Ruifang Xie

Research Insterests

• Isotope geochemistry
• Climate change
• Sedimentology

Current Research

• The provenance of eolian dust component of deep-sea sediments has the potential to offer insights into changes in past atmospheric circulation patterns. One way in which to determine the provenance of dust in deep-sea sediments is to use radiogenic isotopic tracers which can fingerprint potential dust sources. Several numerical models have shown that sources of dust to the Eastern Equatorial Pacific (EEP) are from areas as diverse as Asia, North, Central, and South America, and, perhaps, even Africa. Yet, there is only one study that has shed light on dust provenance in the tropical Pacific ocean on a glacial-interglacial time scale. The goal of this study is to perform a temporal analysis of Nd, Sr, and Pb isotope ratios in the detrital components extracted from deep-sea sediments in the EEP along a meridional transect at 110ºW from 3ºS to 7ºN (ODP Leg138, Sites 848 – 853). This study is the first one to investigate dust provenance in such a high resolution that covers only the past 25ky. Our study suggests a southerly shift of the Intertropical Convergent Zone (ITCZ) during the last glacial.
• The role of ocean circulation in responding to triggering climate changes has been a subject of intense interest. Variations in the strength of Atlantic Meridional Ocean Circulation (AMOC) affect global heat transport and, therefore, climate changes. During the last deglacial, cold periods (Younger Dryas and Heinrich 1) were coupled with the reduction of North Atlantic Deep Water (NADW) formation. Yet, the role that AAIW played during cold events during the last deglacial is still poorly constrained. Different studies using different proxies have provided conflicting results about the AAIW strength during the last glacial cycle. In our study, we are trying to couple Nd isotope ratios of two sediment cores from the Florida Straits with benthic foraminiferal δ¹⁸O data in an effort to investigate the strength of the northward penetration of AAIW during Youger Dryas and Heinrich 1.

Previous Research

• Investigated paleo-sea surface temperature and sea level changes, as well as monsoon intensity changes 6500 years ago by measuring δ¹⁸O, Mg/Ca, and δ¹³C in a 45-year-old coral sampled in the South China Sea. 
• (Undergraduate thesis) Investigated historical diet changes in Bengbu City, Anhui Province, China, in the 1950s by measuring δ¹⁸O and δ¹³C in human enamels, which corresponded to a huge population migration within China right after the Civil War.  

Field Experience

·         Oceanography survey on ²³⁰Th fluxes in determining sediment fluxes, and on developing sea-floor seismic profile. Texas A&M University (upcoming in October, 2010)

·         Plate tectonic geology field trip in Taiwan. Texas A&M University and American Associate Petroleum Geologists. 2010.

·         Environmental ecology field trip in Huangshan Mountain areas, China. University of Science and Technology of China. 2006.

·         Physical geology field trip in Chao Lake district, Anhui Province, China. University of Science and Technology of China. 2005.

Abstracts

• Xie, R., Marcantonio, F., (2009) Deglacial Dust Provenance Changes in the Eastern Equator Pacific and Implications for ITCZ Movement. American Geophysical Union Fall Meeting.
• Xie, R., Marcantonio, F., (2008) Eastern Equatorial Pacific Dust Provenance on Deglacial Timescales. American Geophysical Union Fall Meeting.  
  

Honors & Awards

•    Ocean Drilling and Sustainable Earth Science Scholarship, Texas A&M University, 2010   
• Sigma Xi Grand-in-Aid Research Fund, 2010
• 3^rd price in Student Research Symposium, Department of Geology & Geophysics, Texas A&M University, 2010
• Excellent Undergraduate Research Program, University of Science & Technology of China, 2006
• Outstanding student scholarship, University of Science & Technology of China, 2004-2006

Affiliations

American Associate Petroleum Geologists

American Geophysical Union

Geochemical Society