干旱区生态环境知识资源中心(Arid): The role of iron-bearing minerals for the deep weathering of a hydrothermally altered plutonic rock in semi-arid climate (Chilean Coastal Cordillera)

Arid

DOI	10.1016/j.chemgeo.2022.120922
	The role of iron-bearing minerals for the deep weathering of a hydrothermally altered plutonic rock in semi-arid climate (Chilean Coastal Cordillera)
	Hampl, Ferdinand J.; Schiperski, Ferry; Byrne, James M.; Schwerdhelm, Christopher; Kappler, Andreas; Bryce, Casey; von Blanckenburg, Friedhelm; Neumann, Thomas
通讯作者	Hampl, FJ
来源期刊	CHEMICAL GEOLOGY
ISSN	0009-2541
EISSN	1872-6836
出版年	2022
卷号	604
英文摘要	Weathering is a fundamental process that controls the development of Earth's surface by the formation of erodible material and the release of mineral-bound nutrients. Weathering at depth has been predominantly studied in humid environments, where fluid flow sets mineralogical transformations, whereas (semi-)arid regions were barely investigated in this respect. In many studies the weathering of iron-bearing minerals was shown to play a major role for the advance of weathering at depth. Weathering of iron-bearing minerals is often superimposed on factors that precondition rocks for weathering such as hydrothermal alteration and fracturing by tectonic stress. The low degree of water-rock interactions in (semi-)arid climates offers the opportunity to single out the preconditioning factors and explore the role of iron-bearing minerals for weathering in detail. To this end the interactions of tectonic fracturing, hydrothermal alteration and weathering were investigated in a deep, weakly weathered profile of plutonic rock in a semi-arid region (Santa Gracia, Northern Chile). The profile was recovered by an 87-m-deep drill core and a 2-m-deep soil pit which were used to investigate the mineral composition, magnetic susceptibility, geochemical gradients, and Fe redox-state. Non-cemented fractures of tectonic origin were identified as pathways for the transport of fluids and reagents to depth that are fuelling the initial weathering reactions. Previous hydrothermal fluids mainly migrated along the same fractures and altered the properties of the original bedrock. Therefore, the weathering features along fractures depend on the preconditioning by hydrothermal alteration and tectonic stress which affected the vicinity of these fractures. From the fracture surfaces, water and O-2 diffuse into the rock and initiate oxidation and dissolution-reprecipitation reactions. Our study shows that the transformation of iron-bearing silicates (especially biotite) to Fe(III) (oxyhydr)oxides and clay minerals is the dominant weathering-promoting process as it produces stress which leads to micro-fracturing of the rock and finally to the formation of saprolite. Deciphering the links between tectonic fracturing, hydrothermal alteration, and weathering-induced fracturing by iron-bearing silicates in semi-arid settings provides unique insights into the controls of deep weathering in regions with limited fluid flow.
英文关键词	Critical Zone Semi-arid Deep weathering Weathering-induced fracturing Martitisation Hydrothermal alteration
类型	Article
语种	英语
收录类别	SCI-E
WOS记录号	WOS:000810937900003
WOS关键词	GRANITIC-ROCKS ; REDOX FRONT ; OXIDATION ; MAGNETITE ; KINETICS ; REPLACEMENT ; REGOLITH ; BEDROCK ; STATE ; TRANSFORMATION
WOS类目	Geochemistry & Geophysics
WOS研究方向	Geochemistry & Geophysics
资源类型	期刊论文
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/392129
推荐引用方式 GB/T 7714	Hampl, Ferdinand J.,Schiperski, Ferry,Byrne, James M.,et al. The role of iron-bearing minerals for the deep weathering of a hydrothermally altered plutonic rock in semi-arid climate (Chilean Coastal Cordillera)[J],2022,604.
APA	Hampl, Ferdinand J..,Schiperski, Ferry.,Byrne, James M..,Schwerdhelm, Christopher.,Kappler, Andreas.,...&Neumann, Thomas.(2022).The role of iron-bearing minerals for the deep weathering of a hydrothermally altered plutonic rock in semi-arid climate (Chilean Coastal Cordillera).CHEMICAL GEOLOGY,604.
MLA	Hampl, Ferdinand J.,et al."The role of iron-bearing minerals for the deep weathering of a hydrothermally altered plutonic rock in semi-arid climate (Chilean Coastal Cordillera)".CHEMICAL GEOLOGY 604(2022).