TABLE 13. Organic carbon cumulative mass and age-interval accumulation rates for cores Sb1a and SB1c, St. Bernard Parish, Louisiana.
St. Bernard cores SB1a and SB1c (location: 29o58"53' N, 89o55"27' W; SB1a sampled 03/18/1996, SB1c sampled 03/20/1996).
Corrected
depth
intervals
by age
range
(cm)
1
Assignments
by age
interval
2
Interval
period
(yr)
Organic carbon
cumulative mass
(kg m
-2)3
Organic carbon
accumulation rate
(kg m
-2 yr-1)
SB1a SB1c SB1a SB1c4
0-15 1964-96 32 3.85 4.99 0.12 0.16
15-28 1952-64 12 7.16 9.20 0.28 0.35
28-52 1905-52 47 13.04 16.71 0.13 0.16
52-85 1830-1905 75 23.40 27.53 0.14 0.14
85-127 870 yr BP-1830 704 -- 41.50 -- 0.02-0.02
127-166 1140-870 yr BP 270 -- 53.76 -- 0.03-0.08
166-236 1920-1140 780 -- 75.73 -- 0.02-0.03
236-265 1980-1920 60 -- 85.25 -- 0.06-xxx5
265-305 2360-1980 380 -- 98.24 -- 0.03-0.05
305-345 2670-2360 310 -- 113.85 -- 0.04-0.08
345-384 3180-2670 510 -- 129.37 -- 0.03-0.04
1Depths corrected for compaction, 6.8% (core SB1a) and 29.1% (core SB1c). Depths for 1964 (15 cm) and 1952 (28 cm) were taken from 14C data (fig. 6) for core SB1a and used both for cores SB1a and SB1c.
2Ages determined from radiocarbon analysis and diagnostic stratigraphic markers. Greatest uncertainty in ages between 85 and 195 cm (see section Data Interpretation and Summary).
3Organic carbon (OC) cumulative mass = S (OC x bulk density x 10000) / 1000.
4Minimum and maximum accumulation rates are reported for intervals in SB1c below 85 cm based on the errors in 14C age determinations (table 1).
5A maximum accumulation rate cannot be calculated for this interval because the ages for the interval boundaries "cross over". The assigned ages of 1980 yr BP and 1920 yr BP may not be statistically different.
Source: U.S. Geological Survey Open-File Report 98-36. Carbon storage and late Holocene chronostratigraphy of a Mississippi River deltaic marsh, St. Bernard Parish, Louisiana H.W. Markewich, ed.).

Last Updated on 2/5/98
By Gary R. Buell