Evolution of the northwestern margin of the Basin and RangeInsights from new geologic mapping in northeastern California

Egger, Anne E.1 (annegger@stanford.edu) and Colgan, Joseph P.21 GES Department, Stanford University, Stanford, CA 94305 2 U.S. Geological Survey, Menlo Park, CA 94025

Session 105208

Key features • Rock units exposed in the map area record volcanic activity from late Eocene through the Pliocene with a peak in subduction-related volcanism ~26-27 Ma

• All units vary laterally in thickness over relatively short distances (a few kilometers)

• Oligocene and Miocene volcanic edifices built upon each other, indicating the persistence of significant topographic relief

• Both mid-Miocene and late Miocene basalt flows are locally derived, and never extended over the entire map area

• Mid-Miocene lava flows are fed by N-S-oriented dikes and cut by N-S-oriented normal faults

• Late Miocene lava flows flowed into fault-bound basins and are cut by a later series of N-S-oriented normal faults

• The Surprise Valley changes from a full graben in the southern portion of the map area to a half-graben in the north, with a complex of buried horsts and grabens in the intervening region

Today

5 Ma

10 Ma

15 Ma

20 Ma

25 Ma

30 Ma

35 Ma

40 Ma

Deposition of volcaniclastic sediments in alluvial plain, being shed off andesitic volcano ~20 km SSW of map area (Egger et al, 2009). Possibly an intra-arc extensional basin.

Development of andesitic stratovolcano centered near Cedar Pass, including shallow intrusives and ignimbrites, characteristically rich in hornblende.

Development of subduction-related ba-saltic shield volcano; up to 2 km of basalt flows, breccias, and mafic tuffs centered near Solider Creek.

Development of Hays Volcano and thin basalt flows capping Cedar Pass complex.

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EN

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Development of numerous basaltic volca-noes, many still evident in topography today. Feeder dikes suggest some E-W-directed extension at this time; flows are transitional between arc-related and low-K olivine tholeiites.

Extension, horst-and-graben normal faulting

Extensive silicic volcanism, including eruption of Alturas tuff and numerous ob-sidian domes, possibly related to New-berry volcanic trend.

Widespread flows of low-K olivine tholei-ites (LKOTs), thin basalt flows layered with tuffs, tuffaceous sediments, and lake sedi-ments. Localized flows fill topography

Extension, focus of uplift on the Surprise Valley Fault, many small faults cut LKOTs

Paleoseismology reveals moderate rate of slip along the Surprise Valley Fault in the Quaternary (Personius et al, 2009)

Axelrod, D.I., 1966, Potassium-argon ages of some western Tertiary floras: American Journal of Science, v. 264, p. 497-506.

Carmichael, I.S.E., Lange, R.A., Hall, C.M., and Renne, P.R., 2006, Faulted and tilted Pliocene olivine-tholeiite lavas near Alturas, NE California, and their bearing on the uplift of the Warner Range: Geological Society of America Bulletin, v. 118, p. 1196-1211.

Duffield, W.A., and McKee, E.H., 1986, Geochronology, structure, and basin-range tectonism of the Warner Range, northeastern California: Geological Society of America Bulletin, v. 97, p. 142-146.

Duffield, W.A., Weldin, R.D., and Davis, W.E., 1976, Mineral resources of the South Warner Wilderness, Modoc County, California: U. S. Geological Survey Bulletin, v. B1385, p. 31.

Egger, A.E., Colgan, J.P., and York, C., 2009, Provenance and palaeogeographic implications of Eocene-Oligocene sedimentary rocks in the northwestern Basin and Range: International Geology Review, v. 51, p. 900 - 919.

Hedel, C.W., 1984, Maps showing geomorphic and geologic evidence for late Quaternary displacement along the Surprise Valley and associated faults, Modoc County, California, Miscellaneous Field Studies Map: Reston, VA, U. S. Geological Survey.

Lerch, D.W., Klemperer, S.L., Glen, J.M.G., Ponce, D.A., Miller, E., and Colgan, J., 2007, Crustal structure of the northwestern Basin and Range Province and its transition to unextended volcanic plateaus: Geochemistry Geophysics Geosystems, v. 8, p. 1-21.

Personius, S.F., Crone, A.J., Machette, M.N., Mahan, S.A., and Lidke, D.J., 2009, Moderate rates of late Quaternary slip along the northwestern margin of the Basin and Range Province, Surprise Valley fault, northeastern Califor-nia: J. Geophys. Res., v. 114.

Mapping in the South Warner Wilderness done by Duffield et al, 1976

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0 20 4084 12 16 24 363228 56524844

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0 20 4084 12 16 24 363228 524844-4

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0 20 4084 12 16 24 363228 524844-4

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Ti

TcpTlb

Qal

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Tat

Tlb

Qf

Qc

Ti

Ti

Ti

Ti

Tsc

Qls

Qls

Tsu

Tdc

Tdc

Qal

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Qof

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Tmrv

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Qal

Qls

ThvTlw

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Qoa

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Qpd

Qpd

Tmv-u

Qp

Qe

Qc

Qe

Qe

Qp

Qal

Qal

Tcp

Tmb

Tmb

Qls

Qls

Qls

Qpl

Qpl

Qls

Qols

Qols

Qpl (?)

Qe

Qe

Qe

Qf

Qf

Qe

Qe

Ql

Qc

QeQp

Qal

Tlb

TmbQpb

Qpl

Tlb

Tmr

Tmr

Tlb

Tts

Tts

Qpl (?)

Ti

Qc

Qc

Qc

Qf

Qf

Tsc

Qal

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Tlb

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QplQoa

Tcp

Tlb

Tlb

Qof

Qal

Qof

QalQc

Tmr

Tlb

TlbTlb

Tmt

Tcp

Qc

7.3 ± 0.3 Ma

27.46 ± 0.61 Ma

27.50 ± 0.21 Ma

26.42 ± 0.05 Ma

26.6 ± 1.1 Ma

3.98 ± 0.06 Ma

14.57 ± 0.08 Ma

2.76 ± 0.2 Ma

14.5 ± 0.4 Ma

23.91 ± 0.13 Ma

15.44 ± 0.17 Ma

15.53 ± 0.11 Ma

25.4 ± 1 Ma

14.1 ± 0.4 Ma

14.1 ± 0.4 Ma

15.7 ± 0.5 Ma15.8 ± 0.5 Ma

33.9 ± 2.7 Ma

26.3 ± 1 Ma

17.3 ± 0.6 Ma

31.1 ± 1.3 Ma

3.84 ± 0.06 Ma

19.22 ± 0.27 Ma

28.8 ± 1.1 Ma

4.28 ± 0.16 Ma

4.36 ± 0.13 Ma

26.54 ± 0.08 Ma

30.02 ± 0.52 Ma

27.07 ± 0.22 Ma

26.26 ± 0.13 Ma

15.15 ± 0.55 Ma

40.8 ± 3 Ma

8.08 ± 0.09 Ma

5.95 ± 0.08 Ma

4.33 ± 0.08 Ma

27.17 ± 0.33 Ma

26.53 ± 0.06 Ma25.76 ± 0.06 Ma

26.82 ± 0.08 Ma

26.64 ± 0.08 Ma

26.04 ± 0.06 Ma

24.18 ± 0.34 Ma

120°0'0"W120°10'0"W120°20'0"W

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0 2 4 6 8 101km

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Vya

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Plush

Likely

Alturas

Madeline

Lakeview

FortBidwell

GooseLake

LakeAbert

EagleLake

CrumpLake

Clear LakeReservoir

Warner R

ange

Crustal refraction line

OREGONCALIFORNIA

NEVADAOREGON

Har

t M

ount

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War

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Hays C

anyon R

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119°0'0"W120°0'0"W121°0'0"W

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"N41

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41°0

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Seismicity(magnitude)

2.0 - 2.9

3.0 - 3.9

4.0 - 4.9

>5.0

Normal fault

Surprise Valley Fault B

lack Rock R

ange

SheldonPlateau

ModocPlateau

Granite R

ange

Calico

Mo

untains

Gerlach

15

Dike

Geochronology

Symbols

Strike and dip of bedding

Horizontal bedding

Volcanic vent

Normal fault

Contact

Normal fault, concealed

Map units

Qal

Qf

Qc

Qe

Qhs

Ql/Qp

Qls

Qoa

Qof

Qols

Qpb

Qpd

Qpl

Tlb

Tts

Tmr

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Tmba

Tmt

Tmb

Trt

Tmv-u

Tbm

Tcp

Ti

Thv

Tsc

Tlw

Tdc

Tscc

Tsbn

Tsu

Tmrv

Holocene sediments Oligocene volcanic rocks

Oligocene sedimentary rocks

Eocene rocks

Late Miocene volcanic rocks

Mid-Miocene volcanic rocks

Pleistocene sediments

Alluvium

Fan deposits

Bald Mountain basalt

Cedar Pass volcanic complex

Intrusive rocks of Cedar Pass complex

Hays Volcano

Soldier Creek volcanics*

Lost Woods Formation*

Deep Creek Formation*

Steamboat Formation, Cougar Cliffs member*

Steamboat Formation, Badger’s Nose member*

Oligocene sedimentary rocks, undifferentiated

McCulley Ranch Formation*

Low-K olivine tholeiitic basalts

Tuffs and tuffaceous sediments

Late Miocene rhyolites

Alturas tuff

Basalt and andesite flows

Tuff and reworked tuff

Basalt flows

Rhyolitic and andesitic ash flow tuffs

Early Miocene volcanic rocks

Mid-Miocene volcanic rocks, undifferentiated

Colluvium

Eolian deposits (sand dunes)

Hot spring deposits

Lake and playa deposits

Landslides

Older alluvium

Older fan deposits

Older landslide deposits

Pleistocene beach gravels of Lake Surprise

Pleistocene deltas of Lake Surprise

Pleistocene lake sediments of Lake Surprise

Strike and dip of fault plane70

Holocene fault scarp (Hedel, 1984)

this study

Carmichael et al., 2006

Duffield and McKee, 1986

Axelrod, 1966* names from Martz, 1968

Regional setting:The edge of extension

Along the northwestern margin of the Basin and Range province, slip on the Sur-prise Valley Fault has resulted in the uplift of the Warner Range. New geologic map-ping in the Warner Range and surrounding region documents a complex history of volcanism and extension from the Eocene to the present, recorded by volcanic rock units that display significant variability in their distribution, along-strike stratigraphic thickness, and their relationship to normal faults and pre-existing topography.

At the base of the range, a late Eocene to early Oligocene (34-31 Ma) volcaniclastic alluvial sandstone and conglomeratic sequence is exposed for about 25 km along strike, decreasing in thickness from 1500-200 m south to north. These rocks are overlain by a series of overlapping volcanic edifices that record Oligocene arc vol-canism from 28–24 Ma. In the southern part of the range, Oligocene volcanic rocks are unconformably overlain by Miocene (19–12 Ma, predominantly 16–14 Ma) tuffs and locally-sourced mafic lava flows. Mid-Miocene rocks were never present in the northern part of the range, however, where the Oligocene rocks are directly overlain by late Miocene (10–7 Ma) rhyolite flows.

The modern profile and elevation of the Warner Range thus includes a large com-ponent of “original” topography. Although high elevations (<3000 m) in the central Warner Range (Warren Peak) correspond to the greatest stratigraphic throw on the Surprise Valley Fault, the southern Warner Range (Eagle Peak) sits at a similar el-evation, despite significantly less throw on the fault there, due to substantial Mio-cene volcanic edifices in the footwall.

On the west side of the Warner Range, the ~11 Ma Alturas tuff and ~3-7 Ma basalt flows appear to have been deposited in pre-existing topography developed in part through motion along normal faults. These flat-lying units are also cut by faults, however, suggesting at least two episodes of faulting: one between 14 and 11 Ma and one after 3–4 Ma. Pliocene basalt flows are also present east of the Warner Range, where they dip 10-15° west and are cut by numerous normal faults. Despite the similarity of these basalt flows on either side of the range, new mapping indi-cates they never formed a continuous sheet and thus cannot be used to calculate the total offset and long-term slip rate along the Surprise Valley Fault.

Abstract

Geology of the Warner Range

Evolution of the margin

Velocity model along crustal refraction line shown above, from Lerch et al., 2007. Note thinning of crust from ~36 km to ~30 km across the profile. SV = Surprise Valley.

Regional map of the northwestern margin of the Basin and Range, including seis-micity from 1875 to 2008 (historical earthquakes from California Division of Mines and Geology; 1973 to present from USGS/NEIC). Crustal refraction line from Lerch et al., 2007.

References