LEAD ISOTOPE COMPOSITION OF HYDROTHERMAL PRECIPITATES FROM THE NORTH FIJI BASIN

Title
LEAD ISOTOPE COMPOSITION OF HYDROTHERMAL PRECIPITATES FROM THE NORTH FIJI BASIN
Author(s)
김종욱; 이경용; Peter Halbach; 김기현
KIOST Author(s)
Kim, Jong Uk(김종욱)
Publication Year
2006-06-01
Abstract
Hydrothermal sulfides were recovered from the16°50’S triple junction area in the North Fiji Basin, at a water depth of ca. 1900 m. The chimney samples can be divided into three groups based on their major metal contents: 1) type 1 (Fe-Cu-rich), 2) type 2 (Fe-Cu-rich with minor Zn), and 3) type 3 (Zn-rich) chimneys. Type 1 chimneys are mainly composed of chalcopyrite and pyrite, and are enriched in elements commonly precipitated under high temperature conditions (> 300oC), such as Cu, Co, Mo, and Se. Type 3 chimneys consist dominantly of sphalerite and marcasite with traces of pyrite and chalcopyrite, and are enriched in elements commonly associated with relatively low temperatures (150 to 250oC), such as Zn, Cd, Pb, As, and Ga. Type 2 chimneys have a mineralogy similar to that of type 1 chimneys although their trace metal contents range between those of type 1 and type 3 samples. Type 2 chimneys appear to be the products of low-temperature replacement, which might be related to formation of type 3 chimneys, of type 1 chimneys. The trace element composition of basaltic rocks indicates that magma generation in the triple junction area was influenced by two different sources: N-MORB and E-MORB. Sulfur and lead isotope patterns of the hydrothermal chimneys show distinct differences between the type 1 and type 3 chimneys. The type 1 sulfides (δ34S = 2.8±1.2‰; 206Pb/204Pb = 18.082 to 18.132; 207Pb/204Pb = 15.440 to 15.481; 208Pb/204Pb = 37.764 to 37.916) are depleted in 34S and have lower Pb isotope ratios compared to types 2 and 3 chimneys (δ34S = 4.1±0.9‰; 206Pb/204Pb = 18.122 to 18.193; 207Pb/204Pb = 15.475 to 15.554; 208Pb/204Pb = 37.882 to 38.150). The higher δ34S values for types 2 and 3 sulfides than type 1 sulfides can be explained by mixing of hydrothermal fluids with ambient seawater. The more radiogenic Pb isotope composition of types 2 and 3 chimneys compared to type 1 chimneys suggest that the formation of types 2 and 3 chimneys were possibly related
URI
https://sciwatch.kiost.ac.kr/handle/2020.kiost/30992
Bibliographic Citation
Minerals of the Ocean-3, pp.67, 2006
Publisher
VNIIOkeangeologia
Type
Conference
Language
English
Publisher
VNIIOkeangeologia
Related Researcher
Research Interests

Geochemistry,Submarine hydrothermal system,Deep-sea mineral,지구화학,해저열수시스템,해양광물자원

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