Processes of hydrothermal alteration in early Archaean oceanic crust

早期太古宙洋壳热液蚀变过程

• 批准号: 207638145
• 负责人: Professorin Dr. Annika Dziggel
• 金额: --
• 依托单位: Institut für Geologie, Mineralogie und Geophysik
• 依托单位国家: 德国
• 项目类别: Infrastructure Priority Programmes
• 财政年份: 2011
• 资助国家: 德国
• 起止时间: 2010-12-31 至 2015-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/207638145?language=en
• 关键词: Processes; hydrothermal; alteration; early; Archaean

Strongly silicified volcanic rocks and associated sediments are a common phenomenon in Mesoarchaean greenstone belts, including the Barberton greenstone belt in South Africa. The silicification is generally interpreted as a result of interaction with Archaean seawater in shallow subseafloor convection cells. One of the most unusual aspects of the hydrothermal systems is the presence of abundant tourmaline, reflecting exceptionally high contents of dissolved boron. However, the source of silica and boron has not been constrained unequivocally, and the role of other potential fluids in the formation of the hydrothermal systems (e.g. higher-temperature hydrothermal fluids) has not been explored. Because the zones of silification and tourmaline mineralization commonly underlie sediments that contain some of the oldest evidence for microbial life on Earth, the early hydrothermal systems potentially reflect an important habitat for microbial life on the Archaean seafloor. Within the framework of the ICDP “Barberton Drilling Project: Peering into the Cradle of Life” this project aims to investigate the processes of seafloor hydrothermal alteration and boron metasomatism, using detailed petrology, fluid inclusion analysis, and in situ B-isotope analysis in tourmaline. The results will provide important constraints on the source, composition and physico-chemical evolution of the interacting fluid(s), and will give detailed insights into the mechanisms of subseafloor hydrothermal alteration in the Mesoarchaean.

强烈的硅化火山岩和相关的沉积物是中非绿色的绿岩带中的一种常见现象，在南非的绿岩带被一般解释为浅层的海水。在大量的电气石中，脱糖硼的反射异常高。 HAT在早期的早期水热系统上含有一些微生物寿命，这可能反映出ICDP“ Barberton Drilling Project：该项目旨在调查过程”或热[使用详细的质学，流体包容分析和原位B异位分析的硼龙交代，结果将对相互作用的液体的组成和物理化学演变提供限制，从而提供了详细的见解中间的水热改变。

项目成果

Tourmaline B-isotopes as tracers of fluid sources in silicified Palaeoarchaean oceanic crust of the Mendon Formation, Barberton greenstone belt, South Africa

电气石 B 同位素作为南非巴伯顿绿岩带门登组硅化古太古代洋壳流体源的示踪剂

• DOI: 10.1016/j.chemgeo.2015.10.009
• 发表时间: 2015
• 期刊: Chemical Geology
• 影响因子: 3.9
• 作者: Farber;Dziggel;Trumbull;Wiedenbeck
• 通讯作者: Wiedenbeck

Fluid inclusion analysis of silicified Palaeoarchaean oceanic crust – A record of Archaean seawater?

• DOI: 10.1016/j.precamres.2015.05.020
• 发表时间: 2015-09
• 期刊: Precambrian Research
• 影响因子: 3.8
• 作者: Katja Farber;A. Dziggel;F. Meyer;W. Prochaska;A. Hofmann;C. Harris