当前位置: X-MOL 学术J. Geol. › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Detrital Zircon Geochronology: New Evidence for an Old Model for Accretion of the Southwest Baltic Shield
The Journal of Geology ( IF 1.8 ) Pub Date : 1999-09-01 , DOI: 10.1086/314370
de Haas GJ , Andersen , Vestin

Disruption of the original crustal architecture as a result of tectonic events often complicates studies of the crustal evolution of Precambrian cratons. Ion‐probe U‐Pb dating of detrital zircons is one way to circumvent this problem. It yields a “fingerprint” of the source of the metasedimentary host that can be used to tie the host to a counterpart elsewhere. In this study, ion‐probe U‐Pb dating of detrital zircons from segments of the late Mesoproterozoic Southwest Scandinavian Domain (SSD) of the Baltic Shield provides new evidence for an old model of crustal evolution and tectonic development. Zircon ages for both the pebble and matrix fraction of the Seljord conglomerate, Telemark sector, Norway, show a 1.9–1.7‐Ga frequency maximum, as was previously recognized for metasediments from the adjacent Bamble sector. However, the Telemark metasediments lack evidence for significant input of 1.4–1.6‐Ga‐old crustal material, characteristic of some of the Bamble metasediments. A maximum depositional age of ca. 1450 Ma is inferred for the Seljord conglomerate and a quartzite from the Bamble sector. Definite evidence for significant amounts of pre‐1.6‐Ga crust in the SSD is absent. Instead, provenance from the early Mesoproterozoic Svecofennian Domain for the 1.9–1.7‐Ga crust is proposed, supported by the omnipresence of small amounts of Archean zircons and the distribution of Nd model ages of these and other SSD metasediments. It is proposed that the SSD originally formed a single, continuous belt, fringing the Baltic Shield, with the northernmost segments transported to their current position west of the Oslo rift along north‐south‐trending shear zones, i.e., at odds with the commonly held view of progressive westward growth of the Baltic Shield. The detrital zircon ages from the Faurefjell quartzite, Rogaland–Vest Agder sector, cluster around 1.65 Ga and reveal a maximum depositional age of \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape $$1244\pm 40$$ \end{document} Ma. Its deviating depositional setting indicates that the Rogaland sector evolved in a different setting, shielded from the crust of Svecofennian age. Instead, its ages allow for a source terrain within the Mesoproterozoic crust of South Norway.

中文翻译:

碎屑锆石年代学:西南波罗的海地盾增生旧模型的新证据

由于构造事件,原始地壳结构的破坏常常使对前寒武纪克拉通地壳演化的研究复杂化。碎屑锆石的离子探针 U-Pb 定年是规避此问题的一种方法。它产生了变沉积宿主来源的“指纹”,可用于将宿主与其他地方的对应物联系起来。在这项研究中,来自波罗的海地盾的晚中元古代西南斯堪的纳维亚域 (SSD) 段的碎屑锆石的离子探针 U-Pb 定年为地壳演化和构造发展的旧模型提供了新的证据。挪威 Telemark 部门 Seljord 砾岩的鹅卵石和基质部分的锆石年龄显示出 1.9-1.7-Ga 的最大频率,这与之前对来自相邻 Bamble 部门的变沉积物的认识相同。然而,Telemark 变质沉积物缺乏 1.4-1.6-Ga 年龄地壳物质的显着输入证据,这是一些 Bamble 变质沉积物的特征。最大沉积年龄约。Seljord 砾岩和 Bamble 部门的石英岩推断为 1450 Ma。SSD 中存在大量 pre-1.6-Ga 地壳的确切证据不存在。相反,提出了 1.9-1.7-Ga 地壳的早期中元古代 Svecofennian 域的物源,这得到了少量太古代锆石的普遍存在以及这些和其他 SSD 变沉积物的 Nd 模型年龄分布的支持。有人提出,SSD 最初形成一个单一的、连续的带,环绕波罗的海地盾,最北端的部分沿着南北走向的剪切带运输到奥斯陆裂谷以西的当前位置,即,与波罗的海地盾逐渐向西增长的普遍观点不一致。来自 Faurefjell 石英岩、Rogaland-Vest Agder 部分的碎屑锆石年龄聚集在 1.65 Ga 附近,并揭示了最大沉积年龄 \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm } \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyr} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{ 7}{6} \begin{document} \landscape $$1244\pm 40$$ \end{document} Ma. 其偏离的沉积环境表明罗加兰地区在不同的环境中演化,不受 Svecofennian 时代地壳的影响。相反,它的年龄允许在挪威南部的中元古代地壳内有一个源地形。
更新日期:1999-09-01
down
wechat
bug