近日，美国加州大学Margaret L. Odlum及其团队的最新研究，揭示了利用碎屑金红石和锆石年代学和地球化学方法追踪显生宙洋盆的开合旋回。相关论文发表在2024年2月21日出版的《地质学》杂志上。

研究使用南Pyrenees山脉二叠纪至始新世硅质碎屑岩的碎屑锆石U-Pb和碎屑金红石U-Pb年代学和微量元素分析，以捕捉洋盆开合的超大陆旋回。碎屑金红石年龄谱显示峰值约为ca.100Ma与Pyrenean山区的断裂和超伸展有关，200Ma与中大西洋岩浆省有关，330Ma、375Ma和400Ma与俯冲和Rheic洋壳形成有关。金红石中Zr的测温和金红石中Cr-Nb的系统学为进一步了解变质相(峰值变质温度)和源岩岩性(基性与长英质亲和关系)提供了依据。

碎屑锆石年龄谱的峰值约为ca.300Ma、450Ma和600Ma与主要造山活动和长英质岩浆活动有关，Th/U比值提供了有关锆石相对形成温度的信息。这些独立记录的对比表明，碎屑金红石反映了裂谷作用、岩浆弱造山作用和海洋岩石圈过程，而碎屑锆石则反映了大陆岩石圈作用。综合碎屑锆石和金红石数据集存档了多个威尔逊旋回的过去地质事件。

据研究人员介绍，沉积盆地提供了构造和地表过程的深时档案，碎屑矿物U-Pb测年和地球化学方法可以用来追踪古地理、岩浆作用和地壳演化。锆石保存了超大陆长期(数十亿年)的旋回记录；然而，它偏向于保存长英质地壳记录。碎屑金红石通过对裂谷作用和基性岩浆作用、变质作用、中下地壳折返、俯冲作用和岩浆造山作用的时间和温度进行限制，补充了碎屑锆石记录。

附：英文原文

Title: Tracking cycles of Phanerozoic opening and closing of ocean basins using detrital rutile and zircon geochronology and geochemistry

Author: Margaret L. Odlum, Tomas N. Capaldi, Kelly D. Thomson, Daniel F. Stockli

Issue&Volume: 2024-02-21

Abstract: Sedimentary basins provide a deep time archive of tectonic and Earth-surface processes that can be leveraged by detrital mineral U-Pb dating and geochemistry to track paleogeography, magmatism, and crustal evolution. Zircon preserves the long-term (billions of years) record of supercontinent cycles; however, it is biased toward preserving felsic crustal records. Detrital rutile complements the detrital zircon record by providing constraints on the time and temperature of rifting and mafic magmatism, metamorphism, exhumation of the middle and lower crust, subduction, and amagmatic orogenesis. We use detrital zircon U-Pb and detrital rutile U-Pb geochronology and trace element analysis of Permian to Eocene siliciclastic rocks in the southern Pyrenees to capture supercontinent cycles of ocean basins opening and closing. Detrital rutile age spectra show peaks at ca. 100 Ma associated with rifting and hyperextension in the Pyrenean realm, 200 Ma associated with the Central Atlantic Magmatic Province, and 330 Ma, 375 Ma, and 400 Ma associated with subduction and Rheic Ocean crust formation. Zr-in-rutile thermometry and rutile Cr-Nb systematics provide further insight into metamorphic facies (peak metamorphic temperatures) and source rock lithology (mafic versus felsic affinity). Detrital zircon age spectra have peaks at ca. 300 Ma, 450 Ma, and 600 Ma associated with major orogenic events and felsic magmatism, and Th/U ratios provide information on relative zircon formation temperatures. Comparison of these independent records shows that detrital rutile reflects rifting, magma-poor orogenesis, and oceanic lithospheric processes, while detrital zircon detects continental lithospheric processes. Integrated detrital zircon and rutile data sets archive past geological events across multiple Wilson cycles.

DOI: 10.1130/G51826.1

Source: https://pubs.geoscienceworld.org/gsa/geology/article/doi/10.1130/G51826.1/635318/Tracking-cycles-of-Phanerozoic-opening-and-closing