Journal of Coastal Research SI 39 1723 - 1726 ICS 2004 (Proceedings) Brazil ISSN 0749-0208

HORN FILHO, N.O.; DIEHL, F.L.;AMIN JR,A. H; MEIRELES, R.P. andABREU, J.G. de., 2006. Coastal geologyof the central-northern coast of the State of Santa Catarina, Brazil. Journal of Coastal Research, SI 39 (Proceedingsof the 8th International Coastal Symposium), 1723 - 1726. , SC, Brazil, ISSN 0749-0208.

The coastal province of the central-northern coast of the State of is comprised of two geological sub-provinces: a) basement and b) basin, the submerged portion of which corresponds to continental shelf. Thesurface sector of this basin represents the coastal plain, delimited by two interdigitated depositional systems: (1) thecontinental, confined to the highlands of the basement and (2) the transitional or coastal, a product of the successiveeustatic oscillations occurring during the Quaternary period. The continental units include colluvium, alluvial fanand alluvial deposits of the undifferentiated Quaternary period. The coastal units include the marine (beach), eolic,lagoonal, fluvial-lagoonal and paludial deposits of late Pleistocene (120ka) and Holocene (5.1ka present) periods.

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Coastal geology, sedimentology, geomorphology.ADITIONAL INDEX WORDS:

ABSTRACT

Coastal Geology of the Central-Northern Coast of the State of

Santa Catarina, Brazil

N. O. Horn Filho; F. L. Diehl; A. H. Amin Jr. ; R.P. Meireles and J.G.N. de Abreu

INTRODUCTION METHODS

The coastal plain includes a series of geomorphologicalfeatures and depositional facies of various sedimentationenvironments. They include the marine, eolic, lagoonal, fluvial,estuarine, and paludial domains, among others; all correlatedwith the transgressive processes and episodes occurring duringthe Quaternary period.

This article is a consequence of the results of the projectMorphodynamic, geologic and paleogeographic study of thecoastal plain of the central-northern coast of andin particular, of the sub-project Geological mapping of thecoastal plain of the central-northern coast of the State of

, Brazil, which was developed between 1994 and1998 by researchers of the University of , with thesupport of the . It constitutes thebasis of forthcoming multidisciplinary studies, owing to the factthat it presents fundamental geological elements of the coastalQuaternary period, as shown in preliminary publications of

and (1995a,b), (1995),(1995), (1996), and

(1996), . (1996a,b; 1997),(2000), (2003) e (2003).

The coastal plain of the area studied (1,399km) is located inthe northern region of the central sector of the State of

, between the 2630' and 2725' latitude south and4825' and 4845' longitude west (Figure 1), adjacent to a 220km extension of south Atlantic ocean on the southeasternbrazilian coast. The plain is crossed, from north to south, by theBR101 highway, which runs parallel to the coastline adjacent toAtlantic ocean. The area delineated forms part of theplanialtimetric maps, on the pages for (IBGE, 1974),

(IBGE, 1981a), (IBGE, 1981b) and(IBGE, 1983). It represents a coastal sector with

intense tourism activity and human occupation, which hascaused significant environmental changes.

On the coastal plain, the main units were studied from ageological, geomorphologic, sedimentological and

perspective, the product of which isrepresented by the geological map of the coastal Quaternary ofthe central-northern coast of the State of , in thesouth of Brazil, at a scale of 1:120,000.

A bibliographic review was initially made of the principalworks carried out on the area under consideration, focusing inparticular, on studies with a geological basis. Next, apreliminary analysis was carried out of the satellite images, at ascale of 1:100,000, in order to gain an overal view of the region.

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HORN FILHO DIEHL HORN FILHODIEHL DIEHL DIEHL HORNFILHO HORN FILHO AMIN JR.

ABREU MEIRELES

palaeogeographical

Departament of Geosciences, CFH,UFSC, Florianpolis, 88040-900, SC,Brasil horn@cfh.ufsc.br

Journal of Coastal Research Special Issue 39, 2006,

Geological Oceanography Laboratory,CTTMar, UNIVALI, Itaja, 88302-202,SC, Brasil fdiehl@cttmar.univali.br

Center for Studies in Coastal andOceanic Geology, UFRGS, PortoAlegre, 91540-000, RS, Brasilquaternario@msn.com

Figure 1. Localization map.

RIO GRANDE DO SUL-------------29 23' 55" S.

The map image of the central-northern coast of1996) (Figure 1), was very important for the

carrying out of this stage of the work. The next phase consistedof an interpretation of the aerial photographs from the1977/1978 aerial survey, at a scale of 1:25,000, generatingpreliminary geological maps. This was followed by thefieldwork in the area to be mapped, during which 144 surfacesamples of rocks and sediments were collected, which weresubmitted to granulometric analysis. The field data were addedto the Geographical Information System - GIS.

The coastal province of the central-northern coast ofis comprised of two fundamental geological sub-

provinces: the crystalline basement and the basin. Thesector of this basin with an outcropping surface represents thecoastal plain, demarcated by two interdigitated depositionalsystems: (1) continental, confined to elevations typical ofcrystalline basement and, (2) transitional or coastal, the result ofsuccessive eustatic fluctuations during the Quaternary period.

The principal deposits of the coastal plain include: eluvial,coluvial and alluvial fan deposits; fluvial deposits of thefloodplains; fluvial deposits of the marginal dikes; lagoonaldeposits; eolic deposits; marine beach deposits, paludialdeposits and beach deposits (Figure 2).

The quaternary outcropping deposits on the coastal plain ofthe central-northern coast of the State was subdivided accordingto age of formation, with characteristics of undifferentiatedQuaternary, late Pleistocene and Holocene periods.

In the area of the study, the following lithostratigraphic unitsof the crystalline basement are outcropping (Table 1):

Granulitic Complex; MetamorphicComplex; Formation of the Group;Granite; Migmatite Nucleus of and granite-gnessicStrip of , both of the Complex, and theintrusive suites of and . These units,of the archean, proterozoic and eo-paleozoic periods, areformed of granites, granitoids, gneisses, quartzites, migmatites,metaultramafics, micaschists, metacalcareas, marbles andarenites.

The continental deposits include the eluvial and coluvialdeposits, the alluvial fan deposits and the fluvial deposits,accumulated in an undifferentiated way during the entireQuaternary period. They are restricted to the tops of theelevations of the crystalline basement, at altitudes higher than20m, for the eluvials and coluvials; between 15 and 20m, for thealluvials fans and between 2 and 15m, for the alluvial deposits.

The pleistocenic deposits include the intertidal marine beachdeposits, partially or totally covered by eolic sediments and theadjacent lagoonal deposits. The terraces of the flat and slightly

undulating surface characterize the predominant form ofmarine and lagoonal deposits, whose altitudes reach maximumvalues of 12-17m and 10-12m, respectively. Both deposits areformed of fine and medium sands, well selected and ochre tolight brown in color. The overlying eolic sands are fine and red,yellow and brown in color.

The holocenic deposits include the intertidal marine beachdeposits covered by eolic sediments, lagoonal deposits orfluvial-lagoonal deposits and the paludial deposits.

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RESULTS

Coastal Geology

The marine beaches are in the form of terraces with flat tolightly undulating surfaces, alternated by depressions, humidand enriched by organic material. These are formed by asuccession of long, straight ridges and hollows, which may becontinuous and/or discontinuous, lying parallel to the currentcoastline, and reaching maximum altitudes of 3 to 7m in theelevations, and 1 to 2m, in the depressions. In terms of theirsedimentology, they consist of fine, medium and coarse sands,which are selected, mature and quartzose.

The lagoonal deposits, in the form of terraces of up to 4-5m inaltitude, appear around the lakes and lagoons, consisting of siltand sand-clay sediments, generally enriched with organicmaterial. These are formed by the processes of flooding anderosion in depressions during higher holocenic sea levels, whenthe extension of the lagoon reached larger areas than at present.

The fluvial lagoonal deposits, at altitudes of 4-5m, are mainlylocated in the regions of fluvial courses and consist of finesediments, originating from fluvial transport of clastic detritusto the interior of coastal lagoonal bodies.

The paludial deposits are associated with tidal plains inprotected marine areas, such as tidal channels, inlets and bays.They are comprised of silt-clay sediments, rich in organicmaterial, with vegetation cover typical of mangrove regions(

) and salt marshes ( ).

The formation of these pleistocenic and holocenic deposits ofthe coastal plain of the central-northern coast ofis closely linked to the changes in sea level which occurredduring the Quaternary period. These changes were controlledby tectonic and climatic factors, and alterations in the level ofthe oceans, known as tectonic, glacial and geoid eustasies,respectively 1980).

(1994) defined seven geoevolutional phases forthe coastal plains of the southeast and south of Brazil, four ofwhich were selected to describe the geological evolution of thearea studied.

Phase I Maximum Yarmoutian transgression/regression,corresponding to the Mindel/Riss interglacial period (120ka)Formation of continental deposits (eluvial, coluvial and alluvialfans), undifferentiated, from the beginning of this phase untilthe present day, in diverse climatic conditions. Formation of the

Avicenia schaueriana, Rhizophora mangle, LagunculariaRacemosa Spartina

Santa Catarina

Paleogeography

(MORNER,VILLWOCK

Journal of Coastal Research Special Issue 39, 2006,

Horn et al.1724

Figure 2. Geological diagram of the central-northern coastal province.

Journal of Coastal Research Special Issue 39, 2006,

alluvial deposits, forming part of the main fluvial courses of theregion. Higher sea level than today, eroding these deposits andthose of the exposed crystalline basement in the region of thecontinental islands.

Phase II Maximum Sangamonian-Wisconsiniantransgression/regression, corresponding to Riss/Wurminterglacial period (120ka - 18ka) Formation of marinedeposits, eolic and lagoonal deposits of the upper Pleistocene.Higher sea level than today, erosion of the pre-existing depositsand consolidation of the plains of pleistocenic beach ridges.

Phase III Maximum Flandrian transgression (18ka - 5.1ka)Total or partial erosion of the pre-formed deposits, leading tothe formation of cliffs of up to 4m in height. Higher sea levelthan today, but with lower values than during the Pleistoceneepoch.

Phase IV Current regression (5.1Ka - present) Formation ofbeach, eolic, lagoonal and fluvial-lagoonal deposits, limited tothe pleistocenic deposits through the cliffs formed in phase III.Formation of marine terraces, resulting from the gradualadvance of the coastline, leading to plains of coastal regressivebeach ridges. In low energy environments, the first paludialdeposits are formed, and continue to form until the present day.

The principal mineral occurrences associated with thelithological types of crystalline basement and the Quaternarycontinental and coastal deposits, include: a) rocks - granites,schists, marbles, metacalcareas, quartzites, pyroxenites,migmatites and quartzites, among others, used for foundationsand walls in civil construction, decorative stone, material forgravel, paving of sidewalks and roads, rocky outcrops of thecoastline, as a soil corrective and for the cement industry; b)sediments - sands and pebbles, for civil construction, paving ofstreets, landfill of low-lying areas or areas subject to flooding;and clays for the ceramics and pottery industry.

Based on the geomorphological and sedimentologicalcharacteristics of the surface deposits, the coastal plain of thecentral-northern coast may be subdivided into five distinctsectors, from north to south: (1) the sector; (2) the

river sector; (3) the peninsula sector; (4)the river sector and (5) the sector.

The stratigraphy of the immersed coastal plain overlying theopen marginal basin, includes the Quaternarysedimentary sequence settled on pre-mesozoic lithologicaltypes of the shield, denominated crystallinebasement. This sedimentary sequence includes continental andc o a s t a l d e p o s i t s , o f t h e u n d i f f e r e n t i a t e d a n dpleistocenic/holocenic epochs, respectively. These depositswere controlled by the sucession of transgressive and regressivemarine events associated with paleoclimatic episodes.

The geological units of the coastal plain are represented bycoluvial, alluvial fan, fluvial, fluvial-lagoonal, lagoonal,marine, eolic and paludal deposits. These units were originatedduring four geoevolutive phases defined in thepaleogeographical evolution by: phase I, characterizes themaximum of the Yarmoutian transgression/regression

(

Journal of Coastal Research Special Issue 39, 2006,

HORN FILHO, POLETTE, DIEHL,

HORN FILHO, DIEHL, AMIN JR

HORN FILHO, DIEHL, AMIN JR

HORN FILHO, DIEHL, AMIN JR

INSTITUTO BRASILEIRO DE GEOGRAFIA E ESTATSTICA

INSTITUTO BRASILEIRO DE GEOGRAFIA E ESTATSTICA

INSTITUTO BRASILEIRO DE GEOGRAFIA E ESTATSTICA

INSTITUTO BRASILEIRO DE GEOGRAFIA E ESTATSTICA

MORNER,

MEIRELES.

VILLWOCK,

N.O.; M. and F.L. 1995b.Aspectos geoecolgicos da plancie costeira adjacente praia Brava, Santa Catarina, Brasil.

(Niteri, Brasil,ABEQUA), pp. 142-150.N.O.; F.L. and ., 1996a.

Quaternary geology of the central-northern coastal plain ofthe Santa Catarina State, southern Brazil.

(Beijing, China,IUGS), p. 202-202.

N.O.; F.L. and ., A.H., 1996b.Geologia do Quaternrio da plancie costeira do litoralcentro-norte do estado de Santa Catarina, Brasil.

(Salvador, Brasil, SBG), v.5, pp. 278-280.N.O.; F.L. and ., A.H., 1997.

Geologia e paleogeografia do Quaternrio costeiro do litoralcentro-norte do Estado de Santa Catarina, sul do .

(Curitiba, Brasil, ABEQUA),pp. 71-75.

-IBGE., 1974.

Florianpolis, Brasil: IBGE/SEPLAN, s 1:50,000, 1sheet.

-IBGE., 1981a.

Florianpolis, Brasil: IBGE/SEPLAN, s1:50,000, 1 sheet.

-IBGE., 1981b.Florianpolis, Brasil: IBGE/SEPLAN, s 1:50,000, 1sheet.

-IBGE., 1983.Florianpolis, Brasil: IBGE/SEPLAN, s 1:50,000, 1sheet.

N.A., 1980. Eustasy and sea-level changes.84, 123-152.

R.P., 2003. Sedimentologia da provncia costeira dolitoral centro-norte de Santa Catarina: Universidade do Valedo Itaja, Monografia de concluso de curso deOceanografia, 102p.

J.A., 1994. A costa brasileira: geologia e evoluo., 7, 38-49.

Proceendigs of the 5Congresso da Associao Brasileira de Estudos doQuaternrio

Proceendigs of the

30 International Geological Congress

Proceendigs of the 39 Congresso Brasileiro de Geologia

Brasil

Proceendigs of the 6 Congresso da Associao Brasileirade Estudos do Quaternrio

Mapa planialtimtico da folha de Biguau.

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Mapa planialtimtico da folha de BarraVelha. cale

Mapa planialtimtico da folha de Itaja.cale

Mapa planialtimtico da folha de Cambori.cale

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