DOI: 10.1590/2317-4889201720170057 ARTICLE Evidence of an Marine Isotope Stage 3 transgression at the Baixada Santista, south-eastern Brazilian coast Evidência de uma transgressão na Baixada Santista durante o Estágio Isotópico 3 André da Silva Salvaterra1, Rosangela Felício dos Santos1, Alexandre Barbosa Salaroli1, Rubens Cesar Lopes Figueira1, Michel Michaelovitch de Mahiques1,2* ABSTRACT: In this paper, we present new evidence regarding a RESUMO: Neste artigo, apresentamos novas evidências sobre a trans- Marine Isotope Stage 3 (MIS3) transgression on the south-eastern gressão ocorrida Estágio Isotópico 3 (MIS3) na costa do sudeste do Brasil Brazilian coast (Baixada Santista coastal plain). Data collected from (Baixada Santista). Dados coletados por meio de um ensaio de pene- a Standard Penetration Test (SPT) drilling reveal the occurrence of tração em solo (SPT) revelam a ocorrência de sedimentos mixohalinos myxohaline sediments between cal BP 45,000 and 41,000. A de- entre 45.000 e 41.000 anos a.P. Uma sequência mais profunda, que eper sequence, which shows a clear transition from terrestrial to a mostra clara transição de ambiente continental para um mixohalino, foi myxohaline environment, was associated with MIS5e. Organic and associada ao Estágio Isotópico 5e (MIS5e). Marcadores orgânicos e in- inorganic proxies have been used to recognize the variations on the orgânicos foram usados para reconhecer as variações dos ambientes ter- terrestrial/myxohaline/marine deposits, as well as to infer about cli- restre/mixohalino/marinho, bem como inferir sobre o clima e a energia mate and energy of the depositional environment. Environmental do ambiente deposicional. Uma mudança ambiental, que poderia cor- change, which could correspond to a sea-level peak or the occurrence responder a um pico do nível do mar ou à ocorrência de condições mais of drier conditions, was recognized between 43,000 and 42,000 cal secas, foi reconhecida entre 43.000 e 42.000 anos a.P. Os resultados re- BP. The results reinforce the need for future works on MIS3 variabi- forçam a necessidade de futuros trabalhos sobre a variabilidade do MIS3 lity on the South American Atlantic coast. na costa atlântica sul-americana. KEYWORDS: Marine Isotope Stage 3; Late Pleistocene; sea-level. PALAVRAS-CHAVE: MIS3; Pleistoceno superior; nível do mar. 1Instituto Oceanográfico, Universidade de São Paulo – USP, São Paulo (SP), Brazil. E-mails: [email protected], [email protected], [email protected], [email protected], [email protected] 2Instituto de Energia e Meio Ambiente, Universidade de São Paulo – USP, São Paulo (SP), Brazil. E-mail: [email protected] *Corresponding author Manuscript ID: 20170057. Received in: 04/19/2017. Approved in: 09/01/2017. 693 Brazilian Journal of Geology, 47(4): 693-702, December 2017 MIS3 Transgression, SE Brazil INTRODUCTION Brazilian coast might need to be reviewed due to the possi- ble occurrence of an MIS3 highstand. The Marine Isotope Stage 3 (MIS3) corresponds to the In this paper we analyze a new set of sedimentolog- time interval between 60 and 25 ka (Siddall et al. 2008) and ical and geochemical data, coming from a drilling per- is marked by a series of abrupt oscillations, corresponding formed in the Baixada Santista coastal plain (southeast to in the form of warming periods (Chappell 2002, Van Brazil), with evidence of two transgressive events, one Meerbeeck et al. 2009). Estimates based on δ18O chronol- of them with evidence of an MIS3 transgression. Data ogies and U/Th dating of coral reefs indicate that during will be compared with other evidence of an MIS3 sea- this time interval sea level oscillated between 80 and 30 m level rise, reported in the SW Atlantic as well as in other below present sea level (mbsl) (Chappell & Shackleton 1986, coastal areas. Lambeck and Bard 2000, Chappell 2002, Pahnke et al. 2003, Rabineau et al. 2006). Short-term oscillations in time inter- vals between 6,000–7,000 years followed by 10–15 m sea- STUDY AREA level rise events, corresponding to Heinrich events, occurred in this time interval (Chappell 2002). The study site (Fig. 1) is located in the so-called Baixada On the other side, there are several papers that report Santista coastal plain, an area covered by Late Pleistocene the occurrence of MIS3 highstands at levels considerably / Holocene coastal and marine muddy to sandy deposits, shallower than those ones reported by the traditional sea originally associated with two main transgressive events: level curves (Cann et al. 1993, Murray-Wallace et al. 1993, Cananeia (MIS 5e) and Santos (Mid-Holocene) (Suguio Rodriguez et al. 2000, Murray-Wallace 2002, Hanebuth & Martin 1978b). et al. 2006, Simms et al. 2009, Doğan et al. 2012). Towards the continent the coastal plain is limited by the In South America, other examples of MIS3 highstands Serra do Mar mountain range, exhibiting a width, variable have been described both in the Atlantic and Pacific coasts from a few to almost 20 km. The Quaternary sediments are (Isla 1990, Isla & Schnack 2016), but part of these data locally interrupted by Pre-Cambrian massifs, forming groups have been disproved by Schellmann and Radtke (1997), of hills that are aligned according to SW-NE (Almeida & who compared radiocarbon data with Electron Spin Carneiro 1998). Resonance (ESR) information. In the Brazilian coast, According to Suguio and Martin (1978a), the Cananeia Silva et al. (2014) recognized a lagoonal environment, Transgression is associated with a sea level rise that reached dated from 47,000 to 36,000 BP, in the Maricá coastal about 8 m above present sea level (mapsl), while the Santos plain (state of Rio de Janeiro). Transgression reached 4.5 mapsl. Aspects of the evolution Additionally, a complete set of coherent (no age rever- of the deposits were studied by Suguio and Martin (1978a) sal) radiocarbon ages in both organic matter and foramin- and Coelho et al. (2010). Angulo et al. (2006) reviewed the ifera, ranging from 39,000 to about 24,000 BP, marks the Mid- to Late Holocene sea-level changes and defined an transition of myxohaline to freshwater conditions in a shal- envelope in which the maximum sea-level of 5.6 cal yr BP low-water (6 mbsl) deposit in the São Sebastião Channel ranged from 2 to about 4 mapsl. (state of São Paulo) (Mahiques et al. 2011). Other unpub- On the other hand, there is almost no information lished (thesis) data, from the Paraná state, also report MIS3 about the position of the sea-level of the eastern to south- high levels in the shelf and adjacent coastal plain (Souza ern Brazilian between the climatic optimum of the MIS5e 2005, Veiga 2005). and the early Holocene. Corrêa (1996) proposed a sea- The main criticism of the papers dealing with MIS3 high- level curve between the Last Glacial Maximum and the stands is associated with the limitations of the radiocarbon early Holocene, based on the position of abrasion terraces as a geochronological tool. Indeed, a significant part of the on the southern Brazilian continental shelf and comparing MIS3 interval cannot be dated with confidence beyond cal them with global sea-level curves. Vicalvi et al. (1978) rec- BP 45,000, and contamination of older materials with young ognized a paleo-lagoon at the Abrolhos Depression (Eastern carbon can result in apparent MIS3 ages (Murray-Wallace Brazilian shelf), dating them at 10,600 yr BP (uncalibrated). et al. 1993, Yim 1999, Hanebuth et al. 2006). On the other Finally, Mahiques et al. (2011), presented four datings on hand, the introduction of the Accelerator Mass Spectrometry different material from a beach-rock located at 13 mbsl São (AMS) technique to radiocarbon dating (Dorn et al. 1989) Sebastião (southeastern Brazil), which gave calibrated ages brought another perspective to the original chronology lim- around 8,200 yr BP. itation of cal BP 30,000 years. Thus, it is possible that sev- Suguio and Martin (1978a) provided an interpreta- eral Pleistocene samples dated in the original studies of the tive profile of sedimentary deposits in the area (Fig. 2), 694 Brazilian Journal of Geology, 47(4): 693-702, December 2017 André da Silva Salvaterra et al. recognizing continental sediments, marine and sand dunes 23º57.2512’S and 46º24.6018’W, at the altitude of 8 mbsl of Late Pleistocene age, transitional sediments and Holocene (Fig. 1). From the SPT drilling, a cylinder of 15 cm was lagoonal deposits, in addition to modern alluvium deposits recovered at each 1 meter. Samples were then air-dried and located at the base of the Serra do Mar range. kept in polyethylene vials until laboratory analysis. The lower terrains lead to the establishment of a com- Radiocarbon dating was performed on the organic fraction plex of estuarine channels, bordered by mangrove vegeta- of sediment samples by the Accelerator Mass Spectrometry tion. On the other side, the sandy deposits and a significant (AMS) at Beta Analytic Laboratories (Miami, United States). part of the hills are presently occupied by urban, industrial Calibrated ages have been calculated according to the SH13 and port infrastructure, which makes the Baixada Santista Southern Hemisphere Calibration (Hogg et al. 2016). one of the most developed areas of Brazil. Grain size was performed in a Malvern Mastersizer 2000 laser diffraction system. Approximately 4 g of dry sediment were leached with H2O2 until the complete removal of the organic METHODS matter. Finally, 20 mL of a solution of 25% sodium hexamet- aphosphate was added as a dispersant. Results were obtained In this paper, we analyzed a 58.45 m long Standard in intervals of 1/4φ, and statistical parameters were calculated Penetration Test (SPT) drilling, located at the coordinates with the aid of the Gradistat macro (Blott & Pye 2001). -23 -23.2 -23.4 1,300 1,200 -23.6 1,100 1,000 -23.8 900 800 700 -24 600 Meters 500 400 -24.2 300 200 100 -24.4 0 -100 -24.6 -200 -24.8 -25 -47.4 -47.2 -47 -46.8 -46.6 -46.4 -46.2 -46 -45.8 -45.6 Figure 1.