In 1994, we conducted a geophysical and geological survey of Shatsky Rise (cruise TN037 of Thomas G. Thompson). We collected seismic reflection, swath bathymetric (Hydrosweep), and potential field (magnetic, gravity) data, as well as a number of dredges and cores. The bathymetric and magnetic data and their interpretations have been published elsewhere (Nakanishi et al., 1999; Sager et al., 1999). In this paper, we present the results of seismic reflection data acquisition.
A total of 3213 km of seismic reflection data were collected over Shatsky Rise using a six-channel streamer and air gun sources (Figs. F1, F2, F3, F4, F5). The acquisition geometry, recording parameters, and processing sequence are summarized in Figure F6 and Table T1. The 6-channel Teledyne streamer consisted of a 70-m tow leader, a 5-m weighted section, a 25-m stretch section, six 25-m active sections, and two additional spare active sections (Fig. F6). Two different air gun sources were used. A single generator-injector (45/105 in3) air gun was used primarily when conducting long profiles between survey areas over the highs. This source could be towed at relatively high speeds (~7 nmi/hr) and produced two-fold data. The second source, an array of four air guns (80, 108, 150, 200 in3), was used to conduct most of the detailed surveys over the South, Central, and North Highs. Profiles collected with this array were run at ~5 nmi/hr, resulting in three-fold coverage. We recorded the seismic reflection data at 1 ms in SEGY format on 4-mm (DAT) and 8-mm (Exabyte) tapes using "a2d" seismic acquisition software on a Sun workstation. Following the cruise, the data were completely processed through migration using the steps shown in Table T1. The entire seismic reflection data set collected over Shatsky Rise is presented in Figures F7, F8, F9, F10, F11, F12, F13, and F14.