North Atlantic Transect: A Wide-Aperture, Two-Ship Multichannel Seismic Investigation of the Oceanic Crust

摘要

The North Atlantic Transect experiment collected a unique set of two-ship, multichannel seismic data across oceanic crust spanning almost 200 m.y. in age from the Blake-Bahama Plateau, off the U.S. East Coast, to the Mid-Atlantic Ridge near 23 deg. N. A large, synthetic receiving array was simulates by having two ships, each equipped with a large air gun source array and a multichannel streamer, steam in line maintaining a fixed separation while alternately firing their guns and recording arrivals generated by shots from both ships. More than 3800 km of wide-aperture common depth point (CDP) data with a total synthetic aperture of more than 10 km were collected along the transect. At intervals along thnis wide-aperture profile, 11 expanding spread porofiles were also acquired on oceanic crust of various ages: in the Jurassic and Cretaceous quiet zones, on magnetic anomalies MO, 34, 26, and 5, in the Mid Atlantic Ridge rift valley, on the Blake-Bahama Plateau, and north of the Puerto Rico Trench on the Antilles Outer Ridge. These data have provided some remarkable new images of the oceanic crust. A very continuous Moho reflection is observed along most of the western half of the transect. The character of the Moho reflection and its appropriate depth appear to vary only slightly over distances of several tens of kilometer. although major changes incrustal thickness and seismic stratigraphy are observed along the profile. (Reprints)