气候变化领域集成服务门户(CCPortal): Rock magnetic signature of a Miocene playa cycle in Central Asia and environmental implications

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DOI	10.1007/s00531-019-01761-3
	Rock magnetic signature of a Miocene playa cycle in Central Asia and environmental implications
	Verestek V.; Appel E.; Frisch K.; Voigt S.
发表日期	2019
ISSN	14373254
起始页码	2271
结束页码	2290
卷号	108 期号:7
英文摘要	The increased aridification of Central Asia during the Miocene coincides in time with lake formations and the evolution of playa environments in the region. However, Miocene continental climate dynamics and the forcing of aridification are still not well constrained. Neogene lacustrine mudflat deposits in the Ili Basin in southeast Kazakhstan provide a well-exposed paleoclimate archive. Here, we present a detailed rock magnetic study of a middle Miocene playa cycle deposited in a closed basin. We use high-resolution rock magnetic parameters, lithological studies and geochemistry to reconstruct the playa environment and the depositional conditions. The rock magnetic mineralogy of the playa cycle is controlled by hematite and two fine-grained magnetite phases. Increased magnetic concentrations occur during dry mudflat conditions, with a lower groundwater table and increased aridity. The underlying processes controlling the observed variation in magnetic concentrations are a complex interplay of diagenetic processes during and after deposition. The data support an authigenic origin of both magnetite phases, one formed before and the other after sediment consolidation. Early diagenetic formation of fine-grained magnetite by microbial activity is followed by post-depositional formation of a secondary fine-grained magnetite phase. The rock magnetic results such as magnetic concentration-dependent parameters, ARM/SIRM and s-ratio indicate a sensitive record of (ground) water availability and aridity changes in the Ili Basin. We suggest that they can serve as an effective proxy for detailed paleo-environment reconstruction of playa evolution, not only in the middle Miocene Ili Basin but also in comparable floodplain/playa lake settings. © 2019, Geologische Vereinigung e.V. (GV).
英文关键词	Central Asia; Paleoclimate; Playa; Rock magnetism
语种	英语
scopus关键词	aridification; climate forcing; climate variation; geomagnetism; lacustrine deposit; Miocene; paleoclimate; playa; Central Asia; Ili Basin; Kazakhstan
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/147776
作者单位	Department of Geosciences, University Tübingen, Hölderlinstraße 12, Tübingen, 72074, Germany; Institute of Geosciences, Goethe University Frankfurt, Altenhöferallee 1, Frankfurt, 60438, Germany
推荐引用方式 GB/T 7714	Verestek V.,Appel E.,Frisch K.,et al. Rock magnetic signature of a Miocene playa cycle in Central Asia and environmental implications[J],2019,108(7).
APA	Verestek V.,Appel E.,Frisch K.,&Voigt S..(2019).Rock magnetic signature of a Miocene playa cycle in Central Asia and environmental implications.International Journal of Earth Sciences,108(7).
MLA	Verestek V.,et al."Rock magnetic signature of a Miocene playa cycle in Central Asia and environmental implications".International Journal of Earth Sciences 108.7(2019).