Award Date

8-2006

Degree Type

Thesis

Degree Name

Master of Science in Geoscience

Department

Geoscience

First Committee Member

Matthew Lachniet, Chair

Second Committee Member

Ganqing Jiang

Third Committee Member

Mike Nicholl

Fourth Committee Member

Barbara Luke

Number of Pages

90

Abstract

Although the El Nino/Southern Oscillation (ENSO) is the most important source of inter-annual climate variability in the tropics, its Holocene history is poorly understood, particularly in Central America. A high resolution (-3.8 years/sample) paleoclimate record of Central American rainfall variability has been reconstructed from a U /Th-dated stalagmite (7890 to 6490 yrs B.P.) from Costa Rica to constrain the onset and variability of ENSO throughout the Holocene, and to determine its role in generating regional climate anomalies. I suggest drier conditions, forced by El Nino, are represented by higher 5180 values, and are correlative with higher 513C values, indicating that soil respiration rates are affected by regional climate variability, which are recorded in the speleothem stratigraphy gray-scale values. This study provides new evidence, based on 3 different proxies, that throughout the middle Holocene, rainfall was operating at interdecadal timescales, which I attribute to ENSO and the PDQ.

Keywords

Costa Rica; Holocene Geologic Period; Paleoclimatology; Speleothems

Disciplines

Climate | Environmental Indicators and Impact Assessment | Geology

Language

English

Comments

Best copy available

Incomplete paper data


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