Uranium and thorium enrichment in rocks from the base of DSDP hole 465A, Hess Rise, central North Pacific

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doi: 10.1016/0009-2541(82)90050-X
Author(s): Hein, James R.; Koski, Randolph A.; Morgenson, Lisa A.
Author Affiliation(s): Primary:
U. S. Geol. Surv., Menlo Park, CA 94025, United States
Volume Title: Chemical Geology
Source: Chemical Geology, 36(3-4), p.237-251. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0009-2541 CODEN: CHGEAD
Note: In English. 2 p. refs.; illus.
Summary: U and Th are concentrated in Cretaceous limestone, chert, ash, basalt and other rock types in DSDP site 465 located on the southern Hess Rise. U concentrations = or <194 p.p.m. on a carbonate-free basis, are among the highest recorded for any deep-sea deposits. U was derived from sea-water and concentrated by absorption on terrigenous (humic) organic matter in limestone in a shallow marine environment. U and Th were probably concentrated further by low-T hydrothermal fluids emanating from the basaltic basement. Mainly montmorillonite, an alteration product of basalt and ash, and organic matter in sedimentary rocks acted as hosts for U and Th. The unique combination of sediments rich in humic organic matter, abundant smectite in altered ash and basalt, and warm hydrothermal solutions provided the necessary conditions for migration and concentration of U and Th. Chemical analyses of 15 rocks from hole 465 are presented, with XRD analyses of 13 samples.
Year of Publication: 1982
Research Program: DSDP Deep Sea Drilling Project
IPOD International Phase of Ocean Drilling
Key Words: 02 Geochemistry; Abundance; Actinides; Anaerobic environment; Basalts; Carbon; Carbonate rocks; Chemically precipitated rocks; Chert; Cretaceous; DSDP Site 465; Deep Sea Drilling Project; East Pacific; Enrichment; Geochemistry; Hess Rise; Humic acids; Humic substances; IPOD; Igneous rocks; Leg 62; Limestone; Mesozoic; Metals; Minor elements; North American Pacific; North Pacific; Northeast Pacific; Northwest Pacific; Organic acids; Organic carbon; Organic compounds; Organic materials; Pacific Ocean; Petrology; Pyroclastics; Rocks; Sedimentary petrology; Sedimentary rocks; Stratigraphy; Thorium; Trace elements; Uranium; Volcanic ash; Volcanic rocks; West Pacific
Coordinates: N340000 N340000 E1750000 E1750000
Record ID: 1984002886
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom, Reference includes data from PASCAL, Institute de l'Information Scientifique et Technique