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surface area and potential energy, should Emergence of Emergence of paired
correlate with increases in sedimentary flux blueschist & UHP high dT/dP & interm. dT/dP
metamorphism
metamorphism
into Earth’s oceans. Analysis of Phanerozoic 8 Snow Snow Wilson A
ball
ball
sedimentary rock records suggests that Earth Earth cycle
increasing sedimentary flux correlates with onset
increases in Sr/ Sr ratios in marine lime- 20
87
86
stones (Hay et al., 2001). Detrital zircon age 12
peaks have been attributed to increases in Boring billion
sedimentary flux associated with wide-
spread continental collisions and convergent Yb/Gd % S-Type
margin magmatism (Campbell and Allen, 16
2008; McKenzie et al., 2016). However, other 10
authors have favored increases in preserva-
tion for these age peaks (Hawkesworth et
al., 2009), and zircon abundance does not 20
always correlate with increases in Sr/ Sr
86
87
ratios in Earth’s oceans over time (Fig. 1B). 0
Increases in sedimentary flux derived
from weathering of a greater proportion of P G R N Su K Wilson B
cycle
elevated continental crust should, however, 1.0 Sc onset 0
occur associated with an increase in flysch Boring billion
deposition. Flysch successions include inter-
bedded graywackes and shales rich in quartz 0.8 500
and feldspars, which, when water-saturated,
are fertile sources for the generation of
S-type granites (Collins and Richards, 2008; Th/Yb 0.6 1000
Zhu et al., 2020). Thus, S-type granite pro-
duction may serve as a proxy for previous
intervals of increased flysch deposition. We 4.0 1500
identified zircons that are likely to have been 0.4
derived from S-type granite using the trace NOE GOE O Atmosphere O 2 (atm)
element discrimination procedure of Zhu et O 2 O 2 2 2000
al. (2020), wherein S-type granites typically 0.2 0
have elevated phosphorus concentrations rel- Rift-Drift Rift-Drift Rift-Drift K Wilson C
ative to I-type granites because apatite 1.9 P G R N Sc Su cycle
[Ca (PO ) (OH,F,Cl)] crystallization is sup- onset 140
5
4 3
pressed in the S-type magmas. To test the
hypothesis that the peaks in crustal thickness 1.5
were associated with an increase in S-type Boring billion
granites, we integrated S-type zircons iden- 51
tified within our data set with those found U/Yb Number of Passive Margins
through an examination of zircons from 52 1.1 38
of Earth’s major rivers (Zhu et al., 2020).
Peaks in S-type zircon percentages overlap 25
or even postdate the latter stage of increases 0.7
in crustal thickness identified here (Fig. 3A). 12
Thus, increasing radiogenic Sr input into
Earth’s oceans appears to be related to (1) the 0.3 0
weathering of a greater proportion of radio- 0 1.0 2.0 3.0 4.0
genic rocks produced and exposed as the Age (Ga)
crust thickened during the Paleoproterozoic
and Neoproterozoic time intervals, and (2) Figure 3. (A) Average Yb/Gd (crustal thickness proxy) compared to the percentage of S-type zircons
concomitant increases in continental weath- with its 95% confidence envelope. (B) Th/Yb (crustal input proxy) compared to a global compilation of
ering and sedimentary flux into the oceans. ages versus temperature/pressure (T/P) (°C/GPa) of high dT/dP (granulite−ultrahigh temperature
[UHP]) (red); intermediate dT/dP (eclogite−high-pressure granulite) (purple); and low dT/dP (high-
The results reviewed above provide pressure−UHP) metamorphism (blue) from Brown and Johnson (2018). (C) U/Yb (crustal input and fluid
important confirmation that increases in Sr input proxy) compared to a global compilation of passive margin abundance from Bradley (2008).
Tenure of supercontinent/cratons from Bradley (2011), increases in atmospheric oxygen, early “whiffs”
recorded in marine carbonates correlate of oxygen (green arrows) and intervening boring billion from Holland (2006) and Lyons et al. (2014), and
with first-order changes in convergent mar- snowball Earth glaciations adapted from Sobolev and Brown (2019). Supercontinent/craton
abbreviations: K—Kenor; Su—Superia; Sc—Sclavia; N—Nuna; R—Rodina; G—Gondwana; P—Pangea.
gin tectonism over time (Bataille et al., NOE—Neoproterozoic oxygenation event; GOE—Great oxygenation event.

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