Alethéa Ernandes Martins Sallun

Quaternary colluvial episodes (Upper Paraná River Hydrographic Basin, Brazil)

Colluvial deposits occur extensively in the Upper Parana River Hydrographic Basin (UPRHB) in Southeastern, Southern, and Western central Brazil. These deposits were recognized as an allostratigraphic unit and related to creeping during the Quaternary. Every studied colluvial profile is homogeneous, which indicates relatively long periods of landscape stability that is sufficient for the development of a thick soil cover. The deposits were dated by luminescence and indicate periods of more intense colluvial deposition between 6 and 220 ky B.P. These events correspond approximately to the transitions between the oxygen isotope stages 2-3-4 and 5-6, suggesting that this aggradation was influenced by climatic changes. However, the most important alluviation episode was tentatively correlated with the Middle to Upper Pleniglacial of the Wisconsin glaciation. The most intensive and frequent periods of precipitation that occurred during climate transitions are probably correlated with aggradation events. The regularity of the colluvial deposits suggests continuous uplift accompanied by sediment deposition throughout the UPRHB due to neotectonic activity during the last million years.

Proposição formal do Alogrupo Alto Rio Paraná (SP, PR e MS)

From an allostratigraphic viewpoint, it is possible to recognize stratigraphic units representative of Quaternary geological history in the Upper Rio Parana Hydrographic Basin. These sedimentary deposits are superimposed on Cretaceous lithostratigraphic units of the Parana Basin and have been grouped together as the Alto Rio Parana Allogroup, made up of colluvial deposits of the Paranavai Alloformation and alluvial deposits of the Parana Alloformation. The Paranavai Alloformation consists of arenaceous to rudaceous homogeneous colluvial deposits, formed in place or following limited transportation from weathered Cretaceous lithostratigraphic units, predominantly belonging to the Bauru Supersequence. The Parana Alloformation is formed by fluvial terrace deposits developed within the Paranavai Alloformation and associated with the Upper Rio Parana palaeodrainage system. The sedimentary record of the Upper Rio Parana basin bears testimony to important palaeoclimatic changes and/or neotectonic events from at least 1 Ma ago to the present day that allow characterization of Cenozoic geologic-geomorphologic evolutionary phases in the study area.

Datação absoluta por luminescência do Alogrupo Alto Rio Paraná (SP, PR e MS)

The Alto Rio Parana Allogroup is a Quaternary stratigraphic unit of the Upper Parana River Hydrographic Basin (Sao Paulo, Parana and Mato Grosso do Sul), constituted by the Paranavai Alloformation (colluvial deposits) and the Parana Alloformation (alluvial deposits). These deposits have been dated by Thermoluminescence (TL) and Optically Stimulated Luminescence (OSL) methods, which indicated absolute depositional ages between 6,200±750 and 980,000±100,000 years B.P. for the Paranavai Alloformation, and 14,000±2,000 and 240,000±30,000 years B.P. for the Parana Alloformation. These ages show that the Upper Parana River was active during the last million years in modeling relief by both constructive (terraces) and destructive (dissection) processes. These events are probably related to palaeoclimatic changes and/or neotectonic activities, which gave rise to base level fluctuations and, consequently, transformations of topographic relief.

O carste no plano de manejo do Parque Estadual Intervales e zona de amortecimento, Estado de São Paulo, Brasil

Located in the valleys of the Ribeira de Iguape and Paranapanema Rivers, where karst features and a large number of caves can be found, the Intervales State Park and its buffer zone lie within an area of Proterozoic carbonate rocks that are of great interest to the mining industry. Based on geomorphological and geological studies, the characterization of the karst was performed in order to develop a management plan for the Intervales State Park and its buffer zone. With this, it was possible to defi ne the degree of vulnerability of the karst aquifer to contamination. The areas of greatest vulnerability are those that facilitate injection of contaminants directly into the aquifer, being characterized by such karst features as caves and sinks. In regions where recharge occurs exclusively via diffuse infi ltration, and runoff convergence with surface watercourses, the degree of vulnerability is lower. Considering this analysis, areas with the greatest impact potential were identifi ed and recommendations made regarding management of the park and its buffer zone.

Benthic Foraminifera as Evidence of Paleoenvironmental Changes between 9400 and 8300 cal YBP at the Juréia-Itatins Ecological Station Paleolagoon (SP, Brasil)

ABSTRACT Silva, J.B.; Duleba, W.; Sallun, A.M., and Suguio, K., 2014. Benthic foraminifera as evidence of paleoenvironmental changes between 9400 and 8300 cal YBP at the Juréia-Itatins Ecological Station paleolagoon (SP, Brasil). Many aspects of the Santos Transgression (∼21,227–20,448 to ∼5558–4558 cal YBP) remain controversial, especially before approximately 7800 cal YBP, because of the paucity of data for the Brazilian coast. In this context, benthic foraminiferal assemblages from between 9400 and 8385 cal YBP were analyzed from the S03 core collected at the Juréia-Itatins Ecological Station (JIES) with the aim of clarifying the behavior of the relative sea level along the Brazilian coast during this period. Microfaunal, taphonomical, and morphometric analyses of these microorganisms permitted recognition of eight paleoenvironmental conditions within the lagoon then existing at JIES. There were four phases of conspicuous marine contributions (9400–9338, 9072–8894, 8656–8641, and 8594–8500 cal YBP) with a climax at 8656 cal YBP, when the environment became more favorable to the growth, preservation, or both of benthic foraminifera. They were intercalated with two phases of prominent continental contributions (9338–9072 and 8500–8385 cal YBP), when there was an increase in the local hydrodynamic gradient at the S03 core sampling site. Furthermore, between 8806 and 8672 cal YBP and between 8625 and 8594 cal YBP, the benthic foraminifera are absent, most likely because of the lower pH of the mixohaline/limnetic waters present when the continental contribution was highest. These different phases of marine and continental contributions could be explained by the higher or lower inflow of seawater to the paleolagoon of the JIES and by changes of the regional rainfall. RESUMO Muitos aspectos da Transgressão Santos (∼21.227–20.448 a ∼5558–4558 anos cal AP) são ainda controvertidos, especialmente antes de aproximadamente 7800 anos cal AP, devido à diferença de detalhamento de dados na costa brasileira. Nesse contexto, foram analisadas associações de foraminíferos bentônicos no testemunho S03, coletado na Estação Ecológica Juréia-Itatins (EEJI), entre 9400 e 8385 anos cal AP, para colaborar com o conhecimento acerca do nível relativo do mar na costa brasileira sudeste durante esse período. As análises microfaunísticas, tafonômicas, e morfométricas das testas e associações desses microorganismos permitiram a determinação de oito fases distintas nas condições paleoambientais na laguna então existente na EEJI. Houve quatro fases de contribuição oceânica mais conspícua (9400–9338, 9072–8894, 8656–8641, e 8594–8500 anos cal AP) com clímax há 8656 anos cal AP, quando o ambiente se tornou mais favorável ao crescimento, à preservação, ou ambos dos foraminíferos bentônicos. Elas foram entrecortadas por duas fases de contribuição continental proeminente (9338–9072 e 8500–8385 anos cal AP), quando houve aumento do gradiente hidrodinâmico local no local de coleta do testemunho S03. Além disso, entre 8806 e 8672 anos cal AP e entre 8625 e 8594 anos cal AP, os foraminíferos bentônicos estiveram ausentes, muito provavelmente devido ao menor pH das águas oligohalinas/limnéticas presentes quando a contribuição continental à paleolagoa da EEJI foi maior. Essas diferentes contribuições podem estar vinculadas a modificações da pluviosidade regional e a diferenças no comportamento marinho durante sua fase transgressiva.

The Colônia Impact Crater: Geological Heritage and Natural Patrimony in the Southern Metropolitan Region of São Paulo, Brazil

The Parelheiros district, located at the extreme southern end of the São Paulo metropolitan region, is historically famous for the occurrence of an unusual circular depression, denominated in the geological literature as Colônia Crater. This prominent geomorphological structure, with a 3.6-km diameter, formed by impact cratering, represents one of the few records of a violent and devastating geological process that shaped the Earth’s surface in the past. The crater lies within an environmental protection area and displays a remarkable landscape, as well as a rich and singular fauna and flora. With a wide geological and biological diversity, the Colônia impact crater is an extraordinary natural heritage and must be rigorously preserved to: (a) conserve its exceptional natural wealth in order to provide continuity to various scientific researches, (b) implement suitable land use and occupation programmes to maintain the crater as an environmental preservation area and (c) encourage the local community’s participation in the development of sustainable tourism in the region.

Estudo Malacológico de Sambaquis de Momuna (Iguape - SP) e o seu significado paleoambiental

Na planicie costeira de Iguape (SP) ocorrem sambaquis, que se acham situados a diferentes distâncias da atual linha de costa. Em geral, os sambaquis mais externos apresentam idades mais novas com predominância de conchas de Anomalocardia brasiliana, enquanto que os sambaquis mais internos, correspondentes a fase de maior expansao lagunar holocenica, entre 5 a 6 ka B.P., comumente apresentam a Crassostrea brasiliana. Alem disso, tem sido verificado que as razoes δ13C(PDB) das conchas variam segundo as posicoes geograficas dos sambaquis, em funcao das flutuacoes do NRM (nivel relativo do mar) com o tempo. Neste trabalho foram estudadas malacofaunas de sambaquis de Momuna 1 e 2, situados na localidade homonima (Iguape, SP), sobre terracos pleistocenicos da Formacao Cananeia (120 ka B.P.).

Geoprocessamento na análise morfoestrutural da região entre Marília e Presidente Prudente (SP)

For a better understanding of the distribution and occurence of Quaternary deposits between Marilia and Presidente Prudente (Sao Paulo State) was done the morphostructural characterization by geoprocessing techniques. The data was obtained by crossing the field surveys, topography, remote sensing products and thematic maps using Geographic Information System (GIS).. The morphometric data enabled the reconnaissance of regional compartments dominated by morphogenetic and pedogenetic processes with well developed colluvial deposits. Geomorphological features exhibited good correlation with the lithological units, the tectonic structures and the presence of colluvial covers. The thicknesses of the colluvial deposits have a close relationship with the permeability and porosity changes that also control differencial erosion in the region. The obtained data will subsidize future decisions on anthropogenic occupations, because the quaternary deposits between Marilia and Preseidente Prudente (SP) exhibit high susceptibility for anthropogenic contaminations of soil and groundwater and erosion.

Sedimentological characterization of the quaternary deposits in the region between Marília and Presidente Prudente, São Paulo State, Brazil

Para caracterizacao sedimentologica e estudos de proveniencia de depositos coluviais de idade quaternaria (9±1 a 980±100 ka A.P. - datados por luminescencia), foram realizadas analises textural e mineralogica. Tais depositos ocorrem extensivamente entre Marilia e Presidente Prudente (SP), superpostos as rochas sedimentares do Grupo Bauru ou rochas basalticas do Grupo Serra Geral (Formacao Serra Geral), ambas de idade cretacica. Sao distribuidos irregularmente na regiao e foram estudados por metodos sedimentologicos e morfologicos. Os depositos coluviais sao compostos de areias muito finas a grossas e inconsolidadas, em sua maioria formada por graos monocristalinos de quartzo, de coloracao avermelhada por impregnacao de oxidos e hidroxidos de ferro. As analises granulometricas mostraram que os depositos coluviais apresentam contribuicao maior de areia argilosa do que as rochas sedimentares sotopostas. O estudo microscopico de minerais pesados transparentes nao-micaceos mostrou que, tanto nas areias finas, quanto nas muito finas, zircao, turmalina, estaurolita e rutilo estao presentes em todas as amostras analisadas. As diferencas granulometricas constatadas entre os depositos coluviais e as rochas sedimentares do Grupo Bauru sao perfeitamente explicaveis por processos pedogeneticos.

Seções de referência de subsuperfície da aloformação Paranavaí

The Paranavai Alloformation is a Quaternary geological formation found in the Upper Parana River Hydrographic Basin (states of Sao Paulo, Parana and Mato Grosso do Sul), composed of colluvial deposits originated from the Cretaceous lithostratigraphic units of the Parana Basin. The sedimentary deposits are reddish brown in color, sandy, non-consolidated, homogeneous, massive, and commonly confused with surface soils and formations. In order to obtain subsurface reference sections for the Paranavai Alloformation, core samples were collected in two regions of the western part of the state of Sao Paulo. The study was conducted involving several parameters (textural, mineralogical, geochemical, isotopic and geochronological) of the sediments of the Paranavai Alloformation and Bauru Group. Two new reference sections were obtained in order to establish the composite-stratotype of its constituent formations: Rancharia reference section (luminescence ages between 71650 ± 9000 and 557000 ± 65000 years BP) and Oriente reference section (luminescence ages between 83000 ± 8500 and 436 ± 53000 years BP). The luminescent ages obtained in this study increase according to the depth of the Paranavai Alloformation, whereas the sediments of the Bauru Group have ages greater than the maximum limit of the geochronological method used. The information obtained from the reference sections shows variability in the patterns of various parameters, proving there were different generations of colluvial deposition throughout the Quaternary period in the western part of the state of Sao Paulo.