The influence of subaquatic springs in lacustrine sedimentation: Origin and paleoenvironmental significance of homogenites in karstic Lake Banyoles (NE Spain)

Autor: Flavio S. Anselmetti, M. Pilar Mata, Santiago Giralt, Blas L. Valero-Garcés, Fernando Barreiro-Lostres, Daniel Ariztegui, Ana Moreno, Alberto Sáez, M. Rico, Mario Morellón
Přispěvatelé: Universitat de Barcelona
Jazyk: angličtina
Rok vydání: 2014
Předmět:
Zdroj: Dipòsit Digital de la UB
Universidad de Barcelona
Recercat. Dipósit de la Recerca de Catalunya
instname
Sedimentary Geology, Vol. 311 (2014) pp. 96-111
Digital.CSIC. Repositorio Institucional del CSIC
ISSN: 0037-0738
DOI: 10.7892/boris.53177
Popis: Banyoles (42°08'N, 2°45'E) is the largest and deepest lake of karstic-tectonic origin in the Iberian Peninsula. The lake comprises two basins and six sub-circularly shaped sub-basins fed by subaquatic springs. Periods of intense groundwater inflow in the deepest sub-basins lead to the fluidization and re-suspension of previously deposited sediments and subsequent settling forming homogenite deposits on the southern basin intermediate platforms. The multiproxy analysis of sediment cores combined with high resolution seismic stratigraphy (3.5kHz pinger and multi-frequency Chirp surveys) allows a precise reconstruction of depositional environments and related hydrological variability and groundwater inflow during the last ca. 7.6cal kyr BP. According to the age model based on 137Cs, 210Pb and AMS 14C dating, homogenite deposition occurred between 7.2 and 5.5cal kyr BP, stopped during the middle Holocene (5.5-2.8cal kyr BP) and greatly increased during the last two millennia with a total of 17 homogenite layers individually up to 75cm-thick. The onset of this unique sedimentation mode at ca. 3cal kyr BP coincides with an increase in lake level, evidenced by the onlapping of fine-grained, distal sediments over coarser massive, carbonate-rich, littoral deposits. A detailed, multidisciplinary study of the homogenites (sedimentology, physical properties, high-resolution elemental geochemistry, mineral composition, grain-size, organic matter content and SEM) combined with seismic stratigraphy demonstrates that the fluidization events triggering the formation of the homogenites were caused by higher and more intense local groundwater inflow, related to increased rainfall during the Late Holocene and likely intensified by land use changes during the last millennium. © 2013 Elsevier B.V.
Financial support for research was provided by the Spanish Inter-Ministry Commission of Science and Technology (CICYT), through the projects GLOBALKARST (CGL2009-08415) and GRACCIE-CONSOLIDER (CSD2007-00067). Additional funding was provided by INTIMATE-COST through a travel grant ‘Short Term Scientific Mission, COST Action ES0907’ in 2011 at IPE-CSIC and University of Barcelona (Spain). M. Morellón and F. Barreiro hold ‘JAE-DOC’ and ‘JAE-PREDOC’ pre and postdoctoral contracts, respectively, both co-funded by C.S.I.C. and the European Social Fund. We acknowledge the Town Hall of Banyoles (Girona) and Club Natació Banyoles for their collaboration in fieldwork activities and Jaime Frigola and Pol Tarrats (Univ. of Barcelona), and Miguel Sevilla and Josu Aranbarri (IPE-CSIC) for coring assistance in 2011. We are also grateful to Irene Brunner, Silvia Bollhalder, Marian Fujak, Alois Zwyssig and Brian Sinnet (Eawag, Switzerland); Adrian Gilli and Stephanie Wirth (ETH-Zürich, Switzerland) and Beatriz Bueno, Aida Adsuar and Miguel Bartolomé (IPE-CSIC, Spain) for their laboratory assistance and collaboration in this research. We thank constructive comments on the manuscript made by Maria Rieradevall (Univ. of Barcelona). We also acknowledge the anonymous reviewers for their helpful comments and their criticism, which led to a considerable improvement in the manuscript.
Databáze: OpenAIRE
Externí odkaz: