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Title'Date to rate': mining the sedimentary record to study tectonic rates and timescales
AuthorKellett, D AORCID logo
SourceEuropean Geophysical Union General Assembly 2019; Geophysical Research Abstracts vol. 21, EGU2019-10315, 2019 p. 1 Open Access logo Open Access
LinksOnline - En ligne
Alt SeriesNatural Resources Canada, Contribution Series 20190400
PublisherEuropean Geophysical Union
MeetingEuropean Geophysical Union General Assembly 2019; Vienna; AT; April 7-12, 2019
Mediaon-line; digital
File formatpdf
ProvinceYukon; British Columbia
NTS104J; 104K; 104L; 104M; 104N; 104O; 105B; 105C; 105D; 105E; 105F; 105G; 105L; 115A; 115G; 115H; 115I; 115J
AreaWhitehorse; Atlin Lake; Dawson; Florence Range
Lat/Long WENS-139.5000 -130.0000 65.0000 58.5000
Subjectstectonics; sedimentology; geochronology; Science and Technology; Nature and Environment; Lower Jurassic; sedimentary basins; tectonic evolution; orogenesis; accretion; erosion; terranes; metamorphism; depositional history; burial history; radiometric dating; uranium lead dating; zircon dates; detrital minerals; clasts; eclogites; muscovite; thermal history; Canadian Cordillera; Intermontane Belt; Whitehorse Trough; Methodology; Phanerozoic; Mesozoic; Jurassic
ProgramGEM2: Geo-mapping for Energy and Minerals Western Cordillera, Yukon Tectonic Evolution - late Mesozoic to Tertiary
Released2019 04 01
AbstractThe geochronological community now has access to a wide range of methods, minerals and decay systems with which to study the tectonic evolution of orogens, particularly dates and rates of metamorphism and deformation. While the preferred dating targets involve direct investigation of metamorphosed and deformed rocks using petrochronological approaches, much of the rock record of orogenesis has generally eroded away, even in active orogens. Their erosional remnants preserved in syn-tectonic sedimentary basins thus provide a highly complementary record of the tectonic evolution of orogenesis. Sedimentary basins are commonly mined for their detrital mineral age populations (e.g. zircon U-Pb), and coupled isotopic analyses (e.g. Hf) allow for increasingly detailed source characterization. However, this is just the tip of the iceberg for information that can be extracted from syn-tectonic basins. In this case study, a range of approaches including detrital clast petrochronology, detrital multi-mineral thermochronology, and geo- and thermochronological double dating are applied to rocks from a syn-tectonic basin to interrogate the complex history of accretion in an accretionary orogen setting.
The Intermontane suite of continental, island arc and oceanic terranes accreted to the western margin of North America in Early Jurassic, initiating the Canadian Cordillera. The Whitehorse trough syn-tectonic basin preserves the erosional record of accretion of these terranes, including igneous, sedimentary and metamorphic sources. Petrochronology of mm-sized eclogite clasts reveals that peak high temperature metamorphism, rapid cooling and exhumation, and deposited into the basin all occurred during Early Jurassic. Detrital muscovite ages indicate exhumation of other metamorphic source rocks during E. Jurassic. U-Pb - U-Th/He double dating of detrital zircon confirms collapse of nascent volcanic rocks into the basin during the same period. Low temperature thermochronometers record post-E. Jurassic burial and shortening of the Whitehorse trough during ongoing collision. This comprehensive and diverse set of date to rate data allows for new hypotheses on the tectonic setting of accretion in the Canadian Cordillera during the Early Jurassic.
Summary(Plain Language Summary, not published)
This publication explores the geological history of an area called the Whitehorse trough in the Canadian Cordillera. The researchers are interested in understanding how different rocks in this region have evolved over time, especially during the Early Jurassic period.
They used various methods, including studying small rocks called eclogite clasts, examining the ages of minerals like muscovite, and dating zircon minerals. These methods helped them understand when and how different rocks formed, were buried, and eventually exposed.
What they found is that a lot of important geological events, such as high-temperature metamorphism, cooling, and the deposition of rocks into the basin, all happened during the Early Jurassic. They also discovered evidence of volcanic rocks collapsing into the basin during the same period.
The scientific impact of this research is that it provides a better understanding of how landmasses came together in this part of North America during the Early Jurassic. It's crucial for geologists to comprehend the Earth's past and the processes that shaped the landscape. This knowledge can help us piece together the history of our planet and can be useful in various fields like geology, tectonics, and the exploration of natural resources.

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