Summary: 2004 Geological Society of America. For permission to copy, contact Copyright Permissions, GSA, or editing@geosociety.org.
Geology; November 2004; v. 32; no. 11; p. 957­960; doi: 10.1130/G20797.1; 4 figures; 1 table. 957
Tropical response to the 8200 yr B.P. cold event? Speleothem
isotopes indicate a weakened early Holocene monsoon in
Costa Rica
Matthew S. Lachniet* Department of Geoscience, MS-4010, University of Nevada, Las Vegas, Nevada 89154, USA
Yemane Asmerom Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, New Mexico 87131,
USA
Stephen J. Burns Department of Geosciences, University of Massachusetts, Amherst, Massachusetts 01003-9297, USA
William P. Patterson Department of Geological Sciences, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2,
Canada
Victor J. Polyak Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, New Mexico 87131,
USA
Geoffrey O. Seltzer Department of Earth Sciences, 204 Heroy Geology Laboratory, Syracuse University, Syracuse, New York
13244, USA
ABSTRACT
A 18O monsoon rainfall proxy record from a U-Th­dated Costa Rican stalagmite
(8840­4920 yr B.P.) documents an early Holocene dry period correlative with the high-
latitude 8200 yr B.P. cold event. High 18O values between ca. 8300 and 8000 yr B.P.
demonstrate reduced rainfall and a weaker monsoon in Central America. A relatively

Source: Asmerom, Yemane - Department of Earth and Planetary Sciences, University of New Mexico
Bradley, Raymond S. - Department of Geosciences, University of Massachusetts at Amherst
Lachniet, Matthew S. - Department of Geoscience, University of Nevada at Las Vegas
Massachusetts at Amherst, University of - Climate System Research Center
Patterson, William P. - Department of Geological Sciences, University of Saskatchewan

Collections: Environmental Sciences and Ecology; Geosciences