Seafloor magnetism in the romanche transform zone (the equatorial atlantic)

Preliminary data on the seafloor magnetism in the equatorial Atlantic are obtained by studying the magnetic properties of dredged rocks, and a 3-D magnetization distribution in the reversed magnetically active, layer is reconstructed from areal survey measurements on both sides of the Romanche transform fault. Geodynamic constraints obtained within the framework of plate tectonics indicate that the seafloor spreading on the northern side of the transform over the last 5 Myr was symmetric and had an average half-rate of 1.82 cm/yr, whereas its half-rate on the southern side (the western slope) in the chron interval C23-C11 was 1.92 cm/yr. The distribution of magnetic characteristics of rocks dredged in the fault zone is sharply inhomogeneous. Rocks adjacent to the fault in the south acquired their magnetization under the action of tectonic stresses. The specific magnetic properties of rocks dredged within the Romanche transform suggest that the development of the transform zone was controlled by relative movements of adjacent blocks in the direction normal to their strike, which led to the formation of a "virtual axis" of spreading. Comparison of measured and calculated values of natural magnetization in the dredged rocks shows that the magnetically active layer in the Romanche transform zone varies in thickness and has a faulted structure.