Award Date

1-1-2006

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Geoscience

First Committee Member

Matthew Lachniet

Number of Pages

83

Abstract

The El Nino/Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO) are the most important sources of interannual to multidecadal climate variability in the tropics. A high resolution ({dollar}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 and/or the PDO, are represented by higher delta 18O values, and are correlative with higher delta13C values, indicating that soil respiration rates are affected by regional climate variability, which are recorded in the speleothem stratigraphy grayscale values. This study provides new evidence, based on 3 different proxies, that throughout the middle Holocene, rainfall was varying at interdecadal timescales, which I attribute to low frequency variability in ENSO and the PDO.

Keywords

Pacific Decadal Oscillation; Active; Costa Rica; ENSO; Evidence; Holocene; Speleothem; El Nino; Southern Oscillation

Controlled Subject

Geology; Geochemistry; Atmospheric physics

File Format

pdf

File Size

2078.72 KB

Degree Grantor

University of Nevada, Las Vegas

Language

English

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