Excess barite accumulation during the Paleocene-Eocene Thermal Maximum

Massive input of dissolved barium from seafloor gas hydrate reservoirs

Gerald R. Dickens, Thomas Fewless, Ellen Thomas, Timothy Bralower

Research output: Contribution to journalArticle

49 Citations (Scopus)

Abstract

A -2% to -3% excursion characterizes carbon isotope records across the Paleocene-Eocene Thermal Maximum (PETM), probably signifying transfer of ∼2000 gigatons of CH4 carbon from seafloor gas hydrate reservoirs to the ocean and atmosphere. During at least 30 k.y. of this carbon cycle perturbation, euhedral barite apparently accumulated in deep-sea sediment faster than before or after. This excess burial of "biogenic barite" has been argued to reflect elevated global primary productivity in surface waters, an interpretation in disagreement with microfossil assemblages. In this paper, we develop a numerical model for the marine Ba cycle to explore possible mechanisms for widespread barite accumulation. This model immediately highlights a fundamental problem with the productivity explanation: Ba has a short residence time in the ocean (∼8000 yr) so that excess Ba output on a global scale over periods >1000 yr signifies excess Ba input. However, a greater Ba input from conventional sources, hydrothermal waters and rivers, seems untenable. Assuming that available Ba records represent increased global output, we suggest an unconventional explanation for widespread barite accumulation. Prior to the PETM, gas hydrate reservoirs stored enormous masses of CH 4 and dissolved Ba 2+ . During the PETM, substantial quantities of gas hydrate converted to free CH 4 gas, increasing pore pressures, and releasing significant amounts of CH4 and dissolved Ba2+ to intermediate waters of the ocean. Consequently, dissolved Ba 2+ concentrations in the deep ocean rose, a smaller fraction of sinking barite particles dissolved, and "biogenic barite" accumulation increased. The model satisfactorily explains available records but forces us to link components of the marine CH 4 and Ba cycles, an endeavor with few constraints.

Original languageEnglish (US)
Pages (from-to)11-23
Number of pages13
JournalSpecial Paper of the Geological Society of America
Volume369
DOIs
StatePublished - Jan 1 2003

Fingerprint

Hypsithermal
gas hydrate
barite
barium
Paleocene
Eocene
seafloor
ocean
productivity
deep-sea sediment
intermediate water
microfossil
carbon cycle
pore pressure
carbon isotope
residence time
perturbation
surface water
atmosphere
carbon

All Science Journal Classification (ASJC) codes

  • Geology

Cite this

@article{38e38204feff44d388485ec82eef1d48,
title = "Excess barite accumulation during the Paleocene-Eocene Thermal Maximum: Massive input of dissolved barium from seafloor gas hydrate reservoirs",
abstract = "A -2{\%} to -3{\%} excursion characterizes carbon isotope records across the Paleocene-Eocene Thermal Maximum (PETM), probably signifying transfer of ∼2000 gigatons of CH4 carbon from seafloor gas hydrate reservoirs to the ocean and atmosphere. During at least 30 k.y. of this carbon cycle perturbation, euhedral barite apparently accumulated in deep-sea sediment faster than before or after. This excess burial of {"}biogenic barite{"} has been argued to reflect elevated global primary productivity in surface waters, an interpretation in disagreement with microfossil assemblages. In this paper, we develop a numerical model for the marine Ba cycle to explore possible mechanisms for widespread barite accumulation. This model immediately highlights a fundamental problem with the productivity explanation: Ba has a short residence time in the ocean (∼8000 yr) so that excess Ba output on a global scale over periods >1000 yr signifies excess Ba input. However, a greater Ba input from conventional sources, hydrothermal waters and rivers, seems untenable. Assuming that available Ba records represent increased global output, we suggest an unconventional explanation for widespread barite accumulation. Prior to the PETM, gas hydrate reservoirs stored enormous masses of CH 4 and dissolved Ba 2+ . During the PETM, substantial quantities of gas hydrate converted to free CH 4 gas, increasing pore pressures, and releasing significant amounts of CH4 and dissolved Ba2+ to intermediate waters of the ocean. Consequently, dissolved Ba 2+ concentrations in the deep ocean rose, a smaller fraction of sinking barite particles dissolved, and {"}biogenic barite{"} accumulation increased. The model satisfactorily explains available records but forces us to link components of the marine CH 4 and Ba cycles, an endeavor with few constraints.",
author = "Dickens, {Gerald R.} and Thomas Fewless and Ellen Thomas and Timothy Bralower",
year = "2003",
month = "1",
day = "1",
doi = "10.1130/0-8137-2369-8.11",
language = "English (US)",
volume = "369",
pages = "11--23",
journal = "Special Paper of the Geological Society of America",
issn = "0072-1077",
publisher = "Geological Society of America",

}

Excess barite accumulation during the Paleocene-Eocene Thermal Maximum : Massive input of dissolved barium from seafloor gas hydrate reservoirs. / Dickens, Gerald R.; Fewless, Thomas; Thomas, Ellen; Bralower, Timothy.

In: Special Paper of the Geological Society of America, Vol. 369, 01.01.2003, p. 11-23.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Excess barite accumulation during the Paleocene-Eocene Thermal Maximum

T2 - Massive input of dissolved barium from seafloor gas hydrate reservoirs

AU - Dickens, Gerald R.

AU - Fewless, Thomas

AU - Thomas, Ellen

AU - Bralower, Timothy

PY - 2003/1/1

Y1 - 2003/1/1

N2 - A -2% to -3% excursion characterizes carbon isotope records across the Paleocene-Eocene Thermal Maximum (PETM), probably signifying transfer of ∼2000 gigatons of CH4 carbon from seafloor gas hydrate reservoirs to the ocean and atmosphere. During at least 30 k.y. of this carbon cycle perturbation, euhedral barite apparently accumulated in deep-sea sediment faster than before or after. This excess burial of "biogenic barite" has been argued to reflect elevated global primary productivity in surface waters, an interpretation in disagreement with microfossil assemblages. In this paper, we develop a numerical model for the marine Ba cycle to explore possible mechanisms for widespread barite accumulation. This model immediately highlights a fundamental problem with the productivity explanation: Ba has a short residence time in the ocean (∼8000 yr) so that excess Ba output on a global scale over periods >1000 yr signifies excess Ba input. However, a greater Ba input from conventional sources, hydrothermal waters and rivers, seems untenable. Assuming that available Ba records represent increased global output, we suggest an unconventional explanation for widespread barite accumulation. Prior to the PETM, gas hydrate reservoirs stored enormous masses of CH 4 and dissolved Ba 2+ . During the PETM, substantial quantities of gas hydrate converted to free CH 4 gas, increasing pore pressures, and releasing significant amounts of CH4 and dissolved Ba2+ to intermediate waters of the ocean. Consequently, dissolved Ba 2+ concentrations in the deep ocean rose, a smaller fraction of sinking barite particles dissolved, and "biogenic barite" accumulation increased. The model satisfactorily explains available records but forces us to link components of the marine CH 4 and Ba cycles, an endeavor with few constraints.

AB - A -2% to -3% excursion characterizes carbon isotope records across the Paleocene-Eocene Thermal Maximum (PETM), probably signifying transfer of ∼2000 gigatons of CH4 carbon from seafloor gas hydrate reservoirs to the ocean and atmosphere. During at least 30 k.y. of this carbon cycle perturbation, euhedral barite apparently accumulated in deep-sea sediment faster than before or after. This excess burial of "biogenic barite" has been argued to reflect elevated global primary productivity in surface waters, an interpretation in disagreement with microfossil assemblages. In this paper, we develop a numerical model for the marine Ba cycle to explore possible mechanisms for widespread barite accumulation. This model immediately highlights a fundamental problem with the productivity explanation: Ba has a short residence time in the ocean (∼8000 yr) so that excess Ba output on a global scale over periods >1000 yr signifies excess Ba input. However, a greater Ba input from conventional sources, hydrothermal waters and rivers, seems untenable. Assuming that available Ba records represent increased global output, we suggest an unconventional explanation for widespread barite accumulation. Prior to the PETM, gas hydrate reservoirs stored enormous masses of CH 4 and dissolved Ba 2+ . During the PETM, substantial quantities of gas hydrate converted to free CH 4 gas, increasing pore pressures, and releasing significant amounts of CH4 and dissolved Ba2+ to intermediate waters of the ocean. Consequently, dissolved Ba 2+ concentrations in the deep ocean rose, a smaller fraction of sinking barite particles dissolved, and "biogenic barite" accumulation increased. The model satisfactorily explains available records but forces us to link components of the marine CH 4 and Ba cycles, an endeavor with few constraints.

UR - http://www.scopus.com/inward/record.url?scp=65649098837&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=65649098837&partnerID=8YFLogxK

U2 - 10.1130/0-8137-2369-8.11

DO - 10.1130/0-8137-2369-8.11

M3 - Article

VL - 369

SP - 11

EP - 23

JO - Special Paper of the Geological Society of America

JF - Special Paper of the Geological Society of America

SN - 0072-1077

ER -