{"title":"弗朗特纳克地层(安大略省格勒维尔省)变质岩的产状和沉积时代","authors":"William H. Peck, Henry Y. Lin","doi":"10.1139/cjes-2024-0029","DOIUrl":null,"url":null,"abstract":"The Mesoproterozoic Frontenac terrane in the southern Grenville Province of Ontario is separated by shear zones from the Composite Arc Belt to the west and the Adirondack Lowlands to the east. The majority of the terrane is made up of granulite-facies metasedimentary rocks that are the oldest lithologies recognized in the terrane. Five samples were selected for U-Pb geochronology to constrain (1) metamorphic age, (2) depositional age of sedimentary protoliths, and (3) source regions of detrital zircon. Two pelitic gneisses and a marble are dominated by metamorphic zircon, whereas two quartzites contain a diverse population of detrital zircon that are surrounded by metamorphic rims. Metamorphic zircon have 206Pb/207Pb ages of 1.19–1.16 Ga, and a small population is 1.22 Ga. These ages correspond to the Shawinigan and Elzevirian orogenies, and provide minimum ages for deposition. The youngest detrital grains with ages of 1.25–1.24 Ga provide maximum depositional ages. Quartzites (and pelitic gneisses) have a wide range of detrital zircon ages that reflect local Mesoproterozoic Grenville sources and Paleoproterzoic and Archean sources in the northern Grenville Province and elsewhere in Laurentia. Most notable is a large population of 1.9–1.8 Ga zircon which point towards derivation from the Penokean orogen in the Midcontinent or Makkovikian–Ketilidian orogen of Labrador and Greenland; indicating long sedimentary transport distances. The similarities in depositional ages and detrital zircon ages between Frontenac terrane and Adirondack metasedimentary rocks suggest a shared sedimentary history which we interpret as deposition in the same Trans-Adirondack backarc basin at ca. 1.25 Ga.","PeriodicalId":9567,"journal":{"name":"Canadian Journal of Earth Sciences","volume":null,"pages":null},"PeriodicalIF":1.3000,"publicationDate":"2024-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Provenance and depositional age of metasedimentary rocks in the Frontenac terrane (Grenville Province, Ontario)\",\"authors\":\"William H. Peck, Henry Y. Lin\",\"doi\":\"10.1139/cjes-2024-0029\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"The Mesoproterozoic Frontenac terrane in the southern Grenville Province of Ontario is separated by shear zones from the Composite Arc Belt to the west and the Adirondack Lowlands to the east. The majority of the terrane is made up of granulite-facies metasedimentary rocks that are the oldest lithologies recognized in the terrane. Five samples were selected for U-Pb geochronology to constrain (1) metamorphic age, (2) depositional age of sedimentary protoliths, and (3) source regions of detrital zircon. Two pelitic gneisses and a marble are dominated by metamorphic zircon, whereas two quartzites contain a diverse population of detrital zircon that are surrounded by metamorphic rims. Metamorphic zircon have 206Pb/207Pb ages of 1.19–1.16 Ga, and a small population is 1.22 Ga. These ages correspond to the Shawinigan and Elzevirian orogenies, and provide minimum ages for deposition. The youngest detrital grains with ages of 1.25–1.24 Ga provide maximum depositional ages. Quartzites (and pelitic gneisses) have a wide range of detrital zircon ages that reflect local Mesoproterozoic Grenville sources and Paleoproterzoic and Archean sources in the northern Grenville Province and elsewhere in Laurentia. Most notable is a large population of 1.9–1.8 Ga zircon which point towards derivation from the Penokean orogen in the Midcontinent or Makkovikian–Ketilidian orogen of Labrador and Greenland; indicating long sedimentary transport distances. 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引用次数: 0
摘要
位于安大略省格勒维尔省南部的中新生代福朗特纳克(Frontenac)陆相被剪切带隔开,西面是复合弧带,东面是阿迪朗达克低地。陆相的大部分由花岗岩成因的变质岩组成,是陆相中公认的最古老的岩性。选取了五个样本进行铀-铅地质年代测定,以确定:(1)变质年龄;(2)沉积原岩的沉积年龄;(3)锆英石的来源地区。两块辉长片麻岩和一块大理岩中主要是变质锆石,而两块石英岩中则含有多种被变质边缘包围的碎屑锆石。变质锆石的 206Pb/207Pb 年龄为 1.19-1.16 Ga,一小部分为 1.22 Ga。这些年龄与沙维尼根(Shawinigan)和埃尔泽维(Elzevirian)造山运动相对应,并提供了沉积的最小年龄。年龄在 1.25-1.24 Ga 之间的最年轻的碎屑岩提供了最大沉积年龄。石英岩(和角闪岩片麻岩)的锆石碎片年龄范围很广,反映了当地中新生代格勒维尔源以及格勒维尔省北部和劳伦西亚其他地区的古生代和阿契安源。最值得注意的是,大量 1.9-1.8 Ga 锆石表明,这些锆石来源于中大陆的佩诺肯造山带或拉布拉多和格陵兰的马科维基-凯蒂里德造山带;这表明沉积运移距离很长。福龙特纳克岩系和阿迪朗达克变质岩的沉积年龄和锆英石碎片年龄相似,这表明它们有着共同的沉积历史,我们将其解释为在大约 1.25 Ga 时沉积于同一个跨阿迪朗达克弧后盆地。1.25 Ga.
Provenance and depositional age of metasedimentary rocks in the Frontenac terrane (Grenville Province, Ontario)
The Mesoproterozoic Frontenac terrane in the southern Grenville Province of Ontario is separated by shear zones from the Composite Arc Belt to the west and the Adirondack Lowlands to the east. The majority of the terrane is made up of granulite-facies metasedimentary rocks that are the oldest lithologies recognized in the terrane. Five samples were selected for U-Pb geochronology to constrain (1) metamorphic age, (2) depositional age of sedimentary protoliths, and (3) source regions of detrital zircon. Two pelitic gneisses and a marble are dominated by metamorphic zircon, whereas two quartzites contain a diverse population of detrital zircon that are surrounded by metamorphic rims. Metamorphic zircon have 206Pb/207Pb ages of 1.19–1.16 Ga, and a small population is 1.22 Ga. These ages correspond to the Shawinigan and Elzevirian orogenies, and provide minimum ages for deposition. The youngest detrital grains with ages of 1.25–1.24 Ga provide maximum depositional ages. Quartzites (and pelitic gneisses) have a wide range of detrital zircon ages that reflect local Mesoproterozoic Grenville sources and Paleoproterzoic and Archean sources in the northern Grenville Province and elsewhere in Laurentia. Most notable is a large population of 1.9–1.8 Ga zircon which point towards derivation from the Penokean orogen in the Midcontinent or Makkovikian–Ketilidian orogen of Labrador and Greenland; indicating long sedimentary transport distances. The similarities in depositional ages and detrital zircon ages between Frontenac terrane and Adirondack metasedimentary rocks suggest a shared sedimentary history which we interpret as deposition in the same Trans-Adirondack backarc basin at ca. 1.25 Ga.
期刊介绍:
The Canadian Journal of Earth Sciences reports current research in climate and environmental geoscience; geoarchaeology and forensic geoscience; geochronology and geochemistry; geophysics; GIS and geomatics; hydrology; mineralogy and petrology; mining and engineering geology; ore deposits and economic geology; paleontology, petroleum geology and basin analysis; physical geography and Quaternary geoscience; planetary geoscience; sedimentology and stratigraphy; soil sciences; and structural geology and tectonics. It also publishes special issues that focus on information and studies about a particular segment of earth sciences.