The inventory of geological heritage of the state of São Paulo, Brazil: Methodological basis, results and perspectives

An inventory of geological sites based on solid and clear criteria is a first step for any geoconservation strategy. This paper describes the method used in the geoheritage inventory of the State of São Paulo, Brazil, and presents its main results. This inventory developed by the geoscientific community aimed to identify geosites with scientific value in the whole state, using a systematic approach. All 142 geosites representative of 11 geological frameworks were characterised and quantitatively evaluated according to their scientific value and risk of degradation, in order to establish priorities for their future management. An online database of the inventory is under construction, which will be available to be easily consulted and updated by the geoscientific community. All data were made available to the State Geological Institute as the backbone for the implementation of a future state geoconservation strategy.The authors acknowledge the Science Without Borders Programme, Process 075/2012, which supported this study and the São Paulo Research Foundation (FAPESP), Process 2011/17261-6. We also thanks C. Mazoca for his help with maps and figures.info:eu-repo/semantics/acceptedVersio

Tree community variation in a tropical continental island according to slope aspect and human interference

ABSTRACT Associating description of unrecorded tropical tree community structure to sampling approaches that can help determine mechanisms behind floristic variation is important to further the comprehension of how plant species coexist at tropical forests. Thus, this study had the goals of (i) evaluating tree community structure on the continental island of Marambaia (23°4’37.09”S; 43°59’2.15”W) and (ii) testing the prediction that there are local scale changes in a tropical tree community structure between slopes facing different geographic orientation and with distinct human interference history. We established 60 (0.6 ha) sampling units in three different slope sites with distinct predominant geographic orientation and human interference. We sampled all woody trees with diameter at breast height (dbh) ≥ 5 cm. We found a total of 1.170 individuals representing 220 species, 120 genera and 50 families. The overall tree community structure and structural descriptors (abundance of individuals, basal area, species richness and diversity) varied extensively between the sites. The evidence presented here supports that local scale topography variations and human interference history can be important factors contributing to the known floristic heterogeneity of the Atlantic Rainforest. Future work on the study area should focus on disentangling effects from distinct causal factors over tree community variation and species occurrence

Brazilian Pantanal: A Large Pristine Tropical Wetland

The Pantanal is a Quaternary sedimentary basin located in the central-west region of Brazil. Its origin has been linked to stresses transmitted from the western margin of the South American continent into the interior of the craton. Therefore, the Pantanal is part of the Andean foreland system. It presents alluvial plain morphology with altitudes between 80 and 200 m surrounded by desiccated plateaus. Northeast-southwest-aligned faults, many associated with the Transbrasiliano Lineament, control part of the drainage network within the Pantanal Basin. The Paraguay River meanders through an extensive fluvial plain, bordering Precambrian terrains at the western edge of the basin. The Paraguay River is the main river of a depositional system characterized by fluvial megafans, among which the Taquari River megafan stands out. Since the Late Pleistocene, the Pantanal landscape has been changing in response to a climate shift from colder and drier to wetter and warmer conditions. These climate changes are recorded in the Pantanal landscape, which is marked by relict depositional landforms of varying ages formed in environmental and climatic conditions differing from the present. The thousands of Nhecolândia lakes located in the southern sector of the Taquari megafan are examples of relict landforms. These lakes are mostly freshwater lakes connected through rainwater runoff, forming wide and shallow channels (locally called “vazantes”) that drain the fluvial plain during and after the wet season. In contrast, some saline lakes (locally called “salinas”) remain isolated from the surface drainage and are relict landforms of a degrading landscape. The Pantanal is a large tropical wetland exhibiting mostly native vegetation, where wildlife is preserved in its natural habitats. The rivers building the fluvial megafans are prone to frequent avulsions, shifting their channels according to sediment infilling dynamics in the fluvial plain. These shifts in river courses result in considerable changes in the hydrography and geography of the flood plain.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Department of Applied Geology State University of São Paulo, Avenida 24-A, 1515FAPESP: 2014/06889-2CNPq: 305108/ 2009-3CNPq: 484300/2011-

Sedimentology and Morphological Evolution of the Ilha Comprida Barrier System, Southern São Paulo Coast

Universidade de São Paulo Instituto de Geociências, Rua do Lago 562, 05508-080 São PauloUniversidade Federal do Paraná Setor de Ciências da Terra Centro Politécnico Curitiba, Caixa Postal 19001, 81531-970 Curitiba, ParanáUniversidade Estadual Paulista Instituto de Geociências e Cincêias Exatas, Avenida 24-A 1515, 13506-900 Rio Claro, São PauloUniversidade de São Paulo Programa de Pós-Graduaçao em Geoquímica e Geotectônica, Rua do Lago 562, 05508-080 São PauloUniversidade de São Paulo Instituto de Geociências Programa de Pós-Graduaçao em Geoquímica e Geotectônica, Rua do Lago 562, 05508-080 São PauloUniversidade Estadual Paulista Instituto de Geociências e Cincêias Exatas, Avenida 24-A 1515, 13506-900 Rio Claro, São Paul

W-Au skarns in the Neo-Proterozoic Serido Mobile Belt, Borborema Province in northeastern Brazil: an overview with emphasis on the Bonfim deposit

The Serido Mobile Belt (SMB) is located in the Borborema Province in northeastern Brazil and consists of a gneiss basement (Archean to Paleo-Proterozoic), a metasedimentary sequence (marble, quartzites, and schists), and the Brasiliano igneous suite (both of Neo-Proterozoic age). In this region, skarns occur within marble and at the marble-schist contact in the metasedimentary sequence. Most of the skarn deposits have been discovered in the early 1940s, and since then, they have been exploited for tungsten and locally gold. Recently, the discovery of gold in the Bonfim tungsten skarn has resulted in a better understanding of the skarn mineralization in this region. The main characteristics of the SMB skarns are that they are dominantly oxidized tungsten skarns, with the exception of the Itajubatiba and Bonfim gold-bearing skarns, which are reduced based on pyrrhotite as the dominant sulfide, garnet with high almandine and spessartine component, and elevated gold contents. In the Bonfim deposit, pressure estimates indicate that the skarns formed at 10- to 15-km depth. The mineralized skarns present the prograde stage with almandine, diopside, anorthite, and actinolite-magnesio-hornblende, and titanite, apatite, allanite, zircon, and monazite as accessory minerals. The retrograde stage is characterized by alkali feldspar, clinozoisite-zoisite-sericite, calcite, and quartz. Scheelite occurs in four ore-shoots distributed within the marble and at the marble-schist contact. The main ore body is 5-120 cm wide and contains an average of 4.8-wt.% WO3, which occurs in the basal marble-schist contact. Fold hinges appear to control the location of high-grade scheelite. The late-stage gold mineralization contains bismite (Bi2O3), fluorine-bearing bismite, native bismuth, bismuthinite (Bi2S3), and joseite [Bi-4(Te,S)(3)], and also chlorite, epidote, prehnite, chalcopyrite, and sphalerite. This gold-bismuth-tellurium mineralization exhibits a typical late character and occurs as a black fine-grained mineral assemblage controlled by conjugate brittle-ductile faults (and extensional fractures) that crosscut not only the banding in prograde skarn but also the retrograde alkali feldspar and clinozoisite-zoisite-sericite assemblage. The Au-Bi-Te-bearing minerals are intergrown with retrograde epidote, prehnite, chlorite, chalcopyrite, and sphalerite, indicating that gold mineralization at Bonfim is linked to a late-stage skarn event. The polymetallic nature of the Bonfim deposit can be used as an important guide for the exploration of this type of skarn deposit in the Borborema Province, which potentially contains significant new, undiscovered gold and polymetallic deposits