The Seven Sisters Hydrothermal System: First Record of Shallow Hybrid Mineralization Hosted in Mafic Volcaniclasts on the Arctic Mid-Ocean Ridge
We document the discovery of an active, shallow, seafloor hydrothermal system (known as the Seven Sisters Vent Field) hosted in mafic volcaniclasts at a mid-ocean ridge setting. The vent field is located at the southern part of the Arctic mid-ocean ridge where it lies on top of a flat-topped volcano...
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MDPI AG
2020-05-01
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| Series: | Minerals |
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| Online Access: | https://www.mdpi.com/2075-163X/10/5/439 |
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| author | Ana Filipa A. Marques Desiree L. Roerdink Tamara Baumberger Cornel E. J. de Ronde Robert G. Ditchburn Alden Denny Ingunn H. Thorseth Ingeborg Okland Marvin D. Lilley Martin J. Whitehouse Rolf B. Pedersen |
| author_facet | Ana Filipa A. Marques Desiree L. Roerdink Tamara Baumberger Cornel E. J. de Ronde Robert G. Ditchburn Alden Denny Ingunn H. Thorseth Ingeborg Okland Marvin D. Lilley Martin J. Whitehouse Rolf B. Pedersen |
| author_sort | Ana Filipa A. Marques |
| collection | DOAJ |
| description | We document the discovery of an active, shallow, seafloor hydrothermal system (known as the Seven Sisters Vent Field) hosted in mafic volcaniclasts at a mid-ocean ridge setting. The vent field is located at the southern part of the Arctic mid-ocean ridge where it lies on top of a flat-topped volcano at ~130 m depth. Up to 200 °C phase-separating fluids vent from summit depressions in the volcano, and from pinnacle-like edifices on top of large hydrothermal mounds. The hydrothermal mineralization at Seven Sisters manifests as a replacement of mafic volcaniclasts, as direct intraclast precipitation from the hydrothermal fluid, and as elemental sulfur deposition within orifices. Barite is ubiquitous, and is sequentially replaced by pyrite, which is the first sulfide to form, followed by Zn-Cu-Pb-Ag bearing sulfides, sulfosalts, and silica. The mineralized rocks at Seven Sisters contain highly anomalous concentrations of ‘epithermal suite’ elements such as Tl, As, Sb and Hg, with secondary alteration assemblages including silica and dickite. Vent fluids have a pH of ~5 and are Ba and metal depleted. Relatively high dissolved Si (~7.6 mmol/L Si) combined with low (0.2–0.4) Fe/Mn suggest high-temperature reactions at ~150 bar. A δ<sup>13</sup>C value of −5.4‰ in CO<sub>2</sub> dominated fluids denotes magmatic degassing from a relatively undegassed reservoir. Furthermore, low CH<sub>4</sub> and H<sub>2</sub> (<0.026 mmol/kg and <0.009 mmol/kg, respectively) and <sup>3</sup>He/<sup>4</sup>He of ~8.3 R/Ra<sub>corr</sub> support a MORB-like, sediment-free fluid signature from an upper mantle source. Sulfide and secondary alteration mineralogy, fluid and gas chemistry, as well as δ<sup>34</sup>S and <sup>87</sup>Sr/<sup>86</sup>Sr values in barite and pyrite indicate that mineralization at Seven Sisters is sustained by the input of magmatic fluids with minimal seawater contribution. <sup>226</sup>Ra/Ba radiometric dating of the barite suggests that this hydrothermal system has been active for at least 4670 ± 60 yr. |
| first_indexed | 2024-03-10T19:48:17Z |
| format | Article |
| id | doaj.art-0e0510a06936473497dc2e6363aeec39 |
| institution | Directory Open Access Journal |
| issn | 2075-163X |
| language | English |
| last_indexed | 2024-03-10T19:48:17Z |
| publishDate | 2020-05-01 |
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| series | Minerals |
| spelling | doaj.art-0e0510a06936473497dc2e6363aeec392023-11-20T00:34:39ZengMDPI AGMinerals2075-163X2020-05-0110543910.3390/min10050439The Seven Sisters Hydrothermal System: First Record of Shallow Hybrid Mineralization Hosted in Mafic Volcaniclasts on the Arctic Mid-Ocean RidgeAna Filipa A. Marques0Desiree L. Roerdink1Tamara Baumberger2Cornel E. J. de Ronde3Robert G. Ditchburn4Alden Denny5Ingunn H. Thorseth6Ingeborg Okland7Marvin D. Lilley8Martin J. Whitehouse9Rolf B. Pedersen10K.G. Jebsen Centre for Deep Sea Research, University of Bergen, 5007 Bergen, NorwayK.G. Jebsen Centre for Deep Sea Research, University of Bergen, 5007 Bergen, NorwayNOAA/PMEL & CIMRS, Oregon State University, 2115 SE OSU Drive, Newport, OR 97365, USAGNS Science, 1 Fairway Drive, Avalon, P.O. Box 30-368, Lower Hut 6315, New ZealandGNS Science, 1 Fairway Drive, Avalon, P.O. Box 30-368, Lower Hut 6315, New ZealandK.G. Jebsen Centre for Deep Sea Research, University of Bergen, 5007 Bergen, NorwayK.G. Jebsen Centre for Deep Sea Research, University of Bergen, 5007 Bergen, NorwayK.G. Jebsen Centre for Deep Sea Research, University of Bergen, 5007 Bergen, NorwaySchool of Oceanography, University of Washington, Seattle, 98195-7940 WA, USADepartment of Geosciences, Swedish Museum of Natural History, SE-10405 Stockholm, SwedenK.G. Jebsen Centre for Deep Sea Research, University of Bergen, 5007 Bergen, NorwayWe document the discovery of an active, shallow, seafloor hydrothermal system (known as the Seven Sisters Vent Field) hosted in mafic volcaniclasts at a mid-ocean ridge setting. The vent field is located at the southern part of the Arctic mid-ocean ridge where it lies on top of a flat-topped volcano at ~130 m depth. Up to 200 °C phase-separating fluids vent from summit depressions in the volcano, and from pinnacle-like edifices on top of large hydrothermal mounds. The hydrothermal mineralization at Seven Sisters manifests as a replacement of mafic volcaniclasts, as direct intraclast precipitation from the hydrothermal fluid, and as elemental sulfur deposition within orifices. Barite is ubiquitous, and is sequentially replaced by pyrite, which is the first sulfide to form, followed by Zn-Cu-Pb-Ag bearing sulfides, sulfosalts, and silica. The mineralized rocks at Seven Sisters contain highly anomalous concentrations of ‘epithermal suite’ elements such as Tl, As, Sb and Hg, with secondary alteration assemblages including silica and dickite. Vent fluids have a pH of ~5 and are Ba and metal depleted. Relatively high dissolved Si (~7.6 mmol/L Si) combined with low (0.2–0.4) Fe/Mn suggest high-temperature reactions at ~150 bar. A δ<sup>13</sup>C value of −5.4‰ in CO<sub>2</sub> dominated fluids denotes magmatic degassing from a relatively undegassed reservoir. Furthermore, low CH<sub>4</sub> and H<sub>2</sub> (<0.026 mmol/kg and <0.009 mmol/kg, respectively) and <sup>3</sup>He/<sup>4</sup>He of ~8.3 R/Ra<sub>corr</sub> support a MORB-like, sediment-free fluid signature from an upper mantle source. Sulfide and secondary alteration mineralogy, fluid and gas chemistry, as well as δ<sup>34</sup>S and <sup>87</sup>Sr/<sup>86</sup>Sr values in barite and pyrite indicate that mineralization at Seven Sisters is sustained by the input of magmatic fluids with minimal seawater contribution. <sup>226</sup>Ra/Ba radiometric dating of the barite suggests that this hydrothermal system has been active for at least 4670 ± 60 yr.https://www.mdpi.com/2075-163X/10/5/439seafloor hydrothermal systemvolcaniclast-hosted VMSfluid chemistryradiometric dating |
| spellingShingle | Ana Filipa A. Marques Desiree L. Roerdink Tamara Baumberger Cornel E. J. de Ronde Robert G. Ditchburn Alden Denny Ingunn H. Thorseth Ingeborg Okland Marvin D. Lilley Martin J. Whitehouse Rolf B. Pedersen The Seven Sisters Hydrothermal System: First Record of Shallow Hybrid Mineralization Hosted in Mafic Volcaniclasts on the Arctic Mid-Ocean Ridge Minerals seafloor hydrothermal system volcaniclast-hosted VMS fluid chemistry radiometric dating |
| title | The Seven Sisters Hydrothermal System: First Record of Shallow Hybrid Mineralization Hosted in Mafic Volcaniclasts on the Arctic Mid-Ocean Ridge |
| title_full | The Seven Sisters Hydrothermal System: First Record of Shallow Hybrid Mineralization Hosted in Mafic Volcaniclasts on the Arctic Mid-Ocean Ridge |
| title_fullStr | The Seven Sisters Hydrothermal System: First Record of Shallow Hybrid Mineralization Hosted in Mafic Volcaniclasts on the Arctic Mid-Ocean Ridge |
| title_full_unstemmed | The Seven Sisters Hydrothermal System: First Record of Shallow Hybrid Mineralization Hosted in Mafic Volcaniclasts on the Arctic Mid-Ocean Ridge |
| title_short | The Seven Sisters Hydrothermal System: First Record of Shallow Hybrid Mineralization Hosted in Mafic Volcaniclasts on the Arctic Mid-Ocean Ridge |
| title_sort | seven sisters hydrothermal system first record of shallow hybrid mineralization hosted in mafic volcaniclasts on the arctic mid ocean ridge |
| topic | seafloor hydrothermal system volcaniclast-hosted VMS fluid chemistry radiometric dating |
| url | https://www.mdpi.com/2075-163X/10/5/439 |
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