북피지분지 중앙확장해령에서의 열수활동

Abstract

In 2012 and 2013, KIOST performed two hydrothermal expeditions aboard the R/V Onnuri in the three targeted areas of hydrothermal activity along the CSR of North Fiji Basin. All targeted areas include sites for hydrothermal activity reported in previous works. Occurrence and distribution of hydrothermal plume were investigated by combined CTD/MAPR casts and tows. We did not detected significant hydrothermal plume signal in N160° segment where only trace of activity was reported. In north of N15° segment, however, vigorous plume signals were detected not only near 16° 57S where both active and inactive hydrothermal sites have been reported, but also near 17° 07S. In addition, we identified distinct plume signal above the site previously known as fossil chimney site near 16° 57S, which indicates possible rejuvenation of the deposit. Along the N-S segment, we identified distinct plume signals possibly originated from at least three different sources. Most plume signals are located along the axis of spreading center, which suggest that hydrothermal activity is mainly controlled by magmatic budget. Our results indicate extensive and various hydrothermal activity along the CSR in the North Fiji Basin, thereby providing valuable insight into hydrothermal activity and formation of deposit in this mature back-arc environment.