Quarterdeck 3.3

Part 1
TAMU-Squared and related geophysical studies of the East Pacific Rise


By Thomas W. Hilde

The Geodynamics Research Institute (GRI) of Texas A&M University and the Geological Survey of Japan (GSJ) are, as this is being written, aboard R/V Gyre and nearing completion of a joint [TAMU]-squared high-resolution seafloor swath mapping and related geophysical investigations of the super-fast spreading segment of the East Pacific Rise (EPR). We have named this investigation FAST (Flux And Spreading Tectonics) Ridge Expedition. The ridge segment being studied lies between 12°-20°S and is a major focus of U.S. and International Ridge programs. The objective of FAST Ridge Expedition is to determine the relationship between micro-, meso-, and macro-scale topographic and structural variations along the ridge and variations in stages of ridge magmatic and tectonic activity. This investigation is in support of the goals of the Japan Ridge-Flux, International Inter-Ridge and U.S. Ridge Projects, and is funded by the Science and Technology Agency (STA) of Japan. FAST Ridge Expedition is also endorsed by NSF as a U.S.-Japan Science Cooperation Program. Our investigation complements previous Ridge Flux Project studies of the region of the EPR carried out aboard R/V Melville (1993) and R/V Yokosuka (1994), during which extensive CTDTN tow-yo surveying and extensive diving observations by Shinkai 6500 were accomplished, respectively. Our studies also complement other recent investigations of the region such as the French Naudur cruise of 1993, previous United States, French and German surveys and the planned U.S. Mantle Electromagnetic and Tomographic (MELT) experiment. Gyre departed Galveston on October 19th and we will complete our studies and disembark Gyre on December 5th in the Galapagos Islands. Gyre should arrive back in Galveston on December 16th.

[69K] Map showing the Gyre cruise track for the FAST Ridge Expedition and the location of the East Pacific Rise.
[104K] Three-dimensional map of the seafloor created by the TAMU-squared system in 1994.
[58K] The TAMU-squared apparatus is towed behind the Gyre.

At the conclusion of FAST Ridge Expedition we will have comprehensive coverage of the 13°-19°S ridge crest and immediate flanks with colocated [TAMU]-squared swath imagery and bathymetry. These data are allowing us to map the distribution, in greater resolution than previously achieved, of the volcanic, magmatic, structural and bathymetric features of the ridge. At the same time we are collecting three-component magnetic, total-field magnetic, and gravity data to aid in determining crustal age and sub-surface structure. A special concentration of effort is being made to acquire very detailed imagery and bathymetry on the 17°10'S to 18°40'S region to complement the abundant geologic, volcanic and magmatic activity data previously collected on or near the seafloor by the 1993 R/V Melville and 1994 R/V Yokosuka cruises. Two ocean bottom heatflow instruments were placed on the ridge crest last year by the submersible Shinkai 6500, at 18°26'S and 17°34'S, to measure variations in the heatflow of this volcanically active ridge over an extended period of time. We have just recovered the instrument from the 18°26'S site and will attempt recovery of the other instrument tomorrow. The integration of all these various types of data with [TAMU]-squared imagery and bathymetry will allow detailed aerial mapping of volcanic, magmatic, geologic and tectonic features for this entire fast-spreading segment of the EPR.
Note: [TAMU]-squared = Texas A&M University Topography and Acoustic Mapping Undersea System [Back to text]

Continued . . .

[Next | Previous | Contents | Home]

Oceanography, Texas A&M University

rshatto@ocean.tamu.edu

URL=http://oceanography.tamu.edu/Quarterdeck/QD3.3/Hilde/hilde-a.html
Updated January 8, 1996