|
本帖最後由 hellman 於 2012-3-1 08:12 編輯
來往加國 發表於 2012-3-1 06:40 
沒有解釋到為何33億年前或者12-17億年前的鑽石以及幾百萬到幾億年的煤樣品為何都包含可檢測的碳-14?這裡存 ...
這是一篇普林斯頓大學地質系在1989年自然雜誌上發表的專業文章, 我認為足夠了. 你有興趣可以自己追蹤參考文獻,和原文,甚至可以和作者本人聯繫. 好像是用激光測定鑽石中包含的氬元素同位素得到的結論. 我不太懂行了,不過相信科學家,特別是美國排名第一的大學學府的科學家. 不過我實在不應該以名氣壓人,但是能夠發表科學文章,一定是經得起考驗的,否則我會重新測定,推翻他的文章,我會成為有名氣的大科學家的.
我對鑽石還真有研究,天然鑽石的特點就是有雜質,鑽石的分級也是從雜質分級的. 看不見雜質的鑽石就是人造的或者是假的. 根據雜質測定鑽石年齡也是自然的.
http://www.nature.com/nature/journal/v340/n6233/abs/340460a0.html
40Ar/39Ar laser-probe dating of diamond inclusions from the Premier kimberlite
D. Phillips*, T. C. Onstott* & J. W. Harris*†
* Department of Geology and Geophysical Sciences, Princeton University, Princeton, New Jersey 08544, USA †Department of Geology and Applied Geology, University of Strathclyde, Glasgow G12 8QQ, UK
INCLUSIONS encapsulated by diamonds at the time of their formation provide a means for determining diamond crystallization ages and the chemistry of the surrounding upper mantle at that time. Sm–Nd studies of peridotitic inclusions, from Cretaceous-age kimberlites in southern Africa, suggest that the diamonds formed 3.3 Gyr ago1. By contrast, eclogite-suite inclusions generally yield younger ages, sometimes approaching the time of kimberlite erup-tion2–4. Here we report the results of 40Ar/39Ar laser-probe analy-ses of individual eclogitic clinopyroxene inclusions from Premier diamonds, which yield a mean age of 1,198 ±14 Myr. This age agrees well with Sm–Nd (ref. 2) and 40Ar/39Ar (ref. 3) analyses on similar Premier inclusions, and is indistinguishable from the inferred time of emplacement of the host kimberlite (1,150–1,230 Myr)2, which implies that diamond formation was essentially synchronous with kimberlite generation. The extrapolated non-radiogenic 40 Ar/36 Ar ratio of 334 ± 102 is similar to the present-day atmospheric composition. This value is inconsistent with Sr and Nd isotopic signatures from Premier eclogite inclusions2, which suggest a depleted mantle source (40Ar/36Ar > 20,000). Pre-entrap-ment equilibration of the inclusions with an 36Ar-rich fluid is the most probable explanation for the low non-radiogenic (40Ar/36Ar) composition.
|
|