The Penultimate Glaciation and Mid- to Late-Pleistocene ... 2014 poster.pdfThe Penultimate...
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The Penultimate Glaciation and Mid- to Late-Pleistocene Stratigraphy in the Central Puget Lowland, Washington 1. Goals: Identification and age of glacial and interglacial deposits in the central Puget Lowland? Kathy Goetz Troost, UW ESS, Seattle, WA [email protected] Booth 325 Ice Advance Multiple glaciers have advanced into the Puget Lowland from British Columbia, the three most recent corresponding with OIS 2, 4, and 6. Unlike the most recent advance, the Fraser Glaciation, any previous glaciations are poorly understood and their deposits are known mostly at type sections. 2. Why?: ecosystems, climate, groundwater sources and storage, planning, and geologic hazards. Deformed, Possession-age (MIS 4, IRSL 65-75 ka), glaciolacustrine beds under I-5 in the Seattle Fault Zone (SFZ).. Till over outwash, typical of all of the glacial advances in the lowland. Map showing extent of last lowland glaciation (MIS 2), ice fronts during recession, and some of the active faults. 3. Methods: 14C, OSL/IRSL, paleomagnetics, fission track, tephrochronology, micro and macrofossils, provenance, mapping, aeromagnetics, geomorphology... Picea Engelmannii Western White Pine Angular unconformity in >400ka glacial deposits in South Whidbey Island Fault Zone (SWIF). IRSL sampling, south end of Whidbey Island. Obligate marine mussels in MIS 4/5 deposits. Predominantly glaciomarine drift Predominantly till and glaciolacustrine Predominantly outwash • Extensive mapping and chronological work led to the discovery of newly identified glacial and interglacial deposits. • Stratigraphic units identified by Dr. Donald Easterbrook in the 1960’s, 70’s, and 80’s, in the northern lowland, can be correlated with glacial and interglacial deposits in the Seattle and Tacoma areas. • MIS 3 deposits indicate nonglacial conditions, and are discontinuous but well distributed in the Puget Lowland. • MIS 4-Possession-age deposits are discontinuous but well distributed throughout the Central Puget Lowland. • The MIS 4-Possession glacier was smaller and did not extend as far as the MIS 2- Vashon glacier. • The relief on the MIS-4 paleotopographic surface is similar to that of MIS-2, so perhaps ice sheet dynamics were somewhat similar. • Multiple lines of evidence point to a wet climate. Climate proxies show that the MIS4 climate was slightly warmer than MIS2. • Extensive glaciomarine and glaciolacustrine deposits suggest more water-laid deposits during MIS 4 than during MIS 2 Vashon glaciation . • The facies model for MIS 4 suggests a wet- based glacier with deep scouring in troughs and drumlin formation on the uplands. 20 Km 4. Findings: •Further extent of MIS 4 glaciation •MIS 5 and 6 deposits in new areas •Newly identified MIS 7 interglacial deposits •Newly identified MIS 8 glacial deposits •Newly identified glacial deposits >400ka 3 1 3 5 7 9 11 13 3.5 4 4.5 5 0 200 400 δ 18 O (0/00) Years (ka) Laschamp Blake Biwa I/ Jamaica Biwa II/ Levantine Biwa III Emperor Brunhes Polarity Subchrons A. Composite stratigraphic column for the south-central Puget Lowland from Troost and Booth, 2008. Reversely magnetized, unique polarity deposits help identify MIS 5. B. Point Evans, Tacoma area, measured section showing multiple lines of evidence for MIS 4, 5, 6, and 8 deposits. Vashon advance outwash (Qva) Lawton Clay Possession till Possession outwash Whidbey Formation Double Bluff Drift Defiance gravel Defiance silt Gig Harbor gravel Double Bluff Till Vashon till (Qvt) Vashon recessional outwash (Qvr) Olympia beds =13.4 +/- .3 ka; 13.4 +/- .2 ka Upland Surface 14 C Elevation, feet Key peat needles bedding deformation, folding diamict dropstones wood, charcoal MIS 5 MIS 6 MIS 8 MIS 4 MIS 2 C. Map showing location of new type sections for MIS 7 (Hamm Creek) and MIS 8 (Defiance Drift) deposits. D. Map and graph showing relative extents of the last 3 three glaciers to extend into the Puget Lowland from the North. The MIS 8 glacier extended at least as far as the MIS 4, Possession. E. Map showing facies from the MIS 4, Possession, glacial advance into the Puget Lowland. The black line shows the limit of the Fraser Glaciation, MIS 2. Base map by Harvey Greenberg, UW. 5. Conclusions: DMF=Devils Mtn Fault SPF=Strawberry Pt. Fault UPF=Utsalady Point Fault SWIF=So. Whidbey Is. Fault SFZ=Seattle Fault Zone TFZ=Tacoma Fault Zone Fraser Possession Double Bluff Defiance Hamm Creek F. Whidbey F. Olympia F. PT Evans MS Before this study Puget Lobe Advances 80-125 (T) 125-190 (T) 60-80 (T) This study After this study cal Many people have provided insight, information, and in- kind services for this research. I wish thank them all, only some are mentioned here: Dr. Derek Booth, advisor, UW Mr. Richard Borden, Rio Tinto Dr. Ray Wells, USGS Dr. Estella Leopold, UW Ms. Shannon Mahan, USGS The late Dr. Richard Stewart, UW Mr. Michael Polenz, WDGER Mr. Tim Walsh, WDGER Mr. David McCormack, Aspect, LLC Mr. Curtis Koger, AESI Ms. Jenny Saltonstall, AESI Dr. Ralph Haugerud, USGS Dr. Jonathan Hagstrum, USGS Dr. Robert Fleck, USGS Dr. Stephen Porter, USGS
Transcript of The Penultimate Glaciation and Mid- to Late-Pleistocene ... 2014 poster.pdfThe Penultimate...
The Penultimate Glaciation and Mid- to Late-Pleistocene Stratigraphy in the Central Puget Lowland, Washington
1. Goals: Identification and age of glacial and interglacial deposits in the central Puget Lowland?
Kathy Goetz Troost, UW ESS, Seattle, WA [email protected]
Booth 325
Ice Advance
Multiple glaciers have advanced into the Puget Lowland from British Columbia, the three most recent corresponding with OIS 2, 4, and 6. Unlike the most recent advance, the Fraser Glaciation, any previous glaciations are poorly understood and their deposits are known mostly at type sections.
2. Why?: ecosystems, climate, groundwater sources and storage, planning, and geologic hazards.
Deformed, Possession-age (MIS 4, IRSL 65-75 ka), glaciolacustrine beds under I-5 in the Seattle Fault Zone (SFZ)..
Till over outwash, typical of all of the glacial
advances in the lowland.
Map showing extent of last lowland glaciation (MIS 2), ice fronts during recession, and some of the active faults.
3. Methods: 14C, OSL/IRSL, paleomagnetics, fission track, tephrochronology, micro and macrofossils,
provenance, mapping, aeromagnetics, geomorphology...
Picea Engelmannii Western White Pine
Angular unconformity in >400ka glacial deposits in South Whidbey
Island Fault Zone (SWIF).
IRSL sampling, south end of Whidbey Island.
Obligate marine mussels in MIS 4/5 deposits.
Predominantly glaciomarine
drift
Predominantly till and
glaciolacustrine
Predominantly outwash
• Extensive mapping and chronological work led to the discovery of newly identified glacial and interglacial deposits.
• Stratigraphic units identified by Dr. Donald Easterbrook in the 1960’s, 70’s, and 80’s, in the northern lowland, can be correlated with glacial and interglacial deposits in the Seattle and Tacoma areas.
• MIS 3 deposits indicate nonglacial conditions, and are discontinuous but well distributed in the Puget Lowland.
• MIS 4-Possession-age deposits are discontinuous but well distributed throughout the Central Puget Lowland.
• The MIS 4-Possession glacier was smaller and did not extend as far as the MIS 2-Vashon glacier.
• The relief on the MIS-4 paleotopographic surface is similar to that of MIS-2, so perhaps ice sheet dynamics were somewhat similar.
• Multiple lines of evidence point to a wet climate. Climate proxies show that the MIS4 climate was slightly warmer than MIS2.
• Extensive glaciomarine and glaciolacustrine deposits suggest more water-laid deposits during MIS 4 than during MIS 2 Vashon glaciation .
• The facies model for MIS 4 suggests a wet-based glacier with deep scouring in troughs and drumlin formation on the uplands.
20 Km
4. Findings:
•Further extent of MIS 4 glaciation
•MIS 5 and 6 deposits in new areas
•Newly identified MIS 7 interglacial deposits
•Newly identified MIS 8 glacial deposits
•Newly identified glacial deposits >400ka
3 1
3
5 7
9 11 13
3.5
4
4.5
5
0 200 400
δ18 O (0
/00)
Years (ka)
Lasc
ham
p
Blak
e
Biw
a I/
Ja
mai
ca
Biw
a II/
Le
vant
ine
Biw
a III
Empe
ror Brunhes
Polarity Subchrons
A. Composite stratigraphic column for the south-central Puget Lowland from Troost and Booth, 2008. Reversely magnetized,
unique polarity deposits help identify MIS 5.
B. Point Evans, Tacoma area, measured section showing multiple lines of evidence for MIS 4, 5, 6, and 8 deposits.
Vashon advance outwash (Qva)
Lawton Clay
Possession tillPossession outwash
Whidbey Formation
Double Bluff Drift
Defiance gravelDefiance siltGig Harbor gravel
Double Bluff Till
Vashon till (Qvt)
Vashon recessional outwash (Qvr)
Olympia beds=13.4 +/- .3 ka; 13.4 +/- .2 ka
Upland Surface
14C
Elev
atio
n, fe
et
Key
peat
needlesbedding
deformation, folding
diamictdropstones
wood, charcoal
MIS 5
MIS 6
MIS 8
MIS 4
MIS 2
C. Map showing location of new type sections for MIS 7 (Hamm Creek) and MIS 8
(Defiance Drift) deposits.
D. Map and graph showing relative extents of the last 3 three glaciers to extend into the Puget Lowland from the North. The MIS 8 glacier extended at least as far as the MIS 4, Possession.
E. Map showing facies from the MIS 4, Possession, glacial advance into the Puget Lowland. The black line shows the limit of the Fraser
Glaciation, MIS 2. Base map by Harvey Greenberg, UW.
5. Conclusions:
DMF=Devils Mtn Fault SPF=Strawberry Pt. Fault UPF=Utsalady Point Fault SWIF=So. Whidbey Is. Fault SFZ=Seattle Fault Zone TFZ=Tacoma Fault Zone
Fraser
Poss
essi
on
Double Bluff
Defiance
Ham
m
Cre
ek F
.
Whi
dbey
F.
Oly
mpi
a F.
PT Evans MS Before this study
Puget Lobe Advances
80-125 (T)
125-190 (T)
60-80 (T)
This study
After this study
cal
Many people have provided insight, information, and in-kind services for this research. I wish thank them all,
only some are mentioned here: Dr. Derek Booth, advisor, UW Mr. Richard Borden, Rio Tinto
Dr. Ray Wells, USGS Dr. Estella Leopold, UW
Ms. Shannon Mahan, USGS The late Dr. Richard Stewart, UW
Mr. Michael Polenz, WDGER Mr. Tim Walsh, WDGER
Mr. David McCormack, Aspect, LLC Mr. Curtis Koger, AESI
Ms. Jenny Saltonstall, AESI Dr. Ralph Haugerud, USGS
Dr. Jonathan Hagstrum, USGS Dr. Robert Fleck, USGS
Dr. Stephen Porter, USGS
