A Blind Test of the Younger Dryas Impact Hypothesis

被引:13
|
作者
Holliday, Vance [1 ,2 ]
Surovell, Todd [3 ]
Johnson, Eileen [4 ]
机构
[1] Univ Arizona, Dept Anthropol, Tucson, AZ 85721 USA
[2] Univ Arizona, Dept Geosci, Tucson, AZ 85721 USA
[3] Univ Wyoming, Dept Anthropol, Laramie, WY 82071 USA
[4] Texas Tech Univ Museum, Lubbock, TX 79409 USA
来源
PLOS ONE | 2016年 / 11卷 / 07期
关键词
SOUTHERN HIGH-PLAINS; LUBBOCK LAKE SITE; EXTRATERRESTRIAL IMPACT; MURRAY SPRINGS; INDEPENDENT EVALUATION; BLACK MATS; BOUNDARY; NANODIAMONDS; EVENT; LAYER;
D O I
10.1371/journal.pone.0155470
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
The Younger Dryas Impact Hypothesis (YDIH) states that North America was devastated by some sort of extraterrestrial event similar to 12,800 calendar years before present. Two fundamental questions persist in the debate over the YDIH: Can the results of analyses for purported impact indicators be reproduced? And are the indicators unique to the lower YD boundary (YDB), i.e., similar to 12.8k cal yrs BP? A test reported here presents the results of analyses that address these questions. Two different labs analyzed identical splits of samples collected at, above, and below the similar to 12.8ka zone at the Lubbock Lake archaeological site (LL) in northwest Texas. Both labs reported similar variation in levels of magnetic micrograins (>300 mg/kg >12.8ka and <11.5ka, but <150 mg/kg 12.8ka to 11.5ka). Analysis for magnetic microspheres in one split, reported elsewhere, produced very low to nonexistent levels throughout the section. In the other split, reported here, the levels of magnetic microspherules and nanodiamonds are low or nonexistent at, below, and above the YDB with the notable exception of a sample <11,500 cal years old. In that sample the claimed impact proxies were recovered at abundances two to four orders of magnitude above that from the other samples. Reproducibility of at least some analyses are problematic. In particular, no standard criteria exist for identification of magnetic spheres. Moreover, the purported impact proxies are not unique to the YDB.
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页数:13
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