6.5 Nonactualistic (Precambriam) Depositional Environments
TIME
BEFORE
PRESENT
Ma
EVOLUTION OF
UFE AND OTHER
IMPORTANT
PROCESSES
COMPosmON OF
ATMOSPHERE
TRACE
MAJOR
------o~----------------~~~~
ü
o N
o a: w
Ia a:
n..
z
<{
W
I
Ü
a:
<{
1000
2000
3000
BIOMINERAUSATION
MElAZOA
(MUL TICELLED)
FIRST EUKARYOTIC
CELLS,
DEVELOPMENT
OFAEROBIC
RESPIRATION
WIDESPREAD
STROMATOUTES
FIRST
STROMATOUTES
ONSEl OF PHOTOSYNTHESIS
PROKARYOTIC
BACTERIA
4000
OUTGASSING OF
EARLY ATMOSPH.
ANDOCEANS
Cl
Z
Ü
:::>
I
0
\
W
\
CI:
\
I
I
\
I
\
i"l-l. \
i ''2 \
\
ACCRETION OF EARTH, 1--_________ _
LOSS OF H 2 AND
HeTOSPACE
QUAUTATIVE
SCALE
PROPERTlES
OFOCEAN
pH
0.1
0.5
1.0
HAUTE/SODA
(1) MINOR O 2 FROM PHOTOLYSIS OF H 2 0
(2) +MINOR CH 4 AND NH 3
RESPONSEOF
SEDIMENTS
BIOCLASTIC
CARBONATES AND
SIUCEOUS SEDIMENTS
FIRST MASSIVE
SULFATE DEPOSITS (?)
I ONSEl OF ABUNDANT
I RED BEDS
BANDED IRON FORMATIONS
(+FeC0:3, Fe-SIUCATES,
ANDCHERl)
URANIUMAND
PYRITE AS PLACER
MINERALS
±PRIMARY DOLOMITES
AND UMESTONES
PRECIPITATION OF
SODIUM CARBONATES (?)
(LATER DISSOLVED AND
REMOVED BY SUBDUCTION)
(CHEMICALLY
PRECIPITATED CHERTS AND
CARBONATES
285
Fig. 6.18. Some characteristics of the (hypothetical)
Precambrian atmosphere, ocean, and sediments.
(Overview, based on several sourees, e.g., Holland
1984; Windley 1984; Kempe and Degens 1985;
Veizer 1988). See text for further explanation