GSA Connects 2024 Meeting in Anaheim, California

Paper No. 4-1
Presentation Time: 8:00 AM

UNRAVELING THE THERMAL-HISTORY INFORMATION IN SEDIMENTARY ROCKS: FIRST RESULTS FROM ZIRCON U/Pb-(U-Th)/He-RAMAN TRIPLE-DATING (Invited Presentation)


HAERTEL, Birk, Earth, Energy and Environment, University of Calgary, 2500 University Dr, NW, Calgary, AB T2N 1N4, Canada and ENKELMANN, Eva, Earth, Energy and Environment, University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4, Canada

Sedimentary rocks are excellent archives for geological processes because they record the cooling history of their source regions, the erosion and transport patterns over large spatial extents, and post-depositional thermal history. However, this multilayered information also complicates the process of extracting thermal histories from sedimentary rocks. To tackle this problem, it is necessary to develop new analytical strategies.

A promising candidate is laser-ablation-based zircon (U-Th)/He (LA-ZHe) dating. Several studies over the last two decades have explored the potential of applying this method to sedimentary rocks and individual detrital grains. It enables us to increase the number of dated grains compared to conventional ZHe dating, which requires time-consuming dissolution of whole grains. More importantly, the less destructive and spatially resolved laser ablation offers the prospect of combining high-n ZHe dating with other dating methods. Matching thermochronological with geochronological ages for each individual grain allows: (1) distinguishing magmatically cooled grains from grains that cooled during exhumation, (2) identifying source regions and tracing their cooling history, (3) comparing provenance information from different cooling populations.

We developed a new triple-dating workflow for zircon at the Geo-and Thermochronology Lab of the University of Calgary. It combines LA-ZHe and U-Pb dating with the radiation-damage-based zircon Raman thermochronometer. This approach constrains the crystallization age (U-Pb) and the timing of cooling through 330 ± 50 °C (Raman) and 180 ± 20 °C (ZHe) for each grain. We present the first results of applying triple-dating to Devonian and Cretaceous sandstone from the Mackenzie Plain, a foreland basin deposit of the Northern Canadian Cordillera.