased contribution from the Thar Desert dunes prior to ∼4.5 ka when flow ceased entirely. This may be linked to climatic drying, northward expansion of the Thar Desert, or changes in drainage style including regional capture, channel abandonment, or active local Thar tributaries. Our data further show a Himalayan river channel east of the present Indus, close to the delta, in the Nara River valley during the middle Holocene. While this cannot be distinguished from the Indus it is not heavily contaminated by reworking from the desert. The Pb system shows some use as a provenance tool, but is not effective at demonstrating whether these Nara sediments represent a Ghaggar-Hakra stream independent from the Indus. Our study highlights an important role for eolian reworking of floodplain sediments in arid rivers such as the Indus.     

The ecological consequences of privatisation in romanian agriculture

There have been many changes in the vegetation cover as a result of the development of settlements and agriculture. Every change in the farming system will be reflected in some ways in the vegetation; and some of these changes may be ecologically undesirable. For example erosion may accelerate as a result of cropping and overgrazing on steeply-sloping hill land with thin soils. Several changes were apparent when agriculture was collectivised and a further transformation is now under way as a result of the privatisation of agriculture and the transition to a market economy. The recent changes are outlined, against a background review of the earlier transformations. Although the situation will only become clearer as the transition proceeds it is evident that ecological problems will have to be given a higher priority.     

Le centenaire de la société Roumaine de géographie (1875–1975)The centennial celebration of the Romanian society of geographical sciences (1875–1975)Hundert jahre Rumänische geographische gesellschart (1875–1975)

The Geographical Society in Romania — founded 15–27 June 1875 — plays an important part in the development of modern Romanian scientific geography. It supports school geography with educational plans and programmes by various treatises and textbooks. The Society has promoted geographical research by recommending several themes relating to Romanian territory, and by publication. In its first decades of activity (1875–1920), it initiated, promoted and supported geographical explorations and expeditions to less-known areas of the world.Its publication — The Bulletin of the Romanian Geographical Society — dealt with especially the results of scientific research work, and the journals Atetura (1949–1968) and Terra (from 1969) published studies, geographical syntheses and methodological articles.The 4000 members of the Geographical Society of Romania are grouped in over 50 branches. The Society has a wide and varied collaboration with many other geographical societies and institutes. In Romania, the Society works with the Institute of Geography, the departments of geography in universities and other institutions.After the experience of the years 1890–1900 (when 32 county dictionaries and the great geographical dictionaries to Romania in 5 volumes were produced), at present the members of our Society are working on 39 geographical monographs to the counties of the S.R. of Romania and the guide to the municipality of Bucharest.     

Alpine polyphase tectono-metamorphic evolution of the South Carpathians: A new overview

The main terrains involved in the Cretaceous–Tertiary tectonism in the South Carpathians segment of the European Alpine orogen are the Getic–Supragetic and Danubian continental crust fragments separated by the Severin oceanic crust-floored basin. During the Early–Middle Cretaceous times the Danubian microplate acted initially as a foreland unit strongly involved in the South Carpathians nappe stacking. Multistage folding/thrusting events, uplift/erosion and extensional stages and the development of associated sedimentary basins characterize the South Carpathians during Cretaceous to Tertiary convergence and collision events. The main Cretaceous tectogenetic events responsible for contraction and crustal thickening processes in the South Carpathians are Mid-Cretaceous (“Austrian phase”) and Latest Cretaceous (“Laramide” or “Getic phase”) in age. The architecture of the South Carpathians suggests polyphase tectonic evolution and mountain building and includes from top to bottom: the Getic–Supragetic basement/cover nappes, the Severin and Arjana cover nappes, and Danubian basement/cover nappes, all tectonically overriding the Moesian Platform. The Severin nappe complex (including Obarsia and Severin nappes) with Late Jurassic–Early Cretaceous ophiolites and turbidites is squeezed between the Danubian and Getic–Supragetic basement nappes as a result of successive thrusting of dismembered units during the inferred Mid- to Late Cretaceous subduction/collision followed by tectonic inversion processes.

Early Cretaceous thick-skinned tectonics was replaced by thin-skinned tectonics in Late Cretaceous. Thus, the former Middle Cretaceous “Austrian” nappe stack and its Albian–Lower Senonian cover got incorporated in the intra-Senonian “Laramide/Getic” stacking of the Getic–Supragetic/Severin/Arjana nappes onto the Danubian nappe duplex. The two contraction events are separated by an extensional tectonic phase in the upper plate recorded by the intrusion of the “Banatitic” magmas (84–73 Ma). The overthrusting of the entire South Carpathian Cretaceous nappe stack onto the fold/thrust foredeep units and to the Moesian Platform took place in the Late Miocene (intra-Sarmatian) times and was followed by extensional events and sedimentary basin formation.     

Nouvelle interprétation tectonique de la montagne Sainte-Victoire (Provence,France)

The explanation normally given for the tectonics of Sainte-Victoire Mountain, a dozen kilometres east of Aix-en-Provence, to the north of the limestone Provence, is incorrect. To the east, the morphology of the Sainte-Victoire is subdued, whereas to the west, before the mountain breaks savagely, the morphology is that of a young mountain as appears in Alpine landscapes. This unusual aspect in the region and the large subvertical faults with vertically striated surfaces that mark the massif to the south and to the west, induce the idea of strong vertical uplifts and caste doubt on the tectonic interpretation given in 1962 by Corroy et al. According to those authors, the Sainte-Victoire is a unit of Jurassic and Cretaceous formations overthrusting 1800 m to the south conglomerates of the Late Cretaceous or Palaeocene. New observations about the conglomerate transgression over the Jurassic and Cretaceous beds, and about the faults around and on the massif do not give evidence of an overthrusting but, on the contrary, induce the idea of a uplift, perhaps still active, in the form of a ‘piano key’ inclined to the northeast. To cite this article: J. Ricour et al., C. R. Geoscience 337 (2005).     

Romania's water resources and their use

In relation to population Romania's water supplies are quite modest. They are provided by the rivers, which meet 89% of the present demand (48% from the Danube and 41% from the interior rivers), and by the underground sources which account for 11%. Mean specific runoff is 4.57 1/sec. km² but there are significant variations through both space and time. The factors responsible for both maximum and minimum runoff are discussed and particular reference is made to the floods of 1970. Load and turbidity levels are also discussed. Underground water sources are described and a review of demand gives particular attention to hydroelectricity and water transport. Principles for future management of water supplies are summarised in conclusion.