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TitleWidespread enigmatic continental exhumation revealed by deep-time thermochronology
AuthorZeitler, P K; McDannell, K T
SourceThermo 2018: 16th International Conference on Thermochronology, conference abstracts; 2018 p. 237
LinksOnline - En ligne (complete volume - volume complet, pdf, 9.72 MB)
Year2018
Alt SeriesNatural Resources Canada, Contribution Series 20180134
MeetingThermo 2018 - 16th International Conference on Thermochronology; Quedlinburg; DE; September 16-21, 2018
Documentbook
Lang.English
Mediapaper; on-line; digital
File formatpdf
Subjectsgeochronology; tectonics; crustal evolution; continental crust; radiometric dating; thermal analyses; feldspar; crustal thickness; cyclic processes; glaciation; Great Unconformity; Snowball Earth; exhumation; underplating; thermochronology; multiple diffusion domain (MDD) analyses; supercontinents
ProgramTransGEM, GEM2: Geo-mapping for Energy and Minerals
Released2018 09 01
AbstractIn deep time, Earth remains thermochronologically underexplored. The geologic records that we do have could reflect significant preservation bias and for such older terranes we have often framed questions in terms of 'events' rather than processes. In this context, thermochronology has great promise for revealing previously unknown aspects of Earth-system evolution. We report on one example involving medium-temperature MDD K-feldspar analysis of current surface exposures on cratons. Our work shows that current exposures of the Superior and Kaapvaal cratons were resident at ~200°C at 1 Ga after having slept through up to a billion years of near-stasis and 'stability'. Depending on details of their thermal histories and crustal temperatures, these rocks then must have experienced 5-10 km of exhumation, only some of it happening in the Phanerozoic. This is an awkward and enigmatic value, especially at the higher end: how could cratonic lithosphere that has been stable for so long (experiencing only minor burial or uplift prior to 1 Ga) find a way to be exhumed from the middle crust? Simple erosion of a low-freeboard continent cannot do this; one explanation could be crustal thickening through underplating. Our results add to recent thermochronological work that documents significant amounts of exhumation associated with the formation of the widespread Great Unconformity and provide support for suggestions that there are links between supercontinent cyclicity, Snowball Earth glaciations, and enhanced erosion in the Neoproterozoic.
Summary(Plain Language Summary, not published)
Thermochronology has great promise for revealing geodynamic processes and aspects of Earth system evolution through deep time. We report on one example involving medium-temperature MDD K-feldspar analysis of current surface exposures on cratons. Our results add to recent thermochronological work that documents significant amounts of exhumation associated with the formation of the widespread Great Unconformity and provide support for suggestions that there are links between supercontinent cycles, Snowball Earth glaciations, and enhanced erosion in the Neoproterozoic.
GEOSCAN ID308426