Geocronologia De Eventos Deposicionais Associados Às Coberturas Superficiais Que Sustentam E Recobrem Níveis De Terraços Marinhos Pleistocênicos E Holocênicos No Litoral Sul De Santa Catarina (Sc)

Abstract

Esta pesquisa objetiva identificar, espacializar e caracterizar morfologicamente níveis de terraços marinhos holocênicos e pleistocênicos dissecados pela dinâmica fluvial do baixo curso do rio Araranguá (SC), localizado no litoral sul do Estado de Santa Catarina. Simultaneamente objetiva correlacioná-los, mediante geocronologia das coberturas superficiais que os sustentam/recobrem, a episódios marinhos transgressivos e regressivos identificados pela literatura paleoclimática nacional e internacional. A metodologia baseou-se na elaboração de modelos digitais de elevação e perfis topográficos a partir de imagens de radar com resolução espacial de 30 metros; realização de trabalhos de campo, testes granulométricos e datações absolutas por Luminescência Opticamente Estimulada (LOE) em grãos de quartzo das coberturas superficiais, utilizando procedimentos indicados pelo protocolo SAR (Single Aliquot Regenerative-dose) em 15 alíquotas. Os resultados evidenciaram 4 níveis de terraços marinhos no litoral sul do Estado de Santa Catarina. Os terraços marinhos de nível I e II foram elaborados por episódios eustáticos pleistocênicos regressivos (MIS5d → NI e NII → >75.000 anos A.P.) que sucederam o máximo da Transgressão Cananeiense há 123.000 anos A.P. (MIS5e). Apresentam superfícies irregulares, bem dissecadas por processos erosivos, havendo afluentes do rio Araranguá, sistemas lagunares e atividades antrópicas. Os terraços marinhos de nível III (NIII → 6.000 ± 820 / 5.000 ± 620 anos A.P.) e IV (NIV → 420 ± 65 / 165 ± 35 anos A.P) foram elaborados por episódios eustáticos holocênicos regressivos que sucederam o máximo da Transgressão Santista há 5.500 anos A.P. (MIS1), os quais apresentam-se mais conservados e menos alterados pelos processos morfoesculturais atuais.

Terraces and their relationship with the river incision in great escarpments passive margin: genetic and geochronological aspects

“…Usually, the terraces found at the Southern Mantiqueira do not adhere completely to the position of depositional levels and their ages, in the same way it was observed, for example, in the works by Oliveira (2012) at the Pomba river basin (MG), by Dias (2015) at the São Paulo Peripheral Depression, and by Rubira and Perez Filho (2019) at the Santa Catarina coast. The Mantiqueira Mountains have an particularity given by the high relief energy and strong rework at slopes and channels that lead to a discontinuous terrace distribution, which can vary from one to three depositional levels with strong adherence to local hydrogeomorphological factors (figure 7).…”

“…Terraces are important landscape geoindicators, preserving depositional registers that are often valuable for deduction regarding climate and tectonic control in the evolution of relief (Leopold et al, 1964;Schumm, 1977;Christofoletti, 1981;Charlton, 2008). Due to that, terraces have been regarded as a nuclear object of study in many studies that are geochronologicaly set in the Quaternary (Etchebehere, 2000;Oliveira, 2012;Rubira;Perez Filho, 2019). In geomorphological contexts of great escarpments, characterized by active tectonics and accentuated fluvial dissection and incision works, these geoforms can take on different meanings, and are thus valuable to understand the neoquaternary evolution of landscape.…”

Genesis and Distribution of Low Fluvial Terraces Formed by Holocene Climate Pulses in Brazil

“…In total, the absolute dating of 114 Optically Stimulated Luminescence (OSL) surface cover samples associated with low river terraces were employed in the present study. In detail, all data collected from 30 rivers were obtained by the Environmental Analysis and Territorial Dynamics of the Laboratory of Geomorphology and Environmental Analysis IG-UNICAMP [27,34,36,37,41,42,44,[66][67][68][69][70][71][72][73].…”

“…Southeast coast areas are linked to estuaries and deltaic plains connected to the mouths of the Paraíba do Sul (see box E) and Ribeira do Iguape (see box F) [75] rivers. Regarding the southern coast of Brazil, we used data from the surficial covers of low terraces located on coastal plains associated with the mouth of the Araranguá (see box G) [36,76] and Itapocu (see box G) [73] rivers. Within the scope of the continental morphological compartments of Northeast Brazil, absolute ages correspond to surficial covers associated with low terraces located at the middle course of the Itapicuru (see box C of Figure 1) [42,69,72] and Grande (see box B) rivers, both in the Southern Sertaneja Depression.…”

“…Southeast coast areas are linked to estuaries and deltaic plains connected to the mouths of the Paraíba do Sul (see box E) and Ribeira do Iguape (see box F) [75] rivers. Regarding the southern coast of Brazil, we used data from the surficial covers of low terraces located on coastal plains associated with the mouth of the Araranguá (see box G) [36,76] and Itapocu (see box G) [73] rivers.…”