大洋地壳增生的锆石年代测定

Zircon dating of oceanic crustal accretion.

作者信息

Lissenberg C Johan, Rioux Matthew, Shimizu Nobumichi, Bowring Samuel A, Mével Catherine

机构信息

Equipe de Géosciences Marines, Institut de Physique du Globe de Paris, 4 Place Jussieu, 75252 Paris Cedex 05, France.

出版信息

Science. 2009 Feb 20;323(5917):1048-50. doi: 10.1126/science.1167330. Epub 2009 Jan 29.

DOI:10.1126/science.1167330

PMID:19179492

Abstract

Most of Earth's present-day crust formed at mid-ocean ridges. High-precision uranium-lead dating of zircons in gabbros from the Vema Fracture Zone on the Mid-Atlantic Ridge reveals that the crust there grew in a highly regular pattern characterized by shallow melt delivery. Combined with results from previous dating studies, this finding suggests that two distinct modes of crustal accretion occur along slow-spreading ridges. Individual samples record a zircon date range of 90,000 to 235,000 years, which is interpreted to reflect the time scale of zircon crystallization in oceanic plutonic rocks.

摘要

地球目前的大部分地壳形成于大洋中脊。对大西洋中脊韦马断裂带辉长岩中锆石的高精度铀铅年代测定表明，那里的地壳以浅部熔体供应为特征，呈高度规则的模式生长。结合先前年代测定研究的结果，这一发现表明，沿着缓慢扩张的洋脊存在两种不同的地壳增生模式。单个样本记录的锆石年代范围为9万年至23.5万年，这被解释为反映了大洋深成岩中锆石结晶的时间尺度。