Mississippi Valley-type deposits: products of brine expulsion by eustatically induced hydrocarbon generation An example from northwestern Australia.

B.N. Eisenlohr, L.A. Thompkins, L.M. Cathles, Mark Barley, David Groves

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

Mechanisms for fluid flow such as compactive dewatering, gravity-driven hydrologic flow, and seismic pumping are not geologically plausible for Mississippi Valley-type (MVT) mineralization in the Lennard Shelf, Canning Basin, northwestern Australia. Sulfides at Cadjebut and the other Lennard Shelf MVT deposits precipitated from overpressured, hydrocarbon-rich brines. The deposits lie below a major mid-Carboniferous unconformity that is linked to a global sea-level fall. Independent evidence at Cadjebut also constrains the time of mineralization to the mid-Carboniferous. A sea-level fall at this time could have raised the sediment-water interface above the thermocline, thereby increasing the temperature of the basin by approximately 16-degrees-C. Model calculations show that a rise in basin temperature would induce sufficient hydrocarbon gas maturation to expel 1005 km3 of brine. This brine volume would be more than sufficient to transport and deposit the metal budget of the known MVT deposits on the Lennard Shelf. The existence worldwide of MVT deposits below unconformities suggests that sea-level-induced hydrocarbon generation could have assisted MVT mineralization in other provinces.
Original languageEnglish
Pages (from-to)315-318
JournalGeology
Volume22
DOIs
Publication statusPublished - 1994

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Mississippi Valley-type deposit
hydrocarbon generation
brine
sea level
mineralization
unconformity
basin
hydrocarbon
valley
sediment-water interface
dewatering
thermocline
fluid flow
maturation
pumping
temperature
sulfide
gravity
metal
gas

Cite this

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title = "Mississippi Valley-type deposits: products of brine expulsion by eustatically induced hydrocarbon generation An example from northwestern Australia.",
abstract = "Mechanisms for fluid flow such as compactive dewatering, gravity-driven hydrologic flow, and seismic pumping are not geologically plausible for Mississippi Valley-type (MVT) mineralization in the Lennard Shelf, Canning Basin, northwestern Australia. Sulfides at Cadjebut and the other Lennard Shelf MVT deposits precipitated from overpressured, hydrocarbon-rich brines. The deposits lie below a major mid-Carboniferous unconformity that is linked to a global sea-level fall. Independent evidence at Cadjebut also constrains the time of mineralization to the mid-Carboniferous. A sea-level fall at this time could have raised the sediment-water interface above the thermocline, thereby increasing the temperature of the basin by approximately 16-degrees-C. Model calculations show that a rise in basin temperature would induce sufficient hydrocarbon gas maturation to expel 1005 km3 of brine. This brine volume would be more than sufficient to transport and deposit the metal budget of the known MVT deposits on the Lennard Shelf. The existence worldwide of MVT deposits below unconformities suggests that sea-level-induced hydrocarbon generation could have assisted MVT mineralization in other provinces.",
author = "B.N. Eisenlohr and L.A. Thompkins and L.M. Cathles and Mark Barley and David Groves",
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Mississippi Valley-type deposits: products of brine expulsion by eustatically induced hydrocarbon generation An example from northwestern Australia. / Eisenlohr, B.N.; Thompkins, L.A.; Cathles, L.M.; Barley, Mark; Groves, David.

In: Geology, Vol. 22, 1994, p. 315-318.

Research output: Contribution to journalArticle

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AU - Groves, David

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AB - Mechanisms for fluid flow such as compactive dewatering, gravity-driven hydrologic flow, and seismic pumping are not geologically plausible for Mississippi Valley-type (MVT) mineralization in the Lennard Shelf, Canning Basin, northwestern Australia. Sulfides at Cadjebut and the other Lennard Shelf MVT deposits precipitated from overpressured, hydrocarbon-rich brines. The deposits lie below a major mid-Carboniferous unconformity that is linked to a global sea-level fall. Independent evidence at Cadjebut also constrains the time of mineralization to the mid-Carboniferous. A sea-level fall at this time could have raised the sediment-water interface above the thermocline, thereby increasing the temperature of the basin by approximately 16-degrees-C. Model calculations show that a rise in basin temperature would induce sufficient hydrocarbon gas maturation to expel 1005 km3 of brine. This brine volume would be more than sufficient to transport and deposit the metal budget of the known MVT deposits on the Lennard Shelf. The existence worldwide of MVT deposits below unconformities suggests that sea-level-induced hydrocarbon generation could have assisted MVT mineralization in other provinces.

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