10.1594/PANGAEA.874690Jones, E J WE J WJonesLaughton, Anthony SAnthony SLaughtonHill, M NM NHillDavies, DDDavies0000-0001-6304-3938PANGAEA1966Event labelIdentificationDEPTH, sediment/rockPositionDeposit typeQuantity of depositSubstrate typeSediment typeDescriptionFile nameUniform resource locator/link to imagePhoto/VideoVisual descriptionMADCAP_62Discovery II (1929)NOAA and MMS Marine Minerals Geochemical Database (NOAA-MMS)1962-02-01T00:00:00Supplementary Dataset10.1016/0011-7471(76)90909-810.7289/V52Z13FT10.7289/V53X84KN26 data pointstext/tab-separated-valuesCreative Commons Attribution 3.0 UnportedThe 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./cm**3) 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.From 1983 until 1989 NOAA-NCEI compiled the NOAA-MMS Marine Minerals Geochemical Database from journal articles, technical reports and unpublished sources from other institutions. At the time it was the most extended data compilation on ferromanganese deposits world wide. Initially published in a proprietary format incompatible with present day standards it was jointly decided by AWI and NOAA to transcribe this legacy data into PANGAEA. This transfer is augmented by a careful checking of the original sources when available and the encoding of ancillary information (sample description, method of analysis...) not present in the NOAA-MMS database.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), 889-907-25.441667-25.39166728.83333328.85Atlantic Ocean