During Ocean Drilling Program Leg 193, a series of holes was drilled within the PACMANUS hydrothermal field located along the Pual Ridge in the Manus Basin, within the territorial waters of Papua New Guinea. This cruise aimed to investigate the three-dimensional nature of the volcanic architecture and structural, hydrological, alteration, and mineralization patterns of an active felsic-hosted hydrothermal system in a backarc basin setting. The area contains zones of low-temperature diffuse hydrothermal venting and high-temperature focused venting with associated sulfide chimneys. A detailed description of the geological setting of this area may be found in Binns, Barriga, Miller, et al. (2002).

Short-wave infrared (SWIR) spectrometry was conducted on board the JOIDES Resolution during Leg 193 and during postcruise research to aid the identification of fine-grained alteration minerals and to help to delineate their mineralogical assemblage. The results of the spectroscopic analysis of core material and powdered samples from Sites 1188 and 1189 are presented in this report. Site 1188 was drilled in a zone of hydrothermal activity characterized by lower-temperature, more diffused venting at the Snowcap site. Site 1189 was drilled in an area of hydrothermal activity characterized by higher-temperature, more focused venting with associated sulfide chimneys and known as Roman Ruins.