Formation mechanisms of low-magnesium calcite and associated barite at cold seeps in today's aragonite sea

当今文石海冷泉中低镁方解石和伴生重晶石的形成机制

• 批准号: 392227523
• 负责人: Dr. Daniel Birgel
• 金额: --
• 依托单位: National Natural Science Foundation of China
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/392227523?language=en
• 关键词: Formation; mechanisms; low; magnesium; calcite

Composite low-magnesium calcite (LMC) and barite have been reported from some modern seep deposits, but the formation conditions of this paragenesis in today's aragonite sea remain largely unconstrained. This project aims to characterize the formation environments of this unusual paragenesis at modern seeps in the Gulf of Mexico. We hypothesize that the precipitation of barite and LMC is governed by the composition of seep fluids, with brine seepage favoring a mineral paragenesis that is rare in the shallow subseafloor at modern seeps elsewhere than in the Gulf of Mexico. The composition of seep fluids that favored barite and LMC formation will be reconstructed by means of organic (lipid biomarkers) and inorganic geochemistry (trace metals; S, O, C stable isotopes). This approach will be complemented by uranium-series age dating of LMC and will use existing data on pore fluid composition of the intermittently active seeps where barite and LMC formed in the past. The application of a comprehensive set of methods of low-temperature geochemistry will lead to the establishment of new proxies that will allow for the recognition of seep-related barite and associated LMC elsewhere. Obtaining such knowledge will be the prerequisite for the reconstruction of the environmental conditions that led to the formation of globally distributed massive barite in the Paleozoic. At least some of the Paleozoic barite deposits bear putative seep obligate fauna. A better reconstruction of the shallow subseafloor environments that favored barite formation in the Paleozoic will consequently foster the identification of the factors that governed the early evolution of chemosynthesis-based ecosystems at seeps.

从某些现代的渗水沉积物中报道了复合材料低镁方解石（LMC）和barite，但这种副膜发生的形成条件在当今的后海中仍然在很大程度上不受限制。该项目旨在表征墨西哥湾现代渗水的这种不寻常旁皮的形成环境。我们假设Barite和LMC的沉淀受渗流液的组成，盐水渗漏有利于在墨西哥湾以外的其他地方的浅层层中的矿物质副膜片。有机（脂质生物标志物）和无机地球化学（Trace Metals; S，O，O，C稳定的同位素），将重建有利于Barite和LMC形成的渗流的渗流组成。 LMC的铀系列年龄年代的年龄将补充这种方法，并将使用现有的数据上的孔流体组成的孔隙流体组成，在过去形成的Barite和LMC过去。一套全面的低温地球化学方法的应用将导致建立新的代理，这些代理将允许在其他地方识别与Seep相关的Barite和相关的LMC。获得此类知识将是重建导致古生代中全球分布的大量芳料的环境条件的先决条件。至少一些古生代的barite沉积物带有推定的渗水术动物动物群。因此，更好地重建了古生物学中有利于巴石形成的浅层子叶环境，将促进鉴定渗透性化学合成生态系统早期演化的因素。