Phanerozoic sedimentary cover history of the Hudson Platform: a heuristic modeling perspective

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Authors

Kalin T. McDannell , Paul B. O'Sullivan, Kerry Gallagher, Scott Boroughs

Abstract

Understanding the long-term erosion and burial history of cratons is challenging due to the incompleteness of the rock record. Low-temperature thermochronology has been applied to provide constraints on these histories and apatite fission-track dating has been one of the preferred methods for the past four decades. Thermochronological data are often inverted for a thermal history along with sparse constraints and other assumptions about the regional geologic evolution. However, imposing certain assumptions will influence the form of the inferred thermal histories, and in some cases this step may limit impartial assessment of the unknown history in terms of what features are required by the data, and those that the data are consistent with (or at least do not contradict). Here we present a study involving laser ablation apatite fission-track data from central Canadian Shield basement rocks collected adjacent to the Hudson Platform Paleozoic nonconformity in northern Manitoba and Ontario. Samples are characterized by up to
~3x the number of dated age grains and >6–8x the number of track length measurements when compared to a conventional fission-track analysis. Inverse thermal history simulations are guided by a heuristic philosophy regarding the use of constraints—this allows us to examine the ability of the model to independently infer geologically plausible time-temperature paths from the fission-track data in isolation, and compare the results with the known geology. The additional data are beneficial for time-temperature resolution using Bayesian methods. The data require two reheating events and indirectly imply periods at cooler (near-surface) conditions in the latest Neoproterozoic to early Paleozoic and in the Jurassic to early Cretaceous—the timing of which are consistent with Hudson Platform unconformities. Inversions establish that the currently exposed basement near the Hudson Bay Basin was buried in the middle-to-late Paleozoic and again in the late Mesozoic--early Tertiary, in agreement with the preserved regional rock record and other thermochronology studies. Sedimentary cover was estimated to be ~1.0 ± 0.25 km thick in the late Paleozoic and up to ~1.25 ± 0.25 km thick in the latest Mesozoic during Cretaceous interior seaway transgression.

DOI

https://doi.org/10.31223/X5M05W

Subjects

Earth Sciences, Geochemistry, Geology, Geomorphology, Physical Sciences and Mathematics, Stratigraphy, Tectonics and Structure

Keywords

apatite fission track, thermochronology, cratons, Bayesian modeling, Canadian Shield, burial history

Dates

Published: 2022-01-19 05:06

Last Updated: 2022-05-18 12:54

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License

CC BY Attribution 4.0 International

Additional Metadata

Conflict of interest statement:
None

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