POPE FOR AN HOUR: MARC CAMPENY

Title: The Catanda extrusive carbonatites (Kwanza Sul, Angola): an example of explosive carbonatitic volcanism

Lecturer: Marc Campeny

Date: Wednesday June the 4th 2014, 12.00h

Place: room 4

Abstract: Carbonatite lavas and pyroclastic rocks are exposed in the volcanic graben of Catanda and represent the only known example of extrusive carbonatites in Angola. A new detailed geological map of the area is presented in this study as well as six different stratigraphic sections. Pyroclastic rocks, apparently unwelded, are dominant in the area and represented in all the stratigraphic columns. They form shallowly to moderately inclined layers, mostly devoid of internal structures, that range in thickness from several centimetres to metres. They are dominantly lapilli tuffs and minor tuffs occasionally comprising pelletal lapilli. Based on their different features and field relationships, at least five different pyroclastic lithofacies have been distinguished in the area. Carbonatitic lavas outcrop in the external parts of the Catanda graben, forming coherent layers interbedded with pyroclastic rocks. Calcite is the most common mineral in the lavas, but other accessory minerals such as fluorapatite, titaniferous magnetite, phlogopite; pyrochlore, baddeleyite, monticellite, perovskite, cuspidine and periclase have also been identified. At least four different types of lavas have been distinguished based on their mineral associations and textural features. This study reveals an overall abundance of pyroclastic material in comparison to lava flows in the Catanda area, suggesting that eruptive processes were dominated by explosive activity similar to what has been described in other carbonatite and kimberlite localities. The Catanda carbonatitic volcanism was associated with monogenetic volcanic edifices with tuff ring or maar morphologies, and at least seven possible eruptive centres have been identified in the area.

For further information: Campeny, M., Mangas, J., Melgarejo, J.C., Bambi, A., Alfonso, P., Gernon, T., Manuel, J. (2014): The Catanda extrusive carbonatites (Kwanza Sul, Angola): an example of explosive carbonatitic volcanism. Bulletin of Volcanology, 76, 818-833

Pope for an hour are talks given by student members of the Barcelona SGA Student Chapter about their recently published research in SCI journals. These talks are adressed to other undergraduate or graduate students as well as to the rest of the scientific community.

TALKS BY PROF. J. RICHARD KYLE

Lecturer: Prof. J. Richard Kyle, C. E. Yager Professor of Geology, Department of Geological Sciences, Jackson School of Geosciences, The University of Texas at Austin. 2275 Speedway, C9000 Austin, Texas 78712-0254. E-mail: Esta dirección de correo electrónico está siendo protegida contra los robots de spam. Necesita tener JavaScript habilitado para poder verlo. . Webpage:  https://www.jsg.utexas.edu/researcher/richard_kyle/

Date: Monday May the 19th 2014, 15.00-17:00h.

Place: room 4

TALK 1 (15:00-16:00h)

Title:  High Resolution X-ray Computed Tomography Studies for Geological Materials: Emphasis on Contributions to Gold Ore Genesis and Processing

Abstract: High resolution X-ray computed tomography (CT) is the industrial equivalent of medical CAT scanning and provides a mechanism for non-destructive studies of the three-dimensional nature of geological materials.  HRXCT produces two-dimensional images ("slices") that reveal the interior of an object as if it had been sliced open along the image plane for viewing. A CT image is generated by differences in X-ray absorption that arise principally from differences in density within the object.  By acquiring a contiguous set of slices, a density map for all or part of a sample volume can be obtained, allowing three-dimensional inspection and measurement of features of interest. 

CT is particularly effective in the study of metallic ores that commonly contain minerals spanning the range of densities of natural materials. Available software can produce grain shape, size, and orientation data from the scanned volume, which can be particularly useful for oriented samples.  CT precisely defines the in-situ location of mineral grains of interest within a sample, which then can be studied in conventional petrographic sections, and other forms of data collected, e.g. isotope or trace element geochemistry.

This talk will review CT principles and diverse applications in geological sciences, with emphasis on ore deposits genetic and applied studies (Kyle et al., 2008; Kyle and Ketcham, in press). Emphasis will be placed on instrumentation, scanning protocols, and studies conducted at the High Resolution X-ray Computed Tomography facility at the University of Texas at Austin http://www.ctlab.geo.utexas.edu

For further information: Kyle, J.R., Mote, A.S., Ketcham, R.A. (2008): High resolution X-ray computed tomography studies of Grasberg porphyry Cu-Au ores, Papua, Indonesia. Mineralium Deposita, 43, 519-532.

TALK 2 (16:00-17:00h)

Title: Giant Pliocene porphyry-skarn Cu-Au deposits, Ertsberg District, Papua, Indonesia: Exploration, production and research in a challenging environment

Abstract: The Ertsberg-Grasberg district in Papua, Indonesia, hosts two giant porphyry and skarn-hosted Cu-Au systems that formed between 3.3 and 2.5 Ma in the Central Range that forms the Highlands of western New Guinea. These Cu-Au systems are associated with two dioritic intrusions, the Grasberg Igneous Complex and the Ertsberg Intrusive Complex, that were emplaced into a deformed sedimentary sequence of Cenozoic carbonate and late Mesozoic siliciclastic strata. Economic mineralization in each of these systems is vertically continuous over at least 1,500 m. Current original ore in place estimations (Leys et al., 2013) indicate that Grasberg-related system contains 7.5 Gt grading 0.70% Cu and 0.64 ppm Au in two deposits, the Grasberg porphyry system and the Kucing Liar skarn. The Ertsberg-related system contains 3.6 Gt grading 0.60% Cu and 0.44 ppm Au in four skarn deposits, the Ertsberg, the Ertsberg East Skarn System, the Dom, and the Big Gossan. All of these deposits represent hypogene mineral concentrations with high complementary gold values, anomalous aspects that makes this district one of the world’s great mineral districts.

This talk will present an overview of the University of Texas at Austin’s long term research in the Ertsberg-Grasberg district, with emphasis on the stockwork and skarn mineralization of the Ertsberg Intrusive Complex.   The challenges to exploration, mining, and research forms an appropriate context to review the region’s geologic, tectonic, and mineralization history.

Biografical summary: Rich Kyle is the C. E. Yager Professor of Geology at the University of Texas at Austin.  Most of his career has focused on strata-controlled metal and industrial mineral resources in sedimentary terranes. Dr. Kyle has conducted field work in more than 40 countries and has supervised more than 50 graduate and post-doctoral students on diverse research projects ranging from sedimentary basins at near surface to deep burial conditions, as well as the interactions of magmatic hydrothermal systems with reactive wallrocks.  He promotes the importance of field experience to complement the traditional classroom education and has led more than 40 major field trips for students, societies, and companies, including last week to Finland and Sweden.

Dr. Kyle’s current interests include the application of high resolution X-ray computed tomography to ore deposit studies, microbial involvement in geological processes, and the role of stratigraphic inheritance in controlling stratabound mineralization.  He has been active in several professional resource geology organizations, particularly the Society of Economic Geologists, for whom he served as an Associate Editor for Economic Geology, as well as the Thayer Lindsley Lecturer.  Dr. Kyle was the Editor-in-Chief for Ore Geology Reviews from 1990 to 2002.   

X RAY IMAGE ANALYSIS: WORK STRATEGY AND APPLICATIONS

Title:  X Ray analysis: work strategy and applications (Análisis de imágenes de Rayos X: estrategia de trabajo y aplicaciones).

Lecturer: Prof. Antonio García Casco. Dept. de Mineralogía y Petrología - Instituto Andaluz de Ciencias de la Tierra, Facultad de Ciencias (Universidad de Granada, Spain).

Date: Tuesday April the 22nd 2014, 12.00h.

Place: room 4

Abstract: In this talk I shall highlight the merits of X-ray mapping for deciphering the nature of geological (and other) materials and processes. X-ray maps are two dimensional images that describe the distribution (concentration) of elements in an area. They are obtained with electron microscopes on polished areas of samples, which are scanned (beam or stage scanning) for a number of element signals (EDS or WDS) at a time, normally concentrated in major and minor amounts, but trace elements can be also scanned under special machine settings. The raw data can be transformed into quantitative (e.g., wt% element, wt% oxide, atoms per formula unit,…) using internal standards and calibration procedures. The processing of a set of images resembles multispectral analysis of an area, and includes image (matrix) manipulation by means of any mathematical operation/function and treatment for mineral identification, mineral abundance, textural-chemical analysis, mineral composition variation (mineral zonation), element distribution along profiles, binary, ternary or quaternary plotting, etc. Since the images are positioned in absolute X-Y space (stage scanning), they are also useful for planning the analytical strategy of particular points/areas of the objects with the microprobe or other instruments (e.g., LA-ICP-MS). Collecting X-ray maps of an area is time-consuming (several hours or tens of hours), but 2D element maps are invaluable for showing details of phase composition in textural/structural/fabric context which are normally non-appreciated in qualitative optical, BSE, or secondary electron images. The information contained in a full set of X-ray element images of an area is vast and can be extracted after appropriate processing. Hence, this technique has become a necessary tool for providing quantitative information for deciphering phase assemblage (i.e., rock) evolution in space and time.

More info: http://www.ugr.es/~agcasco/personal/ >> Imágenes de RX

Biografical summary:

Antonio García Casco, Ph.D. 1993 (University of Granada), is full Professor of Petrology and Geochemistry at the University of Granada. His main research interest are metamorphic geology, phase equilibria, P-T-t paths and experimental petrology, with applications to the geodynamic evolution of plate margins (mostly in the Betics, Variscian and Caribbean belts). He has led several research projects in the Caribbean region. More information available at http://www.ugr.es/~agcasco/personal.

 

Calçotada 2014

Last Saturday March 9th 2014, a group of members of the BCN SGA-Student Chapter spent the day together celebrating a “calçotada” in a picnic area near Vallvidrera. We ate “calçots” - a late-winter vegetable typically eaten in Catalonia - grilled meat and “botifarra” and also some sweets. It was a great opportunity to have a nice day chatting and playing, out of our everyday routine. 

Geological side of High Tech Metals

In connection with the exhibition about Hight Tech Materials held at our Faculty, the BCN_SGA Student Chapter organizes this activity on Wednesday February the 12th. It will consist of several talks devoted to a better understanding of the geological side of these materials.

The activity is thought as a plain explanation of the importance of these elements and materials as essential for our society. The geological setting of convencional and non-convencional deposits will be introduced. The activity will close with a promising debate entitled Mining YES/NO.   

Talk by José María González: ORIGINS OF PLATINUM-GROUP MINERALS IN UPPER MANTLE ROCKS

Title: Origins of platinum-group minerals in upper mantle rocks

Lecturer: Dr. José María González Jiménez (Geochemical Evolution and Metallogeny of Continents (GEMOC); Dep. Earth and Planetary Sciences; Macquarie University, Australia).

Date: Tuesday January the 07th, 2014 at 16:00h

Place: Room 11

Abstract: 

In the upper mantle, the platinum-group elements reside mainly in specific minerals known as the platinum-group minerals (PGMs), and to a lesser extent dissolved in base-metal minerals (including Fe-Ni-Cu sulfides, arsenides) and alloys. They vary widely in distribution, morphology, and chemistry and Os-isotope compositions, suggesting different possible origins. The remarkable abundance of these minerals in chromite-rich rocks may reflect the role of chromite as a physical “collector” of the platinum-group elements during crystallisation of both phases from melts. However, despite a great body of work, the links between the PGMs (and their associated base-metal minerals) and the mechanism of formation of their host chromitites are still unclear and hotly debated. Platinum-group minerals found in the upper mantle chromite-rich rocks show significant Os-isotope heterogeneity on the scale of single micrometric grains enclosed within individual chromite grains. This micro-scale isotopic heterogeneity, and their random spatial distribution within the chromites, argues strongly against an origin of the platinum-group minerals via exsolution from the chromite lattice during post-magmatic cooling. A re-interpretation of their microstructures and Os isotopes analysed in situ had led us to review the traditional models, and to propose several origin(s) for the platinum-group minerals in chromitites. (1) The suites of platinum-group minerals mainly record crystallisation during mixing of multiple different melts and physical entrapment in chromite. (2) Some platinum-group mineral sin chromitites may have been scavenged from wall-rock peridotite during migration of the parental melts of the chromitite. (3) Other platinum-group minerals may have precipitated from metasomatic fluid/melts that infiltrated existing chromitites. The recrystallization of pre-existing platinum-group minerals during polyphase metamorphism or “recycling” of the chromitite into deeper mantle levels can explain the presence of micrometric platinum-group minerals with distinct Os-isotope compositions, associated with minerals such as chlorite.

URANIUM WORKSHOP IN NANCY

Our colleagues from Nancy organized a workshop about Uranium that took place in Nancy on December 12-13th, 2013. Many participants from all over the world attended the workshop.

Belén Torres Cueva, member of the Barcelona SGA Student Chapter participated in the workshop as representative of our association. Belén, recently graduated, is about to commence the Master in Geology and Environmental Management at the University of Huelva.

During the first day of the workshop, talks started with an introduction about the uranium cycle over time followed by the exposition of examples of some important uranium deposits in the world. During the day there was also time for coffee breaks, lunch and an interesting poster session.

The second and final day of the Uranium Workshop, two PhD students exposed their researches. One was about the cycle of uranium and the tectono-metamorphic evolution of the Pan-African orogenic belt of Lufilien (Zambia) and the other session was about The formation of Roll-front deposits in the Erlian basins, China.

This amazing Uranium Workshop concluded with a refreshment and lunch.

FIELDWORK IN THE DOMINICAN REPUBLIC

During three months, Lisard Torró, our president, has developed a fieldwork campaign in the Dominican Republic thanks to a grant awarded by the SEG (Society of Economic Geologists).  This work is part of his PhD Thesis research about the metallogeny of metallic deposits in Cordillera Central in this country.

The main part of the stay was devoted to developing a detailed mapping and sampling in the Los Ranchos Formation materials close to Cotuí city area; with the purpose of finding the fresher outcrops, several tens of rivers and arroyos were gone over, machete in hand. The other part of the campaign was developed in the Cerro Maimón mine and surroundings and consisted of both fieldwork along several rivers and the logging and sampling of drill cores from new prospects in Maimón Fm. and Bayaguana areas.

During his stay, Lisard taught two subjects at ITECO, the unique university of the country with a program in Geology. A total of 42 students had to bear his lessons!

Júlia Farré, a last-year student of Geology at UB and the 4th year Student Committee of our Student Chapter, had also the opportunity to work in Dominican Republic in order to develop the fieldwork related with her Final Degree Thesis about the petrology and geochemistry of the most deformed rocks in the Maimón Formation; this Formation hosts the Cerro Maimón mine, currently the only VMS deposit under production in the Caribbean. During the week she spent there, a comprehensive field and core sampling was carried out.

Both insist to stress their gratitude to all collaborators (SEG, CORMIDOM-PERYLIA, EVERTON and individuals) that allowed them to develop an essential part of their research as well as, although the hard work carried out, to live a superb vital experience.