Extreme galactic wind and Wolf–Rayet features in infrared mergers and infrared quasi-stellar objects     

S. Lípari  †  R. Terlevich  ‡  R. J. Díaz  †  Y. Taniguchi  W. Zheng  †  Z. Tsvetanov  G. Carranza  H. Dottori 《Monthly notices of the Royal Astronomical Society》2003,340(1):289-303

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Effects of fracture lineaments and in-situ rock stresses on groundwater flow in hard rocks: a case study from Sunnfjord, western Norway     

Helge Henriksen  Alvar Braathen 《Hydrogeology Journal》2006,14(4):444-461

Systematic field mapping of fracture lineaments observed on aerial photographs shows that almost all of these structures are positively correlated with zones of high macroscopic and mesoscopic fracture frequencies compared with the surroundings. The lineaments are subdivided into zones with different characteristics: (1) a central zone with fault rocks, high fracture frequency and connectivity but commonly with mineral sealed fractures, and (2) a damage zone divided into a proximal zone with a high fracture frequency of lineament parallel, non-mineralized and interconnected fractures, grading into a distal zone with lower fracture frequencies and which is transitional to the surrounding areas with general background fracturing. To examine the possible relations between lineament architecture and in-situ rock stress on groundwater flow, the geological fieldwork was followed up by in-situ stress measurements and test boreholes at selected sites. Geophysical well logging added valuable information about fracture distribution and fracture flow at depths. Based on the studies of in-situ stresses as well as the lineaments and associated fracture systems presented above, two working hypotheses for groundwater flow were formulated: (i) In areas with a general background fracturing and in the distal zone of lineaments, groundwater flow will mainly occur along fractures parallel with the largest in-situ rock stress, unless fractures are critically loaded or reactivated as shear fractures at angles around 30° to σ_H; (ii) In the influence area of lineaments, the largest potential for groundwater abstraction is in the proximal zone, where there is a high fracture frequency and connectivity with negligible fracture fillings. The testing of the two hypotheses does not give a clear and unequivocal answer in support of the two assumptions about groundwater flow in the study area. But most of the observed data are in agreement with the predictions from the models, and can be explained by the action of the present stress field on pre-existing fractures.  相似文献   

Weights of Evidence Modeling of Mineral Potential: A Case Study Using Small Number of Prospects,Abra, Philippines   总被引：9，自引：1，他引：9  

Carranza  Emmanuel John M. 《Natural Resources Research》2004,13(3):173-187

Weights of evidence (WofE) modeling usually is applied to map mineral potential in areas with large number of deposits/prospects. In this paper, WofE modeling is applied to a case study area measuring about 920 km² with 12 known porphyry copper prospects. A pixel size of 100 m × 100 m was used in the spatial data analyses to represent in a raster-based GIS lateral extents of prospects and of geological features considered as spatial evidence. Predictor maps were created based on (a) estimates of studentized values of positive spatial association between prospects and spatial evidence; (b) proportion of number of prospects in zones where spatial evidence is present; and (c) geological interpretations of positive spatial association between prospects and spatial evidence. Uncertainty because of missing geochemical evidence is shown to have an influence on tests of assumption of conditional independence (CI) among predictor maps with respect to prospects. For the final predictive model, assumption of CI is rejected based on omnibus test but is accepted based on a new omnibus test. The final predictive model, which delineates 30% of study area as zones with potential for porphyry copper, has 83% success rate and 73% prediction rate. The results demonstrate plausibility of WofE modeling of mineral potential in large areas with small number of mineral prospects.  相似文献   

Data-Driven Predictive Modeling of Mineral Prospectivity Using Random Forests: A Case Study in Catanduanes Island (Philippines)     

Emmanuel John M. Carranza  Alice G. Laborte 《Natural Resources Research》2016,25(1):35-50

The Random Forests (RF) algorithm is a machine learning method that has recently been demonstrated as a viable technique for data-driven predictive modeling of mineral prospectivity, and thus, it is instructive to further examine its usefulness in this particular field. A case study was carried out using data from Catanduanes Island (Philippines) to investigate further (a) if RF modeling can be used for data-driven modeling of mineral prospectivity in areas with few (i.e., <20) mineral occurrences and (b) if RF modeling can handle predictor variables with missing values. We found that RF modeling outperforms evidential belief (EB) modeling of prospectivity for hydrothermal Au–Cu deposits in Catanduanes Island, where 17 hydrothermal Au–Cu prospects are known to exist. Moreover, just like EB modeling, RF modeling allows analysis of the spatial relationships between known prospects and individual layers of predictor data. Furthermore, RF modeling can handle missing values in predictor data through an RF-based imputation technique whereas in EB modeling, missing values are simply represented by maximum uncertainty. Therefore, the RF algorithm is a potentially useful method for data-driven predictive modeling of mineral prospectivity in regions with few (i.e., <20) occurrences of mineral deposits of the type sought. However, further testing of the method in other regions with few mineral occurrences is warranted to fully determine its usefulness in data-driven predictive modeling of mineral prospectivity.  相似文献   

Application of Discriminant Analysis and Support Vector Machine in Mapping Gold Potential Areas for Further Drilling in the Sari-Gunay Gold Deposit,NW Iran     

Hamid Geranian  Seyed Hassan Tabatabaei  Hooshang H. Asadi  Emmanuel John M. Carranza 《Natural Resources Research》2016,25(2):145-159

In this contribution, we used discriminant analysis (DA) and support vector machine (SVM) to model subsurface gold mineralization by using a combination of the surface soil geochemical anomalies and earlier bore data for further drilling at the Sari-Gunay gold deposit, NW Iran. Seventy percent of the data were used as the training data and the remaining 30 % were used as the testing data. Sum of the block grades, obtained by kriging, above the cutoff grade (0.5 g/t) was multiplied by the thickness of the blocks and used as productivity index (PI). Then, the PI variable was classified into three classes of background, medium, and high by using fractal method. Four classification functions of SVM and DA methods were calculated by the training soil geochemical data. Also, by using all the geochemical data and classification functions, the general extension of the gold mineralized zones was predicted. The mineral prediction models at the Sari-Gunay hill were used to locate high and moderate potential areas for further infill systematic and reconnaissance drilling, respectively. These models at Agh-Dagh hill and the area between Sari-Gunay and Agh-Dagh hills were used to define the moderate and high potential areas for further reconnaissance drilling. The results showed that the nu-SVM method with 73.8 % accuracy and c-SVM with 72.3 % accuracy worked better than DA methods.  相似文献   

Groundwater metering: revisiting a ubiquitous ‘best practice’     

Molle  François  Closas  Alvar 《Hydrogeology Journal》2021,29(5):1857-1870

Hydrogeology Journal - It is often taken for granted that metering is an unarguable ‘best practice’ when it comes to the quantitative management of groundwater resources. This paper...  相似文献   

Reply to discussion of Gabrielsen et al. (2010) by Nielsen et al. (this volume): Latest Caledonian to present tectonomorphological development of southern Norway     

Roy H. Gabrielsen  Jan Inge Faleide  Christophe Pascal  Alvar Braathen  Johan Petter Nystuen  Bernd Etzelmuller  Sejal O'Donnell 《Marine and Petroleum Geology》2010

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Deformation and metamorphism of Devonian rocks in the outer Solund area, western Norway: implications for models of Devonian deformation     

Brian A. Sturt †  Alvar Braathen 《International Journal of Earth Sciences》2001,90(2):270-286

Many modern accounts of the Devonian rocks of western Norway, which emphasise the extensional processes by which the basins were formed, tend to ignore or gloss over the deformation and metamorphism which these rocks have suffered during contractional deformation. The present account describes extensive ductile folding, penetrative cleavage formation and low-grade regional metamorphism developed in the Devonian strata of the outer Solund region. Although the deformation in this area is more intense than in other Devonian basins, it belongs to the same movement plan. It will also be shown that the Devonian rocks of the Scandinavian Caledonides apparently share a common tectonothermal development. This regional contractional event, conceptually, may relate either to a Mid-Late Devonian arc-continent collision, or to a transpressional strain regime.  相似文献   

Physico-chemical seasonal variability of a tropical estuary: major and minor elements in water and air     

L.?Rosales HozEmail author  A.?Carranza Edwards  P.?Carvajal Romero  C.?Mendez Jaime  M.?E.?Ruiz Santoyo 《Environmental Geology》2003,44(7):790-798

The lower reaches of the Coatzacoalcos River in southeast Mexico is an area of intense industrial development. The physico-chemical characteristics of the area have exhibited differences over the years. Apparently from the associated outcroppings of limestone in the Uxpanapa River Basin, the major elements that are dissolved show higher concentrations of Ca, Mg and HCO₃^– in the waters supplied by this river. The water in the Calzadas River contains high concentrations of Ca, SO₄ and HCO₃^– that are associated with the saline domes crossed by this river. Due to industrial discharges, the sulfate concentration is very high in the water and air during April. Nitrate concentration diminishes with salinity. Higher nitrate as well as nitrite and ammonia levels are present during flood season. Phosphate concentration, associated with high oxygen levels, is higher in January. Zn, Cu and Cr are higher during the dry season (April) when dilution is minimal and low levels of TOC are present. The smaller concentrations of Zn and Cu observed in January are associated with high TOC values in water. The lower levels of Cr present in August are associated with high amounts of suspended matter. Pajaritos Lagoon and Teapa-L, with large industrial discharges, have the highest nutrient and dissolved metal concentrations in the area. Air particles smaller than 2.5 m contain Fe, V, Ti, Cu, Zn, and high amounts of S. These anomalous concentrations of sulfates and metals are attributed to anthropogenic sources.  相似文献   

Knowledge-Driven and Data-Driven Fuzzy Models for Predictive Mineral Potential Mapping   总被引：5，自引：0，他引：5  

Porwal  Alok  Carranza  E. J. M.  Hale  M. 《Natural Resources Research》2003,12(1):1-25

In this paper, we describe new fuzzy models for predictive mineral potential mapping: (1) a knowledge-driven fuzzy model that uses a logistic membership function for deriving fuzzy membership values of input evidential maps and (2) a data-driven model, which uses a piecewise linear function based on quantified spatial associations between a set of evidential evidence features and a set of known mineral deposits for deriving fuzzy membership values of input evidential maps. We also describe a graphical defuzzification procedure for the interpretation of output fuzzy favorability maps. The models are demonstrated for mapping base metal deposit potential in an area in the south-central part of the Aravalli metallogenic province in the state of Rajasthan, western India. The data-driven and knowledge-driven models described in this paper predict potentially mineralized zones, which occupy less than 10% of the study area and contain at least 83% of the model and validation base metal deposits. A cross-validation of the favorability map derived from using one of the models with the favorability map derived from using the other model indicates a remarkable similarity in their results. Both models therefore are useful for predicting favorable zones to guide further exploration work.  相似文献