Paleosalinity History of Middle Holocene Lagoonal and Lacustrine Deposits in the Enriquillo Valley, Dominican Republic Based on Pore Morphometrics and Isotope Geochemistry of Ostracoda

Authors

Pamela Medley, University of Mary Washington
Neil E. Tibert, University of Mary Washington
William P. Patterson, University of Saskatchewan
H. Allen Curran, Smith CollegeFollow
Lisa Greer, Washington and Lee University
Jean-Paul Colin, Impasse des Biroulayres

Document Type

Article

Publication Date

2007

Publication Title

Micropaleontology

Abstract

The southwestern region of the Dominican Republic (Enriquillo Valley) contains exceptionally well-preserved, relict marine and saline lake deposits of mid-Holocne age. Abundant euryhaline ostracodes found in this deposit include Cyprideis salebrosa, C. mexicana, C. similis, and C. edentata. Morphometric and geochemical analyses performed on Cyprideis spp. provide high δ¹⁸O and δ¹³C values that are coincident with relative abundances of irregularly shaped pores that permeate the ostracode carapace. We recognize three stratigraphic intervals with distinct ostracode pore shape and stable isotope trends: (I) a 4.5-5.0m interval that contains ostracodes with highly irregular shaped pores (multiradiate) and high amplitude variability in δ¹⁸O and δ¹³C values; (II) a 5.0-5.6m interval comprised of ostracodes with circular pores and an overall trend towards low δ¹⁸O and δ¹³C values; and (III) a 5.6-6.5m interval containing ostracodes with an upward increasing abundance of circular pore shapes coincident with decreasing δ¹⁸O and δ¹³C values. When the Enriquillo lagoon was first separated from the Caribbean Sea approximately 4.3 ka, an arid and evaporative climate led to hypersaline water in a restricted lagoon environment. By the middle to late-Holocene, increased precipitation in the valley resulted in a coastal lake system that became progressively oligohaline. Moderate to small amplitude variability in the salinity proxy data (δ¹⁸O) suggest short-term oscillations in the precipitation-evaporation budgets at that time. At least two marine incursions likely contributed to the ob- served variability in ostracode δ¹⁸O and δ¹³C values. Evidence for abrupt changes in base level indicate that climatic factors or also tectonic activity may have contributed to the observed paleoenvironmental trends recorded in these deposits.

Volume

53

Issue

5

First Page

409

Last Page

419

DOI

0.2113/gsmicropal.53.5.409

Rights

©2007 Micropaleontology

Comments

Archived as published.

Recommended Citation

Medley, Pamela; Tibert, Neil E.; Patterson, William P.; Curran, H. Allen; Greer, Lisa; and Colin, Jean-Paul, "Paleosalinity History of Middle Holocene Lagoonal and Lacustrine Deposits in the Enriquillo Valley, Dominican Republic Based on Pore Morphometrics and Isotope Geochemistry of Ostracoda" (2007). Geosciences: Faculty Publications, Smith College, Northampton, MA.
https://scholarworks.smith.edu/geo_facpubs/48