Magnesium isotope ratios of pore-fluids and dolomites
Magnesium concentrations in deep-sea sediment pore-fluids typically decrease down core due to net precipitation of dolomite or clay minerals in the sediments or underlying crust. To better characterize and differentiate these processes, we have measured magnesium isotopes in pore-fluids and sediment...
Main Authors: | , |
---|---|
Format: | Other/Unknown Material |
Language: | English |
Published: |
PANGAEA
2010
|
Subjects: | |
Online Access: | https://doi.pangaea.de/10.1594/PANGAEA.783095 https://doi.org/10.1594/PANGAEA.783095 |
id |
ftpangaea:oai:pangaea.de:doi:10.1594/PANGAEA.783095 |
---|---|
record_format |
openpolar |
spelling |
ftpangaea:oai:pangaea.de:doi:10.1594/PANGAEA.783095 2024-09-15T18:24:30+00:00 Magnesium isotope ratios of pore-fluids and dolomites Higgins, J A Schrag, Daniel P MEDIAN LATITUDE: 0.327703 * MEDIAN LONGITUDE: -55.076690 * SOUTH-BOUND LATITUDE: -31.552667 * WEST-BOUND LONGITUDE: -142.015650 * NORTH-BOUND LATITUDE: 32.282733 * EAST-BOUND LONGITUDE: 15.660222 * DATE/TIME START: 1994-02-14T04:00:00 * DATE/TIME END: 2001-11-23T00:00:00 2010 application/zip, 2 datasets https://doi.pangaea.de/10.1594/PANGAEA.783095 https://doi.org/10.1594/PANGAEA.783095 en eng PANGAEA https://doi.pangaea.de/10.1594/PANGAEA.783095 https://doi.org/10.1594/PANGAEA.783095 CC-BY-3.0: Creative Commons Attribution 3.0 Unported Access constraints: unrestricted info:eu-repo/semantics/openAccess Supplement to: Higgins, J A; Schrag, Daniel P (2010): Constraining magnesium cycling in marine sediments using magnesium isotopes. Geochimica et Cosmochimica Acta, 74(17), 5039-5053, https://doi.org/10.1016/j.gca.2010.05.019 154-925A 167-1012 175-1082 175-1086 199-1219 Benguela Current South Atlantic Ocean COMPCORE Composite Core DRILL Drilling/drill rig Joides Resolution Leg154 Leg167 Leg175 Leg199 North Atlantic Ocean North Pacific Ocean Ocean Drilling Program ODP dataset publication series 2010 ftpangaea https://doi.org/10.1594/PANGAEA.78309510.1016/j.gca.2010.05.019 2024-08-21T00:02:25Z Magnesium concentrations in deep-sea sediment pore-fluids typically decrease down core due to net precipitation of dolomite or clay minerals in the sediments or underlying crust. To better characterize and differentiate these processes, we have measured magnesium isotopes in pore-fluids and sediment samples from Ocean Drilling Program sites (1082, 1086, 1012, 984, 1219, and 925) that span a range of oceanographic settings. At all sites, magnesium concentrations decrease with depth. At sites where diagenetic reactions are dominated by the respiration of organic carbon, pore-fluid d26Mg values increase with depth by as much as 2 per mil. Because carbonates preferentially incorporate 24Mg (low d26Mg), the increase in pore-fluid d26Mg values at these sites is consistent with the removal of magnesium in Mg-carbonate (dolomite). In contrast, at sites where the respiration of organic carbon is not important and/or weatherable minerals are abundant, pore-fluid d26Mg values decrease with depth by up to 2 per mil. The decline in pore-fluid d26Mg at these sites is consistent with a magnesium sink that is isotopically enriched relative to the pore-fluid. The identity of this enriched magnesium sink is likely clay minerals. Using a simple 1D diffusion-advection-reaction model of pore-fluid magnesium, we estimate rates of net magnesium uptake/removal and associated net magnesium isotope fractionation factors for sources and sinks at all sites. Independent estimates of magnesium isotope fractionation during dolomite precipitation from measured d26Mg values of dolomite samples from sites 1082 and 1012 are very similar to modeled net fractionation factors at these sites, suggesting that local exchange of magnesium between sediment and pore-fluid at these sites can be neglected. Our results indicate that the magnesium incorporated in dolomite is 2.0-2.7 per mil depleted in d26Mg relative to the precipitating fluid. Assuming local exchange of magnesium is minor at the rest of the studied sites, our results suggest that magnesium ... Other/Unknown Material North Atlantic South Atlantic Ocean PANGAEA - Data Publisher for Earth & Environmental Science ENVELOPE(-142.015650,15.660222,32.282733,-31.552667) |
institution |
Open Polar |
collection |
PANGAEA - Data Publisher for Earth & Environmental Science |
op_collection_id |
ftpangaea |
language |
English |
topic |
154-925A 167-1012 175-1082 175-1086 199-1219 Benguela Current South Atlantic Ocean COMPCORE Composite Core DRILL Drilling/drill rig Joides Resolution Leg154 Leg167 Leg175 Leg199 North Atlantic Ocean North Pacific Ocean Ocean Drilling Program ODP |
spellingShingle |
154-925A 167-1012 175-1082 175-1086 199-1219 Benguela Current South Atlantic Ocean COMPCORE Composite Core DRILL Drilling/drill rig Joides Resolution Leg154 Leg167 Leg175 Leg199 North Atlantic Ocean North Pacific Ocean Ocean Drilling Program ODP Higgins, J A Schrag, Daniel P Magnesium isotope ratios of pore-fluids and dolomites |
topic_facet |
154-925A 167-1012 175-1082 175-1086 199-1219 Benguela Current South Atlantic Ocean COMPCORE Composite Core DRILL Drilling/drill rig Joides Resolution Leg154 Leg167 Leg175 Leg199 North Atlantic Ocean North Pacific Ocean Ocean Drilling Program ODP |
description |
Magnesium concentrations in deep-sea sediment pore-fluids typically decrease down core due to net precipitation of dolomite or clay minerals in the sediments or underlying crust. To better characterize and differentiate these processes, we have measured magnesium isotopes in pore-fluids and sediment samples from Ocean Drilling Program sites (1082, 1086, 1012, 984, 1219, and 925) that span a range of oceanographic settings. At all sites, magnesium concentrations decrease with depth. At sites where diagenetic reactions are dominated by the respiration of organic carbon, pore-fluid d26Mg values increase with depth by as much as 2 per mil. Because carbonates preferentially incorporate 24Mg (low d26Mg), the increase in pore-fluid d26Mg values at these sites is consistent with the removal of magnesium in Mg-carbonate (dolomite). In contrast, at sites where the respiration of organic carbon is not important and/or weatherable minerals are abundant, pore-fluid d26Mg values decrease with depth by up to 2 per mil. The decline in pore-fluid d26Mg at these sites is consistent with a magnesium sink that is isotopically enriched relative to the pore-fluid. The identity of this enriched magnesium sink is likely clay minerals. Using a simple 1D diffusion-advection-reaction model of pore-fluid magnesium, we estimate rates of net magnesium uptake/removal and associated net magnesium isotope fractionation factors for sources and sinks at all sites. Independent estimates of magnesium isotope fractionation during dolomite precipitation from measured d26Mg values of dolomite samples from sites 1082 and 1012 are very similar to modeled net fractionation factors at these sites, suggesting that local exchange of magnesium between sediment and pore-fluid at these sites can be neglected. Our results indicate that the magnesium incorporated in dolomite is 2.0-2.7 per mil depleted in d26Mg relative to the precipitating fluid. Assuming local exchange of magnesium is minor at the rest of the studied sites, our results suggest that magnesium ... |
format |
Other/Unknown Material |
author |
Higgins, J A Schrag, Daniel P |
author_facet |
Higgins, J A Schrag, Daniel P |
author_sort |
Higgins, J A |
title |
Magnesium isotope ratios of pore-fluids and dolomites |
title_short |
Magnesium isotope ratios of pore-fluids and dolomites |
title_full |
Magnesium isotope ratios of pore-fluids and dolomites |
title_fullStr |
Magnesium isotope ratios of pore-fluids and dolomites |
title_full_unstemmed |
Magnesium isotope ratios of pore-fluids and dolomites |
title_sort |
magnesium isotope ratios of pore-fluids and dolomites |
publisher |
PANGAEA |
publishDate |
2010 |
url |
https://doi.pangaea.de/10.1594/PANGAEA.783095 https://doi.org/10.1594/PANGAEA.783095 |
op_coverage |
MEDIAN LATITUDE: 0.327703 * MEDIAN LONGITUDE: -55.076690 * SOUTH-BOUND LATITUDE: -31.552667 * WEST-BOUND LONGITUDE: -142.015650 * NORTH-BOUND LATITUDE: 32.282733 * EAST-BOUND LONGITUDE: 15.660222 * DATE/TIME START: 1994-02-14T04:00:00 * DATE/TIME END: 2001-11-23T00:00:00 |
long_lat |
ENVELOPE(-142.015650,15.660222,32.282733,-31.552667) |
genre |
North Atlantic South Atlantic Ocean |
genre_facet |
North Atlantic South Atlantic Ocean |
op_source |
Supplement to: Higgins, J A; Schrag, Daniel P (2010): Constraining magnesium cycling in marine sediments using magnesium isotopes. Geochimica et Cosmochimica Acta, 74(17), 5039-5053, https://doi.org/10.1016/j.gca.2010.05.019 |
op_relation |
https://doi.pangaea.de/10.1594/PANGAEA.783095 https://doi.org/10.1594/PANGAEA.783095 |
op_rights |
CC-BY-3.0: Creative Commons Attribution 3.0 Unported Access constraints: unrestricted info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.1594/PANGAEA.78309510.1016/j.gca.2010.05.019 |
_version_ |
1810464855829774336 |