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Lithologic Cross Sections A and B. For analyses of subsurface conditions, 931 wells, 54 geotechnical borings, and 214 test-pit stratigraphic logs were obtained from various public and private institutions. We show only the highest quality well and boring data near the cross sections. 234 wells were incorporated into the subsurface analyses for the diagrammatic cross section (Fig. 4, in pamphlet) and Cross Sections A and B. We show composite information where
wells and borings are closely spaced and (or) where subsurface geologic conditions are stratigraphically consistent over a short distance. Figures M1 and M2 provide geophysical models of these lithologic cross sections. Appendix B provides information on earthquake hypocenters near the cross sections. The relationship between the Sultan River thrust, shown at depth on both cross sections, and the Lake Chaplain nappe is illustrated on Figure 6 in the pamphlet.
CROSS SECTION EXPLANATION
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Arrows show relative fault movement in the plane of the cross section.
Arrow point shows fault movement toward the viewer; arrow feathers show fault movement away from the viewer.
Water well or boring; water well labels begin with W; boring labels begin with B.
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CARPENTER CREEK F
AULT
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NO. 4
WOODS
CREEK
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NO. 5
WOODS
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DS
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THREE
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ICE-CONTACT
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COMPLEX
JOH
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NS
SWAM
P
ZONE
SULTAN RIVER THRUST FAULT
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MO
NROE SYNCLINE
FRENCH CREEK KA
ME COMPLEX
THREE LAKES
HILL FAULT
121°52′30″48°00′00″
122°00′00″48°00′00″
R 6 E R 7 E
T 29 N
T 28 N
55′00″ 55′00″
55′00″
55′00″
57′30″
121°52′30″
47°52′30″
122°00′00″47°52′30″
57′30″
57′30″
57′30″R 6 E R 7 E
T 29 N
T 28 N
Disclaimer: This product is provided ‘as is’ without warranty of any kind, either expressed or implied, including, but not limited to, the implied warranties of merchantability and fitness for a particular use. The Washington Department of Natural Resources and the authors of this product will not be liable to the user of this product for any activity involving the product with respect to the following: (a) lost profits, lost savings, or any other consequential damages; (b) fitness of the product for a particular purpose; or (c) use of the product or results obtained from use of the product. This product is considered to be exempt from the Geologist Licensing Act [RCW 18.220.190 (4)] because it is geological research conducted by or for the State of Washington, Department of Natural Resources, Division of Geology and Earth Resources.
© 2015 Washington Division of Geology and Earth Resources
Lambert conformal conic projectionNorth American Datum of 1927; to place on North American Datum of 1983,
move the projection lines approximately 17 meters north and 92 meters east as shown by crosshair corner ticks
Base map from scanned and rectified U.S. Geological Survey Lake Roesiger 7.5-minute quadrangle, 1997
Shaded relief generated from a lidar bare-earth digital elevation model (available from Puget Sound Lidar Consortium, http://pugetsoundlidar.ess.washington.edu/); sun azimuth 315°; sun angle 45°; vertical exaggeration 0.03
GIS by Joseph F. Schilter and Christina L. FrattaliDigital cartography by by Anne C. Olson, J. Eric Schuster, and Ian J. Hubert Editing and production by Alexander N. Steely
This geologic map was funded in part by the U.S. Geological Survey National Cooperative Geologic Mapping Program.
7000 FEET1000 10000 2000 3000 4000 5000 6000
0.5 1 KILOMETER1 0
0.51 0 1 MILE
SCALE 1:24,000
contour interval 20 feet
Geologic Map of the Lake Roesiger 7.5-minute Quadrangle,Snohomish County, Washington
Joe D. Dragovich, Shannon A. Mahan, Megan L. Anderson, James H. MacDonald Jr., Joseph F. Schilter, Christina L. Frattali, Curtis J. Koger, Daniel T. Smith, Bruce A. Stoker, S. Andrew DuFrane, Michael P. Eddy, Recep Cakir, and Kirsten B. Sauer
October 2015
APPROXIMATE MEANDECLINATION, 2015
MA
GN
ETI
C N
OR
TH
TRU
E N
OR
TH
16.1°
WASHINGTON DIVISION OF GEOLOGY AND EARTH RESOURCESMAP SERIES 2015-01
Lake Roesiger 7.5-minute Quadrangle
Pamphlet accompanies map
http://www.dnr.wa.gov/geology/
LAKE
CHA
PLAI
N
SNO
HOM
ISH
VERL
OT
SULT
AN
LAKE
STE
VENS
MAL
TBY
LAKE
ROES
IGER
GRA
NITE
FAL
LS
MO
NRO
E
Verlot
Maltby
Monroe
Lake Stevens
Granite Falls
Sultan2
29
9
203
522
92
Research supported by the U.S. Geological Survey, National Cooperative Geologic Mapping Program, under USGS award number G14AC00212. The views and conclusions contained in this document are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the U.S. Government.
MAJOR FINDINGS
• Deposits of the Olympia nonglacial interval and Whidbey Formation contain a record of the ancient Skykomish River in the southern half of the map area. These deposits are generally tilted south toward the broad axis of the Monroe syncline, a fold which is part of a family of neotectonic structures that control the lower Skykomish River valley.
• The Monroe synclinal basin continues from the Skykomish Valley across the southwest corner of the map area. Geophysical data, mapping, and geochronology indicate that this fold is cored by latest Pleistocene deposits of the Olympia nonglacial interval.
• The Explorer Falls basin preserves a thick sequence of weathered Pleistocene Pilchuck River alluvium. These deposits originally formed in a small graben which has been locally inverted.
• The northwest-trending Woods Creek fault zone is right-lateral to oblique and forms the eastern edge of the Everett basin.
DESCRIPTION OF MAP UNITS(See the pamphlet for detailed map unit descriptions and Table 1 for a summary of sediment provenance)
Quaternary Sedimentary Deposits
HOLOCENE NONGLACIAL DEPOSITS
Peat—Peat, muck, and organic silt and clay, locally with diatomite and thin beds of Mazama ash; loose or soft.
Alluvium—Sand, silt, gravelly sand, and sandy pebble gravel; unit locally includes peat and organic sediments and (or) cobble gravel; clasts subrounded to rounded; some subangular to angular clasts in alluvium near Woods Creek; loose; well stratified and sorted; sand is planar bedded. LP, SP, or PP provenance, depending on nearest major river system.
Landslide deposits (Holocene to latest Pleistocene)—Unsorted mixture of clay, silt, sand, gravel, and wood debris (diamicton) or boulder gravel, and local minor sand or gravel; loose. The absence of a mapped landslide does not imply the absence of hazard.
Alluvial fan deposits (Holocene to latest Pleistocene)—Diamicton, alluvial gravel, boulder gravel, and sand; loose, poorly to moderately sorted; moderately stratified to massive; locally contains significant amounts of debris flow deposits.
PLEISTOCENE GLACIAL AND NONGLACIAL DEPOSITS
Deposits of the Vashon Stade of the Fraser Glaciation
Recessional Deposits
Recessional glaciolacustrine (glacial lake) deposits—Silt and clayey or sandy silt to silty sand, typically with scattered dropstones; local lenses of sand or gravel; soft; deposited in proglacial lakes.
Outwash sand deposits—Sand and pebbly sand with some interbeds of silty sand, silt, or gravel; loose or soft; unstratified, weakly stratified, planar bedded, laminated, or rarely crossbedded.
Deltaic outwash and kame-delta deposits—Sandy cobble gravel, gravel, pebbly sand; loose; moderately to well sorted; thin to very thickly bedded; well stratified with conspicuous high-amplitude foreset beds.
Fluvial outwash deposits—Cobble and boulder gravel, gravel, pebbly sand, and interbeds of sand and rare silt; loose; moderately to well stratified; beds subhorizontal; locally crossbedded with many rip-up clasts.
Ice-contact deposits—Cobble to boulder gravel and gravel, locally containing diamicton, silty pebbly gravel, sand, pebbly sand, or silt; loose; moderately stratified and medium to very thickly bedded; abrupt grain-size changes common. Locally divided into:
Ice-contact kames—Cobble and boulder gravel, gravel, sand, and pebbly sand, with rare lenses of diamicton; loose; crossbedded, with localized oversteepened or slumped strata; cut-and-fill structures and common rip-up clasts of till or silt.
Outwash gravel deposits, undivided—Poorly exposed boulder–pebble gravel to pebbly sand; loose; massive to crudely bedded; largely ice-contact deposits; may include any of the gravelly Vashon recessional facies.
Advance Proglacial and Subglacial Deposits
Lodgment till—Diamicton (unsorted mixture of clay, silt, sand, and gravel); dense; matrix-supported; accreted at the base of the Vashon-age ice; typically has a friable shear fabric.
Advance outwash deposits—Sand and pebble gravel, sand and cobble gravel, and local silt; dense; well sorted and stratified; thinly to thickly bedded; deltaic and channel bar foresets, cut-and-fill structures, and common silt rip-up clasts.
Advance glaciolacustrine deposits—Silt, clayey silt, pebbly silt, and diamicton; locally contains very thin to thick beds of sand, scattered dropstones, and iceberg melt-out or flow till; stiff or dense; stratification and sorting vary; massive to thinly bedded, laminated, or varved.
Pre-Fraser Glacial and Nonglacial Deposits
Deposits of the Olympia nonglacial interval—Sand, sandy silt, silty sand, and silt, with some clay and (or) organic silty clay in the southwest corner of the map area; minor peat, charcoal, disseminated detrital organic matter, and gravel beds; sand typically yellow, gray-brown, or brown-gray with distinctive dark gray-orange oxidation; dense; well stratified; laminated to very thickly bedded; liquefaction features common; SP provenance.
Whidbey Formation—Sand, silt, and silty sand with lesser pebbly sand, clay, gravel, organic sediment including peat; lenses of (cobble) gravel observed regionally; sand is a light yellowish brown and weathers to a distinctive orange-gray; dense or hard; well sorted and stratified; SP provenance.
Double Bluff till (cross section only)—Diamicton; very dense and massive bedded; laterally extensive in the subsurface beneath the Whidbey Formation in the southern part of the map area.
Pre-Hamm Creek nonglacial deposits—Pebble gravel, gravelly sand, pebbly sand, sand, silty sand, silt with local cobble gravel and clay; sand is typically yellowish brown to pale brown, weathers orange; oxidized and strongly weathered with conspicuous mica; thin to very thickly bedded; well stratified; cross bedding, graded beds, charcoal, logs, or disseminated organic matter are common. PP provenance in the northern parts of the quadrangle, and SP provenance at one site (33D) along the south-central border of the map area.
Pre-Hamm Creek nonglacial deposits, locally derived—Sand, pebbly sand, sandy pebble gravel, with less gravel, cobble–boulder gravel, or rare silt; locally contains peat, logs, or organic sediments; distinct local Western mélange belt (LP) provenance.
Pre-Fraser glacial and nonglacial deposits, undivided (Pleistocene to Pliocene?)(cross section only)—Dense to very dense gravel, boulder gravel, sand, silt, clay, and diamicton; may locally contain peat or organic sediments.
Tertiary Volcanic, Intrusive, and Sedimentary Rocks
Rhyolite of Hughes Lake (Miocene)—Poorly exposed, high-K, calc-alkaline rhyolite flow and crystal-vitric to vitric-crystal (lapilli) tuff; white to pinkish white, weathers light yellowish brown; U-Pb zircon age of 23.300 ±0.032 Ma at site 31S.
Rocks of Bulson Creek (Oligocene to Eocene)—Lithic to lithofeldspathic sandstone with less conglomerate, pebbly sandstone, siltstone, or coal with minor claystone; mostly preserved in the Explorer Falls and (or) Everett basins.
Mesozoic Low- to Medium-Grade Metamorphic Rocks
Western mélange belt of Tabor and others (1993), undivided (Cretaceous to Jurassic)(cross section only)—Meta-argillite, metasandstone, greenstone, metachert, with less metadiabase, metatonalite, slate, amphibolite, hornblendite, phyllite, minor marble with meta-quartz-diorite; ultramafic rocks rare regionally.
Metavolcanic rocks—Low-grade greenstone derived from metamorphosed basaltic to andesitic tuff and volcanic flows of basaltic andesite to dacite.
Metasedimentary rocks—Low-grade marine feldspathic to feldspatholithic subquartzose metasandstone, silty metasandstone, meta-argillite, metatuff, and chert-pebble metaconglomerate; minor metachert and rare marble; well to moderately sorted.
Metagabbro—Medium-grade metagabbro, quartz metagabbro, feldspathic hornblendite and amphibolite; less metatrondhjemite or metatonalite; metadiabase and rare meta-quartz-diorite are reported regionally; medium to coarse grained; generally slightly foliated to schistose or gneissose.
Holocene to Tertiary Tectonic Zones
Tectonic zone—Cataclasite, fault breccia, clay-rich fault gouge, protomylonite, and (or) moderately to strongly slickenlined, fractured, and veined rocks in and near fault zones; variously colored and mottled; commonly altered. Unit Qtz is mapped where deformation is demonstrably Quaternary in age, such as along the Dubuque Road fault in the western part of the quadrangle.
GEOLOGIC SYMBOLS
Contact—Solid where location accurate; long-dashed where approximately located; queried where identity or existence questionable
Fault, unknown offset—Solid where location accurate; short-dashed where inferred; dotted where concealed; queried where identity or existence questionable
Thrust fault—Solid where location accurate; dotted where concealed; triangles on upper (structurally higher) plate
Reverse fault—Solid where location accurate; long-dashed where approximately located; dotted where concealed; queried where identity or existence questionable; rectangles on upthrown block.
High-angle dip-slip fault—Dotted where concealed; queried where identity or existence questionable; U, upthrown block; D, downthrown block
Right-lateral strike-slip fault—Solid where location accurate; long-dashed where approximately located; dotted where concealed; queried where identity or existence questionable; arrows show relative motion
High-angle right-lateral, oblique-slip fault—Solid where location accurate; short-dashed where inferred; dotted where concealed; queried where identity or existence questionable; arrows show relative horizontal motion; U, upthrown block; D, downthrown block
High-angle left-lateral, oblique-slip fault—Short-dashed where inferred; dotted where concealed; queried where identity or existence questionable; arrows show relative horizontal motion; U, upthrown block; D, downthrown block
Anticline—Short-dashed where inferred; dotted where concealed; queried where identity or existence questionable
Syncline—Short dashed where inferred; dotted where concealed; queried where identity or existence questionable
Fluvial terrace scarp—Identity and existence certain; location accurate; hachures point downslope
Landslide scarp—Identity and existence certain; location accurate; hachures point downslope
Cross section line
Location of Figure 4 cross section in accompanying pamphlet
Direction of downslope movement of landslide
Inclined bedding—showing strike and dip
Horizontal bedding
Inclined bedding in unconsolidated sedimentary deposits—showing strike and dip
Inclined foreset bedding in unconsolidated sedimentary deposits—showing strike and dip
Inclined cleavage—showing strike and dip
Vertical cleavage—showing strike
Inclined metamorphic or tectonic foliation—showing strike and dip
Vertical metamorphic or tectonic foliation—showing strike
Small, minor inclined fault—showing strike and dip
Small, minor vertical or near-vertical fault—showing strike
Inclined slickenline, groove, or striation on fault surface—showing bearing and plunge
Slickenside—showing strike and dip
Inclined mylonitic foliation—showing strike and dip
Geochronology sample location, uranium-lead (U-Pb)
Geochronology sample location, infrared stimulated luminescence (IRSL)
Significant site
Earthquake hypocenter; number corresponds to focal mechanisms in Appendix B
Water well
Drill hole for hydrocarbon exploration
Drill hole or test pit
?
?
?
DU
?
?
DU ?
DU ??
??
??
A′A
31S
W487
BH-13
BH-6
48
67
55
5
32
60
86
36
30
33A
23N
Quake 6
KJigbw
KJmsw
KJmvw
KJmw
„vr
…Ec
Qa
Qaf
Qco
Qcph
Qgtd
Qcphl
Qgnpf
Qcws
Qgav
Qgic
Qgik
Qglv
Qglr
Qgod
Qgof
Qgog
Qgos
Qgtv
Qls
Qp
Qtz
tz
?
?
??Qcph
Qgnpf
Qcphl
KJigbw
KJmw KJmswKJmvw
…Ec
„vr
Qglr Qgos Qgod
Qgtv Qgav Qglv
Qgof Qgic Qgik Qgog
Qls QafQp Qa
Qco
Qcws
Qgtd
The pamphlet provides direct or indirect age constraints for many of the geologic units, including new IRSL ages for glacial and nonglacial deposits (Appendix A). See Morrison (1991) for Pleistocene age constraints on the glacial and nonglacial intervals. Tabor and others (1993) indicate that the Western mélange belt meta-intrusive rocks (unit KJigbw) are ~150–170 Ma and are about the same age or older than the Kimmeridgian to Valanginian (157–134 Ma) metasedimentary rocks of the belt. However, detrital zircon U-Pb ages for unit KJmsw (Dragovich and others, 2014) indicate that the metasandstone in this unit is locally as young as 74 Ma.
FRASERGLACIATION
POSSESSIONGLACIATION
DOUBLE BLUFFGLACIATION
2.588 Ma
Holocene
QU
ATE
RN
AR
Y
Ple
isto
cene
TER
TIA
RY
Jurassic
Paleogene
Neogene
Cretaceous66 Ma
145 Ma
200 Ma
HAMM CREEK INTERGLACIAL
INTERVAL
DEPOSITS OF THE OLYMPIA NONGLACIAL INTERVAL
DEPOSITS OF THE WHIDBEY INTERGLACIAL INTERVAL
DEPOSITS OLDER THAN HAMM CREEK INTERGLACIAL INTERVAL
(~60–80 ka)
(~130–190 ka)
(>300–550 ka)
(~190–245 ka)
(~80–130 ka)
(~20–60 ka)
CORRELATION OF MAP UNITS
Glacial Geologic Units
Bedrock Geologic Units
Nonglacial Geologic Units
THREE L
A K E S
H
I LL
FAU LT
Explorer
Falls
basin
Sh-4Sh-8
Sh-3
33F
47A
33A
33B
35A
35B
33C
33D33E
28M
SUBGLACIALTUNNEL
5Q 302C
26T
25H
44E44D
39S120D
31S
2A11P
41AF
23N37N
39A
36N
10M
CARPE NTE R
C R E E K F
AU LT
Snohomish
Lake Roesiger quadrangle
Lake Chaplain
Lake Roesiger
Flowing Lake
Storm Lake
ChainLake
LakeHughes
LakeCochran
0 2 4miles
47A
33F
10M
Sh-8
significant site
IRSL age site
U-Pb age site
oil and gas exploration well
Figure M3. Map of oil and gas exploration wells, age sites, and significant sites in and near the Lake Roesiger quadrangle. The Three Lakes Hill and Carpenter Creek faults are shown schematically.
gravity station
Gra
vity
(mG
als)
Mag
netic
s (nT
)D
epth
(ft)
A A′Modeled Cross Sections
observed calculated
-55
-50
-45
-40
-35
-300
-200
-100
6 9 12
3,000
2,000
1,000
0
-1,000
gravity station
Distance (km)
B′Bobserved calculated
-50
-45
-40
-35
9 12 15
3,000
2,000
1,000
0
-1,000
Gra
vity
(mG
als)
Dep
th (f
t)
Tertiary rocks
Western mélange belt
Tectonic zones
Δρ = -650
Δρ = 30 to 50
Δρ = 10 to 30
Δρ = 170
Δρ = -400
Δρ = 10
χ = 1 to 2
χ = 0
χ = 50
χ = 0.4
χ = 2
χ = 2
metagabbro, unit KJigbw
unit …Ec
metasedimentary, unit KJmsw
unit KJmw, excluding metagabbro
cataclasite of unit KJmw
undifferentiated Quaternary deposits
Δρ = -650 χ = 4 unit Qco
Quaternary deposits
Geologic unitsSusceptibility
Density contrast(kg/m3)
Δρ = -650 χ = 4 unit Qcws
Δρ = -650 χ = 2 to 5 unit Qgnpf
Δρ = -70 to 0 χ = 0 cataclasite of unit KJmsw χ = 40 to 50
cataclasite of unit KJigbw
Δρ = -490 to -470 χ = 0 cataclasite of unit …Ec
Δρ = 80 to 110
Figure M2. Geophysical models A and B correspond to lithologic Cross Sections A–A′ and B–B′ (both at 2.5x vertical exaggeration) and show the match between modeled density and magnetic susceptibility from the cross sections and the observed gravity and aeromagnetic values. Here we use the total field magnetic anomaly to interpret both the shallow and deep-seated structures that contribute to the magnetic anomalies of the region, unlike in Figure M1, which focuses on near-surface structures.
Although we modeled the gravity data, we did not model the aeromagnetic data for B–B′ because most or all of the aeromagnetic anomalies along this transect are either to the east or west of the cross section line (see Fig. M1) and do not reflect the subsurface structure along the transect. Aeromagnetic data sampling distance along A–A′ is approximately twice the flightline spacing. Gravity data points are shown where good data control exists within 1.5 km of the line. The models extend to infinity in both directions perpendicular to the profiles, and data is tied to the model off to the right of both models, coinciding with locations where the model lines project across models developed in previous studies (Lake Chaplain quadrangle for A–A′ and Sultan quadrangle for B–B′). Δρ is the density contrast relative to normal crust (2,670 kg/m3) used for the model; χ is magnetic susceptibility in SI units x 1,000. Note that the higher susceptibilities for deformed units correspond to deformed metagabbro and lower densities correspond to deformed metasedimentary rocks. Though a wide range of densities for cataclasite of unit KJmsw are included in the model, most of these rocks have Δρ of -10 kg/m3. Solid lines show fault locations that are well constrained by the geophysical data; dashed lines are faults constrained by surficial geologic mapping, but are less certain at depth.
Figure M1. Aeromagnetic anomaly and isostatic gravity map of the Lake Roesiger quadrangle. Base map is reduced-to-pole aeromagnetic anomaly, filtered (upward continued and differenced with original grid) to bring out magnetic anomalies originating from near-surface sources. GB1 through GB4 are four distinct magnetic highs associated with Western mélange belt metagabbro (unit KJigbw). The anomaly at GB1 starts at the label and continues northwest; this whole trend is considered the same anomaly. MS is a gravity low associated with Monroe syncline; NE1 and NE2 are northeast-trending gravity highs; OL is a strong gravity gradient associated with the eastern edge of a thick deposit of Oligocene sediment; SP1 to SP4 are weak aeromagnetic highs that correlate with areas of moderately magnetically susceptible Skykomish River provenance Pleistocene sediment along the northern limb of the Monroe syncline; UL is a small gravity low associated with a small unnamed basin.
GEOPHYSICAL DATA AND INTERPRETATIONS
47°52′30″
122°00′00″48°00′00″
121°52′30″
-50
-50
- 40
-40
- 4 0
-40
- 30
-30
-30
A
A′B′
B
OL
GB1
GB2
GB3
GB4
SP1
SP2
SP3
SP4
MSUL
NE1
NE2
- 2 0
A A′
Gravity measurement locations used to control interpolation of gravity data
Fault—solid where certain; dashed where inferred; dotted where uncertain
Gravity contours—hachures point in the direction of decreasing gravity values; contour interval 1 milligal
Gravity and magnetic profile line
0
0 0.5
1
1 mi
2 km
Aeromagnetic anomaly in nanoTeslas (nT)
0 2-2-5 5 10-10 20-20
