Raymond R. Anderson Iowa Geological Survey

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Raymond R. AndersonIowa Geological Survey
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N
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Iowa Geological Survey Annual Report Volume
21 1912
Iowa Geological Survey Annual Report Volume 33 928
Manson town well 1
Manson town well 2
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1953 IGS-USGS Manson water investigation
Early rotary drill rig used to drill the Manson
1-A and 2-A cores
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1955 interpretation of Manson drill
datacryptovolcanic structure
coreholes
Hoppin, R.A., and Dryden, J.E., 1958, An unusual
Occurrence of Pre-Cambrian rocks beneath
GlacialDrift Near Manson, Iowa. Journalof
Geology, v. 66, p. 694-699.
modified from Dryden, 1955
Dryden, J.E., 1955, Study of a Well Core from
Crystalline Rocks Near Manson Iowa unpublished
Master's Thesis, State University of Iowa, Iowa
City, Iowa, 89 p.
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Science, 1980, vol. 208
asteroid 10 km in diameter
crater 200 km diameter
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At least two candidate impact structures do
exist in North America the Sierra Madera
structure, Texas (6), and the Manson structure,
Iowa (7, 8). Both structures have definite
shock-metamorphic characteristics, and both are
more than 10 km in diameter. Both are less than
Lower Cretaceous age, although neither structure
has been accurately dated. Of the two, Manson
seems the stronger candidate.

Bevan M. French
French, B., 1984, Impact Event at the
Cretaceous-Tertiary Boundary A Possible Site
Science, v. 226, p. 353.
"The Manson structure in particular should be
studied in more detail to determine its true
extent, its exact age, and its possible
connection to the K-T impact event."
Bevan M. French

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Microscopic study of water well samples
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1984
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Pre-drilling interpretive profile of the Manson
Impact Structure
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MANSON CORE-DRILLING PROJECT1991-1992
PROJECT GOALS
1. More accurately determine impact age
2. Identify type of impactor
3. Compare target rocks to K-T boundary materials
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drilled 1,901 m hole - rock-bit 591 m
collected 1,283 m core98 recovery
Drilling of the Manson M-3 Core near Clare
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MORPHOLOGY OF THE
MANSON IMPACT STRUCTURE
Apparent Crater
E
W
Transient Crater
Undisturbed
Crater
Undisturbed
Crater
Central
Strata
Strata
Moat
Peak
Moat
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
0
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
5
km
0
5
10 km
x
x
x
x
x
x
x
x
x
Glacial Drift
Cretaceous Rocks
Paleozoic Strata
Proterozoic Red Clastic Rocks
Transported, Brecciated Strata
x
Proterozoic Crystalline Basement
Transient Crater
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IMPACT ROCKS
IN THE MANSON STRUCTURE
Central Peak
Crater Moat
Terrace Terrane
Phanerozoic-Clast Breccia
Keweenawan-Shale
Overturned
Clast Breccia
Sedimentary Strata
Crystalline
Clast Breccia
(Melt Matrix)
Crystalline
Clast Breccia
(Sandy Matrix)
Proterozoic
Crystalline
Megablocks
(cross section from crater center to eastern edge)
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Core of ProterozoicCrystalline Megablocksfrom
the MansonCentral Uplift
2-A441
M-10 619
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Manson 2-a 170.0
PDFs in quartz grains
0.5 mm
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Manson 2-a 172.0
ripped and fractured biotite grain
1 mm
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M-1459
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Manson M-1 669.7
Manson M-1 669.7
Crystalline-clast breccia with sandy matrix
Crystalline-clast breccia with sandy matrix
1 mm
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Manson M-1 670.0 x
crystalline-clast breccia with sandy matrix
0.5 mm
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partial melting ofsandy matrix
0.5 mm
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M-1657
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Manson M-10 - 337.0melt flow banding
0.5 mm
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0.5 mm
Manson M-1 angular melt clastin melt matrix
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Manson M-1 - 357.0sanadine in glass
0.5 mm
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M-10 274
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IMPACT ROCKS
IN THE MANSON STRUCTURE
Central Peak
Crater Moat
Terrace Terrane
Phanerozoic-Clast Breccia
Keweenawan-Shale
Overturned
Clast Breccia
Sedimentary Strata
Crystalline
Clast Breccia
(Melt Matrix)
Crystalline
Clast Breccia
(Sandy Matrix)
Proterozoic
Crystalline
Megablocks
(cross section from crater center to eastern edge)
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M-2265
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Witzke, B.J., and Anderson, R.R., 1996.
Sedimentary-clast breccias of the Manson impact
structure in Koeberl, C., and Anderson,
R.R., The Manson Impact Structure, Iowa Anatomy
of an Impact Crater Geological Society of
America Special Paper 302, p 115 144.
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Witzke, B.J., and Anderson, R.R., 1996.
Sedimentary-clast breccias of the Manson impact
structure in Koeberl, C., and Anderson,
R.R., The Manson Impact Structure, Iowa Anatomy
of an Impact Crater Geological Society of
America Special Paper 302, p 115 144.
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IMPACT ROCKS
IN THE MANSON STRUCTURE
Central Peak
Crater Moat
Terrace Terrane
Phanerozoic-Clast Breccia
Keweenawan-Shale
Overturned
Clast Breccia
Sedimentary Strata
Crystalline
Clast Breccia
(Melt Matrix)
Crystalline
Clast Breccia
(Sandy Matrix)
Proterozoic
Crystalline
Megablocks
(cross section from crater center to eastern edge)
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MANSON M-4 Welch
m-4
M-4
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MORPHOLOGY OF THE
MANSON IMPACT STRUCTURE
Apparent Crater
E
W
Transient Crater
Undisturbed
Crater
Undisturbed
Crater
Ring
Ring
Central
Strata
Strata
Moat
Peak
Moat
Graben
Graben
x
x
x
x
x
0
x
x
x
x
x
x
x
x
x
x
5
km
0
5
10 km
x
x
x
x
x
x
x
x
x
Glacial Drift
Cretaceous Rocks
Fall-Back (Suevite)
Paleozoic Strata
Phanerozoic Clast Breccia
Proterozoic Red Clastic Rocks
x
x
(Debris Flow)
Proterozoic Crystalline Basement
Transported, Brecciated Strata
Transient Crater
Brecciated Crystalline Rock
Anderson, R.R., Witzke, B.J., and
Hartung, J.B., 1996. Impact materials recovered
by research core drilling in the Manson Impact
Structure, Iowa in Ryder, G., Fastovsky, D., and
Gartner, S., eds., The Cretaceous-Tertiary Event
and Other Catastrophes in Earth History
Geological Society of America Special Paper 307,
p. 527 540.
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Glen IzettUSGS
Sanidine
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Manson Ejecta in the Crow Creek Member
Ontario
Manitoba
Montana
North Dakota
Minnesota
Cretaceous
Precambrian
South Dakota
Wyoming
Manson
Structure
N
Nebraska
Iowa
Paleozoic
Colorado
km
100
200
300
0
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IGS geologist Brian Witzke collecting samples of
Crow Creek Fm. at the Yankton (S.D.) Quarry
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Crow Creek Mbr.
PDFs in quartz grain
0.1 mm
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Koeberl, Christian, and Shirey, Steven B, 1994,
Manson Impact Structure, Iowa Re-Os isotope
systematics indicate presence of cosmic component
in impact breccia. in Geological Society of
America Abstracts with Programs, vol. 26, no. 5,
pp. 24, April 1994.
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Chris Koeberlat Kentland
1996
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Late Cretaceous Paleogeography
65 Ma
74.1 Ma
Greenhorn Transgression
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Sedimentation History in the Area of the Manson
Impact Structure
250 m
20 m
45 m
25 m
35 m
130 m
250 m
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10 km
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THE MANSON M-1 THRU M-11 CORES
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M-1t.d. 214 m
1984
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M-2t.d. 214 m
1984
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M-3t.d. 294 m
1984
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M-4t.d. 381 m
1984
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1984
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M-7t.d. 735 m
1984
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M-8t.d. 590 m
1984
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M-9t.d. 64 m
1984
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M-10t.d. 625 m
1984
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M-11t.d. 453 m
1984
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the end
Thanks,Ray Anderson
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any questions ?
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AGE DETERMINATIONS FOR THE MANSON IMPACT STRUCTURE
millions of years ago
?
0
10
20
30
40
60
Tertiary Cretaceous
65
70
80
74.1 0.1 Ma
90
100
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