气候变化领域集成服务门户(CCPortal): Cooling rates of pyroclastic deposits inferred from mineral magnetic investigations: a case study from the Pleistocene Mýtina Maar (Czech Republic)

CCPortal

DOI	10.1007/s00531-020-01865-1
	Cooling rates of pyroclastic deposits inferred from mineral magnetic investigations: a case study from the Pleistocene Mýtina Maar (Czech Republic)
	Lied P.; Kontny A.; Nowaczyk N.; Mrlina J.; Kämpf H.
发表日期	2020
ISSN	14373254
起始页码	1707
结束页码	1725
卷号	109 期号:5
英文摘要	Tephra layers of the Mýtina Maar, Czech Republic, contain ferrimagnetic Mg–Al-rich titanomagnetite, which is suggested to originate from a fractionated alkaline CO2-rich lithospheric mantle melt. We investigated the magnetic mineralogy and Curie temperature (TC) from tephra deposits of two drill cores (< 9 m depth). TC calculated (208 ± 14 °C) from chemical composition (Fe2+0.8Mg0.5Fe3+1.1Al0.3Ti0.3O4) is in accordance with TC retrieved from cooling curves of temperature-dependent magnetic susceptibility measurements (195–232 °C). However, thermomagnetic curves are irreversible either with lower (type I) or higher (type II) TC in the heating curve. All curves show transition temperatures above ca. 390 °C, indicating maghemitization. We interpret the irreversibility of TC (∆TC) in terms of different degrees of cation ordering, overprinted or masked by different degrees of maghemitization, which is a low-temperature phenomenon. Negative ∆TC indicates that original deposited titanomagnetite has cooled faster and, therefore, has stored a lower degree of cation ordering compared to heating/cooling rate of 11 °C/min in the Kappabridge. Type II with positive ∆TC indicates higher degree of cation ordering, and, therefore, slower cooling rate. The central part of this deposit shows most severe maghemitization, indicating rather wet emplacement. We, therefore, suggest different eruption styles for deposition of type I pyroclastics with more phreatomagmatic and type II pyroclastics with more phreato-Strombolian eruption styles. Our study is a new approach to discriminate different cooling histories in maar deposits using the Curie temperature of titanomagnetite. We suggest that this method has the potential to discriminate different emplacement modes resulting from different eruption styles. © 2020, The Author(s).
英文关键词	Cation ordering effect; Curie temperature; Eger rift system; Maar-diatreme volcano; Maghemitization; Pyroclastic emplacement mechanism; Titanomagnetite
语种	英语
scopus关键词	cooling; emplacement; mineral alteration; Pleistocene; pyroclastic deposit; tephra; volcanic eruption; Czech Republic
来源期刊	International Journal of Earth Sciences
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/147657
作者单位	Institute for Applied Materials-Applied Materials Physics, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, 76344, Germany; Division of Structural Geology, Institute of Applied Geosciences, Karlsruhe Institute of Technology, Karlsruhe, Germany; Section Climate Dynamics and Landscape Evolution, German Research Centre for Geosciences GFZ Potsdam, Telegrafenberg, Potsdam, 14473, Germany; Institute of Geophysics, Czech Academy of Sciences, Boční II, Praha 4, 141 31, Czech Republic; Section Organic Geochemistry, German Research Centre for Geosciences GFZ Potsdam, Telegrafenberg, Potsdam, 14473, Germany
推荐引用方式 GB/T 7714	Lied P.,Kontny A.,Nowaczyk N.,et al. Cooling rates of pyroclastic deposits inferred from mineral magnetic investigations: a case study from the Pleistocene Mýtina Maar (Czech Republic)[J],2020,109(5).
APA	Lied P.,Kontny A.,Nowaczyk N.,Mrlina J.,&Kämpf H..(2020).Cooling rates of pyroclastic deposits inferred from mineral magnetic investigations: a case study from the Pleistocene Mýtina Maar (Czech Republic).International Journal of Earth Sciences,109(5).
MLA	Lied P.,et al."Cooling rates of pyroclastic deposits inferred from mineral magnetic investigations: a case study from the Pleistocene Mýtina Maar (Czech Republic)".International Journal of Earth Sciences 109.5(2020).