Annotated record of the detailed examination of Mn deposits at the mouth of the Gulf of California during an IPOD Site Survey prior to DSDP Leg 65


During an IPOD site survey at the mouth of the Gulf of California, an axial valley about 50 km long and 600 meters deep was found on the East Pacific Rise (EPR) south of the Tamayo Fracture Zone. Magnetic anomalies along the axis of the rise change character from the axial valley to normal sections of the EPR, and off-axis anomalies tend to meander slightly with age, probably indicating that the axial injection zone wanders slightly with time. Along the Baja California margin the magnetic lineations cut across the bathymetric expression of the margin, suggesting that the original rifting of Baja from the mainland occurred along a roughly linear zone. A decrease of heat flow and an increase in sediment thickness and water depth with age from 0 to 3.5 m.y. are consistent with concepts of plate tectonics. Seismic refraction data across and adjacent to the axis of spreading suggest the presence of low-velocity material under the axis, possibly the result of a magma chamber, and a crust which thickens rapidly away from the axis.

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1989 NOAA-NCEI compiled the NOAA-MMS Marine Minerals Geochemical Database from journal articles, technical reports and unpublished sources from other institutions.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.

Related Identifier
Related Identifier
Related Identifier
Related Identifier
Metadata Access
Creator Lewis, B T R; Snydsman, W E; McClain, J S; Holmes, M L; Lister, C R B
Publisher PANGAEA
Publication Year 1983
Rights Creative Commons Attribution 3.0 Unported;
OpenAccess true
Resource Type Dataset
Format text/tab-separated-values
Size 31 data points
Discipline Earth System Research
Spatial Coverage (-109.203W, 22.332S, -108.150E, 24.775N); Pacific Ocean
Temporal Coverage Begin 1972-04-08T00:00:00Z
Temporal Coverage End 1975-06-01T00:00:00Z