Project Description
Recent research comparing ice-core records of the northern and southern high latitudes has led to questions about the connections between tropical and high latitude climate and about the role of the tropics in global atmospheric and oceanic circulation patterns. Large climate changes that are synchronous north and south of the equator are likely produced by variations in the the concentration and amount of atmospheric water vapor and other gases and the effects of these on oceanic and land surface characterisitics. Because most of the global water vapor is concentrated in the tropics, the equatorial region is key. Until now, few studies of the tropical latitudes of South America have constrained the timing, nature, and magnitude of these climate changes confidently enough to test these ideas of climatic synchroneity.
The Bolivian Altiplano is one of the few sites in the tropics where long, continuous paleoclimate records can be obtained. This, combined with the fact that precipitation in the Altiplano is largely derived from the Amazon Basin, makes the Altiplano an important site for paleoclimate reconstruction. Evidence for greatly increased precipitation (relative to modern) is recorded by large, late Quaternary lake highstands. The timing of these highstands is generally correlative with elevated levels of methane as recorded in the GRIP ice-core record, suggesting a relationship between global methane production and Altiplano moisture. In the presence of such a relationship, a record of changes in tropical effective moisture is essential to our understanding of interhemispheric climate linkages.
In this study, we are attempting to document the nature, timing, and magnitude of tropical climate on the Bolivian Altiplano from the present to at least 35 Ka. Specifically, using cores obtained by drilling a series of bore holes along the valley occupied by the modern Rio Desaguadero, as well as studies of lacustrine and fluvial strata that outcrop in Rio Desaguadero terraces, we are investigating the record of changes in tropical effective moisture (ppt - evap) as recorded in changing Altiplano lake levels.
Student Involvement
Students participating in this project could be involved in field and laboratory sedimentologic and stratigraphic studies aimed at defining depositional environments of the strata present in cores and outcrops, GPS/GIS studies of paleolake shorelines focused on determining the precise areal extent of the paleolake systems, geochemical and paleoecological analysis of lacustrine strata designed to elucidate the physical and chemical characteristics of the paleolakes, and modeling of the fluviolacustrine basin to produce time-slice geographic reconstructions of basin and volumetric water balance models that will allow determination of Holocene moisture fluctuations.
For the adventurous, some of these studies would involve travel to, and field work in, South America. Not all studies associated with the project require travel, however. Some of the studies can be done entirely in the lab. All of the studies, even the field-oriented studies, involve a significant lab or computer component. Graduate student funding is available as research assistantships (the project is NSF funded) and as teaching assistantships from the East Carolina University Geology Department. Out-of-state tuition waivers may be available for qualified students.
Interested students should contact the project leader, Dr. Catherine A. Rigsby (Department of Geology, East Carolina University, Greenville, NC 27858) for more information. E-mail inquiries are encouraged and will receive the most prompt response. Applications to the ECU M.S. program in Geology can be obtained by submitting a request via the Geology Department web site. Information on ECU’s interdisciplinary coastal resources management Ph.D. program -- which includes climate change research -- can be obtained via the CRM web site.