LABISE: foundation and 25 years of activities

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      Alcides N. Sial was introduced to low- and high-temperature stable isotope geochemistry by Prof. Lynton Land during post-doctoral work in the Department of Geological Sciences of the University of Texas (UT), at Austin (1977‒1978). He learned about oxygen gas extraction from silicates using a conventional, high-vacuum extraction line having bromine Br2F5 as main reagent, besides hydrogen gas extraction and how to run an old-fashioned Nuclide gas-source mass spectrometer.
      The positive experience at UT encouraged Sial to broaden his background on stable isotope geochemistry and to visit other stable-isotope laboratories in USA. With this purpose, he spent the entire year of 1983 in the University of Georgia at Athens, where he was exposed to multiple applications of stable isotopes and related laboratorial techniques. In the same year, he spent two months at the Department of Geology of the Memorial University of Newfoundland, learning the analytical method for rare-earth element analysis by X-ray fluorescence from Prof. Brian Fryer.
      The challenging complexity of granites, their metallogeny and importance in reconstruction of geotectonic setting, have stimulated A.N. Sial to found the Nucleus for Granite Studies (NEG) in the Department of Geology of the UFPE on February 1984. Since then, the NEG has developed petrological, geochemical and isotopic studies on granitic rocks of northeastern Brazil, Argentina, Chile, Uruguay and India, mainly on igneous processes and investigation of the source of granitic magmas. The name of this Nucleus was changed to Nucleus for Geochemical Studies in 1995, preserving the NEG acronym.

Figure 1.
The Stable isotope Laboratory (LABISE) of the Department of Geology, Federal University of Pernambuco, founded in 1990.

      In 1988, two conventional high-vacuum extraction lines (carbonate and silicate) were built with the help of David Wenner and Andrew Clarke while A.N. Sial was in post-doctoral work and V.P. Ferreira a Ph.D. student in the University of Georgia at Athens. In that year, they spent the entire month of August in the Geological Survey of Japan at Tsukuba, learning from Prof. Akira Sasaki, the technique of extraction of sulfur from igneous rocks using the Kiba solution and gas-source mass spectrometry for sulfur isotopes. The scientific experience acquired from all these stable-isotope laboratories in USA and Japan led A.N. Sial to found, with financial support of the PADCT (Program of Support to Scientific and Technological Development, financed by the World Bank), a stable isotope laboratory (LABISE) in the Federal University of Pernambuco, pioneering in Brazil the analysis of oxygen isotopes from silicates, in September 1990. In this endeavor, the Department of Geology had the sympathy from the Rector, Prof. Edinaldo Bastos, who built the physical space to accommodate this laboratory, comprising two high-vacuum extraction lines (Fig. 1a) and a stable isotope ratio analyzer mass spectrometer (SIRA II) (Fig. 1b) besides office space for faculty members. The high-vacuum extraction lines (carbonate and silicate) were built in the workshop of the University of Georgia at Athens and transferred to Recife where they were reassembled by A. N. Sial, G. Mariano and V.P. Ferreira. Prof. Efrem Maranhão, who replaced Prof. Edinaldo Bastos, and Prof. Mozart Neves Ramos, financially supported the expansion of the physical space of the LABISE to accommodate an X-ray fluorescence laboratory (Rigaku-3000) in 1994 and a sample preparation room in 1996.

Figure 2.
(a) Conventional high-vacuum extraction lines for carbonate (front) and for silicate (back).
(b) Stable isotope ratio analyzer mass spectrometer (SIRA II).

      In 1996, A. N. Sial and V.P. Ferreira spent couple of weeks in East Kilbride, Scotland, visiting with Prof. Anthony E. Fallick the analytical facilities of the Scottish Universities Research and Reactor Centre (SURRC) one of the most complete set of stable-isotope laboratories in Europe. They also visited with Prof. John Valley the Department of Geology and Geophysics of the University of Wisconsin, at Madison in 2001, learning on CO2 laser-based high vacuum extraction lines for silicates. Upon their return, the LABISE underwent its latest physical expansion to accommodate an ion-exchange laboratory (clean station), a CO2 laser-based oxygen extraction line from silicates and oxides (built by Zachary Sharp, University of New Mexico), and an elemental combustion system (COSTECH) for carbon and nitrogen analyses, on-line with a Thermofinigan Delta V Advantage gas-source mass spectrometer and more recently, a GasBench II to go along this spectrometer.
      Sial and Ferreira are igneous petrologists (basalts, mantle petrology, granites) since they were hired by UFPE (A.N. Sial, March 1967, and V.P. Ferreira, August 1989), but versatility, enthusiasm and curiosity have led them to other venues, as isotope stratigraphy. From 1986 to 1994, the NEG‒LABISE counted with the participation of Gorki Mariano who had been also trained in the University of Georgia and helped in the first stages of installation of the stable isotope laboratory besides the running of a fluorine high-vacuum extraction line. The NEG-LABISE has kept close scientific cooperation on granite studies and isotope stratigraphy with researchers from Brazil, Argentina, Chile, Uruguay, Colombia, Mexico, Portugal, India and United States.

Figure 3.
(a) CO2 laser-based oxygen extraction line from silicates and oxides;
(b) GasBench II and an elemental combustion system (COSTECH) for carbon and nitrogen analyses on-line with a Thermofinigan Delta V Advantage gas-source mass spectrometer;
(c) Clean station.

Figure 4.
(a) Rigaku-3000 XRF unit; (b) Sample preparation room.

      In 1985, the NEG organized a workshop on Granitic Magmatism and Associated Mineralizations at Caruaru, Pernambuco, gathering about 15 enthusiastic young Brazilian granitologists. A field trip in northeastern Brazil to the Cachoeirinha‒Salgueiro Belt helped bringing their attention to granitoids of uncommon diversity and evolution. The same group of granitologists gathered again in 1987 at Salvador, Bahia, in the International Symposium on Granites and Associated Mineralizations (ISGAM) and in 1997 in a second edition of the ISGAM, all of these Meetings organized by the NEG‒LABISE. Besides the ISGAM series, other international Meetings were organized, on two themes: Granitic Magma and Associated Mineralizations (MAGMA) within the frame of the International Geological Congress (31st, 32nd and 33rd IGC) or Brazilian Academy of Science (Rio, 1993), and on isotope geology (4th South American Symposium on Isotope Geology = SSAGI, 2003). Since 1992, the NEG-LABISE has annually organized a Meeting of the Brazilian Academy of Sciences at Recife, and a short course (75 hours/class) on stable and radiogenic isotopes and their multiple applications, with participants from all over the country. The NEG-LABISE has attempted to disseminate granite petrology and high and low-temperature geochemistry of stable isotopes by teaching short courses in several universities in Brazil, including UFRGS, UFRJ, UFPA, UFPE, UFMG, UFMT, University of Chile (Santiago, 2003), Latin-American Congress (Medellin, 2011) and in several Brazilian Meetings.

Figure 5.
Some participants of the “Stable and Radiogenic Isotopes” course in August 2015.

      The study of Neoproterozoic magmatic epidote-bearing granitoids in northeastern Brazil, Paleozoic in Argentina and Tertiary in Chile, represents perhaps one of highlight contributions from the NEG‒LABISE to the granite-petrology field in papers published in international journals (1999, 2003, 2008, 2011, 2015). In these papers it was proposed that partial digestion of magmatic epidote by its calc-alkaline or high- K calc alkaline host magma could be used to estimate speed of host magma ascent.

Figure 6.
Pie-chart giving an idea of publications emerged from the NEG-LABISE (1984-2015).

      From 1995 on, the NEG-LABISE scientific interest was broadened to include isotope chemostratigraphy and from then on, a continuous and fruitful cooperation with colleagues from Argentina (Silvio Peralta, Gilberto Florencio Aceñolaza, R. Narcizo Alonso and Alejandro J. Toselli), Uruguay (Claudio Gaucher and Jorge Bossi) and Chile (Miguel Angel Parada). This group has documented by the first time in South America the isotope record of the Steptoean positive isotope carbon excursion (SPICE) and recognized by the first time the Sunwaptan negative carbon isotope excursion (SNICE) in the Argentine Precordillera. Moreover, they recognized by the first time in South America the record of the Ordovician MDICE, GICE and HICE positive carbon isotope excursions. Anil Maheswari, A.N. Sial, Claudio Gaucher, Andrey Bekker, Valderez P. Ferreira, Jorge Bossi and Wilson Romano have contrasted the record of the Paleoproterozoic Lomagundi excursion in India, Brazil and Uruguay. They found that this excursion is recorded in both shallow-water and deep-water carbonates negating a significant impact of stromatolite productivity and hypersaline conditions on carbon isotope values of carbonates deposited in shallow-water, open-marine and isolated basins.

Figure 7.
Analytical support given by the LABISE to severla institutions since its foundation in 1990.

      Annually, the LABISE through the Post-graduation in Geology, offers two courses on Chemostratigraphy (45 hour classes), one devoted to the Precambrian and the other one, to the Phanerozoic. Based on these two courses, the LABISE was responsible to prepare the Chapter 2 of a recent book published by Elsevier on Elemental and Isotope Chemostratigraphy (M. Ramkumar, ed.: Chemostratigraphy, Concepts, Techniques and Applications. Elsevier, pp. 23–64., ISBN 9780124199682).
      In the last five years, the research in the NEG‒LABISE was turned to the possible use of Hg as a tracer of volcanism during events of extreme climatic changes. At present, it is being built a database with Hg analyses (supposedly of volcanic origin) from Cryogenian‒Ediacaran cap carbonates and from carbonates across the Cretaceous‒Paleogene boundary of several localities (Europe, South America and India). The intent is to evaluate the extension of participation of volcanism versus bolide impact on the mass extinction of the K‒T boundary. A new project focusing the Permian‒Triassic boundary is under way.
      The contagious enthusiasm of the NEG‒LABISE team for science has attracted young geologists for graduate studies (over fifty students have been supervised/co-supervised in Master´s or doctoral-degree work or both or traineeship), post-doctoral work, or long or short-term visit of geoscientists (Anil Maheswari, Manoj K. Pandit, Lalchand Govindram Gwalani, Vinod C. Tewari from India; Ignacio Sabino Garcia and Lucia Peral Gomez, from Argentina; Jean Pierre Tchouankoue, from Cameroon, Marcelo Solari, from Chile; Pedro Morais from Portugal, besides several Brazilian researchers). Over two hundred scientific papers (most of them in international journals), about 20 book chapters, 3 books and 12 special issues, most of international Journals (Lithos, Chemical Geology, Precambrian Research, Gondwana Research, Journal of South American Earth Sciences, Annals of the Brazilian Academy of Science, Revista Brasileira de Geociências) have emerged from the NEG‒LABISE team.
      On its 25th anniversary, the LABISE aims at significant contribution to the development of stable-isotope geology in South America and with this purpose will lend analytical support to scientific projects in several countries of this continent as well as to thesis/dissertations all over Brazil.