Diatom paleoecology of the Mar Chiquita lagoon delta, Argentina
- 77 Downloads
A 68 cm thick outcrop of diatomaceous sediments at the head of Mar Chiquita Lagoon on the Argentine coast near Buenos Aires provides evidence of Holocene paleoenvironmental changes related to sea level changes and freshwater input to the lagoon system. Salinity tolerances of extant diatom taxa were used for the reconstruction and multivariate analytical techniques were applied to reduce subjective interpretations of the diatom percentage data.
The basal half of the record was deposited before 3000 years ago and fossil diatoms indicate generally freshwater conditions with one fluctuation in mesohalobous diatoms suggesting brackish water conditions at a depth of about 60 cm. Polyhalobous (marine) diatoms characterize the record after 3000 years ago and large numbers of epiphytic diatoms indicate salt marsh environments with episodic seawater fluctuations to supratidal levels. Freshwater diatoms returned at the top of the outcrop, presumably as a result of the restriction of the historic marine inlet to the lagoon and the effects of freshwater inflow to the basin.
Key wordsdiatoms paleoecology multivariate analysis coastal lagoon Holocene environmental changes South America Argentina
Unable to display preview. Download preview PDF.
- Fontes, J. Ch., F. Gasse, Y. Callot, J. C. Plaziat, P. Carbonel, P. A. Dupeuble & I. Kaczmarska, 1985. Freshwater to marine like environments from Holocene lakes in northern Sahara. Nature 317: 608–610.Google Scholar
- Hendey, N. I., 1964. An introductory account of the smaller algae of the British coastal waters. Part V. Bacillariophyceae (Diatoms). Fish. Invest. Series IV. Her Magesty's Stationery Office, London, 315 pp.Google Scholar
- Hustedt, F., 1957. Die diatomeen des flussytems der weser im Gebiet der Hansestadt Bremen. Abh. Naturwiss. Verein. Bremen XXXIV, 34: 173–440.Google Scholar
- Kolbe, R. W., 1927. Zur Okologie, morphologie und systematik der brackwasser diatomeen. Pflanzenforschung 7: 1–145.Google Scholar
- Schnack, E. J., J. L. Fasano & F. I. Isla, 1982. The evolution of Mar Chiquita lagoon coast, Buenos Aires province, Argentina. In Colquhoun, D. J. (ed.). Holocene sea level fluctuations: magnitude and causes. Univ. S. Carolina, Columbia, S.C.: 143–155.Google Scholar
- Vos, P. C. & H. de Wolf, 1988. Methodological aspects of paleoecological diatom research in coastal areas of the Netherlands. Geol. Mijnbouw 67: 31–40.Google Scholar
- Wilkinson, L, 1986. SYSTAT: the system for statistics. Evanston, IL: SYSTAT, INC.Google Scholar