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SUMMARY:Insights into the drivers of Ediacaran-Cambrian phosphogenesis fro
 m phosphorites of the Khuvsgul Group\, Mongolia - Dr Eliel Antilla\, ETH Z
 urich
DTSTART:20251125T120000Z
DTEND:20251125T130000Z
UID:TALK237340@talks.cam.ac.uk
CONTACT:Alexandra Turchyn
DESCRIPTION:Phosphorus\, a limiting nutrient for life on geological timesc
 ales\, can accumulate in concentrated\, ore-grade deposits\, called phosph
 orites.  A secular increase in the size and abundance of phosphorites in t
 he stratigraphic record across the Ediacaran-Cambrian boundary has been pu
 tatively linked to an increase in nutrient flux to the global oceans\, and
  further associated with concomitant changes in the redox state of Earth
 ’s surface environments and the rise and diversification of animals. How
 ever\, the precise age and depositional setting of many phosphorites from 
 this ~130 Myr interval remain poorly constrained\, preventing quantitative
  tests of hypothesized drivers of the Ediacaran-Cambrian phosphogenic epis
 ode.\n \nIn this talk\, I will discuss how new age and tectonostratigraphi
 c models for the Cambrian phosphorites of the Khuvsgul Group\, Mongolia\, 
 provide new insights into the timing and mechanisms of Ediacaran-Cambrian 
 phosphogenesis. The Khuvsgul Group phosphorites\, which include a Doushant
 uo-Pertatataka-type microfossil assemblage\, were deposited in the pro-for
 eland basin between 534 and 531 Ma\, at least 40 million years later than 
 the phosphatized Weng’an Biota of the Doushantuo Formation of South Chin
 a. Tectonically-mediated basinal topography associated with foreland devel
 opment was a necessary condition for phosphogenesis along the Cambrian Tuv
 a-Mongolia-Zavkhan margin\, with different styles of phosphate mineralizat
 ion associated with variable sediment starvation and migrating redox bound
 aries across the margin. In conjunction with an updated compilation of age
 s and geological context of other Ediacaran-Cambrian phosphorites\, our mo
 dels for the Khuvsgul Group suggest that the Ediacaran-Cambrian increase i
 n preserved phosphorite deposits represents the opening of a taphonomic wi
 ndow in which a long-term\, sustained increase in redox potential enabled 
 increased authigenic phosphate accumulation over a protracted period in ma
 rginal marine environments with the requisite tectono-stratigraphic and se
 dimentological conditions.
LOCATION:Department of Earth Sciences\, Tilley Lecture Theatre
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