Chemical composition of ferromanganese crusts and manganese nodules from the Indian and Southern Ocean ...

• Main Author: Andersen, M E
• Format: Dataset
• Language: English
• Published: PANGAEA 1978
• Subjects: Event label; Identification; DEPTH, sediment/rock; Manganese; Iron; Cobalt; Copper; Nickel; Lead; Titanium; Zinc; Aluminium; Calcium; Magnesium; Cadmium; Chromium; Lithium; Molybdenum; Vanadium; Deposit type; Description; Piston corer; Gravity corer; Dredge; Atomic absorption spectrometry AAS; ELT33; ELT48; ELT50; ELT54; Shackleton75/5; Eltanin; Shackleton; NOAA and MMS Marine Minerals Geochemical Database NOAA-MMS; Southern Ocean
• Online Access: https://dx.doi.org/10.1594/pangaea.881835; https://doi.pangaea.de/10.1594/PANGAEA.881835

Excess 230Th dominates the alpha activity of the surface regions of manganese nodules and deep sea sediments. If uranium series eguilibrium is maintained, total alpha activity depth profiles should be as useful in determining sedimentation rates as are 230Th measurements. We have used cellulose nitrate alpha track recorders pressed against manganese nodule slabs to record high resolution alpha activity "maps' of a large number of nodules. Total alpha activity profiles have also been obtained for several sediment cores. From the approximately 90 nodule profiles measured to date, 73 show simple, approximately exponential depth dependence; about 2/3 of these have inferred deposition rates of 4-10 mm/10power6 yr. Ten profiles show statistically significant breaks in slope, suggesting growth rate changes. Within single dredge hauls there is little variation in growth rates, although different portions of the same nodule sometimes exhibit different growth rates. There is no correlation between depth and measured ... : 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1989 NOAA-NCEI compiled the NOAA-MMS Marine Minerals Geochemical Database from journal articles, technical reports and unpublished sources from other institutions.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. ...