Description of manganese deposits collected by R/V Nothwind during the 1963 expedition in the Laptev sea ...

• Main Authors: Holmes, M L, Creager, Joe S
• Format: Dataset
• Language: English
• Published: PANGAEA 1974
• Subjects: Event label; Identification; DEPTH, sediment/rock; Position; Deposit type; Quantity of deposit; Size; Substrate type; Sediment type; Description; Gravity corer; Visual description; NW63; Northwind; NOAA and MMS Marine Minerals Geochemical Database NOAA-MMS; Laptev Sea; laptev
• Online Access: https://dx.doi.org/10.1594/pangaea.859299; https://doi.pangaea.de/10.1594/PANGAEA.859299

The 400-km-wide, low gradient Laptev Sea continental shelf consists of flat terrace-like features at regular depth intervals from 10 to 40 m below present sea level. The five large submarine valleys traversing the shelf do not continuously grade seaward, but contain elongated, closed basins. These terraces and closed basins plus deltaic sediments associated with the submarine valleys quite possibly mark sea level Stillstands, and enable reconstruction of the paleogeography of the Laptev Sea shore line at five periods during post-Wisconsin (Holocene) time. Radiocarbon dates on the silty-clay to clayey-silt sediments from cores of the northeastern Laptev Sea indicate average sedimentation intensity of 2 to 15 mg/cm2/yr. The presence of manganese nodules and crusts in surface samples from less than 55 m depths and a general decrease in total foraminiferal abundances with depth in the cores suggest that the present deposition rate is less than when sea level was lower. The main components of the shelf deposits ... : 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1989 NOAA-NCEI compiled the NOAA-MMS Marine Minerals Geochemical Database from journal articles, technical reports and unpublished sources from other institutions.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. ...