STRATIGRAPHIC CORRELATION AND SIGNAL PROPAGATION ACROSS SEDIMENTARY SYSTEM SEGMENTS USING U-PB DETRITAL ZIRCON GEOCHRONOLOGY: INSIGHTS FROM THE LATE PLEISTOCENE MISSISSIPPI RIVER AND DEEP SEA FAN

Abstract

The Mississippi River fluvial network has undergone significant modifications during the Pleistocene that are attributed to fluctuations in northern hemisphere ice sheets. Terrigenous sediments in the Mississippi deep­ sea fan, Gulf of Mexico, preserve stratigraphic changes in U­Pb detrital zircon (DZ) provenance that are interpreted to result from up ­system changes in sediment supply and source area, largely driven by ice sheet dynamics and the sedimentary system response. Here, we build on existing work focused on sediment composition, geochemistry, and DZ provenance of the Mississippi deep­sea fan, by measuring U­Pb ages of DZs from deposits in upstream (and time correlative) ancient Mississippi River deposits, which would have fed submarine fans in the Gulf of Mexico. We performed reconnaissance level sampling of full glacial to early deglacial age deposits in the Western Lowlands and central Mississippi Valley (depositional ages of ~25 ka and ~15 ka, respectively). We hypothesize that measured DZ age patterns from ancient river sediments in the Mississippi Valley should be similar to those found in the upper most, time ­correlative deep­ sea fan deposits. If this hypothesis is verified by new DZ provenance results, it would demonstrate (1) the utility of relatively high resolution stratigraphic correlation using DZ geochronology across source to sink system segments, and (2) further improve our understanding of the effects of ice sheets on functioning of continent­ scale source to sink systems. Furthermore, this result would suggest rapid system response timescales to external forcing, and rapid signal propagation from source to sink. However, if fluvial deposits contain DZ age patterns with significant departures from those of correlative deep­sea fan deposits, interpretations of rapid signal propagation or preservation from source to sink, and inversion of stratigraphic records from the Mississippi deep­ sea fan may need to be reevaluated. This phase of our study targets some of the youngest late Pleistocene deposits in the Mississippi Valley and Mississippi fan, and future work will analyze older fluvial deposits (ca. 70-40 ka) to further test the applicability of U­Pb DZ methods to stratigraphic correlation across sedimentary system segments.
GSA Annual Meeting in Phoenix, Arizona, USA ­ 2019

Full text

Stragraphic correlaon and signal propagaon across sedimentary system segments using
U-Pb detrital zircon geochronology: insights from the late Pleistocene Mississippi River and deep-sea fan
1Jourdan Speessen, 1Cody C. Mason, 1Jack Heltzer, 1G. Paul Miles II,
2Daniel F. Stockli, 3Brian W. Romans, and 4Andrea Fildani
1University of West Georgia, 2UT Ausn, 3Virginia Tech, 4Equinor Research Center, Ausn Texas
Maximum extent of
major glacial lakes
Mississippi River
Drainage Basin
Maximum ice extent
during last glacial maximum
Lower Mississippi
Valley
North
615
Mississippi
submarine fan
Maps and cross sections B-B’, C-C’
after Rittenour et al. (2007)
Undifferentiated Tertiary
?
100
80
60
40
20
0
-20
0 20 40 60 80 100
100
80
60
40
20
0
-20
m, asl
Hb
Hmm4
Hmm1
Mississippi
River
Ridge
Prairie
Fm
Rondo
Dudley
Melville
Ridge
Ash Hill
(fluvial) 25 ka
Hal
Prairie
Fm
B'
?
BSamples MV01 C'
Undifferentiated Ter tiary
?
???
20 100
100
80
60
40
20
0
-20
-40
m, asl
Prairie
Fm
Hma
Lower Macon
Ridge
Mississippi
River
Hmm1
Kennett
15 ka Hmm3 Hb
(Morehouse) Hmm2
Kennett
40 60 80 120
0140
100
80
60
40
20
0
-20
-40
CSamples MV03
0
50
100
150
200
250
300
350
400
450
500
SH MIS Depth
(mbsf)
Seismic
Horizon
H20
2
5a
4
3
1
5b
20
30
0
Bedrock crystallization ages
Relative proportions of
U-Pb DZ ages
DSDP Leg 96
Core Site 615
615-5
(n=84)
615-6
(n=96)
615-7
(n=112)
615-8
(n=113)
615-9
(n=114)
615-10
(n=152)
615-11
(n=160)
App.
Grenville
Granite-
Rhyolite
Yavapai-
Mazatzal
Trans-Hudson
/dleihSnaidanaC
gnimoyW
Western
Cordillera
U-Pb DZ
samples
Hypothesis: disnct detrital zircon (DZ) age spectra from deep-sea fans can be correlated to fluvial strata
Benton Hills
IL
Bell
l
l
l
l
l
ll
l
l
l
l ll
l
l
l
l
l
l
ll
ll
l
C
C’
B
B’
marine
shelf slope
deep-sea
uvio-deltaic
Miss. Valley coastal
plain
canyon-fan
delta
A
not to scale
B C
~100 m
01000 2000 3000 Ma
~100 km
above H20
below H20
MIS-2
MIS-3,
4, 5a
MIS-2
MIS-3-5a
Do fluvial deposits preserve DZ age
spectra idencal to those from correlave
deep-sea deposits?
DZ age spectra?
>29 ka <29 ka
schemac deep-sea core
and DZ age spectra
>29 ka
<29 ka
ms
seismic horizon (H20)
The Mississippi River fluvial network has undergone significant modificaons during the Pleistocene that are aributed to fluctuaons in northern hemisphere
ice sheets. Terrigenous sediments in the Mississippi deep-sea fan, Gulf of Mexico, preserve stragraphic changes in U-Pb detrital zircon (DZ) provenance that are
interpreted to result from up-system changes in sediment supply and source area, largely driven by ice sheet dynamics and the sedimentary system response.
Here, we build on exisng work focused on sediment composion, geochemistry, and DZ provenance of the Mississippi deep-sea fan, by measuring U-Pb ages of
DZs from deposits in upstream (and me correlave) ancient Mississippi River deposits, which would have fed submarine fans in the Gulf of Mexico.
We performed reconnaissance level sampling of full glacial to early deglacial age deposits in the Western Lowlands and central Mississippi Valley (deposional
ages of ~25 ka and ~15 ka, respecvely). We hypothesize that measured DZ age paerns from ancient river sediments in the Mississippi Valley should be similar
to those found in the upper most, me-correlave deep-sea fan deposits. If this hypothesis is verified by new DZ provenance results, it would demonstrate (1)
the ulity of relavely high resoluon stragraphic correlaon using DZ geochronology across source to sink system segments, and (2) further improve our
understanding of the effects of ice sheets on funconing of connent-scale source to sink systems. Furthermore, this result would suggest rapid system response
mescales to external forcing, and rapid signal propagaon from source to sink. However, if fluvial deposits contain DZ age paerns with significant departures
from those of correlave deep-sea fan deposits, interpretaons of rapid signal propagaon or preservaon from source to sink, and inversion of stragraphic
records from the Mississippi deep-sea fan may need to be reevaluated. This phase of our study targets some of the youngest late Pleistocene deposits in the
Mississippi Valley and Mississippi fan, and future work will analyze older fluvial deposits (ca. 70 – 40 ka) to further test the applicability of U-Pb DZ methods to
stragraphic correlaon across sedimentary system segments.
ABSTRACT
Scan the QR code to link to a downloadable
abstract in Research Gate
STUDY AREA
Deep-sea Sediment Provenance Mississippi Fluvial System
Figures (A, B, C) from Mason et al. in prep
Deep-sea fan data from Fildani et al. (2018)
MV01 25 ka
MV03 15 ka
Ohio River
Missouri River
Upper Mississippi River
Lower Mississippi/delta
Above H20 MIS-2
Below H20 MIS-3/4/5
MV01 N=3 (n=362/365)
MV03 N=3 (n = 377/377)
Ohio River N=3 (n = 286/286)
Missouri River N=2 (n = 192/193)
Upper Mississippi River N=1 (n = 95/96)
Lower Mississippi/delta N=3 (n = 590/597)
Above H20 N=4 (n = 404/405)
Below H20 N=3 (n = 424/426)
MV01 bulk sed (n=124/125)
MV03 bulk sed (n=126/126)
MV01 250-125 (n=109/110)
MV01 125-63 (n=129/130)
MV03 250-125 (n=121/121)
MV03 125-63 (n=130/130)
MV01 bulk sed
MV03 bulk sed
MV01 250-125
MV01 125-63
MV03 250-125
MV03 125-63
0%
10%
20%
30%
40%
50%
60%
>500 μm 500-250 μm 250-125 μm 125-630 μm <63 μm
bulk weight % vs. grain size (μm)
MV01
MV03
METHODS AND RESULTS
U-Pb Detrital Zircon Geochronology From the Ancient and Modern Mississippi System
Methods: We used a power auger and a vibracore to recover sand-sized
sediment from previously dated (Rienour et al., 2007) Pleistocene
Mississippi River deposits overlain by >2-3 m of Peoria loess.
We sieved bulk sediment into medium, fine, and very fine size fracons.
We then applied laser ablaon–inducvely coupled plasma–mass
spectrometry U-Pb dang of zircon grains at the UTChron Lab.
We ploed DZ data using detritalPy (Sharman et al., 2018)
Images (le to right): troubleshoong a slightly broken
power auger in the mud, enjoying the sights of West Helena
(eastern Arkansas), the crew with our (ineffectual) vibracore,
and finally sampling success at site MV01.
Results:
1. MV01 (25 ka, W. Lowlands) has less Gondwanan/Appalachian DZs
than MV03 (15 ka, E. Lowlands).
2. MV01 has more Archean DZs, e.g. Trans-Hudson/Penokean and
Wyoming/Superior than MV03.
3. MV01 samples have a pronounced Jurassic (~160 Ma) age mode
compared to MV03.
4. DZs from different grain size fracons are broadly similar, except in
MV01 250-125 (fine sand). These results are inconclusive, but merit
further examinaon.
5. DZs in our new 25 – 15 ka fluvial samples are most similar to
“above H20” deep-sea fan DZ samples.
Figures (above and right): Cumulave distribuon funcons, kernel density
esmates and histograoms from U-Pb DZ samples used in this study. (above) Top to
boom: amalgamated late Pleistocene fluvial samples, modern fluvial to deltaic
samples from the Mississippi system (Blum and Pecha, 2014; Iizuka et al., 2010),
and deep-sea fan samples (Fildani et al., 2018).
(right): Bulk late Pleistocene fluvial DZ samples, and those seived into 250 - 125 μm
(f sand), and 125 - 63 μm (very fine sand).
INTERPRETATIONS
CONCLUSIONS AND FUTURE WORK
U-Pb DZ Sample Similarity Mississippi River to fan Sediment Roung
Acknowledgements:
We thank Equinor for funding a poron of this study.
References:
Rienour, T.M., Blum, M.D., Goble, R.J., 2007. Fluvial evoluon of the lower Mississippi River valley during the last 100
k.y. glacial cycle: Response to glaciaon and sea-level change. Geol. Soc. Am. Bull. 119, 586–608.
doi:10.1130/B25934.1
Fildani, A., Hessler, A.M., Mason, C.C., Mckay, M.P., Stockli, D.F., 2018. Late Pleistocene glacial transions in North
America altered major river drainages , as revealed by deep-sea sediment. Sci. Rep. 1–8.
doi:10.1038/s41598-018-32268-7
Sharman, G.R., Sharman, J.P., Sylvester, Z., 2018. detritalPy : A Python - based toolset for visualizing and analysing
detrital geo - thermochronologic data 202–215. doi:10.1002/dep2.45
Iizuka, T., Komiya, T., Rino, S., Maruyama, S., Hirata, T., 2010. Detrital zircon evidence for Hf isotopic evoluon of
granitoid crust and connental growth. Geochim. Cosmochim. Acta 74, 2450–2472. doi:10.1016/j.gca.2010.01.023
Vermeesch, P., 2013. Mul-sample comparison of detrital age distribuons. Chem. Geol. 341, 140–146.
doi:10.1016/j.chemgeo.2013.01.010
Conclusions: Our new data suggest that ancestral Missouri-Mississippi River
sediments with deposional ages between 15 - 25 ka strongly influenced
the composion of me-correlave deep-sea fan deposits in the Gulf of
Mexico. The apparent high connecvity of system segments suggest rapid
signal propagaon across the sediment roung system.
A logical follow up queson is “what are the DZ age signitures of fluvial
samples in the Mississippi Valley between ca. 40 -70 ka, and will they
resemble ‘below H20’ deep-sea fan DZ samples?”
Future Work: Sample ancient Mississippi River deposits correlave to the
lower-older fan (below H20; MIS-4, MIS-5a).
Figures (above): Muldimenonal scaling map for DZ samples from the Mississippi system.
For explanaon of axes, see Vermeesch, (2013), produced using detritalPy (Sharman et al.,
2018). (right): Mississippi River Valley with Late Pleistocene river channel locaons, and
pies showing propoons of U-Pb DZ ages present in samples.
Interpretaons:
DZ age spectra of the modern Missouri River are highly similar to samples
from both the Western and Eastern Lowlands, between 25 - 15 ka,
respecvely. Similarity of deep-sea fan samples (above H20; <29 ka) and
me correlave fluvial samples MV01, MV03, suggests the fan was heavily
influenced by the composion of up-system fluvial sediment, and most
likely by the DZ composion of the ancient Missouri River.
Modern Ohio River
Modern Missouri River Modern Upper
Mississippi River
MV03 bulk sed
15 ka
MV01
bulk sed
25 ka
Modern Lower Mississippi
River/delta
MIS-2 Mississippi fan
Above H20
Fluvial to
deep-sea fan transfer
Ohio River
Mississippi fan
Below H20 Upper
Mississippi River
Lower Mississippi
River/delta
Missouri River
MV03 125-63 MV01 125-63
MV01 250-125
MV01
bulk sed
MV03 250-125
Mississippi fan
Above H20
MV03
bulk sed
Western Cordilla (280-0 Ma)
Gondwana/Appalachian (280-800 Ma)
Grenville (900-1300 Ma)
Yavapai/Mazatzal (1600-1800 Ma)
Granite/Rhyolite (1500-1300 Ma)
Trans-Hudson/Penokean (1800-2000 Ma)
Wyoming/Superior (>2500 Ma)
Mississippi fan (above H20)
most similar to 25 - 15 ka
fluvial samples, modern
Missouri fluvial samples
Mississippi fan (below H20)
most similar to modern
Upper Mississippi, Missouri,
and Ohio fluvial samples