Marine deposits of the Chuy Formation (Late Pleistocene) and isostatic readjustments in the area of Laguna de Rocha (Uruguay)




quaternary, glaciations, isostasy, sea-level, oxygen isotopes


The Chuy Formation is characterized by up to 135 m of an alternation of green pelites and fine to coarse sandstones with sparse invertebrate fossils. The marine deposits are interbedded with continental, loessic deposits of the Libertad Formation and overlain by the Dolores Formation, made up of mudstones with calcareous concretions.

The results of the radiocarbon dating showed calibrated ages of 13.9±0.2, 41.5±1.9 and 50±3 ka BP on bioclasts of marine fossils at an elevation (above sea level, asl) of -2.8, -6.13 and -8 m respectively. Such ages and elevations are in disagreement with the sea-level evolution inferred for the Late Pleistocene. Two possible explanations are: (a) the ages represent minimum ages and deposition took place during the last interglacial at 115-130 ka (Marine Isotope Stage MIS 5e), or (b) they represent depositional ages but the area experimented large isostatic readjustments during and after the last glaciation. Several lines of evidence suggest a Late Pleistocene age for the upper Chuy Formation, including the d18O curve obtained from invertebrate shells, which shows large secular variations consistent with MIS 1 to 7.

The proposed scenario envisages significant subsidence between 50-20 ka due to the far-field effects of glacial load in the Andes/Patagonia. At 20 ka the eustatic regression outpaced subsidence, leading to continentalization of the Laguna de Rocha area. Marine conditions returned at 15 ka and into the Holocene, except for continental deposits (Dolores Formation) at ca. 11-10 ka (Younger Dryas). An uplift of 115 m took place between 15 and 9 ka in the area, which is interpreted as post-glacial rebound. In the Holocene, moderate subsidence was further recorded. A regional trend is observed, with uplift of marine deposits increasing towards the W-SW, which is consistent with an explanation as post-glacial isostatic rebound.


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Abre P, Blanco G, Gaucher C, Frei D, Frei R. Provenance of the Late Ediacaran Rocha Formation, Cuchilla Dionisio Terrane, Uruguay: tectonic implications on the assembly of Gondwana. Precambrian Res [Internet]. 2020 [cited 2022 Mar 31];342:105704. doi:10.1016/j.precamres.2020.105704.

Adkins JF, Boyle EA, Curry WB, Lutringer A. Stable isotopes in deep-sea corals and a new mechanism for vital effects. Geochim Cosmochim Acta. 2002;67:1129-43.

Angulo RJ, Lessa GC, de Souza MC. A critical review of mid-to late-Holocene sea-level fluctuations on the eastern Brazilian coastline. Quat Sci Rev. 2006;25:486-506.

Barboza EG, Dillenburg SR, do Nascimento Ritter M, Angulo RJ, da Silva AB, Rosa MLCC, Caron F, de Souza MC. Holocene sea-level changes in southern Brazil based on high-resolution radar stratigraphy. Geosciences [Internet]. 2021 [cited 2022 Mar 31];11: 326. doi:10.3390/geosciences11080326.

Bard E, Hamelin B, Delanghe-Sabatier D. Deglacial meltwater pulse 1B and Younger Dryas sea levels revisited with boreholes at Tahiti. Science. 2010;327:1235-7.

Blackwell PG, Buck CE, Reimer PJ. Important features of the new radiocarbon calibration curves Quat Sci Rev. 2005;25:408-13.

Blanco G, Abre P, Cabrera J, Gaucher C. Formación Rocha. In: Bossi J, Gaucher C, editors. Geología del Uruguay. Vol. 1, Predevónico. Montevideo: Polo; 2014. p. 401-8.

Bossi J, Ferrando L, Montaña J, Campal N, Morales H, Gancio F, Schipilov A, Piñeyro D, Sprechmann P. Carta geológica del Uruguay: escala 1:500.000. Montevideo: Geoeditores; 1998. 145p.

Bossi J, Ferrando L. Carta Geológica del Uruguay: escala 1/500.000 versión digital. Montevideo: Facultad de Agronomía; 2001. 1 CD­ROM.

Bossi J, Ferrando LA, Fernández A, Elizalde G, Morales H, Ledesma J, Carballo E, Medina E, Ford I, Montaña J. Carta geológica del Uruguay: escala 1/1.000.000. Montevideo: MAP; 1975. 32p.

Bossi J, Gaucher C. The Cuchilla Dionisio Terrane, Uruguay: an allochthonous block accreted in the Cambrian to SW-Gondwana. Gondwana Res. 2004;7:661-74.

Bossi J, Navarro R. Geología del Uruguay. Montevideo: Universidad de la República; 1991. 2v.

Bossi J, Ortiz A. Geología del Holoceno. In: García-Rodríguez F, editor. El Holoceno en la zona costera del Uruguay. Montevideo: Facultad de Ciencias; 2011. p. 13–48.

Bossi J, Schipilov A. Rocas ígneas básicas del Uruguay. Montevideo: Facultad de Agronomía; 2007. 363p.

Bracco R, García-Rodríguez F, Inda H, del Puerto L, Castiñeira C, Panario D. Niveles relativos del mar durante el Pleistoceno final – Holoceno y las costas de Uruguay. In: García-Rodríguez F, editor. El Holoceno en la zona costera del Uruguay. Montevideo: Facultad de Ciencias; 2011. p. 65-92.

Bracco R, Ures C. Las variaciones del mar y el desarrollo de las culturas prehistóricas del Uruguay. In: Actas II Congreso Uruguayo de Geología; 1998 May 13-18, Punta del Este, Uruguay. Montevideo: Facultad de Ciencias; 1998. p. 16-28.

Castiglioni EA. Variaciones del nivel del mar, glacio- e hidroisostáticas en la Laguna de Rocha y zonas aledañas, Uruguay [doctoral’s thesis]. Bahía Blanca (AR): Universidad Nacional del Sur; 2020. 227p.

Cernuschi F, Dilles JH, Kent AJR, Schroer G, Raab AK, Conti B, Muzio R. Geology, geochemistry and geochronology of the Cretaceous Lascano East Intrusive Complex and magmatic evolution of the Laguna Merín Basin, Uruguay. Gondwana Res. 2015;28:837-57.

Chappell J, Shackleton NJ. Oxygen isotopes and sea level. Nature. 1986;324:137-40.

Closs D. Estratigrafia da Bacia de Pelotas, Rio Grande do Sul. Iheringia Sér Geol. 1970;3:3-76.

Cohen MCL, França MC, de Fátima Rossetti D, Pessenda LCR, Giannini PCF, Lorente FL, Buso Jr AA, Castro D, Macario K. Landscape evolution during the late Quaternary at the Doce River mouth, Espírito Santo State, southeastern Brazil. Palaeogeogr Palaeoclimatol Palaeoecol. 2014;415:48-58.

Craig H. Isotopic standards of carbon and oxygen and correction factors for mass-spectrometric analysis of carbon dioxide. Geochim Cosmochim Acta. 1957;12:133-49.

Davies BJ, Darvill CM, Lovell H, Bendle JM, Dowdeswell JA, Fabel D, Garcia J-L, Geiger A, Glasser NF, Gheorghiu DM, Harrison S, Hein AS, Kaplan MR, Martin JRV, Mendelova M, Palmer A, Pelto M, Rodes A, Sagredo EA, Smedley RK, Smellie JL, Thorndycraft VR. The evolution of the Patagonian Ice Sheet from 35 ka to the present day (PATICE). Earth Sci Rev [Internet]. 2020 [cited 2022 Mar 31];204:103152. doi:10.1016/j.earscirev.2020.103152.

DeJong BD, Bierman PR, Newell WL, Rittenour TM, Mahan SA, Balco G, Rood DH. Pleistocene relative sea levels in the Chesapeake Bay region and their implications for the next century. GSA Today. 2015;25(8):4-10.

Delaney PJV. Quaternary geologic history of the coastal plain of Rio Grande do Sul, Brasil. Baton Rouge: Louisiana State University Press; 1963. 63p.

Dillenburg SR, Barboza EG, Rosa MLC, Caron F, Cancelli R, Santos-Fischer CB, Lopes RP, do Nascimento Ritter M. Sedimentary records of marine isotopic stage 3 (MIS 3) in southern Brazil. Geo-Mar Lett. 2019;40:1099-108.

Elizalde G. Conservación y mejora de playas. Montevideo: UNESCO; 1976. 12p.

Fairbanks RG. A 17,000-year glacio-eustatic sea level record: infuence of glacial melting rates on the Younger Dryas event and deep ocean circulation. Nature. 1989;342:637-42.

Fariña RA, Tambusso PS, Varela L, Czerwonogora A, Di Giacomo M, Musso M, Bracco R, Gascue A. Arroyo del Vizcaíno, Uruguay: a fossil-rich 30-ka-old megafaunal locality with cut-marked bones. Proc Biol Sci [Internet]. 2013 [cited 2022 Mar 31];281(1774):20132211. doi:10.1098/rspb.2013.2211.

Fjeldskaar W, Lindholm C, Dehls JF, Fjeldskaar I. Postglacial uplift, neotectonics and seismicity in Fennoscandia. Quat Sci Rev. 2000;19:1413-22.

Fjeldskaar W. The amplitude and decay of the glacial forebulge in Fennoscandia. Nor J Geol. 1994;74:2-8.

García-Rodríguez F, Metzeltin D, Sprechmann P, Trettin R, Stams G, Beltrán-Morales LF. Upper Pleistocene and Holocene paleosalinity and trophic state changes in relation to sea level variation in Rocha Lagoon, southern Uruguay. J Paleolimnol. 2004;32:117-35.

García-Rodríguez F, Witkowski A. Inferring sea level variation from relative percentages of Pseudopodosira kosugii in Rocha lagoon, SE Uruguay. Diatom Res. 2003;18:49-59.

Gómez EA, Perillo GME. Sediment outcrops underneath shoreface-connected sand ridges, outer Bahía Blanca estuary, Argentina. Quaternary of South America and Antarctica Peninsula. 1995;9:27-42.

Goñi JC, Hoffstetter R. Uruguay. In: Hoffstetter R, editor. Lexique stratigraphique international, Fascicule 9-a. Paris: Centre National de la Recherche Scientifique; 1964. p. 1-202.

Goso H. Cuaternario: programa de estudio y levantamiento de suelos. Montevideo: MGAP; 1972. 12p.

Goso H. El Cenozoico en el Uruguay. Montevideo: Instituto Geológico del Uruguay; 1965. 36p.

Goso H, Anton D. Estado actual de los conocimientos sobre el Cuaternario en el Uruguay. In: Anais do XXVIII Congresso Brasileiro de Geologia; 1974; Porto Alegre. São Paulo: Sociedade Brasileira de Geologia; 1974. p. 1-7.

Guilderson TP, Burckle L, Hemming S, Peltier WR. Late Pleistocene sea level variations derived from the Argentine Shelf. Geochemistry Geophys Geosystems [Internet]. 2000 [cited 2022 Mar 31];1(12). doi:10.1029/2000GC000098.

Hajdas I, Bonani G, Moreno PI, Ariztegui D. Precise radiocarbon dating of Late-Glacial cooling in mid-latitude South America. Quat Res. 2003;59:70-8.

Hoefs J. Stable isotope geochemistry. Berlin: Springer; 1997. 201p.

Hughen KA, Baillie MGL, Bard E, Warren Beck J, Bertrand CJH, Blackwell PG, Buck CE, Burr GS, Cutler KB, Damon PE, Edwards RL, Fairbanks RG, Friedrich M, Guilderson TP, Kromer B, McCormac G, Manning S, Bronk Ramsey C, Reimer PJ, Reimer RW, Remmele S, Southon JR, Stuiver M, Talamo S, Taylor FW, VAN der Plicht J, Weyhenmeyer CE. Marine04 marine radiocarbon age calibration, 0–26 Cal Kyr Bp. Radiocarbon. 2004;46(3):1059–86.

Inda H, García-Rodríguez F, del Puerto L, Acevedo V, Metzeltin D, Castiñeira C, Bracco R, Adams JB. Relationships between trophic state, paleosalinity and climatic changes during the first Holocene marine transgression in Rocha Lagoon, southern Uruguay. J Paleolimnol. 2006;35:699-713.

Jablonski D, Roy K, Valentine JW. Out of the tropics: evolutionary dynamics of the latitudinal diversity gradient. Science. 2006;314:102-6.

Keith ML, Weber JN. Carbon and Oxigen isotopic composition of selected limestones and fossils. Geochim Cosmochim Acta. 1964;28:1787-16.

Klicpera A. Carbonate secreting organisms in clastic shelf systems and their potential as environment archive [doctoral’s thesis]. Bremen (DE): Universität Bremen; 2014. 199p.

Lambeck K, Rouby H, Purcell A, Sun Y, Sambridge M. Sea level and global ice volumes from the Last Glacial Maximum to the Holocene. Proc Natl Acad Sci U S A. 2014;111:15296-303.

Lantzsch H, Hanebuth TJ, Chiessi CM, Schwenk T, Violante RA. The high-supply, current-dominated continental margin of southeastern South America during the late Quaternary. Quat Res. 2014;81:339-54.

LeGrande AN, Schmidt GA. Global gridded data set of the oxygen isotopic composition in seawater. Geophys Res Lett [Internet]. 2006 [cited 2022 mar 31];33:12604. doi:10.1029/2006GL026011.

Lima LG, Dillenburg SR, Medeanic S, Barboza EG, Rosa MLC, Tomazelli LJ, Dehnhardt BA, Caron F. Sea-level rise and sediment budget controlling the evolution of a transgressive barrier in southern Brazil. J S Am Earth Sci. 2013;42:27-38.

Lisiecki LE, Raymo ME. A Pliocene‐Pleistocene stack of 57 globally distributed benthic δ18O records. Paleoceanography. 2005;20:1-17.

Lisiecki LE, Raymo ME. Diachronous benthic δ18O responses during late Pleistocene terminations. Paleoceanography [Internet]. 2009 [cited 2022 Mar 31];24:PA3210. doi:10.1029/2009PA001732.

Lopes RP, Oliveira LC, Figueiredo AMG, Kinoshita A, Baffa O, Buchmann FS. ESR dating of Pleistocene mammal teeth and its implications for the biostratigraphy and geological evolution of the coastal plain, Rio Grande do Sul, southern Brazil. Quat Int. 2010;212:213-22.

Machado JPSL, Jelinek AR, Stephenson R, Gaucher C, Bicca MM, Chiglino L, Genezini FA. Low-temperature thermochronology of the South Atlantic margin along Uruguay and its relation to tectonic events in West Gondwana. Tectonophysics [Internet]. 2020 [cited 2022 Mar 31];784:228439. doi:10.1016/j.tecto.2020.228439.

Martínez S, Coimbra JC, Rojas A. Last Interglacial mollusks from the subsurface of the Rio Grande do Sul Coastal Plain, southernmost Brazil. J S Am Earth Sci [Internet]. 2019 [cited 2022 Mar 31];96:102331. doi:10.1016/j.jsames.2019.102331.

Martinez S, del Río CJ, Rojas A. A Pleistocene (MIS 5e) mollusk assemblage from Ezeiza (Buenos Aires Province, Argentina). J S Am Earth Sci. 2016;70:174-87.

Martínez S, Rojas A. Relative sea level during the Holocene in Uruguay. Palaeogeogr Palaeoclimatol Palaeoecol. 2013;374:123-31.

Martı́nez S, Ubilla M, Verde M, Perea D, Rojas A, Guérèquiz R, Piñeiro G. Paleoecology and geochronology of Uruguayan coastal marine Pleistocene deposits. Quat Res. 2001;55:246-54.

O'Neil JR, Clayton RN, Mayeda TK. Oxygen isotope fractionation in divalent metal carbonates. J Chem Phys. 1969;51:5547-58.

Pados T, Spielhagen RF, Bauch D, Meyer H, Segl M. Oxygen and carbon isotope composition of modern planktic foraminifera and near-surface waters in the Fram Strait (Arctic Ocean): a case study. Biogeosciences. 2015;12:1733-52.

Petit JR, Jouzel J, Raynaud D, Barkov NI, Barnola JM, Basile I, Bender M, Chappellaz J, Davis M, Delaygue G, Delmotte M, Kotlyakov VM, Legrand M, Lipenkov VY, Lorius C, Pépin L, Ritz C, Saltzman E, Stievenard M. Climate and atmospheric history of the past 420,000 years from the Vostok ice core, Antarctica. Nature. 1999;399:429-36.

Reimer PJ. Composition and consequences of the IntCal20 radiocarbon calibration curve. Quaternary Res. 2020;96:22-7.

Rojas A, Martínez S. Marine Isotope Stage 3 (MIS 3) Versus Marine Isotope Stage 5 (MIS 5) Fossiliferous Marine Deposits from Uruguay. In: Gasparini GM, Rabassa J, Deschamps C, Tonni EP, editors. Marine Isotope Stage 3 in Southern South America, 60 KA BP-30 KA BP. Cham: Springer; 2016. p. 249-78.

Rosa MLCDC, Barboza EG, Abreu VDS, Tomazelli LJ, Dillenburg SR. High-frequency sequences in the quaternary of Pelotas Basin (coastal plain): a record of degradational stacking as a function of longer-term base-level fall. Braz J Geol. 2017;47:183-207.

Rostami K, Peltier WR, Mangini A. Quaternary marine terraces, sea-level changes and uplift history of Patagonia, Argentina: comparisons with predictions of the ICE-4G (VM2) model of the global process of glacial isostatic adjustment. Quat Sci Rev. 2000;19:1495-525.

Schmidt GA, Bigg GR, Rohling EJ. Global Seawater Oxygen-18 Database [Internet]. v1.22. [place unknown]: NASA; 1999 [cited 2022 Mar 31]. Available from:

Scott TW, Swift DJ, Whittecar GR, Brook GA. Glacioisostatic influences on Virginia's late Pleistocene coastal plain deposits. Geomorphology. 2010;116:175-88.

Sprechmann P. The paleoecology and paleogeography of the Uruguayan coastal area during the Neogene and Quaternary. Zitteliana. 1978;4:3-72.

Thompson WG, Goldstein SL. A radiometric calibration of the SPECMAP timescale. Quat Sci Rev. 2006;25:3207-15.

Tonni EP, Carbonari JE, Huarte R. Marine sediments attributed to marine isotope stage 3 in the southeastern Buenos Aires province, Argentina. Current Research in the Pleistocene. 2010;27:154-6.

Ubilla M, Martínez S. Geology and paleontology of the quaternary of Uruguay. New York: Springer; 2016. 77p.

Waelbroeck C, Labeyrie L, Duplessy EM, McManus JC, Lambeck FK, Balbona E, Labracherie M. Sea-level and deep water temperature changes derived from benthic foraminifera isotopic records. Quat Sci Rev. 2002;21:295-305

Weber JN, Woodhead PMJ. Temperature dependance of oxygen-18 concentration in reef coral carbonates. J Geophys Res. 1972;77:463-73.

Wickert AD, Anderson RS, Mitrovica JX, Naylor S, Carson EC. The Mississippi River records glacial-isostatic deformation of North America. Sci Adv [Internet]. 2019 [cited 2022 Mar 31];5(1):eaav2366. doi:10.1126/sciadv.aav2366.

Willig MR, Kaufman DM, Stevens RD. Latitudinal gradients of biodiversity: pattern, process, scale, and synthesis. Annu Rev Ecol Evol Syst. 2003;34:273-309.




How to Cite

Castiglioni E, Gaucher C, Perillo GME, Sial AN. Marine deposits of the Chuy Formation (Late Pleistocene) and isostatic readjustments in the area of Laguna de Rocha (Uruguay). Agrocienc Urug [Internet]. 2022 May 27 [cited 2023 Feb. 1];26(NE1):e799. Available from: