Growth of diagenetic ferromanganese nodules in an oxic deep-sea sedimentary environment, Northeast Equatorial Pacific

Author(s): Jung, Hoi-Soo; Lee, Chang-Bok
Author Affiliation(s): Primary:
Korea Ocean Research and Development Institute, Deep-sea Research Center, Seoul, South Korea
Seoul National University, South Korea
Volume Title: Marine Geology
Source: Marine Geology, 157(3-4), p.127-144. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0025-3227 CODEN: MAGEA6
Note: In English. 81 refs.; illus., incl. 2 tables, sketch map
Summary: To study the accretion mechanism of diagenetic ferromanganese nodules formed in an oxic deep-sea sedimentary environment, manganese nodules, sediments, and pore waters were sampled in the northeast equatorial Pacific. Diagenetic ferromanganese nodules are ellipsoidal to discoidal in shape, rough in surface texture, enriched in Cu, Ni and 10 Å-manganite, and are ubiquitous on the abyssal plain; hydrogenetic nodules are polynucleated, irregular in shape, smooth in surface texture, enriched in Co and δ-MnO2, and occur dominantly on seamounts. Numerous microlayers with diagenetic or hydrogenetic characteristics occur successively in the nodules. Concentration of nitrate in sediment pore waters indicates that overall redox conditions are oxic. However, Mn-oxide grains on the walls of burrows and worm tubes are interpreted to be reprecipitated metal ions supplied from oxygen-depleted microenvironments that formed in the oxic sediment column by decomposition of organic matter. Active mixing of bottom sediments by benthic fauna and bottom currents is indicated by ubiquitous burrows, worm tubes, and tracks and trails, high values in sediment mixing coefficients (>1 cm2/yr), and scattering of data points in depth profiles of pore water nitrate concentrations. We suggest that diagenetic ferromanganese nodules in an oxic deep-sea sedimentary environment grew from remobilized metal ions as well as reprecipitated Mn-oxide grains, which were supplied to the nodules episodically during the stirring of bottom sediments by benthic fauna and intermittent strong bottom current flow. Abstract Copyright (1999) Elsevier, B.V.
Year of Publication: 1999
Research Program: DSDP Deep Sea Drilling Project
Key Words: 02 Geochemistry; 07 Marine Geology and Oceanography; Aerobic environment; Biogenic structures; Bioturbation; Bottom currents; Cores; Currents; DSDP Site 163; Deep Sea Drilling Project; Deep-sea environment; Diagenesis; East Pacific; Equatorial Pacific; Ferromanganese composition; Geochemistry; Hydrochemistry; Isotopes; Lead; Lebensspuren; Leg 16; Marine environment; Marine sediments; Metals; Nitrate ion; Nitrite ion; Nodules; North Pacific; Northeast Pacific; Pacific Ocean; Pb-210; Pore water; Precipitation; Radioactive isotopes; Sedimentary structures; Sediments; Surface textures
Coordinates: N100000 N100000 W1460000 W1470000
N111442 N111442 W1501730 W1501730
N090000 N090000 W1500000 W1510000
Record ID: 1999034390
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands