{"title":"Polyphase formation of a Neoarchean auriferous fault zone network in the Michipicoten greenstone belt, southern Superior craton","authors":"Chong Ma, Bruno Lafrance, J. Montreuil","doi":"10.1139/cjes-2023-0120","DOIUrl":null,"url":null,"abstract":"Correlating structurally distinctive fault zones for understanding an unknown deformation system at the regional scale remains a challenge for understanding orogenic evolution and gold endowment. The current study deals with this challenge in the southern Michipicoten greenstone belt (MGB) of the Superior craton focusing on a Neoarchean auriferous fault zone network. Three deformation events associated with episodic gold mineralization are revealed in the ca. 2745 Ma host granitoid: (1) NW‒SE shortening recorded by the subvertical Grace and Minto B fault zones and locally the inclined Jubilee and Hornblende fault zones; (2) top-to-NNE strike-slip to oblique faulting indicated primarily by the dominant structures of the Jubilee and Hornblende fault zones; and (3) top-to-NE extension demonstrated by the northeast-dipping Parkhill #4 and Cooper fault zones. Fault zone lithologies and mineral assemblages suggest that the localization of deformation for the formation of these fault zones was controlled by rheological heterogeneities and syn-deformation fluids. The first and second events are correlated with two shortening events in a gold-endowed, structurally and kinematically distinctive deformation zone of the northern MGB. This correlation based on deformation processes suggests a larger footprint of gold mineralization associated with a regional deformation in the MGB and has implications for investigating structural evolution of orogens and orogenic gold mineralization in general.","PeriodicalId":9567,"journal":{"name":"Canadian Journal of Earth Sciences","volume":null,"pages":null},"PeriodicalIF":1.3000,"publicationDate":"2024-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Canadian Journal of Earth Sciences","FirstCategoryId":"89","ListUrlMain":"https://doi.org/10.1139/cjes-2023-0120","RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"GEOSCIENCES, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
Correlating structurally distinctive fault zones for understanding an unknown deformation system at the regional scale remains a challenge for understanding orogenic evolution and gold endowment. The current study deals with this challenge in the southern Michipicoten greenstone belt (MGB) of the Superior craton focusing on a Neoarchean auriferous fault zone network. Three deformation events associated with episodic gold mineralization are revealed in the ca. 2745 Ma host granitoid: (1) NW‒SE shortening recorded by the subvertical Grace and Minto B fault zones and locally the inclined Jubilee and Hornblende fault zones; (2) top-to-NNE strike-slip to oblique faulting indicated primarily by the dominant structures of the Jubilee and Hornblende fault zones; and (3) top-to-NE extension demonstrated by the northeast-dipping Parkhill #4 and Cooper fault zones. Fault zone lithologies and mineral assemblages suggest that the localization of deformation for the formation of these fault zones was controlled by rheological heterogeneities and syn-deformation fluids. The first and second events are correlated with two shortening events in a gold-endowed, structurally and kinematically distinctive deformation zone of the northern MGB. This correlation based on deformation processes suggests a larger footprint of gold mineralization associated with a regional deformation in the MGB and has implications for investigating structural evolution of orogens and orogenic gold mineralization in general.
将结构上独特的断层带关联起来,以了解区域尺度上未知的变形系统,仍然是了解造山演化和金赋存的一项挑战。目前的研究针对的是苏必利尔陨石坑南部米希皮科腾绿岩带(MGB)的这一挑战,重点是新元古代的含金断层带网络。在约 2745 Ma 的主花岗岩中,发现了三个与偶发性金矿化有关的变形事件。它们是:(1) 由俯冲的格雷斯和明托 B 断层带以及局部倾斜的朱比利和霍恩布伦德断层带记录的 NW-SE 向缩短;(2) 主要由朱比利和霍恩布伦德断层带的主要结构显示的自上而下向 NNE 的走向滑动到斜向断裂;以及 (3) 由向东北倾斜的 Parkhill #4 和 Cooper 断层带显示的自上而下向 NNE 的延伸。断层带岩性和矿物组合表明,形成这些断层带的变形定位受到流变异质性和同步变形流体的控制。第一个和第二个事件与 MGB 北部一个金赋存、结构和运动学上独特的变形带中的两个缩短事件相关联。这种基于变形过程的相关性表明,金矿化的更大足迹与 MGB 的区域变形有关,对研究造山带的结构演化和造山带金矿化具有普遍意义。
期刊介绍:
The Canadian Journal of Earth Sciences reports current research in climate and environmental geoscience; geoarchaeology and forensic geoscience; geochronology and geochemistry; geophysics; GIS and geomatics; hydrology; mineralogy and petrology; mining and engineering geology; ore deposits and economic geology; paleontology, petroleum geology and basin analysis; physical geography and Quaternary geoscience; planetary geoscience; sedimentology and stratigraphy; soil sciences; and structural geology and tectonics. It also publishes special issues that focus on information and studies about a particular segment of earth sciences.