Annotated record of the detailed examination of Mn deposits from the Madcap Volcano in the Madeira-Cape Verde Abyssal plain, supplement to: Jones, E J W; Laughton, Anthony S; Hill, M N; Davies, D (1976): A geophysical study of part of the western boundary of the Madeira-Cape Verde Abyssal plain. Deep Sea Research and Oceanographic Abstracts, 13(5), 889-907


The results are discussed of a geophysical survey undertaken by R.R.S. Discovery II early in 1962 in an area centred on 29° 15'N, 25° 5'W at the western extremity of the Madeira-Cape Verde Abyssal Plain. Seismic investigations show that the sediments are underlain by an intermediate layer about 2 km in thickness of velocity 4.1-5.4 km/sec which overlies a deep layer 5.2-km thick of velocity 6.3-6.8 km/sec. Refracted arrivals on the longest seismic line give a depth of 13.2 km to the M discontinuity.Magnetic results indicate that the topography of the abyssal hills in the western part of the area is probably continued eastwards as sub-bottom relief beneath the sediments of the abyssal plain. They also support the hypothesis that the intermediate seismic layer (layer 2) is composed predominantly of volcanic rocks. Examination of a well-defined magnetic anomaly over one topographic feature ("The Madcap Volcano") shows it to be composed of magnetized rocks (I = 8.4 × 10-3 e.m.u./cm3) having a direction of magnetization which points upwards at 25° with an azimuth of 305°. Measurements at ten heat flow stations show that the average geothermal flux in this region is 1.20 (±0.11) µcal/cm**2/sec.

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Metadata Access
Creator Jones, E J W; Laughton, Anthony S; Hill, M N; Davies, D
Publisher PANGAEA - Data Publisher for Earth & Environmental Science
Publication Year 1966
Rights Creative Commons Attribution 3.0 Unported
OpenAccess true
Language English
Resource Type Supplementary Dataset
Format text/tab-separated-values
Size 26 data points
Discipline Earth System Research
Spatial Coverage (-25.442W, 28.833S, -25.392E, 28.850N); Atlantic Ocean