Laser Raman Spectroscopy as a Tool for In Situ Mineralogical Analyses on the Seafloor

In situ sensors capable of real-time measurements and analyses in the deep ocean are necessary to fulfil the potential created by the development of deep-sea platforms such as AUVs and cabled observatories. Laser Raman spectroscopy is an optical technique which is capable of in situ molecular identification of solids, liquids and gases, and is well suited to extreme environments. At present, it is not possible to identify the chemical composition of minerals in situ . Raman spectroscopy has been used successfully for mineral identification in the laboratory. The development of a sea-going Raman system capable of deployment on an ocean observatory or AUV will allow in situ analyses of minerals that are deposited and precipitated at hydrothermal vent and other seafloor sites. This will provide insights into processes occurring in the subsurface which affect ocean chemistry. This paper presents both sea-going and laboratory Raman data of a variety of minerals found in the deep ocean, and instrument parameter issues for a sea-going system optimized for in situ mineralogical analyses on the seafloor