加拿大艾伯塔大学Benjamin J.C. Neil和Yan Luo的研究组在加拿大Rae克拉通发现一个3.3-3.1 Ga的巨大地体，并研究了其对古代大陆生长时间和范围的启示。相关论文于2023年4月19日发表于国际顶尖学术期刊《地质学》杂志上。

研究人员表示，来自3.6-3.0 Ga火成岩的锆石Hf同位素数据的全球汇编展示了，包括来自PRT和世界其他13个地体的样本在内，ca.3.31和ca.3.32Ga的相对年轻(初始εHf -2至+3)的岩石群。其他全球锆石数据集也记录了3.3-3.2Ga之间的年龄峰值，以及一组大约3.2Ga的广泛球粒陨石的初始εHf值。因此，3.3 -3.2 Ga时期可能是地球上大陆净增长增强的时期，PRT是从那个时期保存下来的最大的地体之一。

此外，来自世界范围内3.3 -3.1 Ga的PRT花岗岩和3.5 -3.0 Ga的火成岩的锆石Hf同位素数据几乎没有提供母岩浆与前3.6 Ga大陆物质相互作用或源自前3.6 Ga大陆物质的证据。与一些大陆生长模型相反，后者观察表明，3.6 Ga形成的大陆地壳体积相对较小。

据悉，地球上最大的古代(> 3.0 Ga) 地壳岩层，结晶年龄＞3.0 Ga和\或Sm-Nd亏损地幔模型年龄≥3.2 Ga的花岗岩类岩石在加拿大Rae克拉通的西部边缘确定了一个约1000×100km的带，将此称为佩里河岩层(PRT)。来自花岗岩类的锆石U-Pb-Hf-O同位素和全岩地球化学数据显示，PRT是一个3.3-3.2 Ga的幼年地体，部分受ca.3.1 Ga的岩浆作用的进一步演化改造。这些发现要求重新评估地球上古代大陆生长的时间和范围。

附：英文原文

Title: Discovery of a giant 3.3–3.1 Ga terrane in the Rae craton, Canada: Implications for the timing and extent of ancient continental growth

Author: Benjamin J.C. Neil, Daniel B. Tersmette, Thomas Chacko, Larry M. Heaman, Bruce A. Kjarsgaard, Edith Martel, Robert A. Creaser, D. Graham Pearson, Richard A. Stern, S. Andrew Dufrane, Yan Luo

Issue&Volume: 2023-04-19

Abstract: We report the discovery of one of the largest ancient (>3.0 Ga) crustal terranes on Earth. Granitoids with crystallization ages >3.0 Ga and/or Sm-Nd depleted mantle model ages ≥3.2 Ga define a ~1000 × 100 km belt on the western margin of the Rae craton, Canada, referred to herein as the Perry River terrane (PRT). Zircon U-Pb-Hf-O isotope and whole-rock geochemical data from granitoids show that the PRT is a predominantly juvenile 3.3–3.2 Ga terrane that was partially reworked by more evolved ca. 3.1 Ga magmatism. These findings call for a reassessment of the timing and extent of ancient continental growth on Earth. A global compilation of zircon Hf isotope data from 3.6 to 3.0 Ga igneous rocks reveals clusters of relatively juvenile (initial εHf -2 to +3) rocks at ca. 3.31 and ca. 3.23 Ga, which include samples from the PRT and 13 other terranes worldwide. Other global zircon data sets also document age peaks between 3.3 and 3.2 Ga, and a cluster of broadly chondritic initial εHf values around 3.2 Ga. The 3.3–3.2 Ga period may therefore have been a time of enhanced net continental growth on Earth, and the PRT is one of the largest terranes preserved from that time. Furthermore, zircon Hf isotope data from 3.3–3.1 Ga PRT granitoids and 3.5–3.0 Ga igneous rocks worldwide yield little evidence for parent magmas that interacted with or derived from pre–3.6 Ga continental material. Contrary to some continental-growth models, this latter observation suggests that the volume of continental crust established by 3.6 Ga was relatively small.

DOI: 10.1130/G51110.1

Source: https://pubs.geoscienceworld.org/gsa/geology/article/doi/10.1130/G51110.1/622511/Discovery-of-a-giant-3-3-3-1-Ga-terrane-in-the-Rae