Possible causes and consequences of regional Na-metasomatism: the case of the Sudbury Impact Structure, Ontario, Canada

区域性纳交代作用的可能原因和后果：以加拿大安大略省萨德伯里撞击结构为例

• 批准号: 521601478
• 负责人: Professor Dr. Hartwig E. Frimmel
• 金额: --
• 依托单位: Lehrstuhl für Geodynamik und Geomaterialforschung
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/521601478?language=en
• 关键词: Possible; causes; consequences; regional; Na

Sodium metasomatism is a widespread geological phenomenon on a regional scale over distances of hundreds of kilometers, the causes of which, especially within the continental crust, are poorly understood so far. It can be related to pervasive circulation of NaCl-rich solutions derived from metamorphism of evaporitic, halite-bearing sedimentary sequences, or to possibly magma-derived overpressured fluids that can have a high mineralizing potential as exemplified by iron oxide-copper-gold (IOCG) deposits. One of the most obvious mineralogical expressions of Na-metasomatism is albitization, an extreme metasomatic process that results in the mobility even of elements traditionally considered relatively fluid-immobile. Regional albitization of Palaeoproterozoic rocks is a well-known but poorly understood phenomenon in the area around the 1.85 Ga Sudbury impact structure (one of the biggest of its kind in the world) in Ontario (Canada). Based on results achieved in a recent DFG-supported project in the area, it is more widespread than previously recognized and intimately associated with intense brecciation. Its age and geological cause remain unresolved. Albitization and brecciation could be related to the Sudbury impact but also to sodic alkali magmatism or basin-wide fluid circulation in the course of Palaeoproterozoic orogenies. The aim of this research project is the characterization of the type and extent of Na-metasomatism in the area around Sudbury and to clarify whether it is related to the impact event, to alkaline magmatism unrelated to the impact or to some other cause altogether. In the former case, it would have consequences on our understanding of how hydrothermal systems could be formed by impacts on the (early) Earth surface with implications on the formation of early life environments. In the case of a non-impactogenic but magmatogenic origin, however, it would have profound implications for the prospectivity of the region for a range of commodities, including critical metals, as typically found in IOCG ore districts or alkaline magmatic provinces. The said aim will be achieved through a combination of geological field work, petrography, mineralogical, mineral-chemical, geochemical and isotopic studies as well as geochronological analyses.

在数百公里的距离上，钠钠钠是一种广泛的地质现象，其原因，尤其是在大陆地壳中，到目前为止，其原因尚不清楚。它可能与富含NaCl的溶液的普遍循环有关，这些溶液源自蒸发，含有淡盐的沉积物序列的变质，或可能与岩浆衍生的过压液具有高矿化潜力，从而被铁氧化铁（IOCG）具有很高的矿化潜力。 Na-夸张的最明显的矿物学表达之一是抗衡，这是一种极端的代理过程，甚至导致传统上被认为是相对流体的元素的迁移率。古代古代岩石的区域性化是在安大略省（加拿大）的1.85 GA Sudbury撞击结构（世界上最大的同类产品之一）周围该地区的众所周知但知之甚少的现象。基于该地区最近由DFG支持的项目取得的结果，它比以前认可的更为广泛，并且与强烈的角化相关。它的年龄和地质原因仍未解决。在古代造山造成的过程中，抗衡和接血性可能与萨德伯里的影响有关，也与苏迪克碱性岩浆或盆地范围的流体循环有关。该研究项目的目的是表征萨德伯里（Sudbury）周围地区的Na-夸张的类型和程度，并澄清它是否与影响事件有关，与与影响或其他原因无关的碱性岩浆主义与碱性岩浆主义无关。在前一种情况下，这将对我们对如何通过对（早期）地球表面的影响形成水热系统的理解产生影响，这对早期生活环境的形成产生了影响。然而，在非冲突性但岩浆生成的起源中，这将对该地区对包括关键金属在内的一系列商品的潜在性产生深远的影响，如IOCG矿区或碱性岩浆省的通常发现。上述目标将通过地质田间工作，岩石学，矿物学，矿物质，地球化学和同位素研究以及地质学分析的结合来实现。