| Title | Widespread enigmatic continental exhumation revealed by deep-time thermochronology |
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| Author | Zeitler, P K; McDannell, K T |
| Source | Thermo 2018: 16th International Conference on Thermochronology, conference abstracts; 2018 p. 237 |
| Links | Online - En ligne (complete volume - volume complet,
pdf, 9.72 MB)
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| Image |  |
| Year | 2018 |
| Alt Series | Natural Resources Canada, Contribution Series 20180134 |
| Meeting | Thermo 2018 - 16th International Conference on Thermochronology; Quedlinburg; DE; September 16-21, 2018 |
| Document | book |
| Lang. | English |
| Media | paper; on-line; digital |
| File format | pdf |
| Subjects | geochronology; tectonics; crustal evolution; continental crust; radiometric dating; thermal analyses; feldspar; crustal thickness; cyclic processes; glaciation; Great Unconformity; Snowball
Earth |
| Program | GEM2:
Geo-mapping for Energy and Minerals TransGEM |
| Released | 2018 09 01 |
| Abstract | In 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 ID | 308426 |
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