Highly variable magmatic accretion at the ultraslow-spreading Gakkel Ridge
Crustal accretion at mid-ocean ridges governs the creation and evolution of the oceanic lithosphere. Generally accepted models<sup>1-4</sup> of passive mantle upwelling and melting predict notably decreased crustal thickness at a spreading rate of less than 20 mm year<sup>-1</sup>. We conducted the first, to our knowledge, high-resolution ocean-bottom seismometer (OBS) experiment at the Gakkel Ridge in the Arctic Ocean and imaged the crustal structure of the slowest-spreading ridge on the Earth. Unexpectedly, we find that crustal thickness ranges between 3.3 km and 8.9 km along the ridge axis and it increased from about 4.5 km to about 7.5 km over the past 5 Myr in an across-axis profile. The highly variable crustal thickness and relatively large average value does not align with the prediction of passive mantle upwelling models. Instead, it can be explained by a model of buoyant active mantle flow driven by thermal and compositional density changes owing to melt extraction. The influence of active versus passive upwelling is predicted to increase with decreasing spreading rate. The process of active mantle upwelling is anticipated to be primarily influenced by mantle temperature and composition. This implies that the observed variability in crustal accretion, which includes notably varied crustal thickness, is probably an inherent characteristic of ultraslow-spreading ridges.
Authors
- Caicai Zha (ORCID: https://orcid.org/0000-0002-8103-8427)
- Pingchuan Tan (ORCID: https://orcid.org/0000-0002-3448-7051)
- Weiwei Ding (ORCID: https://orcid.org/0000-0002-9944-2356)
- Jian Lin (ORCID: https://orcid.org/0000-0002-6831-2014)
- Jason Phipps Morgan (ORCID: https://orcid.org/0000-0002-3100-0877)
- Jie Chen (ORCID: https://orcid.org/0000-0002-4674-8351)
- Jiabiao Li (ORCID: https://orcid.org/0000-0003-1807-4043)
- Jianggu Lu (ORCID: https://orcid.org/0000-0001-7430-0100)
- Tao Zhang (ORCID: https://orcid.org/0000-0002-1205-989X)
- Yejian Wang (ORCID: https://orcid.org/0000-0002-8089-0706)
- Fansheng Kong (ORCID: https://orcid.org/0000-0003-1648-6933)
- J. Dyment (ORCID: https://orcid.org/0000-0002-7677-0541)
- Xiaodong Wei (ORCID: https://orcid.org/0000-0002-9279-2927)
- Xiongwei Niu (ORCID: https://orcid.org/0000-0003-1051-768X)
- Yinxia Fang (ORCID: https://orcid.org/0009-0006-9458-2444)
Institutions
- Centre National de la Recherche Scientifique (FR)
- Institut de physique du globe de Paris (FR)
- Chinese Academy of Sciences (CN)
- Université Paris Cité (FR)
- Ministry of Natural Resources (CN)
- Southern University of Science and Technology (CN)
- Institute of Oceanology (CN)
- South China Sea Institute Of Oceanology (CN)
- Second Institute of Oceanography (CN)
Publication Details
- Journal
- Nature
- Published
- 2024-08-21
- DOI
- https://doi.org/10.1038/s41586-024-07831-0
- Citations
- 28
- Primary Topic
- Geological and Geochemical Analysis
- Type
- article
- Field-Weighted Citation Impact
- 14.96
Funders
- National Natural Science Foundation of China
- Chinese Arctic and Antarctic Administration
- Natural Science Foundation of Zhejiang Province