High resolution hematite and goethite records from ODP 1143, South China Sea; co-evolution of monsoonal precipitation and El Niño over the past 600,000 years

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doi: 10.1016/j.epsl.2007.09.022
Author(s): Zhang Yi Ge; Ji, Junfeng; Balsam, William L.; Liu Lianwen; Chen Jun
Author Affiliation(s): Primary:
Nanjing University, Institute of Surficial Geochemistry, Nanjing, China
University of Texas at Arlington, United States
Volume Title: Earth and Planetary Science Letters
Source: Earth and Planetary Science Letters, 264(1-2), p.136-150. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0012-821X CODEN: EPSLA2
Note: In English. 66 refs.; illus., incl. 1 table, sketch map
Summary: Precipitation has a larger variability than temperature in tropical monsoon regions, thus it is an important climate variable. However, reconstructions of long-term rainfall histories are scarce because of the lack of reliable proxies. Here we document that iron oxide minerals, specifically the ratio of hematite to goethite (Hm/Gt), is a reasonable precipitation proxy. Using diffuse reflectance spectrophotometry, we measured samples from Ocean Drilling Program (ODP) 1143 drilling site (9°21.72'N, 113°17.11'E, 2777 m water depth) for hematite and goethite, whose formation processes are favored by opposing climate conditions. In order to determine the content of hematite and goethite we produced a set of calibration samples by removing the iron oxides to generate the natural matrix to which hematite and goethite in known percentages were added. From these calibration samples we developed a transfer function for determining hematite and goethite concentration from a sample's spectral reflectance. Applying this method to ODP 1143 sediments (top 34 m of a 510 m core with sampling interval of 10 cm) we were able to reconstruct a continuous precipitation history for SE Asia of the past 600 kyr using the Hm/Gt ratio as a proxy of the precipitation variability of Asian monsoon. The reliability of this Hm/Gt proxy is corroborated by its consistency with the stalagmite δ18O data from South China. Comparing long-term Hm/Gt records with the surface temperature gradient of equatorial Pacific Ocean, we found that monsoon precipitation and El Nino are correlated for the last 600 kyr. The development of El Niño-like conditions decreased SE Asia precipitation, whereas precipitation increases in response to La Niña intensification. Abstract Copyright (2007) Elsevier, B.V.
Year of Publication: 2007
Research Program: ODP Ocean Drilling Program
Key Words: 24 Surficial Geology, Quaternary Geology; Atmospheric precipitation; Cenozoic; Diffuse reflectance spectra; El Nino; Goethite; Hematite; Hydrologic cycle; La Nina; Leg 184; Marine sediments; Mekong River basin; Monsoons; North Pacific; Northwest Pacific; ODP Site 1143; Ocean Drilling Program; Oxides; Pacific Ocean; Paleoclimatology; Quaternary; Reconstruction; Sediments; South China Sea; Transfer functions; West Pacific
Coordinates: N092143 N092143 E1131707 E1131707
Record ID: 2008080177
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands