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12. Comparability of heavy mineral data – The first interlaboratory round robin test

Author

Dunkl, I, von Eynatten, H, Andò, S, Lünsdorf, K, Morton, A, Alexander, B, Aradi, L, Augustsson, C, Bahlburg, H, Barbarano, M, Benedictus, A, Berndt, J, Bitz, I, Boekhout, F, Breitfeld, T, Cascalho, J, Costa, P, Ekwenye, O, Fehér, K, Flores-Aqueveque, V, Führing, P, Giannini, P, Goetz, W, Guedes, C, Gyurica, G, Hennig-Breitfeld, J, Hülscher, J, Jafarzadeh, M, Jagodziński, R, Józsa, S, Kelemen, P, Keulen, N, Kovacic, M, Liebermann, C, Limonta, M, Lužar-Oberiter, B, Markovic, F, Melcher, F, Miklós, D, Moghalu, O, Mounteney, I, Nascimento, D, Novaković, T, Obbágy, G, Oehlke, M, Omma, J, Onuk, P, Passchier, S, Pfaff, K, Lincoñir, L, Power, M, Razum, I, Resentini, A, Sági, T, Salata, D, Salgueiro, R, Schönig, J, Sitnikova, M, Sternal, B, Szakmány, G, Szokaluk, M, Thamó-Bozsó, E, Tóth, Á, Tremblay, J, Verhaegen, J, Villaseñor, T, Wagreich, M, Wolf, A, Yoshida, K, Dunkl, István, von Eynatten, Hilmar, Andò, Sergio, Lünsdorf, Keno, Morton, Andrew, Alexander, Bruce, Aradi, László, Augustsson, Carita, Bahlburg, Heinrich, Barbarano, Marta, Benedictus, Aukje, Berndt, Jasper, Bitz, Irene, Boekhout, Flora, Breitfeld, Tim, Cascalho, João, Costa, Pedro J. M., Ekwenye, Ogechi, Fehér, Kristóf, Flores-Aqueveque, Valentina, Führing, Philipp, Giannini, Paulo, Goetz, Walter, Guedes, Carlos, Gyurica, György, Hennig-Breitfeld, Juliane, Hülscher, Julian, Jafarzadeh, Mahdi, Jagodziński, Robert, Józsa, Sándor, Kelemen, Péter, Keulen, Nynke, Kovacic, Marijan, Liebermann, Christof, Limonta, Mara, Lužar-Oberiter, Borna, Markovic, Frane, Melcher, Frank, Miklós, Dóra Georgina, Moghalu, Ogechukwu, Mounteney, Ian, Nascimento, Daniel, Novaković, Tea, Obbágy, Gabriella, Oehlke, Mathias, Omma, Jenny, Onuk, Peter, Passchier, Sandra, Pfaff, Katharina, Lincoñir, Luisa Pinto, Power, Matthew, Razum, Ivan, Resentini, Alberto, Sági, Tamás, Salata, Dorota, Salgueiro, Rute, Schönig, Jan, Sitnikova, Maria, Sternal, Beata, Szakmány, György, Szokaluk, Monika, Thamó-Bozsó, Edit, Tóth, Ágoston, Tremblay, Jonathan, Verhaegen, Jasper, Villaseñor, Tania, Wagreich, Michael, Wolf, Anna, Yoshida, Kohki, Dunkl, I, von Eynatten, H, Andò, S, Lünsdorf, K, Morton, A, Alexander, B, Aradi, L, Augustsson, C, Bahlburg, H, Barbarano, M, Benedictus, A, Berndt, J, Bitz, I, Boekhout, F, Breitfeld, T, Cascalho, J, Costa, P, Ekwenye, O, Fehér, K, Flores-Aqueveque, V, Führing, P, Giannini, P, Goetz, W, Guedes, C, Gyurica, G, Hennig-Breitfeld, J, Hülscher, J, Jafarzadeh, M, Jagodziński, R, Józsa, S, Kelemen, P, Keulen, N, Kovacic, M, Liebermann, C, Limonta, M, Lužar-Oberiter, B, Markovic, F, Melcher, F, Miklós, D, Moghalu, O, Mounteney, I, Nascimento, D, Novaković, T, Obbágy, G, Oehlke, M, Omma, J, Onuk, P, Passchier, S, Pfaff, K, Lincoñir, L, Power, M, Razum, I, Resentini, A, Sági, T, Salata, D, Salgueiro, R, Schönig, J, Sitnikova, M, Sternal, B, Szakmány, G, Szokaluk, M, Thamó-Bozsó, E, Tóth, Á, Tremblay, J, Verhaegen, J, Villaseñor, T, Wagreich, M, Wolf, A, Yoshida, K, Dunkl, István, von Eynatten, Hilmar, Andò, Sergio, Lünsdorf, Keno, Morton, Andrew, Alexander, Bruce, Aradi, László, Augustsson, Carita, Bahlburg, Heinrich, Barbarano, Marta, Benedictus, Aukje, Berndt, Jasper, Bitz, Irene, Boekhout, Flora, Breitfeld, Tim, Cascalho, João, Costa, Pedro J. M., Ekwenye, Ogechi, Fehér, Kristóf, Flores-Aqueveque, Valentina, Führing, Philipp, Giannini, Paulo, Goetz, Walter, Guedes, Carlos, Gyurica, György, Hennig-Breitfeld, Juliane, Hülscher, Julian, Jafarzadeh, Mahdi, Jagodziński, Robert, Józsa, Sándor, Kelemen, Péter, Keulen, Nynke, Kovacic, Marijan, Liebermann, Christof, Limonta, Mara, Lužar-Oberiter, Borna, Markovic, Frane, Melcher, Frank, Miklós, Dóra Georgina, Moghalu, Ogechukwu, Mounteney, Ian, Nascimento, Daniel, Novaković, Tea, Obbágy, Gabriella, Oehlke, Mathias, Omma, Jenny, Onuk, Peter, Passchier, Sandra, Pfaff, Katharina, Lincoñir, Luisa Pinto, Power, Matthew, Razum, Ivan, Resentini, Alberto, Sági, Tamás, Salata, Dorota, Salgueiro, Rute, Schönig, Jan, Sitnikova, Maria, Sternal, Beata, Szakmány, György, Szokaluk, Monika, Thamó-Bozsó, Edit, Tóth, Ágoston, Tremblay, Jonathan, Verhaegen, Jasper, Villaseñor, Tania, Wagreich, Michael, Wolf, Anna, and Yoshida, Kohki

Abstract

Heavy minerals are typically rare but important components of siliciclastic sediments and rocks. Their abundance, proportions, and variability carry valuable information on source rocks, climatic, environmental and transport conditions between source to sink, and diagenetic processes. They are important for practical purposes such as prospecting for mineral resources or the correlation and interpretation of geologic reservoirs. Despite the extensive use of heavy mineral analysis in sedimentary petrography and quite diverse methods for quantifying heavy mineral assemblages, there has never been a systematic comparison of results obtained by different methods and/or operators. This study provides the first interlaboratory test of heavy mineral analysis. Two synthetic heavy mineral samples were prepared with considerably contrasting compositions intended to resemble natural samples. The contributors were requested to provide (i) metadata describing methods, measurement conditions and experience of the operators and (ii) results tables with mineral species and grain counts. One hundred thirty analyses of the two samples were performed by 67 contributors, encompassing both classical microscopic analyses and data obtained by emerging automated techniques based on electron-beam chemical analysis or Raman spectroscopy. Because relatively low numbers of mineral counts (N) are typical for optical analyses while automated techniques allow for high N, the results vary considerably with respect to the Poisson uncertainty of the counting statistics. Therefore standard methods used in evaluation of round robin tests are not feasible. In our case the ‘true’ compositions of the test samples are not known. Three methods have been applied to determine possible reference values: (i) the initially measured weight percentages, (ii) calculation of grain percentages using estimates of grain volumes and densities, and (iii) the best-match average calculated from the most reliable analyses f

Published
2020

14. Sand-spits systems from Benguela region (SW Angola). An analysis of sediment sources and dispersal from textural and compositional data

Author

Dinis, P, Huvi, J, Cascalho, J, Garzanti, E, Vermeesch, P, Callapez, P, Dinis P. A., Huvi J., Cascalho J., Garzanti E., Vermeesch P., Callapez P., Dinis, P, Huvi, J, Cascalho, J, Garzanti, E, Vermeesch, P, Callapez, P, Dinis P. A., Huvi J., Cascalho J., Garzanti E., Vermeesch P., and Callapez P.

Abstract

Sand spits are important coastline features in western Angola, but only limited knowledge on their recent evolution and sediment sources were obtained so far. The present study is focused on the Baía Farta and Lobito sand spits of coastal Benguela that develop to the north (i.e. downdrift) of the Coporolo and Catumbela river outlets. We used grain-size distributions, heavy-mineral suites and clay-mineral assemblages of sediments in the Coporolo-Baía Farta and Catumbela-Lobito coastal stretches to characterize the main depositional units and investigate sediment provenance. From the combined grain-size and mineralogical variability in mud and sand samples it is possible to infer sediment sources and dispersal in the two coastal stretches. Kaolinite is mainly derived from the Angola hinterland, and is particularly common in finer grained floodplain sediments from the Catumbela River. Expansive clays (smectite and illite-smectite mixed layers) are inferred to be mainly sourced by Meso-Cenozoic units of the Benguela Basin, being abundant in coarser grained fluvial deposits and in lagoonal deposits near Baía Farta. Sand supplied by the sedimentary units from Benguela Basin and their basement rocks tends to be enriched in epidote associated with blue-green hornblende. The Coporolo River sand is progressively diluted during the longshore northward transport by sand supplied by coastal units. Conversely, beach deposits in the Catumbela-Lobito coastal stretch are mainly sourced by the Catumbela River. A divergent longshore transport from Catumbela river-mouth occurs at Catumbela delta. Sand spit morphology and evolution reflect the patterns of dispersal of bedload and suspended load in settings of contrasting orography and human influence.

Published
2016

18. Evaluation of suspended sediment in a fetch limited beach using optical backscatter sensors: particle size effects

Author

Ribeiro, M., Cascalho, J., Taborda, R., Anabela Oliveira, Freire, P., and Rodrigues, A.

Subjects
Obs, Suspended sediment, Particle size
Abstract

This study is addressed to the evaluation of the suspended sediment concentration in a fetch limited beach (Alfeite Beach) using optical backscatter sensors (OBS) appraising, simultaneously, sensor response to the physical characteristics of suspended particles. In order to achieve these objectives two OBS sensors, deployed at the intertidal zone of Alfeite Beach, measured sediment concentration during a tidal cycle. Sensor output was calibrated with local bottom and suspended sediments (collected with Niskin bottles). Results show that concentration of suspended sediments is highly dependent on particle size and put in evidence the importance of sensor calibration using real suspended sediments 10 4 p DHA/NEC 2010 21-22 de Junho de 2010

Published
2010

19. An efficient implementation of geometric semantic genetic programming for anticoagulation level prediction in pharmacogenetics

Author

Correia, L, Reis, LP, Cascalho, J, Castelli, M, Castaldi, D, Giordani, I, DIAS PEREIRA SA DA SILVA, S, Vanneschi, L, Archetti, F, Maccagnola, D, CASTELLI, MAURO, CASTALDI, DAVIDE FABIO, GIORDANI, ILARIA, DIAS PEREIRA SA DA SILVA, SARA, VANNESCHI, LEONARDO, ARCHETTI, FRANCESCO ANTONIO, MACCAGNOLA, DANIELE, Correia, L, Reis, LP, Cascalho, J, Castelli, M, Castaldi, D, Giordani, I, DIAS PEREIRA SA DA SILVA, S, Vanneschi, L, Archetti, F, Maccagnola, D, CASTELLI, MAURO, CASTALDI, DAVIDE FABIO, GIORDANI, ILARIA, DIAS PEREIRA SA DA SILVA, SARA, VANNESCHI, LEONARDO, ARCHETTI, FRANCESCO ANTONIO, and MACCAGNOLA, DANIELE

Abstract

The purpose of this study is to develop an innovative system for Coumarin-derived drug dosing, suitable for elderly patients. Recent research highlights that the pharmacological response of the patient is often affected by many exogenous factors other than the dosage prescribed and these factors could form a very complex relationship with the drug dosage. For this reason, new powerful computational tools are needed for approaching this problem. The system we propose is called Geometric Semantic Genetic Programming, and it is based on the use of recently defined geometric semantic genetic operators. In this paper, we present a new implementation of this Genetic Programming system, that allow us to use it for real-life applications in an efficient way, something that was impossible using the original definition. Experimental results show the suitability of the proposed system for managing anticoagulation therapy. In particular, results obtained with Geometric Semantic Genetic Programming are significantly better than the ones produced by standard Genetic Programming both on training and on out-of-sample test data. © 2013 Springer-Verlag.

Published
2013

20. The application of microtextural and heavy mineral analysis to discriminate between storm and tsunami deposits

Author

Costa, Pedro J. M., Gelfenbaum, G., Dawson, S., La Selle, S., Milne, F., Cascalho, J., Lira, C. Ponte, Andrade, C., Freitas, M. C., and Jaffe, B.

Abstract

Recent work has applied microtextural and heavy mineral analyses to sandy storm and tsunami deposits from Portugal, Scotland, Indonesia and the USA. We looked at the interpretation of microtextural imagery (scanning electron microscopy) of quartz grains and heavy mineral compositions. We consider inundation events of different chronologies and sources (the AD 1755 Lisbon and 2004 Indian Ocean tsunamis, the Great Storm of 11 January 2005 in Scotland, and Hurricane Sandy in 2012) that affected contrasting coastal and hinterland settings with different regional oceanographic conditions. Storm and tsunami deposits were examined along with potential source sediments (alluvial, beach, dune and nearshore sediments) to determine provenance.Results suggest that tsunami deposits typically exhibit a significant spatial variation in grain sizes, microtextures and heavy minerals. Storm deposits show less variability, especially in vertical profiles. Tsunami and storm quartz grains had more percussion marks and fresh surfaces compared to potential source material. Moreover, in the studied cases, tsunami samples had fewer fresh surfaces than storm deposits.Heavy mineral assemblages are typically site-specific. The concentration of heavy minerals decreases upwards in tsunamigenic units, whereas storm sediments show cyclic concentrations of heavy minerals, reflected in the laminations observed macroscopically in the deposits.

Published
2018
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21. Emplazamiento de algunas estructuras submarinas relacionadas con la tectónica salina y la expulsión de gases en el talud superior y medio del Golfo de Cádiz

Author

Freitas, M.C., Cascalho, J., Taborda, R., Ribeiro, M., Drago, T., Andrade, C., Fatela, F., Cruces, A., Díaz-del-Río-Español, Víctor, Fernández-Salas, L.M., Bruque-Carmona, Gerardo, López-Rodríguez, Francisco José, Rueda, José Luis, Vázquez, Juan Tomás, López-González, Nieves, González-García, Emilio, Palomino, Desirée, Sánchez-Guillamón, Olga, Oporto, Tatiana, Rittierott, Cinja, Rodríguez-Polo, Silvia, Goicoechea, M., Gutiérrez, D., Monroy, F.J., Freitas, M.C., Cascalho, J., Taborda, R., Ribeiro, M., Drago, T., Andrade, C., Fatela, F., Cruces, A., Díaz-del-Río-Español, Víctor, Fernández-Salas, L.M., Bruque-Carmona, Gerardo, López-Rodríguez, Francisco José, Rueda, José Luis, Vázquez, Juan Tomás, López-González, Nieves, González-García, Emilio, Palomino, Desirée, Sánchez-Guillamón, Olga, Oporto, Tatiana, Rittierott, Cinja, Rodríguez-Polo, Silvia, Goicoechea, M., Gutiérrez, D., and Monroy, F.J.

Published
2012

22. Biodiversity and geodiversity in the mud volcano field of the Spanish margin (Gulf of Cádiz)

Author

Freitas, M.C., Cascalho, J., Taborda, R., Ribeiro, M., Drago, T., Andrade, C., Fatela, F., Cruces, A., Rueda, José Luis, González-García, Emilio, Marina-Ureña, Pablo, Oporto, Tatiana, Rittierott, Cinja, López-González, Nieves, Farias, Carlos, Moreira, Juan, López, E., Megina, César, López-González, Pablo José, García-Raso, José Enrique, Gofas, Serge, Salas, C., Bruque-Carmona, Gerardo, López-Rodríguez, Francisco José, Vázquez, Juan Tomás, Fernández-Salas, L.M., Díaz-del-Río-Español, Víctor, Freitas, M.C., Cascalho, J., Taborda, R., Ribeiro, M., Drago, T., Andrade, C., Fatela, F., Cruces, A., Rueda, José Luis, González-García, Emilio, Marina-Ureña, Pablo, Oporto, Tatiana, Rittierott, Cinja, López-González, Nieves, Farias, Carlos, Moreira, Juan, López, E., Megina, César, López-González, Pablo José, García-Raso, José Enrique, Gofas, Serge, Salas, C., Bruque-Carmona, Gerardo, López-Rodríguez, Francisco José, Vázquez, Juan Tomás, Fernández-Salas, L.M., and Díaz-del-Río-Español, Víctor

Published
2012

23. Some evidences of northward fine sediment transport in the northern Portuguese continental shelf

Author

Drago, T, Oliveira, A, Magalhaes, F, Cascalho, J, Jouanneau, Jm, Vitorino, Joao, Drago, T, Oliveira, A, Magalhaes, F, Cascalho, J, Jouanneau, Jm, and Vitorino, Joao

Abstract

On the basis of sedimentological and oceanographical data, a transport scheme for fine-grained material is proposed in order to explain the location of a muddy deposit present in the northern Portuguese continental shelf, north-west off the Douro River mouth. This mid-shelf deposit is recent, active and its main source is apparently the Douro River. The sediment supply can be related with the oceanographic conditions in winter regime, characterised by a poleward along shelf current with a bottom westward component, as a consequence of a south-west wind. The resulting fine sediment transport, essentially made in the bottom nepheloid layer is believed to have a north-west direction., Un schéma de circulation des sédiments fins, sur le plateau continental au nord du Portugal, a été établi à partir de données sédimentologiques et océanographiques. Il explique la présence d'une vasière située au nord-ouest de l'embouchure du Douro; ce dépôt récent et actif proviendrait essentiellement du fleuve. L'apport de sédiment est lié aux conditions hydrologiques hivernales, caractérisées par un courant dirigé vers le nord le long du plateau continental avec, au fond, une composante vers l'ouest due au vent du sud-ouest. Il en résulte que le transport des sédiments fins se fait principalement dans la couche néphéloïde de fond, en direction du nord-ouest.

Published
1998
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34. Comparability of heavy mineral data – The first interlaboratory round robin test

Author

Tea Novaković, Dorota Salata, Monika Szokaluk, Aukje Benedictus, Jasper Berndt, Rute Salgueiro, Keno Lünsdorf, György Szakmány, Flora Boekhout, Jan Schönig, Gabriella Obbágy, Katharina Pfaff, Jasper Verhaegen, Juliane Hennig-Breitfeld, João Cascalho, Walter Goetz, Borna Lužar-Oberiter, Julian Hülscher, Mara Limonta, Pedro Costa, Mahdi Jafarzadeh, Michael Wagreich, Mathias Oehlke, Edit Thamó-Bozsó, Kohki Yoshida, Christof Liebermann, Philipp Führing, Valentina Flores-Aqueveque, Frank Melcher, Ian Mounteney, Nynke Keulen, Ivan Razum, O.C. Ekwenye, Sandra Passchier, Tamás Sági, Anna Wolf, Matthew Power, Irene Bitz, Ogechukwu Moghalu, Peter Onuk, Sergio Andò, Robert Jagodziński, Ágoston Tóth, Carlos Conforti Ferreira Guedes, Dóra Georgina Miklós, Kristóf Fehér, Frane Marković, Tania Villaseñor, Carita Augustsson, Maria Sitnikova, Tim Breitfeld, Marta Barbarano, Heinrich Bahlburg, László Előd Aradi, Jonathan Tremblay, Jenny Omma, Hilmar von Eynatten, Bruce D. Alexander, Andrew C. Morton, Beata Sternal, Sándor Józsa, Daniel Rodrigues do Nascimento, Alberto Resentini, Paulo César Fonseca Giannini, Peter B. Kelemen, Marijan Kovačić, György Gyurica, István Dunkl, Luisa Pinto Lincoñir, Dunkl, I, von Eynatten, H, Andò, S, Lünsdorf, K, Morton, A, Alexander, B, Aradi, L, Augustsson, C, Bahlburg, H, Barbarano, M, Benedictus, A, Berndt, J, Bitz, I, Boekhout, F, Breitfeld, T, Cascalho, J, Costa, P, Ekwenye, O, Fehér, K, Flores-Aqueveque, V, Führing, P, Giannini, P, Goetz, W, Guedes, C, Gyurica, G, Hennig-Breitfeld, J, Hülscher, J, Jafarzadeh, M, Jagodziński, R, Józsa, S, Kelemen, P, Keulen, N, Kovacic, M, Liebermann, C, Limonta, M, Lužar-Oberiter, B, Markovic, F, Melcher, F, Miklós, D, Moghalu, O, Mounteney, I, Nascimento, D, Novaković, T, Obbágy, G, Oehlke, M, Omma, J, Onuk, P, Passchier, S, Pfaff, K, Lincoñir, L, Power, M, Razum, I, Resentini, A, Sági, T, Salata, D, Salgueiro, R, Schönig, J, Sitnikova, M, Sternal, B, Szakmány, G, Szokaluk, M, Thamó-Bozsó, E, Tóth, Á, Tremblay, J, Verhaegen, J, Villaseñor, T, Wagreich, M, Wolf, A, and Yoshida, K

Subjects
Provenance, 010504 meteorology & atmospheric sciences, Análise de dados, provenance, 010502 geochemistry & geophysics, Poisson distribution, 01 natural sciences, symbols.namesake, Minerais pesados, Statistics, SEM-EDX, Range (statistics), Prospecting, 0105 earth and related environmental sciences, Mathematics, interlaboratory comparison, Heavy mineral, Heavy mineral analysis, Raman spectroscopy, Interlaboratory comparison, Comparability, Heavy-mineral analysis, Provenance, SEM-EDX, Raman spectroscopy, Interlaboratory comparison, Mineral resource classification, heavy mineral analysis, symbols, General Earth and Planetary Sciences, Round robin test, Espectroscopia Raman
Abstract

Heavy minerals are typically rare but important components of siliciclastic sediments and rocks. Their abundance, proportions, and variability carry valuable information on source rocks, climatic, environmental and transport conditions between source to sink, and diagenetic processes. They are important for practical purposes such as prospecting for mineral resources or the correlation and interpretation of geologic reservoirs. Despite the extensive use of heavy mineral analysis in sedimentary petrography and quite diverse methods for quantifying heavy mineral assemblages, there has never been a systematic comparison of results obtained by different methods and/or operators. This study provides the first interlaboratory test of heavy mineral analysis. Two synthetic heavy mineral samples were prepared with considerably contrasting compositions intended to resemble natural samples. The contributors were requested to provide (i) metadata describing methods, measurement conditions and experience of the operators and (ii) results tables with mineral species and grain counts. One hundred thirty analyses of the two samples were performed by 67 contributors, encompassing both classical microscopic analyses and data obtained by emerging automated techniques based on electron-beam chemical analysis or Raman spectroscopy. Because relatively low numbers of mineral counts (N) are typical for optical analyses while automated techniques allow for high N, the results vary considerably with respect to the Poisson uncertainty of the counting statistics. Therefore, standard methods used in evaluation of round robin tests are not feasible. In our case the 'true' compositions of the test samples are not known. Three methods have been applied to determine possible reference values: (i) the initially measured weight percentages, (ii) calculation of grain percentages using estimates of grain volumes and densities, and (iii) the best-match average calculated from the most reliable analyses following multiple, pragmatic and robust criteria. The range of these three values is taken as best approximation of the 'true' composition. The reported grain percentages were evaluated according to (i) their overall scatter relative to the most likely composition, (ii) the number of identified components that were part of the test samples, (iii) the total amount of mistakenly identified mineral grains that were actually not added to the samples, and (iv) the number of major components, which match the reference values with 95% confidence. Results indicate that the overall comparability of the analyses is reasonable. However, there are several issues with respect to methods and/or operators. Optical methods yield the poorest results with respect to the scatter of the data. This, however, is not considered inherent to the method as demonstrated by a significant number of optical analyses fulfilling the criteria for the best-match average. Training of the operators is thus considered paramount for optical analyses. Electron-beam methods yield satisfactory results, but problems in the identification of polymorphs and the discrimination of chain silicates are evident. Labs refining their electron-beam results by optical analysis practically tackle this issue. Raman methods yield the best results as indicated by the highest number of major components correctly quantified with 95% confidence and the fact that all laboratories and operators fulfil the criteria for the best-match average. However, a number of problems must be solved before the full potential of the automated high-throughput techniques in heavy mineral analysis can be achieved. info:eu-repo/semantics/publishedVersion

Published
2020

35. Sand-spits systems from Benguela region (SW Angola). An analysis of sediment sources and dispersal from textural and compositional data

Author

Eduardo Garzanti, Pedro M. Callapez, João Huvi, João Cascalho, Pedro Dinis, Pieter Vermeesch, Dinis, P, Huvi, J, Cascalho, J, Garzanti, E, Vermeesch, P, and Callapez, P

Subjects
Provenance, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Floodplain, Geochemistry, Fluvial, Sediment, Heavy mineral, Geology, Grain-size distribution, 010502 geochemistry & geophysics, Coastal Angola, 01 natural sciences, Sedimentary depositional environment, Longshore drift, Sand spits, Sedimentary rock, Suspended load, Clay mineral, Geomorphology, 0105 earth and related environmental sciences, Earth-Surface Processes
Abstract

Sand spits are important coastline features in western Angola, but only limited knowledge on their recent evolution and sediment sources were obtained so far. The present study is focused on the Baia Farta and Lobito sand spits of coastal Benguela that develop to the north (i.e. downdrift) of the Coporolo and Catumbela river outlets. We used grain-size distributions, heavy-mineral suites and clay-mineral assemblages of sediments in the Coporolo-Baia Farta and Catumbela-Lobito coastal stretches to characterize the main depositional units and investigate sediment provenance. From the combined grain-size and mineralogical variability in mud and sand samples it is possible to infer sediment sources and dispersal in the two coastal stretches. Kaolinite is mainly derived from the Angola hinterland, and is particularly common in finer grained floodplain sediments from the Catumbela River. Expansive clays (smectite and illite-smectite mixed layers) are inferred to be mainly sourced by Meso-Cenozoic units of the Benguela Basin, being abundant in coarser grained fluvial deposits and in lagoonal deposits near Baia Farta. Sand supplied by the sedimentary units from Benguela Basin and their basement rocks tends to be enriched in epidote associated with blue–green hornblende. The Coporolo River sand is progressively diluted during the longshore northward transport by sand supplied by coastal units. Conversely, beach deposits in the Catumbela-Lobito coastal stretch are mainly sourced by the Catumbela River. A divergent longshore transport from Catumbela river-mouth occurs at Catumbela delta. Sand spit morphology and evolution reflect the patterns of dispersal of bedload and suspended load in settings of contrasting orography and human influence.

Published
2016

36. Clustering and Selecting Categorical Features

Author

Mário A. T. Figueiredo, Margarida G. M. S. Cardoso, Cláudia Marisa Vasconcelos Silvestre, and Correia, L., Reis, L. P., and Cascalho, J.

Subjects
business.industry, Computer science, Pattern recognition, Feature selection, computer.software_genre, Class (biology), Synthetic data, Categorical variables, Task (computing), Cluster analysis, Finite mixtures models, Expectation–maximization algorithm, Multinomial distribution, Artificial intelligence, Data mining, EM algorithm, business, computer, Categorical variable
Abstract

In data clustering, the problem of selecting the subset of most relevant features from the data has been an active research topic. Feature selection for clustering is a challenging task due to the absence of class labels for guiding the search for relevant features. Most methods proposed for this goal are focused on numerical data. In this work, we propose an approach for clustering and selecting categorical features simultaneously. We assume that the data originate from a finite mixture of multinomial distributions and implement an integrated expectation-maximization (EM) algorithm that estimates all the parameters of the model and selects the subset of relevant features simultaneously. The results obtained on synthetic data illustrate the performance of the proposed approach. An application to real data, referred to official statistics, shows its usefulness. info:eu-repo/semantics/acceptedVersion

Published
2013

37. Emplazamiento de algunas estructuras submarinas relacionadas con la tectónica salina y la expulsión de gases en el talud superior y medio del Golfo de Cádiz

Author

Díaz-del-Río-Español, V. (Víctor), Fernández-Salas, L.M. (Luis Miguel), Bruque-Carmona, G. (Gerardo), López-Rodríguez, F.J. (Francisco José), Rueda, J.L. (José Luis), Vázquez, J.T. (Juan Tomás), López-González, N. (Nieves), González-García, E. (Emilio), Palomino, D. (Desirée), Sánchez-Guillamón, O. (Olga), Oporto, T. (Tatiana), Rittierott, C. (Cinja), Rodríguez-Polo, S. (Silvia), Goicoechea, M., Gutiérrez, D., Monroy, F.J., Freitas, M.C., Cascalho, J., Taborda, R., Ribeiro, M., Drago, T., Andrade, C., Fatela, F., and Cruces, A.

Published
2012

38. Biodiversity and geodiversity in the mud volcano field of the Spanish margin (Gulf of Cádiz)

Author

Rueda, J.L. (José Luis), González-García, E. (Emilio), Marina-Ureña, P. (Pablo), Oporto, T. (Tatiana), Rittierott, C. (Cinja), López-González, N. (Nieves), Farias, C. (Carlos), Moreira, J. (Juan), López, E., Megina, C. (César), López-González, P.J. (Pablo José), García-Raso, J.E. (José Enrique), Gofas, S. (Serge), Salas, C., Bruque-Carmona, G. (Gerardo), López-Rodríguez, F.J. (Francisco José), Vázquez, J.T. (Juan Tomás), Fernández-Salas, L.M. (Luis Miguel), Díaz-del-Río-Español, V. (Víctor), Freitas, M.C., Cascalho, J., Taborda, R., Ribeiro, M., Drago, T., Andrade, C., Fatela, F., and Cruces, A.

Subjects
Centro Oceanográfico de Málaga, Medio Marino
Published
2012

39. Vulcano: A new robotic challenge for legged robots.

Author

Domingos M, Pedro F, Ramos A, Funk MG, Mendes A, and Cascalho J

Abstract

The Vulcano challenge is a new and innovative robotic challenge for legged robots in a physical and simulated scenario of a volcanic eruption. In this scenario, robots must climb a volcano's escarpment and collect data from areas with high temperatures and toxic gases. This paper presents the main idea behind this challenge, with a detailed description of the simulated and physical scenario of the volcano ramp, the rules proposed for the competition, and the conception of a robot prototype, Vulcano , used in the competition. Finally, it discusses the performance of teams invited to participate in the challenge in the context of Azorean Robotics Open, the Azoresbot 2022. This first test for this challenge provided insights into what the participants found exciting and positive and what they found less positive., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Domingos, Pedro, Ramos, Funk, Mendes and Cascalho.)

Published
2023
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40. Major and minor element geochemistry of deep-sea sediments in the Azores Platform and southern seamount region.

Author

Palma C, Oliveira A, Valença M, Cascalho J, Pereira E, Lillebø AI, Duarte AC, and Pinto de Abreu M

Subjects
Azores, Seawater chemistry, Environmental Monitoring, Geologic Sediments chemistry, Trace Elements analysis, Water Pollutants, Chemical analysis
Abstract

The Azores Platform and the Irving and Great Meteor seamounts south of the archipelago (38°N-29°N) have rarely been studied geochemically, a fact which is surprising given that they represent the south-eastern limit of region V outlined in the Convention for the Protection of the Marine Environment of the North-East Atlantic (OSPAR Convention). The main aim of the present work was therefore to characterise the spatial variability of major and minor elements in deep-sea sediment cores from these two regions. XRD and geochemical analyses revealed that whereas the Azores Platform sediments are composed of a mixture of biogenic and detrital volcanic material, those at the seamounts are characterised by carbonated biogenic remains. The latter sediments were found to contain very low amounts of volcanic or hydrothermal detrital material, being almost entirely comprised of CaCO3 (more than 80%)., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Published
2013
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