Cold seep formation from salt diapir-controlled deep biosphere oases

• 成果类型: Article
• 署名作者: Chowdhury, Anirban; Ventura, Gregory T.; Owino, Yaisa; Lalk, Ellen J.; Macadam, Natasha; Dooma, John M.; Ono, Shuhei; Fowler, Martin; Macdonald, Adam; Bennett, Robbie; Macrae, R. Andrew; Hubert, Casey R. J.; Bentley, Jeremy N.; Kerr, Mitchell J.
• 署名单位: Saint Marys University - Canada; Massachusetts Institute of Technology (MIT); Natural Resources Canada; Lands & Minerals Sector - Natural Resources Canada; Geological Survey of Canada; University of Calgary
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-9136
• DOI: 10.1073/pnas.2316878121
• 发表日期: 2024-03-15
• 关键词: thermal-conductivity; methane isotopologue; microbial-production; isotope; gas; oxidation; equilibrium; temperature; maturation; signatures

摘要

Deep sea cold seeps are sites where hydrogen sulfide, methane, and other hydrocarbon - rich fluids vent from the ocean floor. They are an important component of Earth's carbon cycle in which subsurface hydrocarbons form the energy source for highly diverse benthic micro- and macro - fauna in what is otherwise vast and spartan sea scape. Passive continental margin cold seeps are typically attributed to the migration of hydrocarbons generated from deeply buried source rocks. Many of these seeps occur over salt tectonic provinces, where the movement of salt generates complex fault systems that can enable fluid migration or create seals and traps associated with reservoir formation. The elevated advective heat transport of the salt also produces a chimney effect directly over these structures. Here, we provide geophysical and geochemical evidence that the salt chimney effect in conjunction with diapiric faulting drives a subsurface groundwater circulation system that brings dissolved inorganic carbon, nutrient - rich deep basinal fluids, and potentially overlying seawater onto the crests of deeply buried salt diapirs. The mobilized fluids fuel methanogenic archaea locally enhancing the deep biosphere. The resulting elevated biogenic methane production, alongside the upward heat- driven fluid transport, represents a previously unrecognized mechanism of cold seep formation and regulation.