228
To test the preservation potential of the various MOSSFA constituents (lithogenic, biogenic, petrogenic), sedimentary records from the southern GoM were
assessed for any remaining evidence of Ixtoc 1 in 1979–1980. Preliminary visual
inspection provided evidence that a complex laminated section with a preserved
redox record (solid-state manganese) was preserved during the 1979–1980 interval
in the sedimentary record (Fig.  13.4). These laminations and visible redox
boundary were similar to those observed following DWH in the northern GoM.
0
0.5
1
1.5
2
234
Th Inventory (dpm cm -2
)
0
0.5
1
1.5
2
2.5
Apparent 234
Th MAR (g cm
-2
yr
-1
)
0
1
2
3
4
Mar-10
Aug- 10
Feb-11
Aug- 11
Feb-12
Aug- 12
Feb-13
Aug- 13
Feb-14
Aug- 14
Feb-15
Aug- 15
[Re] ppb
Aug
2010
Aug
2012
Aug
2014
Aug
2015
Aug
2013
Aug
2011
Water Depth
M-04
400m
Site ID
P-06
1043m
D-08
1140m
D-10
1520m
DWH
Returning to Steady-State
Recovery
MOSSFA
Pulse
Bioturbation
Fig. 13.3 Stacked plots of
234
Th inventory (disintegrations per minute per cm
2
; modified from
Larson et al. 2018), apparent
234 Th accumulation rate (g cm
−2
 yr
−1 ; modified from Larson et al.
2018), and rhenium concentration (modified from Hastings et al. 2016) from 2010 to 2015 for four
time series sites in the northern GoM (M-04, blue; P-06, green; D-08, yellow; D-10, red). These
plots detail the three postdepositional process periods of (1) MOSSFA flux, (2) recovery, and (3)
return to steady state
P. T. Schwing et al.