Gondwana Research (Gondwana Newsletter Section) c! 4, No. 2, p p . 251-252. 0 2001 international Association for Gondwana Research, Japan. GNL

CONFERENCE REPORT

31’‘ IGC in Rio de Janeiro, 2000

Somnath Dasgupta

Department of Geological Sciences, Jadavpur University, Calcutta, India

The 3lSt International Geological Congress was held at Rio de Janeiro, Brazil, during the period 6-17fh August 2000. About 4000 delegates from more than 67 countries participated in this huge gathering of geoscientists. The focus of the 31st IGC was “Geology and Sustainable Development: Challenges for the Third Millennium”. The delegates were placed in different hotels spread over Rio, and all the meetings were held at Riocentro, about 30 km outside Rio. The scientific program featured comprehensive and multidisciplinary activities related to important problems facing the geological sciences, and included special scientific symposia reflecting the interdisciplinary nature of today’s science, while emphasizing the importance of the geological sciences to human society. Further, the special symposia focused on frontier subjects and highlights of international geoscientific research. The scientific program consisted of colloquia, special symposia, general symposia, short courses, workshops and field trips (pre-congress, syn- congress and post-congress) .

Nine lectures were delivered in the colloquia section by leading authorities on subjects dealing with mineral exploration, energy resources, oil and gas exploration, global climatic changes, prevention of geological hazards and water resource problems. Additionally, four special lectures dealt with sustainable development in the next century, with special focus on Brazil and China. There were eleven sessions of special symposia dealing with topics like origin and evolution of the earth, geoscience, human survival, environment, natural hazards, climatic changes, structure of the lithosphere, global tectonic zones, metallogenesis, basin analysis, lithospheric motions, new technology in geosciences and progress of international geoscience projects. There were twenty eight sessions of general symposia covering stratigraphy, palaeontology, sedimentology, marine geology, igneous petrolom, experimental petrology, metamorphic petrology, geology of mineral deposits, mineral economics, Precambrian geology and fossil fuels. Each session was divided into several subsections.

The geoscientists of the Gondwana Research Group actively participated in many sessions, but were particularly involved in the session on Precambrian geology, and more specifically with the session 9-7: Proterozoic Events in East Gondwana (Convenors: M. Yoshida and S. Dasgupta). Other 6 sessions in the section on Precambrian geology included the oldest continental crust on earth, continental growth in the Precambrian, tectonic evolution of Proterozoic orogenic belts, Precambrian supercontinents, Neoproterozoic supracrustal sequences and tectonic evolution of South America. In total, forty papers were orally presented and there were about two hundred posters in the above six sessions. All the sessions were efficiently conducted and evoked tremendous response and full house. Often the sessions prolonged because of debate and alternate views. This clearly showed the importance of the subjects covered under the section Precambrian geology.

The General Symposium 9-7 “Proterozoic Events in East Gondwana” (IGCP-368)

This symposium consisted of two parts: poster presentations on the 8th August and oral presentations on the gth August. Although twenty-seven posters were listed, nine (presented by scientists from 5 countries) were actually presented. Many participants could not attend, most possibly because of financial constraints. In the oral section, eight keynote lectures were presented by scientists from seven countries as shown below with their abbreviated topics.

Yoshida, M. and others, Pan-African suture; Dalziel, I.W.D., The SWEAT hypothesis revisited; Powell, C. McA., Proterozoic events in Australia; Sengupta, S., Tectonothermal evolution of Schirmacher Hills, Antarctica; Dasgupta, S., Indo-Antarctic correlation; Zhao, Y., Pan- African Grove Mountains in East Antarctica; Windley, B.E and others, Tectonic evolution of Madagascar and Yemen; Kroner, A. and others, The Mozambique Belt of East Africa and Madagascar.

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Poster presentations were 27 papers including 2 general papers, 17 papers from India, and some others from Antarctica, Madagascar and South China. Papers from India were mostly from the Eastern Ghats Mobile Belt; e.g., Acharyya, S., on mafic-ultramafic rocks, Arima and Yoshida, on metamorphism, Kovach and others, on U-Pb and Sm-Nd systematics, Subba Rao and others, on A-type granites, Tsuchiya, T., on sheath folds, and so on. Some papers from South India also appeared (e.g., Miyazaki and others, Nd and Sr isotopes of alkaline complexes). Papers from Antarctica included Bauer and others, on the Pan-African Gruber anorthosite, and Dasgupta and Sengupta, on mafic enclaves within granulites of

Schirmacher Hill. Kroner and others presented U-Pb and Nd isotopic systematics from central Madagacar, and Jian and others gave Proterozoic hotspot events in South China.

The business meeting of the IGCP Project 368 was held on the gth August and it was decided to bring out the proceedings of this session as a special publication of the Geological Society of London.

But for minor hiccups, the 3lSt IGC was perfectly co- ordinated and all the scientists gained through interactions. I t has been decided to hold the 32”d International Geological Congress at Florence, Italy in the year 2004.

Gondwana Research (Gondwana Newsletter Section) V. 4, No. 2, pp. 252-255. 0 2001 International Association for Gondwana Research, Japan. GNL

FIELD EXCURSION

Neoproterozoic Dom Feliciano Belt, Southeastern Brazil: Post-Conference Tour of 31‘‘ IGC in 2000

Masaru Yoshida

Department of Geosciences, Osaka City University, Osaka 558-8585, \span, E-mail: myoshida@sci.osnka-cu.ac.jp -

The Dom Feliciano Belt (sensu lato) of southeastern Brazil forms the south sector of the Proterozoic Mantiquiera Province. It is composed of the western Vila Nova Belt which is a Neoproterozoic juvenile accretional complex, the central Tijucas Belt which is a Neoproterozoic reworked schist belt of volcanic and sedimentary origin possibly representing a continental magmatic arc, and the eastern Dom Feliciano Belt (sensu stricto) which is a Neoproterozoic reworked migmatite-granite terrain with remnants of Paleoproterozoic gneissic blocks (e.g. Chemale, 1998). Rocks of these belts are intruded by many late to post orogenic granite masses, and between the first two belts are developed late orogenic Neoproterozoic basin sediments. Several models of tectonic evolution of this belt have recently been presented, referring several zircon SHRIMP data in association with Sm-Nd systematics. There are, however, controversies among authors.

It was timely at the present state of knowledge (e.g. Basei et al., 2000; Trouw et al., 2000) on the Dom Feliciano Belt within the Gondwana assembly, that 3lSt IGC held in Rio de Janeiro in August 2000 planned a field excursion

to this region. The field excursion of 6 days was organized by scientists of the Federal University of Rio Grande do Sul (UFRGS), including L.A. Hartmann and L.A.D. Fernandes. Observations and discussions in the field, synthesis of recent studies compiled as a bunch of 28 papers running to nearly 500 pages presented to the participants, and detailed discussions with some scientists of UFRGS made during my additional visit to the university facilitated me to obtain a better understanding of this important Brasiliano mobile belt, particularly with respect to its collisional tectonic regime.

The field trip Aft 02 of 31St IGC, “Crustal Evolution of Southern Brazil: Juvenile Accretion and Shear Zones” (Hartmann and Fernandes, 2000) was planned to cover a full picture of the Dom Feliciano Belt (sensu lato) from its northwestern boundary between the Luiz Alves Craton (Archaean and Paleoproterozoic) surrounding Florianopolis, to the centre of the Dom Feliciano Belt (sensu lato) in the south around Port0 Alegre and further southern area. In the following, selected field observations of major outcrops of each geologic unit are given.