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Summary Information for Field Activity 1990-033-FA

Area of Operations: Continental Shelf off Chesapeake Bay, Virginia, North Carolina, United States, North America, North Atlantic

Dates: September 07, 1990 to September 17, 1990

Chief scientist: Greg Miller

   G. M. Purdy and W. S. Holbrook, WHOI

Objectives: Using OBSes and hydrophones, (1) determine an accurate two-dimensional velocity structure across the complete margin province, from pure continental to normal oceanic crust; (2) image the lower crust and moho beneath the marginal sedimentary pile that is invisible to conventional multichannel seismic reflection experiments; (3) undershoot the margin carbonate bank complex and volcaniclastic wedge that thus map the underlying structures; (4) establish the geometry of the moho across the margin; (5) determine the nature of rift stage crust; (6) characterize rifted continental crust; (7) determine the nature of marginal oceanic crust; and (8) constrain models for the source of the East Coast Magnetic Anomaly. These objectives will be accomplished through the following tasks: (1) Wire test 16 new EG&G acoustic transponder/releases. (2) Carry out test deployments of one OBH and one OBS to check suitability of the absolute gain settings. (3) Record absolute shot times accurate to ~1 ms on board GECO SEARCHER. (4) In coordination with the commercial seismic vessel GECO SEARCHER, deploy 12 ocean bottom seismic instruments along line A of the EDGE project's Chesapeake Bay transect. (5) Recover all instruments after recording all GECO SEARCHER's airgun shots along this line. (6) Redeploy three of these instruments to line B. (7) Coordinate shooting operations with deployment of land instuments by Scott Smithson of the U. of Wyoming and Bob Hawman of the University of Georgia.

Type of Activity:

Information to be derived:


Contact: Greg Miller (

InfoBank: uses the identifier E-7-90-CH. Visit this site for more information.

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