DOI: 10.1016/j.palaeo.2015.11.015
论文题名: Sedimentary PGE signatures in the Late Triassic ejecta deposits from Japan: Implications for the identification of impactor
作者: Sato H. ; Shirai N. ; Ebihara M. ; Onoue T. ; Kiyokawa S.
刊名: Palaeogeography, Palaeoclimatology, Palaeoecology
ISSN: 0031-0182
出版年: 2016
卷: 442 起始页码: 36
结束页码: 47
语种: 英语
英文关键词: Chert
; Chondrites
; Impact
; Japan
; Late Triassic
; Platinum group elements
英文摘要: Positive platinum group element (PGE) concentration and negative Os isotope anomalies reported from a claystone layer in the Upper Triassic bedded chert succession of the Sakahogi section, Mino Belt, central Japan, are thought to have been derived from an impact event. Stratigraphic variations and concentrations of PGE were examined in the Sakahogi section to determine the type of the impactor. Upper Triassic claystone layers, where PGE anomalies have been newly discovered in bedded chert successions in southwest Japan, were also examined. These include (i) the Unuma section in the Inuyama area, Mino Belt; (ii) the Hisuikyo section in the Kamiaso area, Mino Belt; and (iii) the Enoura section in the Tsukumi area, Chichibu Belt. Radiolarian and conodont biostratigraphic data indicate that these claystone layers are of upper-middle Norian age. Reconstruction of bedded chert in these sections suggests that they originate from open-ocean pelagic deep-sea sediments deposited in the Panthalassa Ocean.The relatively flat CI chondrite-normalized patterns of the least mobile PGEs (Ir, Ru, and Rh) and the Ru/Ir ratio determined by linear regression analysis suggest that a chondritic impactor is the source of the PGE anomalies preserved in claystone samples from the study sections. Although Ru/Ir ratios cannot conclusively distinguish chondrites from iron meteorites, the Cr/Ir ratios of the claystone layers range from 104 to 105, clearly indicating contribution from chondritic materials. The chondritic impactor of the suggested size (3.3-7.8km in diameter) implies that a large amount of debris and/or climatically active gasses (e.g., sulfur oxides) would have been released from the impactor, which would have had a marked effect on the environment. © 2015 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/68625
Appears in Collections: 过去全球变化的重建
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作者单位: Department of Earth and Planetary Sciences, Kyushu University, Fukuoka, Japan; Department of Chemistry, Tokyo Metropolitan University, Tokyo, Japan; Department of Earth and Environmental Sciences, Kumamoto University, Kumamoto, Japan; Japan Agency for Marine-Earth Science and Technology, Yokosuka, Japan
Recommended Citation:
Sato H.,Shirai N.,Ebihara M.,et al. Sedimentary PGE signatures in the Late Triassic ejecta deposits from Japan: Implications for the identification of impactor[J]. Palaeogeography, Palaeoclimatology, Palaeoecology,2016-01-01,442