SEG GRANTS

Four members of the Barcelona SGA student chapter, Sandra Amores, Marc Campeny, Montgarri Castillo and Lisard Torró, all PhD students, have been awarded a Student Research Grant from the Society of Economic Geologist in order to develop the fieldwork related with their PhD during 2013.

Particularly, these four grants are provided for the Hugh E. McKinstry Fund which granted students whose projects involve studies of mines or ore districts, topical studies toward improved understanding of ore genesis, and experimental research in field applications.

Sandra Amores has been selected to receive a grant for an amount of $US 3,750 to sample and study Monte Verde and Coola carbonatites from Huambo province in Angola. Marc Campeny has been awarded $US 2,500 to carry on with his research in Catanda extrusive carbonatite located in Kwanza Sul, Angola. Montgarri Castillo received $US 3000 in order to advance in her research in diamantiferous kimberlites from Angola. Finally, Lisard Torró has been awarded $US 3000 to finance the fieldwork related with a detailed mapping of the Hatillo Sheet (central Dominican Republic) where Cerro Maimón and the world-class Pueblo Viejo deposits are located.

Congratulations!

TALK BY DR. CARLES CANET

Title: The Sonora stratiform barite deposits: relation and analogy with the methane cold seeps (Els jaciments estratiformes de barita de Sonora: relació i analogia amb els cold seeps de metà).

Lecturer: Dr Carles Canet Miquel. Dept. Recursos Naturales, Instituto de Geofísica & Head of the Dept. Geoquímica, Instituto de Geología (Universidad Nacional Autónoma de México).

Date: Wednesday 26th June 2013, 12.00h.

Place: room 2

Abstract:

The Mazatán barite deposits, Sonora, NW Mexico, represent an outstanding example of Paleozoic bedded barite, a poorly understood type of mineral deposit of major economic interest. The deposits of this type commonly occur hosted by shales and are characterized by the lack of base-metal sulfide mineralization, in contrast to classic sedimentary-exhalative (or SEDEX) deposits. A throughout study of the Mazatán barite deposits, based on petrography, fluid inclusions analyses and isotope geochemistry, confirmed the link between bedded barite and fossil hydrocarbon seeps, thereby leaving hydrothermal vent-related processes ruled out. Hence, modern cold seeps in continental margins would account for the geological setting and genetic aspects of this type of deposit.

The largest barite bodies of Mazatán are hosted within an Upper Carboniferous flysch succession, which formed part of an accretionary wedge related to the subduction of the Rheic Ocean beneath Gondwana. As well, a few barite occurrences are hosted in Upper Devonian, pre-orogenic turbidites. A variety of mineralized structures is displayed by barite, including: septaria nodules, enterolitic structures, rosettes and debris-flow conglomerates. Barite is accompanied by chalcedony, pyrite (framboids) and berthierine. Gas-rich fluid inclusions in barite were analyzed by micro-Raman spectroscopy and methane was identified, suggesting the occurrence of light hydrocarbons in the environment within which barite precipitated. 13C-depleted carbonates (δ13C: -24.3 to -18.7‰) were found in the barite deposits; they likely formed through anaerobic oxidation of methane coupled to sulfate reduction. Besides, these carbonates yield negative δ18O values (-11.9 to -5.2‰) reflecting the isotopic composition of Devonian−Carboniferous seawater; alternatively, this 18O-depletion could reflect late diagenetic processes. Methane-derived carbonates occur at modern hydrocarbon seeps and have been reported from Mesozoic, Cenozoic and even Paleozoic seep sediments, but they have never before been described in Paleozoic bedded barite deposits. δ34S values of barite vary from +17.6 to +64.1‰, with the lowest values overlapping the range for coeval seawater sulfate; this distribution indicates a process of sulfate reduction. Barite precipitation can be explained by mixing of methane- and barium-rich fluids with pore-water (seawater) containing sulfate residual from microbial reduction. Two analyses from barite gave an 87Sr/86Sr within and slightly above the range for seawater at the time of deposition, with 0.708130 and 0.708588, which would preclude the involvement of hydrothermal fluids in the mineralization process.

Congratulations Carlos and Núria!

Two members of the Barcelona SGA Student Chapter, Carlos Arbiol and Núria Bach, have been awarded a very prestigious and competitive scholarship to develop their Master studies at the University of Geneva (Switzerland). Here you can see the list of candidates from all over the world that were also awarded an Excellence Master Fellowship at the Faculty of Sciences of this University. They will study for a two-year degree in Master of Science in Geology, orientation Geochemistry, Petrology and Ore Deposits. Hiding our well-meaning envy, we all wish these two excellent students a very fruitful stay in this fabulous city.

EMU School 2013: Minerals at the nanoscale

Last week Cristina Villanova, our secretary, attended the EMU School 2013 "Minerals at the nanoscale", about fundamentals and aplications of High Resolution Transmission Electron Microscopy in Mineralogy. The course was held in the Centro de Investigación Científica (CIC) of the University of Granada from June 3th to 6th, with the participation of experienced international lecturers, and including practical lessons in the high level transmission electron microscopy facilities of the centre and exercises to learn how to interpret the results obtained by this technique.

 

 

Our secretary accompanied by Dr. Fernando Nieto (left) and Dr. Fernando Gervilla (right), professors of the University of Granada and organizers of the EMU School 2013.

The SGA BCN Student Chapter official T-shirt is now available

We are thrilled to present the new T-shirt of the BCN Student Chapter. The main theme of this design is the Gaudí-style hammer which is the official logo of our association, combined with the sentence “All you need is Ore” making reference to the popular song by The Beatles, capturing our devotion to ore minerals. They also have the SGA logo printed on one sleeve.

The T-shirts are black in colour and are available in different sizes (S, M, L, XL & XXL), in both regular and girly versions.

The price for non-members of the BCN Student Chapter is 15 €. If you are interested to purchase this exclusive T-shirt, please send your request to the official electronic address of the BCN Student Chapter:  Esta dirección de correo electrónico está siendo protegida contra los robots de spam. Necesita tener JavaScript habilitado para poder verlo.

And remember... All you need is Ore!!!

Visiting the Adelaide Mine, the Crocoite’s dream world!

Marc Campeny Crego a PhD student from the BCN-SGA Student Chapter is carrying out a scientific stage in the University of Tasmania (Australia), relatively close to one of the most wonderful mineralogical places in the world: the crocoite’s mines from Mt.Dundas in Zeehan, NW Tasmania.

Crocoite is a very rare lead chromate (PbCrO4) famous for its amazing red colour and its delicate acicular crystallizations. Its type locality is the Tsvetnoi Mine in the Urals region, Russia but the Tasmanian crocoites are considered without doubt the most exceptional specimens all around the world.

Marc visited the Adelaide Mine, an ancient lead and chromium mine now only exploited to extract crocoite specimens for mineralogical collections. 

Talks by Dr Federica Zaccarini and Dr Giorgio Garuti

Dr Zaccarini and Dr Garuti, from the Department of Applied Geosciences and Geophysics at University of Leoben (Austria) are these days here in Barcelona. As we know that they are always willing to collaborate with students, we asked them to lecture us on some topics they are doing research in. They kindly accepted. The talks will be held in Room 10 at the Faculty of Geology on Thursday May 14th at 16.00h. The titles and abstracts are as follow:

Massive sulfide deposits of the northern Apennine ophiolites (Italy)

Sulfide deposits located in the Northern Apennine of Italy have been known as a workable source of copper since 3500 BC, thus providing evidence for the earliest copper exploitation in Western Europe. The most important copper deposits are associated with the Western Alps and Northern Apennine ophiolites, which represent fragments of the sub-oceanic lithosphere that floored the Liguria-Piedmont Tethys. This embryonic ocean formed by divergence of the European and the Adriatic Plates in Jurassic times, and closed between Late Cretaceous and Early Eocene.

The sulfide deposits of the Northern Apennine are characterized by the metal assemblage Fe-Cu-Zn typical of ophiolite-hosted Volcanic Massive Sulfide (VMS) deposits. They consist of the hydrothermal ore assemblage pyrite-chalcopyrite-sphalerite with or without pyrrhotite, galena, magnetite and other accessory ore minerals (linneite, millerite, marcasite, covellite, gold, silver, acanthite, freibergite, ilmenite, rutile, uraninite, hydroromarchite). Quartz, calcite and chlorite are major gangue minerals, along with accessory siderite, epidote, titanite, apatite and zircon. The Northern Apennine deposits represent a rare example of seafloor-stratiform, stratabound, and sub-seafloor stockwork ore-bodies associated with both the ultramafic basement and the basalt volcanic cover in one single ophiolite sequence.

Sulfur isotope values in VMS deposits of the Northern Apennine ophiolites have an overall average of 5.9 δ34S‰, similar to other VMS deposits of the eastern Mediterranean Tethys, i.e. Troodos (4.6‰) and Eastern Turkey (4.2‰). They differ, however, for a much wider range of δ34S, varying from +11.4‰ to -2.9‰.The sulfur isotope variations observed in the Northern Apennine VMS deposits reflect the influence of the different environments of sulfide deposition (seafloor vs. subseafloor) and different lithologies of the host rocks (basalt vs. serpentinite).

Electron microprobe and Raman spectroscopy applied to the identification of platinum group minerals (PGM)

Platinum group minerals (PGM), with few exceptions, occur as small phases less than 10 microns in size. Therefore, to analyze them is a difficult task. Due to their small size, they cannot be investigated by X-ray and, as a consequence, the most used technique to recognize PGM is the electron microprobe. However, this methodology applied to PGM is relatively complicate and consuming-time. In a paper published about 20 years ago [1], it was suggested Raman spectroscopy a possible tool to investigate PGM. Since Raman is a non-destructive and structurally sensitive technique, can be easily used to identify small mineral phases less than 10 microns in size, such as PGM. However only 6 Raman spectra were published for the following natural PGM: cooperite (Pt,Pd,Ni)S, sperrylite (PtAs2), platarsite (PtAsS), moncheite (Pt,Pd)(Te,Bi)2, braggite (Pt,Pd,Ni)S and potarite (PdHg). Therefore, in this contribution preliminary Raman results obtained, for the first time, on a great variety of PGM, are presented. PGM sulphides, arsenides, sulpharsenides display a very well-defined and characteristic spectrum, as typical for the compounds characterized by the presence of covalent bonding. On the contrary, the Raman spectra of a number of alloys and native elements show no discernible scattering bands suggesting that the possible bonds present in these PGM are metallic or ionic. Few PGM, classified as possible Ru bearing oxides, show a broad and weakly scattered spectrum over the range of about 100–800 cm-1. 

The collected data also demonstrated that Raman is sensitive on the compositional variation, particularly in the PGM characterized by a solid solution substitution such as laurite (ideally RuS2)-erlichmanite (ideally OsS2) series. These results confirm that Raman spectroscopy can be considered an innovative and complementary technique with a huge potential to better characterized and identify rare and tiny phases such as PGM. The two main disadvantages of the Raman spectroscopy applied to the investigation of PGM are: 1) some PGM, such native elements and alloys, are not sensitive to this technique and 2) it does not provide a chemical composition of the investigated minerals. Therefore, it is intended to apply the Raman spectroscopy to a great number of different PGM, already chemically characterized by electron microprobe, with the target to create a future and accessible data base of Raman spectra of a great number of different PGM.

[1] Mernagh T.P. and Hoatson D.M. (1995) Can. Mineral., 33, 409-417.

CONGRATULATIONS, DR. CORRAL!

Isaac Corral is the first Barcelona SGA Student Chapter member to finish his Doctoral Thesis, entitled “Geology and Metallogeny of the Cerro Quema Au-Cu Deposit (Azuero Peninsula, Panama)”. It was presented last Friday (10th of May) in the Universitat Autònoma de Barcelona. The Barcelona SGA Student Chapter wishes all the best for the future of such a good scientist!

Doctoral Thesis defense by Isaac Corral

Our colleague and member of the Barcelona SGA Student Chapter, Isaac Corral, will defend his thesis, entitled “Geology and Metallogeny of the Cerro Quema Au-Cu Deposit (Azuero Peninsula, Panama)” on Friday 10th of May. The defense will be held at the Science Faculty (Sala de Graus) of the UAB (Universitat Autònoma de Catalunya) at 11 a.m. Isaac is the first Barcelona SGA Student Chapter member to finish his Doctoral Thesis, so we all wish Isaac all the best with the defense. 

 

SUMMARY

Cerro Quema, located in the Azuero Peninsula (SW Panama) is a structurally and lithologically controlled high sulfidation epithermal Au-Cu deposit. It is hosted by a dacite dome complex intruded within the Río Quema Formation, a volcanosedimentary sequence of Late Campanian to Maastrichtian age deposited in a fore-arc basin. Au-Cu mineralization and hydrothermal alteration is controlled by E-W trending regional faults.

In order to unravel the relationship between the geological evolution of the area and the Cerro Quema mineralization, a detailed study of the tectonostratigraphy, geochemistry and biostratigraphy of the Azuero Peninsula is presented. Additionally, new data on the ore and alteration (hydrothermal and supergene) mineral parageneses and Ar/Ar geochronology (hornblende) is presented to find out the age of the Au-Cu mineralization. The origin and evolution of mineralizing fluids is discussed from fluid inclusion (homogenization temperature and salinity) and stable isotopes (S, O and H) data performed on sulfides, sulfates and silicates.

According to field observations coupled with geochronological and biostratigraphical data, Cerro Quema is a high sulfidation epithermal deposit emplaced during Lower Eocene (~55-49 Ma) times, and is probably related to an underlying porphyry copper system. Mineralizing fluids were of variable temperature (140 - 240ºC) and low salinity (< 5 wt% NaCl eq.). Hydrothermal fluids were sulfide dominant with sulfur of magmatic origin (δ34SΣS= -0.5‰). d18O of fluids in equilibrium with vuggy silica (-2.6 to +3.0‰) and d18O/dD values of kaolinite/dickite (d18O= -10.0 to +13.3‰; dD= -72 to -13‰, respectively), indicate that mineralization was produced by the mixing of hydrothermal fluids with meteoric waters. Cerro Quema is only a part of an extensive hydrothermal system that produced similar deposits in the southern portion of the Azuero Peninsula.

TWO MEMBERS OF THE BARCELONA SGA STUDENT CHAPTER IN HAVANA, CUBA

Our advisor, Dr Joaquín A. Proenza, and our Vice-president, Lisard Torró, attended the V Cuban Earth Science Convention (congress web) in April 1st - 5th that took place in the Convention Palace in Havana, Cuba. This Convention embraced five scientific events (X Cuban Geology Congress, VII Cuban Geophysics Congress, V Cuban Mining Congress, IV Cuban Oil and Gas Congress and the XI Cuban Informatics and Geosciences Congress-GEOINFO) and was attended by more than 650 delegates from the five continents. Joaquín and Lisard presented up to five talks and one poster with the following titles:

  • Alteration minerals domains registered under Loma La Cuaba: new insights on the origin of Pueblo Viejo deposit.
  • Depósitos “no convencionales” de elementos del grupo del platino (EGP).
  • Comparison of trace-element geochemistry of Loma Caribe peridotites (Dominican Republic) with others peridotite bodies along the northern margin of the Caribbean Plate.
  • The evolution of the Caribbean lithospheric mantle seen in platinum-group minerals and zircons from chromitites of the Mayarí-Baracoa Ophiolitic Belt (Cuba).
  • “Garnierite” mineralizations from the Falcondo Ni-laterite deposit (Dominican Republic): new insights from XR quantitative element imaging.
  • Occurrence of scandium and rare earth elements in laterites from Cuba and the Dominican Republic

Joaquín and Lisard also took part in an amazing post conference field trip to ophiolites in the Havana-Matanzas region.

In Havana they met old and good friends of our student chapter such as Carl E. Nelson and José Batista among many other colleagues that we hope that will collaborate with our association in the future.

Doing research in the Antipodes !

Montgarri Castillo i Oliver, a PhD student of the Barcelona SGA Student Chapter, has gone to Sydney for a short research stay. She will join the GEMOC Research group, in Macquarie University (Sydney) and her work will be supervised by Dr. Bill Griffin, Dr. Sue O’Reilly and Dr. Norman Pearson. During the following 3 months, she will carry out U-Pb dating, Sr and Nd isotopes, as well as trace element analyses on perovskite, zircon and titanite grains from several Angolan kimberlites. Additionally, she will analyse trace elements on sulphides from Bolivia and Pb isotopes on pyrochlores from Angola.

Marc Campeny is also doing part of his PhD research in the Antipodes, in Hobart. For two months he will work with Dr. Vadim Kamenetsky in the School of Earth Sciences of the University of Tasmania. He will mainly focus on the study of melt inclusions on apatite and calcite from Angolan carbonatite rocks.

We wish all the best to our colleagues!