Deformation history inferred from magnetic fabric in the southwestern Okcheon metamorphic belt, Korea

详细信息    查看全文

• 作者：Yong-Hee Park ; Seong-Jae Doh ; Wonnyon Kim and Dongwoo Suk
• 关键词：Anisotropy of magnetic susceptibility ; Metamorphism-related deformation ; Magnetic mineralogy ; Okcheon metamorphic belt
• 刊名：Tectonophysics
• 出版年：2005
• 出版时间：2005
• 年：2005
• 卷：405
• 期：1-4
• 页码：169-190
• 全文大小：1213 K

文摘

Magnetic fabric and rock-magnetic studies have been carried out for the non-fossiliferous, low- to medium-grade metasedimentary rocks in the southwestern part of the Okcheon metamorphic belt (OMB). Two major metamorphic events in the study area were previously recognized: regional metamorphism (M₁) in the late Carboniferous to early Permian and contact metamorphism (M₂) due to the intrusion of granite in the middle Jurassic. The metamorphic grade of the study area increases from the biotite zone in southeast through the garnet zone to the staurolite zone towards the northwest. Magnetic fabrics of the study area are generally well defined and can be characterized according to the metamorphic zones. Magnetic foliation is the dominant magnetic fabric in the biotite zone, while magnetic lineation prevails in both garnet and staurolite zones. We interpret the metamorphism-related deformation history of the study area based on magnetic fabrics, magnetic mineralogy and previously reported metamorphic evolution as follows. Penetrative NW-dipping cleavage, represented by magnetic foliation, was formed in the study area by prevailing NW–SE shortening event during the M₁ regional metamorphism in the late Carboniferous–early Permian. This shortening event is interpreted to be associated with the collisional event between the North and South China blocks. Cleavages dipping steeply to the southeast in the staurolite zone are attributed to the pressure exerted from the intrusion of Jurassic granite in the northwestern area.