气候变化领域集成服务门户(CCPortal): The origin of the magnetic record in Eocene-Miocene coarse-grained sediments deposited in hyper-arid/arid conditions: Examples from the Atacama Desert

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DOI	10.1016/j.palaeo.2018.12.009
	The origin of the magnetic record in Eocene-Miocene coarse-grained sediments deposited in hyper-arid/arid conditions: Examples from the Atacama Desert
	Pizarro H.; Rousse S.; Riquelme R.; Veloso E.; Campos E.; González R.; Bissig T.; Carretier S.; Fernández-Mort A.; Muñoz S.
发表日期	2019
ISSN	0031-0182
起始页码	322
结束页码	335
卷号	516
英文摘要	Magnetic proxies for paleoclimate are tools widely used to understand climate variability, yet current proxies focus on loess-derived soils in humid to temperate climate zones, whereas coarse-grained sediments in arid-hyperarid climate zones remain poorly investigated. To test the potential paleoclimatic-environmental significance of the magnetic record of coarse-grained sediments deposited in a region with a mean annual precipitation (MAP) <200 mm yr−1, we selected three previously studied sedimentary sequences from the Atacama Desert (Centinela area) and explored their magnetic properties, paedogenic features, salt chemistry and mineralogy. These sequences were deposited under different climate-environmental conditions from the Eocene to the Miocene, and correspond, from oldest to youngest, to the Atravesados II gravels (AtII), the Arrieros gravels (Arr) and the Ratones sediments (Rat). The magnetic susceptibility values (k) obtained in the stratigraphic record of the gravels are mainly controlled by the concentration of detrital (titano)magnetite, which is concentrated in the finest fraction (<0.5 mm) of sediments. The values decrease in the coarse sediments from AtII to Arr following a climatic transition from arid to hyperarid conditions, an interpretation that is supported by the transition from carbonate-rich (MAP ~ 40 mm yr−1) to sulfate-rich paleosols (MAP < 10 mm yr−1), and changes in the tectonic conditions and/or sedimentary source. In contrast, the Rat fine-grained sediments record changes in paleo-wetland dynamics. The high frequency-dependent magnetic susceptibility (kfd%) values obtained from these layers are mainly controlled by the concentration of authigenic magnetite-maghemite and/or hematite crystals of superparamagnetic/single magnetic size. The increase in kfd% is linked to an increase in the authigenic degree, which is related to variations in the depth of the local water table. These results demonstrate the potential of magnetic proxies to reveal climatic/environmental signals in coarse-grained sediments deposited under desert climate conditions. © 2018 Elsevier B.V.
英文关键词	Atacama gravels; Atacama paleoclimate; Magnetic proxies; Paleoenvironment; Paleosols; Wetland deposits
语种	英语
scopus关键词	arid environment; Eocene; gravel; magnetic susceptibility; mineralogy; Miocene; paleoenvironment; paleosol; precipitation intensity; proxy climate record; salt; sediment analysis; sediment chemistry; sediment thickness; sedimentary sequence; wetland; Atacama Desert; Chile; Rattus
来源期刊	Palaeogeography, Palaeoclimatology, Palaeoecology
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/151086
作者单位	Departamento de Ciencias Geológicas, Universidad Católica del Norte, Av. Angamos 0610, Antofagasta, Chile; GET, Université de Toulouse, IRD, CNRS, UPS, 14 avenue E. Belin, Toulouse, 31400, France; Departamento de Ingeniería y Geotécnia, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, Santiago, Chile; Mineral Deposit Research Unit, Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, 2020–2207 Main Mall, Vancouver, BC V6T 1Z4, Canada; Departamento de Petrología y Geoquímica, Fac. CC. Geológicas, Universidad Complutense de Madrid, C/ José Antonio Novais, Madrid, 28040, Spain
推荐引用方式 GB/T 7714	Pizarro H.,Rousse S.,Riquelme R.,et al. The origin of the magnetic record in Eocene-Miocene coarse-grained sediments deposited in hyper-arid/arid conditions: Examples from the Atacama Desert[J],2019,516.
APA	Pizarro H..,Rousse S..,Riquelme R..,Veloso E..,Campos E..,...&Muñoz S..(2019).The origin of the magnetic record in Eocene-Miocene coarse-grained sediments deposited in hyper-arid/arid conditions: Examples from the Atacama Desert.Palaeogeography, Palaeoclimatology, Palaeoecology,516.
MLA	Pizarro H.,et al."The origin of the magnetic record in Eocene-Miocene coarse-grained sediments deposited in hyper-arid/arid conditions: Examples from the Atacama Desert".Palaeogeography, Palaeoclimatology, Palaeoecology 516(2019).