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Borisov DG, Frey DI, Ivanova EV, Dmitrevskiy NN, Levchenko OV, Fomin VV, Ligi M. Unveiling the contourite depositional system in the Vema Fracture Zone (Central Atlantic). Sci Rep 2023; 13:13834. [PMID: 37620351 PMCID: PMC10449790 DOI: 10.1038/s41598-023-40401-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Accepted: 08/09/2023] [Indexed: 08/26/2023] Open
Abstract
A combination of a high sediment input and intense bottom currents often leads to the formation of contourites (sediments deposited or significantly reworked by bottom currents). Both of these components are present in the Vema Fracture Zone valley which is the most important passageway for the distribution of the Antarctic Bottom Water from the West to the North-East of the Atlantic. However, no contourite drifts, moats or contourite channels have been found in this region in more than half a century of research. The prevailing sedimentation paradigm postulates that turbidity currents have predominantly governed sedimentation in this region during the Pleistocene. This work describes the first example of contourite depositional system identified in the Vema Fracture Zone. The discovery was made through detailed high-resolution sub-bottom profiling, as well as numerical modeling and direct measurements of bottom current velocities. Such systems are exceptionally uncommon in fracture zones. This study highlights the importance of further research of contourites along the Vema Fracture Zone based on modern concepts of contourite and mixed depositional systems. The work also emphasizes the need to reevaluate the impact of bottom currents on sedimentation in this region, and particularly in the narrow segments of the fracture zone valley.
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Affiliation(s)
- Dmitrii G Borisov
- Shirshov Institute of Oceanology, Russian Academy of Sciences, Moscow, Russia.
| | - Dmitry I Frey
- Shirshov Institute of Oceanology, Russian Academy of Sciences, Moscow, Russia
- Moscow Institute of Physics and Technology, Dolgoprudny, Russia
| | - Elena V Ivanova
- Shirshov Institute of Oceanology, Russian Academy of Sciences, Moscow, Russia
| | | | - Oleg V Levchenko
- Shirshov Institute of Oceanology, Russian Academy of Sciences, Moscow, Russia
| | | | - Marco Ligi
- Istituto di Scienze Marine, Consiglio Nazionale delle Ricerche, Bologna, Italy
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Le Roux V, Urann BM, Brunelli D, Bonatti E, Cipriani A, Demouchy S, Monteleone BD. Postmelting hydrogen enrichment in the oceanic lithosphere. SCIENCE ADVANCES 2021; 7:7/24/eabf6071. [PMID: 34108206 PMCID: PMC8189580 DOI: 10.1126/sciadv.abf6071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Accepted: 04/21/2021] [Indexed: 06/12/2023]
Abstract
The large range of H2O contents recorded in minerals from exhumed mantle rocks has been challenging to interpret, as it often records a combination of melting, metasomatism, and diffusional processes in spatially isolated samples. Here, we determine the temporal variations of H2O contents in pyroxenes from a 24-Ma time series of abyssal peridotites exposed along the Vema fracture zone (Atlantic Ocean). The H2O contents of pyroxenes correlate with both crustal ages and pyroxene chemistry and increase toward younger and more refractory peridotites. These variations are inconsistent with residual values after melting and opposite to trends often observed in mantle xenoliths. Postmelting hydrogen enrichment occurred by ionic diffusion during cryptic metasomatism of peridotite residues by low-degree, volatile-rich melts and was particularly effective in the most depleted peridotites. The presence of hydrous melts under ridges leads to widespread hydrogen incorporation in the oceanic lithosphere, likely lowering mantle viscosity compared to dry models.
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Affiliation(s)
- Veronique Le Roux
- Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA.
| | - Benjamin M Urann
- Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
- MIT-WHOI Joint Program, Marine Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
| | - Daniele Brunelli
- Dipartimento di Scienze Chimiche e Geologiche, Università di Modena e Reggio Emilia, Modena, Italy
- Istituto di Scienze Marine, CNR, Bologna, Italy
| | - Enrico Bonatti
- Istituto di Scienze Marine, CNR, Bologna, Italy
- Lamont Doherty Earth Observatory, Columbia University, New York, NY 10027, USA
| | - Anna Cipriani
- Dipartimento di Scienze Chimiche e Geologiche, Università di Modena e Reggio Emilia, Modena, Italy
- Lamont Doherty Earth Observatory, Columbia University, New York, NY 10027, USA
| | - Sylvie Demouchy
- Géosciences Montpellier, Université Montpellier & CNRS, Montpellier, France
| | - Brian D Monteleone
- Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
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High H 2O Content in Pyroxenes of Residual Mantle Peridotites at a Mid Atlantic Ridge Segment. Sci Rep 2020; 10:579. [PMID: 31953494 PMCID: PMC6969183 DOI: 10.1038/s41598-019-57344-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Accepted: 12/29/2019] [Indexed: 11/08/2022] Open
Abstract
Global correlations of mid-ocean-ridges basalt chemistry, axial depth and crustal thickness have been ascribed to mantle temperature variations affecting degree of melting. However, mantle H2O content and elemental composition may also play a role. How H2O is distributed in the oceanic upper mantle remains poorly constrained. We tackled this problem by determining the H2O content of orthopyroxenes (opx) and clinopyroxenes (cpx) of peridotites from a continuous lithospheric section created during 26 Ma at a 11°N Mid-Atlantic Ridge segment, and exposed along the Vema Transform. The H2O content of opx ranges from 119 ppm to 383 ppm; that of cpx from 407 ppm to 1072 ppm. We found anomalous H2O-enriched peridotites with their H2O content not correlating inversely with their degree of melting, although H2O is assumed to be incompatible during melting. Inverse correlation of H2O with Ce, another highly incompatible component, suggests post-melting H2O enrichment. We attribute a major role to post-melting temperature-dependent diffusion of hydrogen occurring above the melting region, where water-rich melt flows faster than residual peridotites through dunitic conduits cross-cutting the uprising mantle. Accordingly, estimates of the H2O content of the MORB mantle source based on H2O in abyssal peridotites can be affected by strong uncertainties.
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Olive JA, Behn MD, Ito G, Buck WR, Escartín J, Howell S. Sensitivity of seafloor bathymetry to climate-driven fluctuations in mid-ocean ridge magma supply. Science 2015; 350:310-3. [PMID: 26472905 DOI: 10.1126/science.aad0715] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Recent studies have proposed that the bathymetric fabric of the seafloor formed at mid-ocean ridges records rapid (23,000 to 100,000 years) fluctuations in ridge magma supply caused by sealevel changes that modulate melt production in the underlying mantle. Using quantitative models of faulting and magma emplacement, we demonstrate that, in fact, seafloor-shaping processes act as a low-pass filter on variations in magma supply, strongly damping fluctuations shorter than about 100,000 years. We show that the systematic decrease in dominant seafloor wavelengths with increasing spreading rate is best explained by a model of fault growth and abandonment under a steady magma input. This provides a robust framework for deciphering the footprint of mantle melting in the fabric of abyssal hills, the most common topographic feature on Earth.
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Affiliation(s)
- J-A Olive
- Lamont-Doherty Earth Observatory, Columbia University, Palisades NY, USA.
| | - M D Behn
- Woods Hole Oceanographic Institution, Woods Hole MA, USA
| | - G Ito
- University of Hawaii, Honolulu HI, USA
| | - W R Buck
- Lamont-Doherty Earth Observatory, Columbia University, Palisades NY, USA
| | - J Escartín
- CNRS, Institut de Physique du Globe de Paris, Paris, France
| | - S Howell
- University of Hawaii, Honolulu HI, USA
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Ligi M, Bonatti E, Cuffaro M, Brunelli D. Post-mesozoic rapid increase of seawater Mg/Ca due to enhanced mantle-seawater interaction. Sci Rep 2013; 3:2752. [PMID: 24067442 PMCID: PMC3783036 DOI: 10.1038/srep02752] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Accepted: 09/06/2013] [Indexed: 11/10/2022] Open
Abstract
The seawater Mg/Ca ratio increased significantly from ~ 80 Ma to present, as suggested by studies of carbonate veins in oceanic basalts and of fluid inclusions in halite. We show here that reactions of mantle-derived peridotites with seawater along slow spreading mid-ocean ridges contributed to the post-Cretaceous Mg/Ca increase. These reactions can release to modern seawater up to 20% of the yearly Mg river input. However, no significant peridotite-seawater interaction and Mg-release to the ocean occur in fast spreading, East Pacific Rise-type ridges. The Mesozoic Pangean superocean implies a hot fast spreading ridge system. This prevented peridotite-seawater interaction and Mg release to the Mesozoic ocean, but favored hydrothermal Mg capture and Ca release by the basaltic crust, resulting in a low seawater Mg/Ca ratio. Continent dispersal and development of slow spreading ridges allowed Mg release to the ocean by peridotite-seawater reactions, contributing to the increase of the Mg/Ca ratio of post-Mesozoic seawater.
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Affiliation(s)
- Marco Ligi
- Istituto di Scienze Marine, CNR, Via Gobetti 101, 40129 Bologna, Italy
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Lissenberg CJ, Rioux M, Shimizu N, Bowring SA, Mével C. Zircon Dating of Oceanic Crustal Accretion. Science 2009; 323:1048-50. [DOI: 10.1126/science.1167330] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- C. Johan Lissenberg
- Equipe de Géosciences Marines, Institut de Physique du Globe de Paris, 4 Place Jussieu, 75252 Paris Cedex 05, France
- Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Matthew Rioux
- Equipe de Géosciences Marines, Institut de Physique du Globe de Paris, 4 Place Jussieu, 75252 Paris Cedex 05, France
- Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Nobumichi Shimizu
- Equipe de Géosciences Marines, Institut de Physique du Globe de Paris, 4 Place Jussieu, 75252 Paris Cedex 05, France
- Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Samuel A. Bowring
- Equipe de Géosciences Marines, Institut de Physique du Globe de Paris, 4 Place Jussieu, 75252 Paris Cedex 05, France
- Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Catherine Mével
- Equipe de Géosciences Marines, Institut de Physique du Globe de Paris, 4 Place Jussieu, 75252 Paris Cedex 05, France
- Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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