Open AccessMagnetic minerals in three Asian rivers draining into the South China Sea: Pearl, Red, and Mekong Rivers
Author(s) -
Kissel Catherine,
Liu Zhifei,
Li Jinhua,
Wandres Camille
Publication year - 2016
Publication title -
geochemistry, geophysics, geosystems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.928
H-Index - 136
ISSN - 1525-2027
DOI - 10.1002/2016gc006283
Subject(s) - weathering , geology , pearl , sedimentary rock , magnetic mineralogy , magnetite , structural basin , geochemistry , precipitation , oceanography , geomorphology , magnetic field , paleontology , geography , magnetization , physics , archaeology , quantum mechanics , remanence , meteorology
The use of the marine sedimentary magnetic properties, as tracers for changes in precipitation rate and in oceanic water masses transport and exchanges, implies to identify and to characterize the different sources of the detrital fraction. This is of particular importance in closed and/or marginal seas such as the South China Sea. We report on the magnetic properties of sedimentary samples collected in three main Asian rivers draining into the South China Sea: the Pearl, Red, and Mekong Rivers. The geological formations as well as the present climatic conditions are different from one catchment to another. The entire set of performed magnetic analyses (low‐field magnetic susceptibility, ARM acquisition and decay, IRM acquisition and decay, back‐field acquisition, thermal demagnetization of three‐axes IRM, hysteresis parameters, FORC diagrams, and low‐temperature magnetic measurements) allow us to identify the magnetic mineralogy and the grain‐size distribution when magnetite is dominant. Some degree of variability is observed in each basin, illustrating different parent rocks and degree of weathering. On average it appears that the Pearl River is rich in magnetite along the main stream while the Mekong River is rich in hematite. The Red River is a mixture of the two. Compared to clay mineral assemblages and major element contents previously determined on the same samples, these new findings indicate that the magnetic fraction brings complementary information of great interest for environmental reconstructions based on marine sediments from the South China Sea.