Microbially-induced carbonate precipitation and alteration in organic-rich marine sediments

微生物引起的碳酸盐沉淀和富含有机物海洋沉积物的蚀变

• 批准号: 218463627
• 负责人: Professor Dr.-Ing. Klaus Wallmann, since 10/2014
• 金额: --
• 依托单位: Forschungseinheit Marine Geosysteme
• 依托单位国家: 德国
• 项目类别: Research Units
• 财政年份: 2013
• 资助国家: 德国
• 起止时间: 2012-12-31 至 2017-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/218463627?language=en
• 关键词: Microbially; induced; carbonate; precipitation; alteration

In the present world, microbially-induced carbonate precipitation is well documented for non-normal marine depositional systems such as hypersaline microbial mats and stromatolites; but information is still scarce on how microbes facilitate carbonate crystallization in organic-rich sediments that are covering vast areas of coastal shelves and continental margins. From the viewpoint of carbonate archive research, this aspect is significant, because fossil carbonate oozes are widely used as proxy carriers in many studies dealing with the reconstruction of the palaeo-environment. It is expected that heterotrophic carbonatogenesis is ubiquitous since the Precambrian and probably always played an important role in the formation of carbonate deposits. The first aim of the project is to provide in-depth analyses of carbonate precipitation in organic-rich sediments mediated by anaerobic heterotrophic microorganisms. More specific objectives include characterization of environmental prerequisites for carbonate precipitation, role of extracellular polymeric substances for crystal nucleation, and alteration of isotopic signatures and element ratios during crystallization. The second aim is the investigation of microbially-induced alteration (“microbial weathering”) of biogenic carbonates in early diagenetic sediment/porewater environments. While the concept of microbial alteration of carbonates (boring and etching of carbonate hardparts) is generally accepted, the mechanisms of the processes involved and the traces that are evident for microbial involvement yet need to be identified. With the investigation of microbial processes in the upper sediment column that are capable of altering carbonates (i.e., weakening of carbonate skeletons and providing pathways for diagenetic fluids), or inducing secondary carbonate precipitation, the analysis of early diagenetic processes in biogenic carbonate deposits from the microbiological perspective is intended.

在当今世界，微生物引起的碳酸盐降水在非正常海洋沉积体系中得到了充分的记录，如高盐微生物席和叠层石；但是，关于微生物如何促进覆盖广大沿海大陆架和大陆边缘的富有机质沉积物中的碳酸盐结晶的信息仍然很少。从碳酸盐岩档案研究的角度来看，这方面具有重要意义，因为在许多古环境重建研究中，化石碳酸盐岩软泥被广泛用作代用载体。预计异养碳酸成因自前寒武纪以来普遍存在，并可能一直在碳酸盐岩矿床的形成中发挥重要作用。该项目的第一个目标是对厌氧异养微生物介导的富有机物沉积物中的碳酸盐沉淀进行深入分析。更具体的目标包括表征碳酸盐沉淀的环境先决条件，细胞外聚合物物质在结晶成核中的作用，以及结晶过程中同位素特征和元素比例的变化。第二个目标是研究早期成岩沉积/孔隙水环境中生物成因碳酸盐的微生物诱导蚀变（“微生物风化”）。虽然微生物改变碳酸盐的概念（碳酸盐硬件的钻孔和蚀刻）被普遍接受，但所涉及的过程机制和微生物参与的明显痕迹仍需要确定。通过对上层沉积柱中能够改变碳酸盐（即弱化碳酸盐骨架并为成岩流体提供途径）或诱导碳酸盐次生沉淀的微生物过程的研究，从微生物学角度分析生物成因碳酸盐矿床的早期成岩过程。