236 Understanding the Neoproterozoic Earth-Life System

Wednesday, 25 September 2019
8:00 AM - 12:00 PM
North Ballroom 120D, North Building

NEOPROTEROZOIC GLOBAL PALEOGEOGRAPHY REVISITED

Paper number: 236-4
Program: Technical Sessions
Time: 9:00 AM – 9:20 AM

Authors

Abstract

Dramatic paleogeographic changes accompanied by mantle plume episodes during the Neoproterozoic likely played dominant roles in the onset of the snowball Earth events and rapid evolution of life. Here we present an update of Neoproterozoic global paleogeography from the Li et al. (2008) model using an updated paleomagnetic database, known geological constraints, and the global LIPs data. New paleomagnetic data allow us to adjust the internal configuration of Australia for a 40° vertical-axis block rotation, the relative position of India to Australia, and the positions of Congo-Sao Francisco, Tarim, Siberia, and North China. The break-up time for Rodinia is also adjusted from by 750 Ma to after 750 Ma. We adapt the recent concept of superocean cycle and an introversion assembly of Rodinia (Li et al., 2019). In our new global paleogeographic animation, Rodinia experienced multiple rapid true polar wander (TPW) events when first assembled, possibly reflecting an initial orthoversion assembly (Mitchell et al., 2012) by ca. 900 Ma over the existing subduction girdle when IITPW was favoured due to the sustained degree-2 mantle structure. Sub-Rodinia mantle plume may started to appear as early as 860 Ma, but only became prominent after 825 Ma. We propose that by 780 Ma Rodinia was located above the previous sub-supercontinent LLSVP, therefore remained latitudinally more stable at an equatorial position untill its break-up. A combination of such an equatorial position with erosion of the 720 Ma Franklin-Irkutsk and earlier Neoproterozoic LIP basalts over both the superplume dome (superswell) and rift shoulders and increasing passive margins as Rodinia broke up, probably led to the Cryogenian snowball Earth episodes.

References

  1. Li, Z.X., Bogdanova, S.V. and 14 others, 2008. Assembly, configuration, and break-up history of Rodinia: a synthesis. Precambrian Research 160, 179–210.
  2. Li, Z.X., Mitchell, R.N., Spencer, C.J., Ernst, R., Pisarevsky, S., Kirscher, U., Murphy, J.B., 2019. Decoding Earth’s rhythms: Modulation of supercontinent cycles by longer superocean episodes. Precambrian Research 323, 1-5.
  3. Mitchell, R.N., Kilian, T.M., Evans, D.A.D., 2012. Supercontinent cycles and the calculation of absolute palaeolongitude in deep time. Nature 482, 208–211.

Geological Society of America Abstracts with Programs. Vol. 51, No. 5

doi: 10.1130/abs/2019AM-334997

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