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[en] Signatures of concealed unconformity- related uranium mineralization at the contact of Chhotanagpur Granite Gneissic Complex [CGGC]/Mahakoshal and Lower Vindhyan Semri sequence have come to light at Baskati, in Vindhyan- Mahakoshal Basin, following a multipronged exploration strategy. Systematic lithogeochemical sampling brought out uranium halos and most significant signals with concentration sufficiently above the normal background closely associated with breccias along reactivated faults and fractures occurring parallel and also oblique to the unconformity contact extending for a strike length of 17 km. Alteration halos and signatures like hematitisation, chloritisation and illitisation characterize the vicinity of these reactivated faults and fractures. Geochemical study indicates a hypogene source for mineralizing fluids supported by geology, structure and lithogeochemistry and an 'unconformity-related uranium mineralization model' has been envisaged with the target area narrowed down for subsurface exploration. (author)
[en] This paper investigates the spatial stationarity of the relationship between landslide susceptibility and associated factors in Three Gorges Reservoir area, a landslide-rich area in China. Two logistic regression (LR) models have been used: A global LR (LR) assumes that the regression coefficients remain constant over the whole region, whereas a geographically weighted LR (GWLR) allows the regression coefficients to differ at the local scale. In LR model, lithology seems to have positive influence on the location of landslides, as it has a positive regression coefficient (0.005), while the other factors all have negative effects on landslide susceptibility as they all have negative coefficients. However in GWLR model, lithology does not always keep positive influence, as its coefficients range from −0.533 to 0.695. These results indicate a degree of spatial variation in the relationship between landslide susceptibility and the influencing factors in the study area. Furthermore, six evaluation criteria, based on the fit and complexity of the models, were used to compare the two approaches: deviance, corrected Akaike’s information criterion (AICc), local percent deviance explained (pdev), receiver operating characteristic curve (ROC), Bayesian information criterion (BIC), and residual Moran’s I. The results suggest that GWLR model provides potential advantages in landslide susceptibility mapping and sheds new light on the spatial non-stationarity of the relationship between landslide susceptibility and its influencing factors.
[en] The phenomenon of resist debris (RD) formation in electron beam lithography (EBL) under various conditions of proximity exposure (PE) effect is discussed. It is found that the PE correction at the preferred resist plane together with adequate beam to beam spacing can provide stable and uniformly distributed RD over the exposed pattern area. As an application of such stable and uniformly distributed RD, the fabrication of an array of closely spaced metal dots has been demonstrated. The approach provides the optimum way for achieving high resolution pattern delineation under the given EBL conditions and constraints. (author)
[en] The Ediacaran-Lower Ordovician successions exposed in the Eastern Pyrenees are updated and revised based on recent U-Pb zircon radiometric ages, intertonguing relationships of carbonate-dominated strata, and onlapping patterns marking the top of volcano-sedimentary complexes. A stratigraphic comparison with neighbouring pre-Variscan outcrops from the Montagne Noire (southern French Massif Central) and Sardinia is related to i) the absence of Cadomian deformation close to the Ediacaran-Cambrian boundary interval; ii) the presence of an episodic, Cadomian-related, acidic-dominant volcanism related to carbonate production punctuating the Ediacaran-Cambrian transition, similar to that recorded in the northern Montagne Noire; and iii) the lack of Guzhangian (Late Cambrian Epoch 3) regressive shoal complexes present in the Montagne Noire and probably in Sardinia.
[en] This research has been designed to contribute with Val le Chico Uruguay formation knowledge, taking into the alkaline type tectonic environment, geochronology, granitoid types, lithologies and mineralizations existing in the area
[en] Dom Feliciano Belt (Fragoso Cesar 1980) is represented in Uruguay so Preciozzi et to the. (1991) defined as Dionisio Blade Belt. It brings together all affected units by metamorphism and deformation during the Brasiliano (sensu Almeida et al. 1973) and magmatism in the same age range, which develops constituting a belt in southeastern Uruguay. Various supra crustal successions have been recognized in the Western domain of this belt in Uruguay, namely Fm. Zanja del Tigre (Sanchez-Bettucci 1998), Lavalleja Group (Bossi 1966), Arroyo del Soldado Group (Gaucher et al. 1996) and Formations Playa Hermosa (Masquelin and Sanchez Bettucci 1993) and Las Ventanas (Midot 1984), among others. The Group has been Lavalleja correlated with Porongos Group and the Brazilian Brusque Metamorphic Complex (Hasui et al. 1975; Silva and Dias 1981). This group has a granitic basement-probably associated gnéissico to Block Valentines (Preciozzi et al. 1979) and the Land Pavas, aged Paleoproterozoicas and Archean (Hartmann et al. 2001). It comprises varied lithologies, metasedimentary; metavolcanic acid; basic and metagabbros metavolcanic
[en] In this paper, we design and develop a new software tool that helps automatic lithofacies segmentation from geological data. Lithofacies is a crucial problem in reservoir characterization, and our study intends to prove that soft computing techniques like Wavelet transform modulus maxima lines (WTMM) and Detrended fluctuation analysis (DFA) approaches allow a geological lithology segmentation from differed well logging. On one hand, WTMM prove to be useful for delimitation of each layer. We based on his sensitivity on the presence of more then one layer, On the other hand, DFA is used to enhance the estimation if the roughness coefficient of each lithology. We use them jointly to segment the lithofacies of wells located in the Algerian Sahara. Obtained results are encouraging to publish this method, because the principal benefit is economic
[en] This research has been designed to contribute with Formacion Valle Chico knowledge, taking into account the alcaline type tectonic environment, geochronology, granitoid types, lithologies and mineralizations existing in the area. (author)