Chemical composition of sediment samples from ODP Leg 164 sites, Blake Ridge
Ocean Drilling Program (ODP) Sites 994, 995, and 997 were drilled into a large gas hydrate deposit on the crest of the Blake Ridge (southeast U.S. margin) where upward CH4 fluxes (F_OUT) are related to depths of pore water SO4**2- depletion. High-resolution pore water SO4**2- and sediment Ba profile...
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ftpangaea:oai:pangaea.de:doi:10.1594/PANGAEA.708278 2023-05-15T17:37:11+02:00 Chemical composition of sediment samples from ODP Leg 164 sites, Blake Ridge Dickens, Gerald Roy MEDIAN LATITUDE: 31.804500 * MEDIAN LONGITUDE: -75.520700 * SOUTH-BOUND LATITUDE: 31.785700 * WEST-BOUND LONGITUDE: -75.545900 * NORTH-BOUND LATITUDE: 31.843100 * EAST-BOUND LONGITUDE: -75.468600 * DATE/TIME START: 1995-11-07T14:08:00 * DATE/TIME END: 1995-12-10T00:10:00 2001-12-03 application/zip, 4 datasets https://doi.pangaea.de/10.1594/PANGAEA.708278 https://doi.org/10.1594/PANGAEA.708278 en eng PANGAEA https://doi.pangaea.de/10.1594/PANGAEA.708278 https://doi.org/10.1594/PANGAEA.708278 CC-BY-3.0: Creative Commons Attribution 3.0 Unported Access constraints: unrestricted info:eu-repo/semantics/openAccess CC-BY Supplement to: Dickens, Gerald Roy (2001): Sulfate profiles and barium fronts in sediment on the Blake Ridge: Present and past methane fluxes through a large gas hydrate reservoir. Geochimica et Cosmochimica Acta, 65(4), 529-543, https://doi.org/10.1016/S0016-7037(00)00556-1 164-994A 164-994C 164-995A 164-997A DRILL Drilling/drill rig Joides Resolution Leg164 Nicaraguan Rise North Atlantic Ocean Ocean Drilling Program ODP Dataset 2001 ftpangaea https://doi.org/10.1594/PANGAEA.708278 https://doi.org/10.1016/S0016-7037(00)00556-1 2023-01-20T07:31:17Z Ocean Drilling Program (ODP) Sites 994, 995, and 997 were drilled into a large gas hydrate deposit on the crest of the Blake Ridge (southeast U.S. margin) where upward CH4 fluxes (F_OUT) are related to depths of pore water SO4**2- depletion. High-resolution pore water SO4**2- and sediment Ba profiles have been constructed at these sites to assess present and past F_out. Pore water SO4**2- profiles are linear with zero SO4**2- concentration occurring at 21.4, 21.6, and 22.8 mbsf at Holes 994A, 995A and 997A, respectively. Using steady state solutions to diffusion equations with appropriate parameters, the steep SO4**2- gradients support upward CH4 fluxes between 7.2 and 8.6 mol/m**2/ky at present-day, with the range primarily reflecting different approaches for incorporating porosity (phi). Taking into account the generally decreasing phi with depth and the high clay content of the sediment, the best estimates for F_out are 7.9, 7.6 and 7.2 mol CH4/m**2/ky at Sites 994, 995 and 997, respectively. However, non-steady state solutions to diffusion equations show that the SO4**2- gradients do not imply steady state conditions. Elevated Ba concentrations (530–1410 ppm) exist in sediment between 18.23 and 20.65, between 17.31 and 20.31, between 19.40 and 21.80, and between 19.58 and 21.91 mbsf at Holes 994A, 994C, 995A, and 997A, respectively. These Ba fronts coincide with highs in bulk sediment Ba/Al (to 0.025) and are caused by Ba cycling just above time averaged depths of SO4**2- depletion. Because the Ba fronts lie immediately above the present-day depths of pore water SO4**2- depletion, and because no other Ba fronts are found in the upper 25 m at the three sites, the depth of SO4**2- depletion beneath the seafloor has been nearly constant for considerable time (>18000 years). Thus, CH4 fluxes can be determined through SO4**2- gradients and steady state solutions to diffusion equations. More importantly, F_out through the crest of the Blake Ridge has not varied significantly across major changes in sea level ... Dataset North Atlantic PANGAEA - Data Publisher for Earth & Environmental Science ENVELOPE(-75.545900,-75.468600,31.843100,31.785700) |
institution |
Open Polar |
collection |
PANGAEA - Data Publisher for Earth & Environmental Science |
op_collection_id |
ftpangaea |
language |
English |
topic |
164-994A 164-994C 164-995A 164-997A DRILL Drilling/drill rig Joides Resolution Leg164 Nicaraguan Rise North Atlantic Ocean Ocean Drilling Program ODP |
spellingShingle |
164-994A 164-994C 164-995A 164-997A DRILL Drilling/drill rig Joides Resolution Leg164 Nicaraguan Rise North Atlantic Ocean Ocean Drilling Program ODP Dickens, Gerald Roy Chemical composition of sediment samples from ODP Leg 164 sites, Blake Ridge |
topic_facet |
164-994A 164-994C 164-995A 164-997A DRILL Drilling/drill rig Joides Resolution Leg164 Nicaraguan Rise North Atlantic Ocean Ocean Drilling Program ODP |
description |
Ocean Drilling Program (ODP) Sites 994, 995, and 997 were drilled into a large gas hydrate deposit on the crest of the Blake Ridge (southeast U.S. margin) where upward CH4 fluxes (F_OUT) are related to depths of pore water SO4**2- depletion. High-resolution pore water SO4**2- and sediment Ba profiles have been constructed at these sites to assess present and past F_out. Pore water SO4**2- profiles are linear with zero SO4**2- concentration occurring at 21.4, 21.6, and 22.8 mbsf at Holes 994A, 995A and 997A, respectively. Using steady state solutions to diffusion equations with appropriate parameters, the steep SO4**2- gradients support upward CH4 fluxes between 7.2 and 8.6 mol/m**2/ky at present-day, with the range primarily reflecting different approaches for incorporating porosity (phi). Taking into account the generally decreasing phi with depth and the high clay content of the sediment, the best estimates for F_out are 7.9, 7.6 and 7.2 mol CH4/m**2/ky at Sites 994, 995 and 997, respectively. However, non-steady state solutions to diffusion equations show that the SO4**2- gradients do not imply steady state conditions. Elevated Ba concentrations (530–1410 ppm) exist in sediment between 18.23 and 20.65, between 17.31 and 20.31, between 19.40 and 21.80, and between 19.58 and 21.91 mbsf at Holes 994A, 994C, 995A, and 997A, respectively. These Ba fronts coincide with highs in bulk sediment Ba/Al (to 0.025) and are caused by Ba cycling just above time averaged depths of SO4**2- depletion. Because the Ba fronts lie immediately above the present-day depths of pore water SO4**2- depletion, and because no other Ba fronts are found in the upper 25 m at the three sites, the depth of SO4**2- depletion beneath the seafloor has been nearly constant for considerable time (>18000 years). Thus, CH4 fluxes can be determined through SO4**2- gradients and steady state solutions to diffusion equations. More importantly, F_out through the crest of the Blake Ridge has not varied significantly across major changes in sea level ... |
format |
Dataset |
author |
Dickens, Gerald Roy |
author_facet |
Dickens, Gerald Roy |
author_sort |
Dickens, Gerald Roy |
title |
Chemical composition of sediment samples from ODP Leg 164 sites, Blake Ridge |
title_short |
Chemical composition of sediment samples from ODP Leg 164 sites, Blake Ridge |
title_full |
Chemical composition of sediment samples from ODP Leg 164 sites, Blake Ridge |
title_fullStr |
Chemical composition of sediment samples from ODP Leg 164 sites, Blake Ridge |
title_full_unstemmed |
Chemical composition of sediment samples from ODP Leg 164 sites, Blake Ridge |
title_sort |
chemical composition of sediment samples from odp leg 164 sites, blake ridge |
publisher |
PANGAEA |
publishDate |
2001 |
url |
https://doi.pangaea.de/10.1594/PANGAEA.708278 https://doi.org/10.1594/PANGAEA.708278 |
op_coverage |
MEDIAN LATITUDE: 31.804500 * MEDIAN LONGITUDE: -75.520700 * SOUTH-BOUND LATITUDE: 31.785700 * WEST-BOUND LONGITUDE: -75.545900 * NORTH-BOUND LATITUDE: 31.843100 * EAST-BOUND LONGITUDE: -75.468600 * DATE/TIME START: 1995-11-07T14:08:00 * DATE/TIME END: 1995-12-10T00:10:00 |
long_lat |
ENVELOPE(-75.545900,-75.468600,31.843100,31.785700) |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
Supplement to: Dickens, Gerald Roy (2001): Sulfate profiles and barium fronts in sediment on the Blake Ridge: Present and past methane fluxes through a large gas hydrate reservoir. Geochimica et Cosmochimica Acta, 65(4), 529-543, https://doi.org/10.1016/S0016-7037(00)00556-1 |
op_relation |
https://doi.pangaea.de/10.1594/PANGAEA.708278 https://doi.org/10.1594/PANGAEA.708278 |
op_rights |
CC-BY-3.0: Creative Commons Attribution 3.0 Unported Access constraints: unrestricted info:eu-repo/semantics/openAccess |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.1594/PANGAEA.708278 https://doi.org/10.1016/S0016-7037(00)00556-1 |
_version_ |
1766136963887267840 |