Sulfur isotope patterns of oceanic crust on Macquarie Island-implications for global sulfur cycling G
Metadata record for data from ASAC Project 2212 See the link below for public details on this project.\n\nFrom the abstracts of two of the references:\n\n --- \nOcean Drilling Program hole 504B revealed an ocean crust hydrothermal sulphur anomaly on the dyke-lava transition, with implications for gl...
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data.gov.au
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| Online Access: | https://researchdata.edu.au/sulfur-isotope-patterns-cycling-g/1938909 http://data.gov.au/dataset/f31aafb1-aa60-46b8-9d90-b8695d20320c |
| Summary: | Metadata record for data from ASAC Project 2212 See the link below for public details on this project.\n\nFrom the abstracts of two of the references:\n\n --- \nOcean Drilling Program hole 504B revealed an ocean crust hydrothermal sulphur anomaly on the dyke-lava transition, with implications for global sulphur sinks. Here we confirm the presence of the anomaly sporadically along 7.5km of dyke-basalt contact on the Macquarie Ridge at Macquarie Island, a 39-9.7 Ma slow-spreading setting. Background contact-zone pyrite S contents average 1845 ppm across ~50 m. However zones of small-scale brittle faulting that commonly occur on and above the dyke-basalt contact average between 5000 and 11000 ppm S (20-30 m widths). These consist of steep ridge-parallel faults and fault splays on the contact, overlain by up to 50m of linked pyritic fault trellis. The contact zone faults are haloed by disseminated pyrite-chlorite, cross-cut by quartz-chlorite-sphalerite and epidote-cemented breccias, containing evidence of turbulent flow. The structural control on sulphur deposition is attributed to the active extensional slow spreading setting. With increasing extension, diffuse mixing across the contact was replaced by channelised flow and dynamic mixing in fault arrays. The magnitude of the dyke-lava transition sulphur sink must be reassessed to take account of this heterogeneity.\n --- \nThere are only a handful of known hydrothermal sulfate occurrences from the mid-ocean ridge crust sub-surface, despite predictions that they should be common because of the imbalance between sulfur concentrations in venting MOR hotsprings, and that of recharging seawater. This deficit indicates that sub-surface sulfate deposition could be a globally important sulfur cycle sink. Therefore any new occurrences add considerably to the information base on sulfate in this environment.\n\nAn important hydrothermal sulfate occurrence is preserved in ~10 Ma MOR crust on the east coast of Macquarie Island, formed during very slow oblique spreading prior ... |
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