Metal flux in black shale sequences

Conference · Wed Jan 01 00:00:00 EST 1992 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:5825785

Parnell, J ^[1]

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1. Queen's Univ., Belfast (United Kingdom). School of Geosciences

Black shales are important to the models used by many metallogenists to explain the concentration of metals in and around ore prospects. In some cases, black shales are inferred to be a ready source of metals which can be leached and concentrated to form a mineral deposit. For others, black shales are a chemical trap in which organic matter absorbs metals from migrating groundwaters and hydrothermal fluids. Clearly, these source and sink models confer fundamentally opposite roles to black shales in the metal budget of a sedimentary base. An assessment of whether one of these roles is predominant must include consideration of the physico-chemical mechanism involved and their timing during basin history. A release of metals from shales can be a consequence of intrinsic diagenetic processes, in addition to scavenging by hydrothermal fluids (i.e. an external source). Major processes in siliciclastic diagenesis include compaction, silica precipitation/dissolution, clay authigenesis and carbonate/sulphate dissolution; the latter two in particular can be a source of metals due to expulsion from the lattice during mineral transformation. Both of these processes can occur on a large scale and liberate large quantities of metal over a short time period. One of several approaches to assessing the metal budget in/out of shales is to compare metal contents in shales outside and inside early diagenetic carbonate concretions which should protect their contents from the processes of deep burial. Results of such analyses suggest that black shales are more likely to absorb than lose metals.

• OSTI ID: 5825785
• Report Number(s): CONF-921058-; CODEN: GAAPBC
• Journal Information: Geological Society of America, Abstracts with Programs; (United States), Vol. 24:7; Conference: 1992 annual meeting of the Geological Society of America (GSA), Cincinnati, OH (United States), 26-29 Oct 1992; ISSN 0016-7592
• Country of Publication: United States
• Language: English

Related Subjects

04 OIL SHALES AND TAR SANDS
BLACK SHALES
SORPTIVE PROPERTIES
METALS
ADSORPTION
OIL SHALE DEPOSITS
GEOCHEMISTRY
DIAGENESIS
GEOLOGIC MODELS
ORES
ORGANIC MATTER
SOURCE ROCKS
CHEMISTRY
ELEMENTS
GEOLOGIC DEPOSITS
MATTER
MINERAL RESOURCES
RESOURCES
ROCKS
SEDIMENTARY ROCKS
SHALES
SORPTION
SURFACE PROPERTIES
040200* - Oil Shales & Tar Sands- Reserves
Geology
& Exploration