![AComparativeEffectivenessAnalysisof Three Continuous ...sites.bu.edu/bionicpancreas/files/2014/07/DamianoCGM2013.pdfence (RD), defined as [(CGMG 2 PG)/ PG], and the absolute relative](https://static.fdocuments.us/doc/165x107/6038333a66f852398e236fb1/acomparativeeffectivenessanalysisof-three-continuous-sitesbuedubionicpancreasfiles201407.jpg)
Framework Geologic Map and Structure Sections along the ... · mspy fys cy cpp vpp fmp cmp vy fpp...
1
U.S. Department of the Interior U.S. Geological Survey Scientific Investigations Map 3395 Sheet 2 of 2 Pamphlet accompanies map Framework Geologic Map and Structure Sections along the Bartlett Springs Fault Zone and Adjacent Area from Round Valley to Wilbur Springs, Northern Coast Ranges, California By Robert J. McLaughlin 1 , Barry C. Moring 1 , Christopher S. Hitchcock 2 , and Zenon C. Valin 1 2018 1 U.S. Geological Survey; 2 InfraTerra, Inc. Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government This plate is offered as an online-only, digital publication. Users should be aware that, because of differences in rendering processes and pixel resolution, some slight distortion of scale may occur when viewing it on a computer screen or when printing it on an electronic plotter, even when it is viewed or printed at its intended publication scale Digital files available at https://doi.org/10.3133/sim3395 Suggested citation: McLaughlin, R.J., Moring, B.C., Hitchcock, C.S., and Valin, Z.N., 2018, Framework geologic map and structure sections along the Bartlett Springs Fault Zone and adjacent area from Round Valley to Wilbur Springs, northern Coast Ranges, California (ver 1.1, September 2018): U.S. Geological Survey Scientific Investigations Map 3395, pamphlet 60 p., 2 sheets, scale 1:100,000, https://doi.org/10.3133/sim3395. ISSN 2329-132X (online) https://doi.org/10.3133/sim3395 KJs Jgb KJom omv oms omd omg omc omb omun Joc Jov Jod Jog Josp fcm ss c v cgl ms b un spo vpo vsm dsm psm ssm fym by cgy cy gy lsy vy uny mspy fys cy cpp vpp fmp cmp vy fpp miy db vmg cmg cgmg smg af Qls Qal Qoa Qt Qty Qto Qtvo Qf Qfy Qfo Qfvo Qgd Qsn Qtrv Qv QTc Tm Te Tep Tcg Ku Kuls Kul Kl Klcg Klls Kssp LIST OF MAP UNITS See Description of Map Units (in pamphlet) for complete unit descriptions. Some unit exposures on the printed or plotted map are too small to distinguish the color for unit identification. These units are labeled where possible, and unlabeled units are attributed in the database. Note that many tiny units, primar- ily blocks, are covered by symbols. UNCONSOLIDATED DEPOSITS Artificial fill (Holocene) Landslide deposits (Holocene and Pleistocene) ALLUVIAL DEPOSITS Alluvial deposits (Holocene and Pleistocene) Older alluvial deposits (Holocene and Pleistocene) TERRACE DEPOSITS Alluvial terrace deposits (Holocene and Pleistocene) Younger alluvial terrace deposits and surfaces (Holocene?) Older alluvial terrace deposits and surfaces (Pleistocene) Very old alluvial terrace deposits and surfaces (Pleistocene) FAN DEPOSITS Alluvial fan deposits (Holocene and Pleistocene) Younger alluvial fan deposits and surfaces (Holocene?) Older alluvial fan deposits and surfaces (Pleistocene) Very old alluvial fan deposits and surfaces (Pleistocene) GLACIAL DEPOSITS Glacial deposits, present locally (Pleistocene) SPRING DEPOSITS Hydrothermal deposits (Pleistocene and younger) Travertine (Pleistocene and younger) VOLCANIC ROCKS Clear Lake Volcanic rocks (Pleistocene) FLUVIAL AND LACUSTRINE FILL Cache Formation (Pleistocene and upper Pliocene) MARINE OVERLAP DEPOSITS Sandstone and lignitic shale of the Covelo area (middle Miocene) Marine sandstone and shale (Eocene) Sandstone, shale, and conglomerate (Eocene and upper Paleo- cene) Conglomerate (Eocene and upper Paleocene) GREAT VALLEY COMPLEX Sandstone, siltstone, and mudstone (Upper Cretaceous, Cenomanian and younger) Limestone (Upper Cretaceous) Sandstone, siltstone, and mudstone with concretionary limestone and conglomerate (Upper and Lower Cretaceous, Ceno- manian to Hauterivian) ELDER CREEK TERRANE Siltstone, mudstone, minor sandstone, conglomerate, and sedimentary serpentinite (Lower Cretaceous, Albian to Hauterivian) Conglomerate (Lower Cretaceous, Albian to Hauterivian) Bioclastic limestone, (Lower Cretaceous, Hauterivian) Sedimentary serpentinite (Lower Cretaceous) Argillite, siltstone, and sandstone (Lower Cretaceous, upper Valanginian, to Upper Jurassic, Tithonian) Megabreccia (Upper Jurassic, Tithonian to Kimmeridgian) Ophiolitic mélange (Lower Cretaceous) Mafic volcanic rocks, including pillow basalt, diabase, and noncumulate gabbroic intrusive rocks Undivided marine clastic rocks, commonly argillitic (Lower Cretaceous and Upper Jurassic) Diabase, mapped locally Gabbro, mapped locally Radiolarian chert, mapped locally (Upper Jurassic, Kimme- ridgian) Blueschist, mapped locally Blocks of unknown lithology COAST RANGE OPHIOLITE Pelagic chert (Upper to Middle Jurassic, Tithonian to Bajocian) Basaltic pillowed flows and flow breccias (Middle Jurassic) Diabase dikes and sills (Middle Jurassic) Gabbro and ultramafic rocks (Middle Jurassic) Serpentinized ultramafic rocks (Middle Jurassic) FRANCISCAN COMPLEX CENTRAL BELT Central Belt Mélange terrane (lower Tertiary and Upper Cretaceous) Undivided mélange (lower Tertiary and Upper Cretaceous) Sandstone and argillite (in part, Upper Cretaceous, Ceno- manian or younger; middle Cretaceous, Aptian or younger; and possibly, Upper Jurassic, Tithonian or younger) Radiolarian chert (Upper Cretaceous to Middle Jurassic) Basaltic volcanic rocks (Jurassic) Conglomerate (Lower Cretaceous and (or) Upper Jurassic or younger) Diabase (Cretaceous or Jurassic?) Metasedimentary rocks (Lower Cretaceous? or younger) Blueschist blocks (Jurassic) Blocks of unknown lithology Pomo terrane (Upper Cretaceous to Upper Jurassic) Basaltic breccia, sandstone, and shale (Upper Cretaceous, Maastrichtean) Alkalic pillow basalt, pillow-breccias, and minor diabase and chert (Jurassic) Marin Headlands-Geysers terrane (Upper Cretaceous to Lower Jurassic) Sandstone and argillite (Upper Cretaceous, Cenomanian? or younger) Conglomerate (Upper Cretaceous, Cenomanian? or younger) Radiolarian chert (Upper Cretaceous, lower Cenomanian to Lower Jurassic, Pliensbachian) Basaltic volcanic rocks (Lower Jurassic) Snow Mountain volcanic terrane (Lower Cretaceous, Valanginian or younger?) Basaltic to rhyolitic volcanics and intrusive rocks Diabasic intrusive rocks, largely sill-like Porphyritic basaltic rocks Metasandstone and argillite EASTERN BELT Yolla Bolly terrane (Upper and Lower Cretaceous to Upper Jurassic, Tithonian) Mélange of the Yolla Bolly terrane (Upper Cretaceous) Blueschist Conglomerate Metachert (Early Cretaceous, Albian or Aptian, to Middle Jurassic, Aelenian) Gabbro Limey mudstone Metavolcanic rocks (Middle Jurassic, Aelenian or older) Metaserpentinite blocks or lenses Unidentified blocks Metasandstone and argillite, locally conglomeratic (Upper and Lower Cretaceous, Cenomanian to Aptian, to Late Jurassic, Tithonian) Metachert (Lower Cretaceous, Albian to Aptian, to Middle Jurassic, Aalenian) Metavolcanic rocks (Middle Jurassic, Aalenian or older) Mafic intrusive rocks (Early Cretaceous) Pickett Peak terrane (Lower Cretaceous, Aptian to Barremian) Undivided metasedimentary and metavolcanic rocks and metachert Metachert Basaltic metavolcanic rocks Mendocino Pass terrane (Lower Cretaceous, Valanginian) Foliated metasandstone, argillite, and minor undivided metachert and greenstone Metachert and greenstone blocks EXPLANATION OF MAP SYMBOLS Contact—Solid where location is accurate; long-dashed where approximate; short-dashed where inferred; dotted where concealed. Queried where identity or existence questionable Fault—Solid where location is accurate; long-dashed where approximate; short-dashed where inferred; dotted where concealed. Queried where identity or existence questionable Fault Lineament—Inferred from features on aerial photography. Dotted where projected beneath surficial deposits Tuff of Clearlake Volcanic rocks (Qv)—Mapped in Cache Formation (QTc) Active trace of Bartlet Springs Fault Zone (Lienkaemper, 2010)—Arrows show relative movement. In cross sections: circled minus, movement away from observer; circled plus, movement towards observer Strike and dip of beds Inclined Overturned Horizontal Vertical Strike and dip of metamorphic fabric in sheared or foliated rocks Inclined Vertical Location of block or lens too small to map in broken formation or mélange Higher-grade metamorphic rock Serpentinite Volcanic rock Sandstone Conglomerate Chert Block of unknown lithology Fossil Location—Map number corresponds to table 1 Hydrothermal bleaching (Quaternary)—Diffuse zone in sedimentary and metasedimentary rocks, characterized by quartz, carbonate, and clay mineral veins and veinlets. Associated with the Barttlet Springs Fault Zone in the vicinity of Neuman Springs Sinter or silica carbonate rocks Travertine • 40 40 30 58 • CENTRAL BELT Yolla Bolly Terrane FRANCISCAN COMPLEX Pickett Peak Terrane Mendocino Pass Terrane EASTERN BELT MARINE OVERLAP DEPOSITS FLUVIAL AND LACUSTRINE FILL Pomo Terrane Central Belt Mélange Terrane Marin Headlands- Geysers Terrane TERTIARY COAST RANGE OPHIOLITE GREAT VALLEY COMPLEX Miocene Eocene Eocene and Paleocene Pleistocene and Pliocene MESOZOIC CENOZOIC Early Jurassic ELDER CREEK TERRANE Rice Valley CORRELATION OF MAP UNITS UNCONSOLIDATED DEPOSITS CRETACEOUS Early Cretaceous JURASSIC Holocene VOLCANIC ROCKS [See Description of Map Units (in pamphlet) for precise unit ages] Late Cretaceous Pleistocene TERRACE DEPOSITS ALLUVIAL DEPOSITS FAN DEPOSITS GLACIAL DEPOSITS SPRING DEPOSITS Late Jurassic Middle Jurassic QUATERNARY QUATERNARY AND TERTIARY Snow Mountain Volcanic Terrane Qls Qfy Qfo Qfvo Qal Qty Qto Qtvo miy Qt Qoa fys fys fmp Qsn ? ? fpp Qtrv ? ? Qf af Qgd Qv Tm Te Tep QTc Tcg fym by cgy cy gy lsy mspy uny vy ? ? ? ? ? ? Kl Klcg Joc Jov Jod Jog Josp ? cmp ? ? ? ? ? ? ? ? ? ? ? ? ? Kssp Klls KJom omb omv omun omg ? ? ? ? ? ? oms omd omc Jgb KJs ss ? c b un cgl db ms v ? fcm spo vpo cmg smg vmg ? ? dsm psm ssm ssm vsm cpp vpp Kuls cy vy Kul Ku cgmg Little Indian Valley Qfo Qtvo Qal Qal Qal fys fcm fcm fcm fcm fym fym fys fys fys fym Qal Tep KJom KJom Kul fpp Kul Qal 4,000 2,000 SEA LEVEL SEA LEVEL 2,000 4,000 6,000 8,000 10,000 12,000 FEET E 4,000 2,000 2,000 4,000 6,000 8,000 10,000 12,000 FEET E' NORTHERN BARTLETT SPRINGS FAULT ZONE NORTHWEST SOUTHEAST NORTHEAST NORTHEAST NORTHEAST SOUTHWEST SOUTHWEST SOUTHWEST SOUTHWEST NORTHEAST SECTION B’–B” SECTION C–C' fcm fcm fcm KJom? fym fys fys Qfy Qal Qoa Josp KJom? Qt fys? fpp fcm fcm fys v Qls Qty Qt Qal Qls Qls c v FEET A NORTHERN BARTLETT SPRINGS FAULT ZONE 4,000 6,000 2,000 SEA LEVEL 2,000 4,000 6,000 8,000 10,000 12,000 4,000 6,000 2,000 SEA LEVEL 2,000 4,000 6,000 8,000 10,000 12,000 FEET A' + _ _ 2,000 4,000 6,000 FEET FEET SEA LEVEL 4,000 2,000 6,000 8,000 SEA LEVEL 2,000 4,000 6,000 6,000 4,000 2,000 B B'' 8,000 10,000 10,000 _ + fys fys fym fym fym fys fys Qty fpp Qal Josp Qfo Tep Qtvo vsm vsm Qgd Qgd Qls vsm Qls Qls fys fys fys Josp Josp Josp KJs KJs? Jov Qal Qfo Qty Qal Qt vsm Qfo Kul KJom B' fcm Qfo Qal Qfo Qfvo Qfy vpo spo Kl Kl KJom Qls Josp fcm? c b fcm Josp Josp fcm fcm Ku Ku Tep NORTHERN BARTLETT SPRINGS FAULT ZONE Snow Mountain BEND IN SECTION SECTION E–E' SECTION E–E' cmg cmg vmg 2,000 SEA LEVEL 4,000 6,000 2,000 SEA LEVEL 4,000 6,000 4,000 6,000 2,000 8,000 10,000 4,000 6,000 2,000 8,000 10,000 14,000 12,000 FEET C FEET C' 14,000 12,000 spo Qal Kl Ku Qls Josp Qal Qty Qal Qfy fys fym fys fym fys fpp KJom fys fym fys vy vy vy Qal fys fys vy cy Josp Jov Qfo Qty Qfo Qfo Qto Qt Qty Qal Qty Josp KJs Qal Qfy Qt Qal v Lower Blue Lake fcm fcm fcm fcm Qal Josp vpo ? ? ? ? ? ? ? NORTHERN BARTLETT SPRINGS FAULT ZONE PACIFIC RIDGE ANTIFORM MIDDLE MOUNTAIN SYNFORM _ + smg Qal Qal Qal Qt? vmg vmg smg smg fcm fcm fcm Qfy Qal Qal Qal Kl? Qoa fcm fcm fcm fcm v Qls vy fys Qal fym fys fys Qls Qls fys fys fys fys Qls Qls fys fys vy miy Josp Josp Josp KJs Jov KJs KJs vy fys fym fys fym fym Josp Josp Josp KJom KJom Qls Qls Qls fcm Josp ss Josp Josp 2,000 SEA LEVEL 4,000 6,000 4,000 2,000 8,000 10,000 12,000 6,000 4,000 2,000 8,000 10,000 12,000 6,000 2,000 SEA LEVEL 4,000 6,000 FEET D FEET D' NORTHERN BARTLETT SPRINGS FAULT ZONE MIDDLE MOUNTAIN SYNFORM PACIFIC RIDGE ANTIFORM smg _ + + LU- DOS RIOS JAMISON RIDGE PLASKETT RIDGE THATCHER RIDGE PLASKETT MEADOWS 122°30' 122°45' 123° 123°15' 39°45' 39°30' 39°15' 39° Figure 2. Map showing quadrangles in map area and sources of geologic data. SALT CANYON WILBUR SPRINGS BENMORE CANYON LODOGA LEESVILLE GILMORE PEAK HOUGH SPRINGS POTATO HILL FOUTS SPRINGS BARTLETT MOUNTAIN BARTLETT SPRINGS STONYFORD SAINT JOHN MOUNTAIN CROCKETT PEAK FELKNER HILL KNEECAP RIDGE HULL MOUNTAIN LAKE PILLSBURY SANHEDRIN MOUNTAIN BRUSHY MOUNTAIN WILLIS RIDGE FOSTER MOUNTAIN VAN ARSDALE RESERVOIR POTTER VALLEY REDWOOD VALLEY ELK MOUNTAIN COW MOUNTAIN UKIAH UPPER LAKE LAKEPORT HIGHLAND SPRINGS KELSEYVILLE CLEARLAKE HIGHLANDS LUCERNE CLEARLAKE OAKS LOWER LAKE WILSON VALLEY GLASCOCK MOUNTAIN 5 5 1 1 6, 15 6, 15 5, 18 5, 27 2, 16, 18 21 12, 13 12, 18 8 1 1 2 18 25 12, 13 1 8 8, 16 10 14, 18 7 9 2 14, 16 4, 16, 18 18 3, 16 18 7, 17, 18 4, 16, 18 18 19, 20 20 11, 7, 22 11 11 11 3, 24 3 11 11 4, 16, 18 23 26 AREA OF MAP EXPLANATION 1 Ohlin and others, 2010 2 Berkland, 1978; CDWR, 1966, 1968, and 1969 3 McLaughlin, R.J., unpublished mapping, 1980–1981 4 McLaughlin and others, 1990 5 Jayko and others, 1989; Clark, 1940 6 Ohlin H.N., 1989, unpublished mapping, 1985 7 Hitchcock, C.S., unpublished mapping, 2012–2013; McLaughlin, R.J., and Moring, B.C., aerial reconnaissance using Google Earth imagery, 2014 8 Etter, 1979; U.S. Forest Service, unpublished mapping 9 Stanford, 1991 10 Berkland, 1973 11 Hearn and others, 1995; Sims and Rymer, 1976; Rymer, 1981 12 Brown and others, 1981; MacPherson, 1983 13 Brown, 1964 14 Suppe and Foland, 1978; Etter, 1979; U.S. Forest Service, unpublished mapping 15 Blake and others, 1992 16 McLaughlin, R.J. and Moring B.C., mapping 2012–2013 17 Ohlin, H.N., unpublished field work, 1980–1981 18 McLaughlin and Moring, aerial reconnaissance using Google Earth imagery, 2012–2014 19 Ohlin, H.N., unpublished mapping, 1979–1981 20 McLaughlin, 1978; Ohlin H.N., and McLaughlin, R.J., unpublished mapping, 1978–1981 21 Lehman, 1974 22 McLaughlin, R.J., and Moring B.C., minor revisions 23 Lawton, 1956 24 Swe and Dickinson, 1970 25 Shervais and others, 2005a, b 26 Lienkaemper, 2010 27 Clark, 1940 1 4 4 6 6 3 2 5 39˚00’ 122˚30’ 122˚0’ 39˚30’ Figure 5. Map showing major structural features in map area and locations of structure and seismicity cross sections. NORTHERN B A R T L E T T S P R I N G S ( Hunt i n g) t5 t4 t3 t1 t2-6 A A' B B' B'' C' C E' E D D' N O R T H E R N BA R T L ETT S PR I N G S Logan Springs Kuikui Pomo B a d R i d g e Bear Valley Resort W ilso n Fa ult Kennedy F a u lt S ulphu r B a n k Konocti B a y B o r a x L a k e C o l l a yo m i Wr i ght Way Big Valley S c o t t s Val l e y C lo v e r V a ll e y S anh e d rin M ountain Little Indian Valley S O U T H E R N B A R T L E T T S P RIN G S Cr oss S p r i n g s EXPLANATION MAJOR FAULTS Active segments of the Bartlett Springs Fault Zone—From aerially interpreted geomorphic features (Lienkaemper, 2010) Other faults, undifferentiated—Includes faults mapped in field and faults inferred from aerial lineaments. Includes faults discussed in this report, though not all named faults on figure are discussed CROSS SECTION Line of structure section Line of seismicity cross section—See figure 5, 12 (Sheet 2) and figure 11 (pamphlet) for additional information MAJOR FOLDS Synforms 1 Bartlett Springs Synform 4 Middle Mountain Synform 5 Unnamed synform Antiforms 2 Pacific Ridge Antiform 3 Wilbur Springs Antiform 6 Bartlett Mountain Antiform EARTHQUAKE EPICENTERS Magnitude 5.2 earthquake, August 10, 2016 Aftershock sequence, August 10, 2016–September 15, 2016 Epicenters 1984–2014 A A' t1 MFZ ~5 Ma MFZ PRESENT Exhumed rocks of the Eastern Belt Partially exhumed rocks of the Central Belt Coastal Belt Coastal Belt Coastal Belt Klamath Block Rice Valley Rice Valley Rice Valley Round Valley Round Valley Round Valley Middle Mountain Middle Mountain Middle Mountain Lower Lake Lower Lake Lower Lake Great Valley Complex and Coast Range ophiolite Neogene Eel River forearc basin Neogene Eel River forearc basin APPROXIMATE AREA OF FIGURE 7 A PALEOCENE–EOCENE MARGIN B ~MIDDLE MIOCENE MARGIN C PRESENT MARGIN EXPLANATION Estuarine deposits of Round Valley area associated with former Neogene (Eel River) forearc basin (Middle Miocene) Sandstone and shale, shallow to deep marine, associated with former Mesozoic–Paleogene Great Valley forearc basin (Eocene and Paleocene) Sandstone shale and conglomerate, marine, and ophiolitic basement and mélange of former Great Valley forearc basin (Upper Cretaceous–Middle Jurassic) Igneous and metasedimentary basement rocks of the Klamath Mountains (Jurassic and older) FRANCISCAN COMPLEX Central Belt (Upper Cretaceaous and older) Eastern Belt (Upper Cretaceous–Upper Jurassic) Coastal Belt (Tertiary and younger) MAJOR FOLD AXES Antiform Synform Figure 6. Geologic maps showing progressive deformation of the northern California margin during transition from subduction to right-lateral strike slip. The Northern Bartlett Springs Fault is viewed as having developed since the Miocene from deformation focused along the Bartlett Springs Synform, one of several northwest-trending folds that preceded northward encroachment of the Mendocino Triple Junction and the San Andreas Fault. The folding formed in response to northeast-southwest transpression across the subduction margin. Dominated by east-west convergence, following exhumation of Eastern and Central Belts of Franciscan Complex from depth of 20–30 km. Yellow circled areas delineate Paleogene deposition near former western margin of the Jurassic–early Cenozoic Great Valley fore-arc basin. Light-pink transparent overlay delineates former southeastern part of early Miocene and younger (Eel River) fore-arc basin based on erosional and tectonic remnants of the former Neogene fore-arc basin that includes yellow-circled Miocene remnant at Round Valley. The Neogene fore arc may have extended much farther to the southeast (Nilsen and Clarke, 1989) and deposition was on exhumed Franciscan and Paleogene rocks of older Great Valley fore-arc basin. Orientations of synforms and antiforms inboard of the subduction margin indicate major northeast-southwest transpression that accompanied or postdated Neogene fore-arc deformation. Slip along the Northern Bartlett Springs Fault is inferred to have right-laterally dismembered the Bartlett Springs Synform since middle to late Miocene formation, uplift, and erosion of the Neogene fore-arc basin. See figure 7 for details of slip restoration of the Bartlett Springs Synform. Showing major strike-slip faults inboard of the San Andreas Fault, the Mendocino Triple Junction, the present subduction margin, and the remaining offshore and uplifted and eroded onshore Neogene (Eel River) fore-arc basin. The present Bartlett Springs Fault Zone extends beyond the Mendocino Triple Junction into the modern subduction margin and dismembers the Bartlett Springs Synform. Reconstruction of this dismemberment can be used to approximate total dextral displacement and approximate a long-term slip rate for the Northern Bartlett Springs Fault. MFZ, Mendocino Fault Zone. 0 0 5 10 15 MILES 10 20 30 KILOMETERS Round Valley Miocene Lower Great Valley Complex Paleogene Circled areas include Paleogene marine strata deposited on Cretaceous and older Great Valley Complex or Coast Range Ophiolite, representing the former westward extent of the Jurassic-Eocene Great Valley forearc basin. Round Valley area also includes remnants of Miocene estuarine strata indicating the former southeastern extent of a Neogene forearc basin (Eel River basin) that formed in the Miocene further to the west (Nilsen and Clarke, 1989). STRATIGRAPHIC AND STRUCTURAL RELATIONS CONSTRAINING RECONSTRUCTION OF NORTHERN BARTLETT SPRINGS FAULT ZONE DISPLACEMENT P AL EOCE NE – E O C E N E C O N V E R G E N T M A R G I N M I O CENE –PAL EO C E N E C O N V E R G E N T M A R G I N C O A S T A L BE L T T H R U S T S A N A N D R E A S F A U L T S A N AN D R E A S F A U L T P R E S E N T C O N V E R G E N T M A R GI N COASTAL BELT THRUST BARTLE TT SPRI NGS FAULT Ma acama F au lt 5 6 3 2 4 1 Figure 7. Schematic reconstruction of Bartlett Springs Synform configuration prior to its dismemberment along the Northern Bartlett Springs Fault Zone (fig. 6 B,C). Also shown are other subparallel folds northeast and southwest of the Bartlett Springs Synform discussed in this report. The restoration suggests a total cumulative oblique dextral slip of approximately 38–47 km for the Northern Bartlett Springs Fault Zone since the middle to late Miocene, based on linking remnants of Paleogene strata deposited along the uplifted and eroded former west margin of the Paleogene and older Great Valley fore arc. Slip could have begun earlier than the Miocene, however, and total displacement could be >50 km. See discussions in pamphlet on Wilbur Springs Dextral Hook and Northern Bartlett Springs Fault. EXPLANATION Nonmarine basin deposits, undifferentiated (Quaternary) Volcanics and deposits of Clear Lake area (Holocene–Pliocene) Estuarine deposits of Round Valley area (Middle Miocene) Sandstone and shale, shallow to deep marine (Eocene and Paleocene) Sandstone and shale, moderately to deep marine, turbiditic (Upper Cretaceous–Upper Jurassic) Ultramafic and mafic rocks of Coast Range ophiolite and ophiolitic mélange (Lower Cretaceous and Upper–Middle Jurassic) FRANCISCAN COMPLEX Central Belt (Upper Cretaceous and older) Mélange Snow Mountain volcanic terrane Eastern Belt (Upper Cretaceous–Upper Jurassic) Yolla Bolly terrane (Upper Cretaceous–Upper Jurassic) Metasandstone and slaty argillite Mélange Pickett Peak terrane (Lower Cretaceous–Upper Jurassic) MAJOR FOLDS Synform Restored Bartlett Springs Synform Middle Mountain Synform Unnamed synform northeast of Rice Valley Antiform Pacific Ridge Antiform Wilbur Springs Antiform Bartlett Mountain Antiform OTHER SYMBOLS Faults Points used to illustrate range in minimum strike–slip displacement for restoration of Bartlett Springs synform configuration 6 6 1 1 1 3 3 2 5 4 4 Clear Lake ~47 Km ~38 Km Approximate range in the minimum amount of slip necessary to restore hypothetical Bartlett Springs synform configuration Potter Valley Little Indian Valley Reservoir Eden Valley Lake Pillsbury Lake Pillsbury Round Valley ? SNOW MOUNTAIN VOLCANIC TERRANE Middle Mountain Lower Lake Rice Valley Round Valley FUTURE NORTHERN BARTLETT SPRINGS FAUL T 0 0 5 10 15 MILES 10 20 30 KILOMETERS Round Valley Miocene Lower Great Valley Complex Paleogene Circled areas include Paleogene marine strata deposited on Cretaceous and older Great Valley Complex or Coast Range Ophiolite, representing the former westward extent of the Jurassic-Eocene Great Valley forearc basin. Round Valley area also includes remnants of Miocene estuarine strata indicating the former southeastern extent of a Neogene forearc basin (Eel River basin) that formed in the Miocene farther to the west (Nilsen and Clarke, 1989). STRATIGRAPHIC AND STRUCTURAL RELATIONS CONSTRAINING RECONSTRUCTION OF NORTHERN BARTLETT SPRINGS FAULT ZONE DISPLACEMENT A B 31-90° Figure 8. Map showing Wilbur Springs Dextral Hook in context of regional structure and long-term transpressional deformation along the Northern Bartlett Springs Fault Zone. A, Partial map of California, showing major fault blocks associated with Miocene and younger development of the San Andreas Fault, northwestward translation of Salinian block, clockwise rotation of Western Transverse Ranges block (Colgan and others, 2012), and Upper Cretaceous–Neogene clockwise rotation of southern Sierra Nevada /Tehachapi block (Chapman and others, 2010). White box outlines Wilbur Springs Dextral Hook. B, An expanded view of Wilbur Springs Dextral Hook derived from figures 6 and 7, showing reconstructed Bartlett Springs Synform and other folds of the dextral hook. Orientations of folds suggest maximum compression was ~N. 41° E. to S. 41° W., ±16°. Geometry and approximate timing of Wilbur Springs Dextral Hook formation is similar to larger-scale dextral hook formed by northward translation of the Salinian block since the early to middle Miocene. Upper Cretaceous–Paleogene rotations in southern Sierra Nevada-Tehachapi block, east-vergent crustal wedging, and unroofing of the Franciscan Complex accompanied shallow subduction of overthickened Farallon Plate and was followed by northward translation of the Salinian block during the Miocene (Chapman and others, 2010, 2012; Saleeby, 2003; Ernst and McLaughlin, 2012). See text for further discussion. Fault abbreviations: CASSZ, Cascadia Subduction Zone; GARFZ, Garlock Fault Zone; HAY-CAFZ, Hayward-Calaveras Fault Zone; MAAFZ, Maacama Fault Zone; MFZ, Mendocino Fault Zone; NBSFZ, Northern Bartlett Springs Fault Zone; NSAFZ, Northern San Andreas Fault Zone; RC-HLDFZ, Rodgers Creek-Healdsburg Fault Zone; SAFZ, San Andreas Fault Zone; SG-HFZ, San Gregorio-Hosgri Fault Zone; WW-KCFZ, White Wolf-Kern Canyon Fault Zone. 5 Ma 10 Ma 15 Ma Western Transverse Ranges block (present) Wilber Springs Dextral Hook SAFZ NSAFZ NSAFZ SAFZ SG-HFZ GARFZ WW-KCFZ Mojave block Southern Sierra Nevada/Tehachapi block Northern Sierra Nevada block NBSFZ NBSFZ MAAFZ MFZ CASSZ HAY-CAFZ RC-HLDFZ Salinian block Coastal Belt Salinian block San Francisco Eureka Bakersfield Monterey San Gabriel Mountains block Santa Rosa Klamath block Round Valley FUTURE NBSFZ FUTURE NBSFZ Reconstructed Bartlett Springs synform 0 0 25 50 75 MILES 50 100 150 KILOMETERS 0 0 5 10 15 MILES 10 20 30 KILOMETERS EXPLANATION Nonmarine basin deposits (Quaternary) Volcanics and deposits of Clear Lake area (Holocene–Pliocene) Eel River forarc basin (Neogene) Crystalline basement rock Western Transverse Ranges block Central Belt (Upper Cretaceaous and older) Eastern Belt (Upper Cretaceous–Upper Jurassic) Coastal Belt (Tertiary and younger) Coast Range ophiolite and ophiolitic mélange (Lower Cretaceous and Upper–Middle Jurassic) SYMBOLS Upper Cretaceous—Neogene clockwise rotation in southern Sierra Nevada Batholith and Tehachapi Mountains block (Chapman and others, 2010) Approximate location of buried tip of Franciscan tectonic wedge—Barbs on roof thrust side of wedge Fault—Arrows show relative movement Thrust fault Vectors of maximum compression—From orientation of fold axes MAJOR FOLD AXES Antiform Synform 31-90° PACIFIC RIDGE ANTIFORM PACIFIC RIDGE ANTIFORM 8/10/16 M 5.1 main shock 8/10/16 M 5.1 main shock 8/10/16 M 5.1 main shock 8/10/16 M 5.1 main shock 8/10/16 M 5.1 main shock BARTLETT SPRINGS FAULT ZONE BARTLETT SPRINGS FAULT ZONE BARTLETT SPRINGS FAULT ZONE BARTLETT SPRINGS FAULT ZONE Snow Mountain + + + + + + 0 -5 -10 -15 -20 t4 t2-6 Depth (km) 0 -5 -10 -15 -20 Depth (km) 0 -5 -10 -15 -20 Depth (km) Distance (km) Distance (km) Distance (km) Distance (km) 0 -5 -10 -15 -20 Depth (km) 0 -5 -10 -15 -20 Depth (km) t4 t3 t2-6 t1 t5 t1 B' Part of structure section B–B’–B“ Part of structure section C–C’ Structure section E–E’ t3 Figure 12. Seismicity cross sections showing hypocentral depth distribution of earthquakes along sections t1, t2-6, t3, t4, and t5 (see fig. 5 for locations). Hypocenters are projected into seismicity cross sections along lines perpendicular to the sections from ~5 km north and south of the section lines. Depths of the 8/10/16 main shock and its aftershock sequence are, respectively, the large pink and small orange triangles. In t1, t2-6, t3, and t4, post-1984 hypocenters are plotted as small green dots. In section t5, red dots are hypocenters projected into the section from southwest of the plane of the cross section; green dots are hypocenters projected into the section from northeast of the cross-section plane. Intersection of the Northern Bartlett Springs Fault with plane of t5 is approximated from intersection of the fault’s projection in t2-6, t3, and t4 with plane of t5 (magenta hexagon symbol). In seismicity cross sections t1, t3, and t5, we superpose parts of structure sections B–B'–B", C–C', and E–E', respectively, that correspond with the seismicity cross sections. See the structure sections for explanation of lithologic units. Note that the axis of a major antiform (Pacific Ridge Antiform) in Franciscan rocks northeast of the Northern Bartlett Springs Fault Zone forms prominent high topography in the hanging-wall block of the Northern Bartlett Springs Fault (sections t3 and t5). EXPLANATION EARTHQUAKE HYPOCENTERS 8/10/16 M 5.1 main shock 8/10/16 through 9/16/16 aftershock sequence Microseismicity 1984–2011 Fault block motion toward observer Fault block motion away from observer Bartlett Springs Fault Zone—Arrows show relative strike-slip motion across fault CROSS SECTION T5 (E–E‘) ONLY Intersections of Northern Bartlett Springs Fault crossing northeast–southwest cross sections t1 (B–B‘–B‘‘), t2-6, t3 (C–C‘), and t4, with the plane of northwest–southwest section t5 (E–E‘) Hypocenters located behind (northeast) of plane of E–E‘ Hypocenters located in front (southwest) of plane of E–E‘ BEND IN SECTION SECTION E–E’ SECTION B–B’–B“ SECTION C–C’ SECTION E–E’ SECTION t5 SECTION E–E’ Distance (km)
Transcript of Framework Geologic Map and Structure Sections along the ... · mspy fys cy cpp vpp fmp cmp vy fpp...
U.S. Department of the InteriorU.S. Geological Survey
Scientific Investigations Map 3395Sheet 2 of 2
Pamphlet accompanies map
Framework Geologic Map and Structure Sections along the Bartlett Springs Fault Zoneand Adjacent Area from Round Valley to Wilbur Springs, Northern Coast Ranges, California
By Robert J. McLaughlin1, Barry C. Moring1, Christopher S. Hitchcock2, and Zenon C. Valin1
20181U.S. Geological Survey;2InfraTerra, Inc.
Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government
This plate is offered as an online-only, digital publication. Users should be aware that, because of differences in rendering processes and pixel resolution, some slight distortion of scale may occur when viewing it on a computer screen or when printing it on an electronic plotter, even when it is viewed or printed at its intended publication scale
Digital files available at https://doi.org/10.3133/sim3395
Suggested citation: McLaughlin, R.J., Moring, B.C., Hitchcock, C.S., and Valin, Z.N., 2018, Framework geologic map and structure sections along the Bartlett Springs Fault Zone and adjacent area from Round Valley to Wilbur Springs, northern Coast Ranges, California (ver 1.1, September 2018): U.S. Geological Survey Scientific Investigations Map 3395, pamphlet 60 p., 2 sheets, scale 1:100,000, https://doi.org/10.3133/sim3395.
ISSN 2329-132X (online)https://doi.org/10.3133/sim3395
KJs
Jgb
KJom
omv
oms
omd
omg
omc
omb
omun
Joc
Jov
Jod
Jog
Josp
fcm
ss
c
v
cgl
ms
b
un
spo
vpo
vsm
dsm
psm
ssm
fym
by
cgy
cy
gy
lsy
vy
uny
mspy
fys
cy
cpp
vpp
fmp
cmp
vy
fpp
miy
db
vmg
cmg
cgmg
smg
af
Qls
Qal
Qoa
Qt
Qty
Qto
Qtvo
Qf
Qfy
Qfo
Qfvo
Qgd
Qsn
Qtrv
Qv
QTc
Tm
Te
Tep
Tcg
Ku
Kuls
Kul
Kl
Klcg
Klls
Kssp
LIST OF MAP UNITS
See Description of Map Units (in pamphlet) for complete unit descriptions. Some unit exposures on the printed or plotted map are too small to distinguish the color for unit identification. These units are labeled where possible, and unlabeled units are attributed in the database. Note that many tiny units, primar-ily blocks, are covered by symbols.
UNCONSOLIDATED DEPOSITSArtificial fill (Holocene)
Landslide deposits (Holocene and Pleistocene)
ALLUVIAL DEPOSITSAlluvial deposits (Holocene and Pleistocene)
Older alluvial deposits (Holocene and Pleistocene)
TERRACE DEPOSITSAlluvial terrace deposits (Holocene and Pleistocene)
Younger alluvial terrace deposits and surfaces (Holocene?)
Older alluvial terrace deposits and surfaces (Pleistocene)
Very old alluvial terrace deposits and surfaces (Pleistocene)
FAN DEPOSITSAlluvial fan deposits (Holocene and Pleistocene)
Younger alluvial fan deposits and surfaces (Holocene?)
Older alluvial fan deposits and surfaces (Pleistocene)
Very old alluvial fan deposits and surfaces (Pleistocene)
GLACIAL DEPOSITSGlacial deposits, present locally (Pleistocene)
SPRING DEPOSITSHydrothermal deposits (Pleistocene and younger)
Travertine (Pleistocene and younger)
VOLCANIC ROCKSClear Lake Volcanic rocks (Pleistocene)
FLUVIAL AND LACUSTRINE FILLCache Formation (Pleistocene and upper Pliocene)
MARINE OVERLAP DEPOSITSSandstone and lignitic shale of the Covelo area (middle Miocene)
Marine sandstone and shale (Eocene)
Sandstone, shale, and conglomerate (Eocene and upper Paleo-cene)
Conglomerate (Eocene and upper Paleocene)
GREAT VALLEY COMPLEX Sandstone, siltstone, and mudstone (Upper Cretaceous,
Cenomanian and younger) Limestone (Upper Cretaceous)
Sandstone, siltstone, and mudstone with concretionary limestone and conglomerate (Upper and Lower Cretaceous, Ceno-manian to Hauterivian)
ELDER CREEK TERRANESiltstone, mudstone, minor sandstone, conglomerate, and
sedimentary serpentinite (Lower Cretaceous, Albian to Hauterivian)
Conglomerate (Lower Cretaceous, Albian to Hauterivian)
Bioclastic limestone, (Lower Cretaceous, Hauterivian)
Sedimentary serpentinite (Lower Cretaceous)
Argillite, siltstone, and sandstone (Lower Cretaceous, upper Valanginian, to Upper Jurassic, Tithonian)
Megabreccia (Upper Jurassic, Tithonian to Kimmeridgian)
Ophiolitic mélange (Lower Cretaceous)
Mafic volcanic rocks, including pillow basalt, diabase, and noncumulate gabbroic intrusive rocks
Undivided marine clastic rocks, commonly argillitic (Lower Cretaceous and Upper Jurassic)
Diabase, mapped locally
Gabbro, mapped locally
Radiolarian chert, mapped locally (Upper Jurassic, Kimme-ridgian)
Blueschist, mapped locally
Blocks of unknown lithology
COAST RANGE OPHIOLITEPelagic chert (Upper to Middle Jurassic, Tithonian to Bajocian)
Basaltic pillowed flows and flow breccias (Middle Jurassic)
Diabase dikes and sills (Middle Jurassic)
Gabbro and ultramafic rocks (Middle Jurassic)
Serpentinized ultramafic rocks (Middle Jurassic)
FRANCISCAN COMPLEX
CENTRAL BELTCentral Belt Mélange terrane (lower Tertiary and Upper
Cretaceous)Undivided mélange (lower Tertiary and Upper Cretaceous)
Sandstone and argillite (in part, Upper Cretaceous, Ceno-manian or younger; middle Cretaceous, Aptian or younger; and possibly, Upper Jurassic, Tithonian or younger)Radiolarian chert (Upper Cretaceous to Middle Jurassic)
Basaltic volcanic rocks (Jurassic)
Conglomerate (Lower Cretaceous and (or) Upper Jurassic or younger)Diabase (Cretaceous or Jurassic?)
Metasedimentary rocks (Lower Cretaceous? or younger)
Blueschist blocks (Jurassic)
Blocks of unknown lithology
Pomo terrane (Upper Cretaceous to Upper Jurassic)Basaltic breccia, sandstone, and shale (Upper Cretaceous, Maastrichtean)Alkalic pillow basalt, pillow-breccias, and minor diabase and chert (Jurassic)
Marin Headlands-Geysers terrane (Upper Cretaceous to Lower Jurassic)Sandstone and argillite (Upper Cretaceous, Cenomanian? or younger)Conglomerate (Upper Cretaceous, Cenomanian? or younger)Radiolarian chert (Upper Cretaceous, lower Cenomanian to Lower Jurassic, Pliensbachian)Basaltic volcanic rocks (Lower Jurassic)
Snow Mountain volcanic terrane (Lower Cretaceous, Valanginian or younger?)Basaltic to rhyolitic volcanics and intrusive rocks
Diabasic intrusive rocks, largely sill-like
Porphyritic basaltic rocks
Metasandstone and argillite
EASTERN BELTYolla Bolly terrane (Upper and Lower Cretaceous to Upper
Jurassic, Tithonian)Mélange of the Yolla Bolly terrane (Upper Cretaceous)
Blueschist
Conglomerate
Metachert (Early Cretaceous, Albian or Aptian, to Middle Jurassic, Aelenian)Gabbro
Limey mudstone
Metavolcanic rocks (Middle Jurassic, Aelenian or older)
Metaserpentinite blocks or lenses
Unidentified blocks
Metasandstone and argillite, locally conglomeratic (Upper and Lower Cretaceous, Cenomanian to Aptian, to Late Jurassic, Tithonian)
Metachert (Lower Cretaceous, Albian to Aptian, to Middle Jurassic, Aalenian)
Metavolcanic rocks (Middle Jurassic, Aalenian or older)
Mafic intrusive rocks (Early Cretaceous)
Pickett Peak terrane (Lower Cretaceous, Aptian to Barremian)
Undivided metasedimentary and metavolcanic rocks and metachert
Metachert
Basaltic metavolcanic rocks
Mendocino Pass terrane (Lower Cretaceous, Valanginian)
Foliated metasandstone, argillite, and minor undivided metachert and greenstone
Metachert and greenstone blocks
EXPLANATION OF MAP SYMBOLSContact—Solid where location is accurate; long-dashed where
approximate; short-dashed where inferred; dotted where concealed. Queried where identity or existence questionable
Fault—Solid where location is accurate; long-dashed where approximate; short-dashed where inferred; dotted where concealed. Queried where identity or existence questionable
Fault Lineament—Inferred from features on aerial photography. Dotted where projected beneath surficial deposits
Tuff of Clearlake Volcanic rocks (Qv)—Mapped in Cache Formation (QTc)
Active trace of Bartlet Springs Fault Zone (Lienkaemper, 2010)—Arrows show relative movement. In cross sections: circled minus, movement away from observer; circled plus, movement towards observer
Strike and dip of bedsInclined
Overturned
Horizontal
Vertical
Strike and dip of metamorphic fabric in sheared or foliated rocksInclined
Vertical
Location of block or lens too small to map in broken formation or mélange
Higher-grade metamorphic rock
Serpentinite
Volcanic rock
Sandstone
Conglomerate
Chert
Block of unknown lithology
Fossil Location—Map number corresponds to table 1
Hydrothermal bleaching (Quaternary)—Diffuse zone in sedimentary and metasedimentary rocks, characterized by quartz, carbonate, and clay mineral veins and veinlets. Associated with the Barttlet Springs Fault Zone in the vicinity of Neuman Springs
Sinter or silica carbonate rocks
Travertine•
40
40
30
58•
CENTRAL BELT
Yolla Bolly Terrane
FRANCISCAN COMPLEX
Pickett PeakTerrane
Mendocino Pass Terrane
EASTERN BELT
MARINE OVERLAP DEPOSITS
FLUVIAL AND LACUSTRINE FILL
PomoTerrane
Central Belt Mélange Terrane
Marin Headlands-
GeysersTerrane
TERTIARY COASTRANGE
OPHIOLITEGREAT VALLEY COMPLEX
Miocene
Eocene
Eocene and Paleocene
Pleistocene and Pliocene
MESOZOIC
CENOZOIC
EarlyJurassic
ELDER CREEK TERRANERice Valley
CORRELATION OF MAP UNITS
UNCONSOLIDATED DEPOSITS
CRETACEOUS
EarlyCretaceous
JURASSIC
Holocene
VOLCANICROCKS
[See Description of Map Units (in pamphlet) for precise unit ages]
LateCretaceous
Pleistocene
TERRACEDEPOSITS
ALLUVIALDEPOSITS
FANDEPOSITS
GLACIAL DEPOSITS
SPRING DEPOSITS
Late Jurassic
Middle Jurassic
QUATERNARY
QUATERNARYAND TERTIARY
Snow Mountain VolcanicTerrane
Qls
Qfy
Qfo
Qfvo
Qal
Qty
Qto
Qtvo
miy
QtQoa
fys
fys
fmp
Qsn
?
?
fpp
Qtrv
?
?
Qf
af
Qgd
Qv
Tm
Te
Tep
QTc
Tcg
fym by cgy cy
gy lsymspy
uny vy?
?
?
?
?
?
Kl
Klcg
Joc
Jov
JodJogJosp
?
cmp
?
?
?
?
??
?
?
?
?
?
?
?
Kssp
Klls
KJom
omb
omv
omun omg
??
?
?
?
?
oms omd
omc
Jgb
KJs
ss
?
cb
un
cgl
db
ms
v
?
fcm
spo
vpo
cmg
smg
vmg
?
?
dsm
psm
ssm
ssm
vsm cpp
vpp
Kuls
cy
vy
Kul
Kucgmg
Little IndianValley
QfoQtvoQal
Qal Qalfys
fcmfcm fcm
fcm
fym
fymfys fys
fys
fym
QalTep KJom
KJom
Kul
fppKul
Qal4,000
2,000
SEA LEVEL SEA LEVEL
2,000
4,000
6,000
8,000
10,000
12,000
FEETE
4,000
2,000
2,000
4,000
6,000
8,000
10,000
12,000
FEETE'
NORTHERN BARTLETT SPRINGS FAULT ZONE
NORTHWEST SOUTHEAST
NORTHEAST
NORTHEAST
NORTHEAST
SOUTHWEST
SOUTHWEST
SOUTHWEST
SOUTHWEST NORTHEAST
SECT
ION
B’–B
”
SECT
ION
C–C'
fcm
fcm
fcm
KJom?
fym
fys
fys
QfyQal
Qoa JospKJom? Qt fys?
fpp
fcmfcm fys
vQls
QtyQtQal
QlsQls
c v
FEETA
NORTHERN BARTLETT SPRINGSFAULT ZONE
4,000
6,000
2,000
SEA LEVEL
2,000
4,000
6,000
8,000
10,000
12,000
4,000
6,000
2,000
SEA LEVEL
2,000
4,000
6,000
8,000
10,000
12,000
FEETA'
+_
_
2,000
4,000
6,000FEET FEET
SEA LEVEL
4,000
2,000
6,000
8,000
SEA LEVEL
2,000
4,000
6,000
6,000
4,000
2,000
B B''
8,000
10,00010,000
_ +
fys fysfym
fymfym
fys
fys
Qty
fppQal
JospQfo
TepQtvo vsm
vsm QgdQgdQls
vsm
Qls Qlsfys fys
fys
Josp Josp
JospKJs
KJs?
JovQal
Qfo QtyQal Qt
vsmQfo
Kul
KJom
B'
fcmQfo QalQfo Qfvo
Qfy
vpospo
Kl
Kl
KJom
Qls Jospfcm?
c b
fcm
Josp
Josp
fcm
fcm
Ku KuTep
NORTHERN BARTLETT SPRINGSFAULT ZONE
Snow Mountain
BEN
D IN
SECT
ION
SECT
ION
E–E'
SECT
ION
E–E'
cmg
cmgvmg
2,000
SEA LEVEL
4,000
6,000
2,000
SEA LEVEL
4,000
6,000
4,000
6,000
2,000
8,000
10,000
4,000
6,000
2,000
8,000
10,000
14,000
12,000
FEETC
FEETC'
14,000
12,000
spo QalKl KuQls
Josp
QalQty
QalQfy fys fym
fys
fym fys
fpp
KJomfys
fymfysvy
vy vyQal
fys fysvy cy Josp
Jov Qfo QtyQfo
Qfo QtoQt Qty
QalQtyJosp KJs
QalQfyQtQalv
Lower Blue Lake
fcm
fcmfcm
fcm
QalJosp
vpo? ? ?
? ? ? ?
NORTHERN BARTLETTSPRINGS FAULT ZONE
PACIFIC RIDGEANTIFORM
MIDDLE MOUNTAINSYNFORM
_ +
smg
QalQal QalQt? vmgvmg
smg
smg fcm fcm fcm QfyQal Qal
Qal
Kl?
Qoa fcm
fcm
fcmfcm
vQls vy
fysQalfym
fysfys
Qls Qlsfys
fysfys
fys Qls Qls fys
fys
vy miyJosp JospJosp
KJsJov
KJs
KJs
vyfys
fym
fys
fym
fym
JospJosp Josp
KJom KJomQls
QlsQls fcm
JospssJosp
Josp
2,000
SEA LEVEL
4,000
6,000
4,000
2,000
8,000
10,000
12,000
6,000
4,000
2,000
8,000
10,000
12,000
6,000
2,000
SEA LEVEL
4,000
6,000FEET
DFEET
D'NORTHERN BARTLETT SPRINGSFAULT ZONEMIDDLE MOUNTAIN
SYNFORM
PACIFIC RIDGEANTIFORM
smg
_ +
+
LU-
DOS RIOSJAMISON RIDGE
PLASKETTRIDGE
THATCHER RIDGE
PLASKETTMEADOWS
122°30'122°45'123°123°15'39°45'
39°30'
39°15'
39°
Figure 2. Map showing quadrangles in map area and sources of geologic data.
SALTCANYON
WILBUR SPRINGSBENMORE CANYON
LODOGA
LEESVILLE
GILMOREPEAK
HOUGH SPRINGS
POTATO HILL
FOUTS SPRINGS
BARTLETTMOUNTAIN
BARTLETT SPRINGS
STONYFORDSAINT JOHNMOUNTAIN
CROCKETT PEAK
FELKNERHILL
KNEECAP RIDGEHULL MOUNTAIN
LAKEPILLSBURY
SANHEDRIN MOUNTAIN
BRUSHYMOUNTAINWILLIS RIDGE
FOSTERMOUNTAIN
VAN ARSDALERESERVOIR
POTTERVALLEY
REDWOODVALLEY
ELKMOUNTAIN
COWMOUNTAIN
UKIAH UPPERLAKE
LAKEPORT
HIGHLAND SPRINGS KELSEYVILLE
CLEARLAKEHIGHLANDS
LUCERNE
CLEARLAKE OAKS
LOWERLAKE
WILSONVALLEY
GLASCOCKMOUNTAIN
5
5
1
1
6, 15
6, 15
5, 18
5, 27
2, 16, 18
21
12, 13
12, 188
1
1
2
18
25
12, 13
18
8,
16
10
14, 18
7
9
2
14, 16
4, 16, 18
18
3, 1618
7, 17, 18
4, 16, 18
18
19, 2020
11, 7,22
11
11
11
3, 24
3
11
11
4, 16, 18
23
26
AREA OFMAP
EXPLANATION1 Ohlin and others, 20102 Berkland, 1978; CDWR, 1966, 1968, and 19693 McLaughlin, R.J., unpublished mapping, 1980–1981 4 McLaughlin and others, 19905 Jayko and others, 1989; Clark, 19406 Ohlin H.N., 1989, unpublished mapping, 19857 Hitchcock, C.S., unpublished mapping, 2012–2013; McLaughlin, R.J., and Moring, B.C., aerial reconnaissance using Google Earth imagery, 20148 Etter, 1979; U.S. Forest Service, unpublished mapping9 Stanford, 199110 Berkland, 197311 Hearn and others, 1995; Sims and Rymer, 1976; Rymer, 198112 Brown and others, 1981; MacPherson, 198313 Brown, 196414 Suppe and Foland, 1978; Etter, 1979; U.S. Forest Service, unpublished mapping15 Blake and others, 199216 McLaughlin, R.J. and Moring B.C., mapping 2012–201317 Ohlin, H.N., unpublished field work, 1980–198118 McLaughlin and Moring, aerial reconnaissance using Google Earth imagery, 2012–201419 Ohlin, H.N., unpublished mapping, 1979–198120 McLaughlin, 1978; Ohlin H.N., and McLaughlin, R.J., unpublished mapping, 1978–198121 Lehman, 197422 McLaughlin, R.J., and Moring B.C., minor revisions23 Lawton, 195624 Swe and Dickinson, 197025 Shervais and others, 2005a, b26 Lienkaemper, 201027 Clark, 1940
1
4
4
6
6
3
2
5
39˚00’
122˚30’ 122˚0’
39˚30’
Figure 5. Map showing major structural features in map area and locations of structure and seismicity cross sections.
NORTHERN BARTLETT SPRIN
GS
(Hunting)
t5
t4
t3
t1
t2-6
A
A'
B
B'
B''C'
C
E'
E
D
D'
NORTHERN BARTLETT SPRINGS
LoganSprings
Kuikui
Pomo
Bad Ridge
Bear Valley Resort
Wilson Fault
Kennedy Fault
Sulphur Bank
Konocti Bay
Borax Lake
Collayomi
Wright Way
Big Valley
Scotts Valley
Clover Valley
Sanhedrin Mountain
Little Indian Valley
SOUTHERN BARTLETT SPRINGS
C
ross
S
prin
gs
EXPLANATION
MAJOR FAULTS
Active segments of the Bartlett Springs Fault Zone—From aerially interpreted geomorphic features (Lienkaemper, 2010)
Other faults, undifferentiated—Includes faults mapped in field and faults inferred from aerial lineaments. Includes faults discussed in this report, though not all named faults on figure are discussed
CROSS SECTION
Line of structure section
Line of seismicity cross section—See figure 5, 12 (Sheet 2) and figure 11 (pamphlet) for additional information
MAJOR FOLDS
Synforms
1 Bartlett Springs Synform
4 Middle Mountain Synform
5 Unnamed synform
Antiforms
2 Pacific Ridge Antiform
3 Wilbur Springs Antiform
6 Bartlett Mountain Antiform
EARTHQUAKE EPICENTERS
Magnitude 5.2 earthquake, August 10, 2016
Aftershock sequence, August 10, 2016–September 15, 2016
Epicenters 1984–2014
A A'
t1
MFZ ~5 Ma
MFZ PRESENTExhumed rocks of the Eastern Belt
Partiallyexhumed rocks of the Central Belt
CoastalBelt
CoastalBelt
CoastalBelt
KlamathBlock
Rice Valley
Rice Valley
Rice Valley
Round Valley
RoundValley Round
Valley
Middle Mountain
Middle Mountain
Middle Mountain
Lower Lake
Lower Lake Lower
Lake
Great Valley Complex andCoast Range ophiolite
Neogene Eel Riverforearc basin
Neogene Eel Riverforearc basin
APPROXIMATEAREA OF FIGURE 7
A PALEOCENE–EOCENE MARGIN B ~MIDDLE MIOCENE MARGIN C PRESENT MARGIN
EXPLANATION
Estuarine deposits of Round Valley area associated with former Neogene (Eel River) forearc basin (Middle Miocene)
Sandstone and shale, shallow to deep marine, associated with former Mesozoic–Paleogene Great Valley forearc basin (Eocene and Paleocene)
Sandstone shale and conglomerate, marine, and ophiolitic basement and mélange of former Great Valley forearc basin (Upper Cretaceous–Middle Jurassic)
Igneous and metasedimentary basement rocks of the Klamath Mountains (Jurassic and older)
FRANCISCAN COMPLEX
Central Belt (Upper Cretaceaous and older)
Eastern Belt (Upper Cretaceous–Upper Jurassic)
Coastal Belt (Tertiary and younger)
MAJOR FOLD AXES
Antiform
Synform
Figure 6. Geologic maps showing progressive deformation of the northern California margin during transition from subduction to right-lateral strike slip. The Northern Bartlett Springs Fault is viewed as having developed since the Miocene from deformation focused along the Bartlett Springs Synform, one of several northwest-trending folds that preceded northward encroachment of the Mendocino Triple Junction and the San Andreas Fault. The folding formed in response to northeast-southwest transpression across the subduction margin.
Dominated by east-west convergence, following exhumation of Eastern and Central Belts of Franciscan Complex from depth of 20–30 km. Yellow circled areas delineate Paleogene deposition near former western margin of the Jurassic–early Cenozoic Great Valley fore-arc basin.
Light-pink transparent overlay delineates former southeastern part of early Miocene and younger (Eel River) fore-arc basin based on erosional and tectonic remnants of the former Neogene fore-arc basin that includes yellow-circled Miocene remnant at Round Valley. The Neogene fore arc may have extended much farther to the southeast (Nilsen and Clarke, 1989) and deposition was on exhumed Franciscan and Paleogene rocks of older Great Valley fore-arc basin. Orientations of synforms and antiforms inboard of the subduction margin indicate major northeast-southwest transpression that accompanied or postdated Neogene fore-arc deformation. Slip along the Northern Bartlett Springs Fault is inferred to have right-laterally dismembered the Bartlett Springs Synform since middle to late Miocene formation, uplift, and erosion of the Neogene fore-arc basin. See figure 7 for details of slip restoration of the Bartlett Springs Synform.
Showing major strike-slip faults inboard of the San Andreas Fault, the Mendocino Triple Junction, the present subduction margin, and the remaining offshore and uplifted and eroded onshore Neogene (Eel River) fore-arc basin. The present Bartlett Springs Fault Zone extends beyond the Mendocino Triple Junction into the modern subduction margin and dismembers the Bartlett Springs Synform. Reconstruction of this dismemberment can be used to approximate total dextral displacement and approximate a long-term slip rate for the Northern Bartlett Springs Fault. MFZ, Mendocino Fault Zone.
0
0 5 10 15 MILES
10 20 30 KILOMETERS
Round Valley
Miocene
Lower Great Valley Complex
Paleogene
Circled areas include Paleogene marine strata deposited on Cretaceous and older Great Valley Complex or Coast Range Ophiolite, representing the former westward extent of the Jurassic-Eocene Great Valley forearc basin. Round Valley area also includes remnants of Miocene estuarine strata indicating the former southeastern extent of a Neogene forearc basin (Eel River basin) that formed in the Miocene further to the west (Nilsen and Clarke, 1989).
STRATIGRAPHIC AND STRUCTURAL RELATIONS CONSTRAINING RECONSTRUCTION OF NORTHERN BARTLETT SPRINGS FAULT ZONE DISPLACEMENT
PALEOCENE–EOCENE CON
VERGENT M
ARG
IN
MIOCEN
E–PALEOCENE CONVERGEN
T MA
RGIN
COASTAL BELT TH
RUST
SAN AN
DREAS FA
ULT
SAN
AN
DREA
S FAULT
PRESENT CO
NVERG
ENT M
A
RGIN
COASTAL BELT THRUST
BARTLETT SPRINGS FAULT
Maacam
a Fault
5
6
3
2
4
1
Figure 7. Schematic reconstruction of Bartlett Springs Synform configuration prior to its dismemberment along the Northern Bartlett Springs Fault Zone (fig. 6 B,C). Also shown are other subparallel folds northeast and southwest of the Bartlett Springs Synform discussed in this report. The restoration suggests a total cumulative oblique dextral slip of approximately 38–47 km for the Northern Bartlett Springs Fault Zone since the middle to late Miocene, based on linking remnants of Paleogene strata deposited along the uplifted and eroded former west margin of the Paleogene and older Great Valley fore arc. Slip could have begun earlier than the Miocene, however, and total displacement could be >50 km. See discussions in pamphlet on Wilbur Springs Dextral Hook and Northern Bartlett Springs Fault.
EXPLANATION
Nonmarine basin deposits, undifferentiated (Quaternary)
Volcanics and deposits of Clear Lake area (Holocene–Pliocene)
Estuarine deposits of Round Valley area (Middle Miocene)
Sandstone and shale, shallow to deep marine (Eocene and Paleocene)
Sandstone and shale, moderately to deep marine, turbiditic (Upper Cretaceous–Upper Jurassic)
Ultramafic and mafic rocks of Coast Range ophiolite and ophiolitic mélange (Lower Cretaceous and Upper–Middle Jurassic)
FRANCISCAN COMPLEX
Central Belt (Upper Cretaceous and older)
Mélange
Snow Mountain volcanic terrane
Eastern Belt (Upper Cretaceous–Upper Jurassic)
Yolla Bolly terrane (Upper Cretaceous–Upper Jurassic)
Metasandstone and slaty argillite
Mélange
Pickett Peak terrane (Lower Cretaceous–Upper Jurassic)
MAJOR FOLDS
Synform
Restored Bartlett Springs Synform
Middle Mountain Synform
Unnamed synform northeast of Rice Valley
Antiform
Pacific Ridge Antiform
Wilbur Springs Antiform
Bartlett Mountain Antiform
OTHER SYMBOLS
Faults
Points used to illustrate range in minimum strike–slip displacement for restoration of Bartlett Springs synform configuration
6
6
1
1
1
3
3
2
5
4
4
ClearLake
~47 Km~38 Km
Approximate range in the minimum amount of slip necessary to restore hypothetical Bartlett Springs synformconfiguration
Potter Valley
Little Indian Valley
Reservoir
Eden Valley
LakePillsbury
Lake Pillsbury
Round Valley
?
SNOW MOUNTAINVOLCANIC TERRANE
Middle Mountain
LowerLake
Rice Valley
Round
Valley
FUTURE NORTHERN BARTLETT SPRINGS FAULT
0
0 5 10 15 MILES
10 20 30 KILOMETERS
Round Valley
Miocene
Lower Great Valley Complex
Paleogene
Circled areas include Paleogene marine strata deposited on Cretaceous and older Great Valley Complex or Coast Range Ophiolite, representing the former westward extent of the Jurassic-Eocene Great Valley forearc basin. Round Valley area also includes remnants of Miocene estuarine strata indicating the former southeastern extent of a Neogene forearc basin (Eel River basin) that formed in the Miocene farther to the west (Nilsen and Clarke, 1989).
STRATIGRAPHIC AND STRUCTURAL RELATIONS CONSTRAINING RECONSTRUCTION OF NORTHERN BARTLETT SPRINGS FAULT ZONE DISPLACEMENT
A B
31-90°
Figure 8. Map showing Wilbur Springs Dextral Hook in context of regional structure and long-term transpressional deformation along the Northern Bartlett Springs Fault Zone. A, Partial map of California, showing major fault blocks associated with Miocene and younger development of the San Andreas Fault, northwestward translation of Salinian block, clockwise rotation of Western Transverse Ranges block (Colgan and others, 2012), and Upper Cretaceous–Neogene clockwise rotation of southern Sierra Nevada /Tehachapi block (Chapman and others, 2010). White box outlines Wilbur Springs Dextral Hook. B, An expanded view of Wilbur Springs Dextral Hook derived from figures 6 and 7, showing reconstructed Bartlett Springs Synform and other folds of the dextral hook. Orientations of folds suggest maximum compression was ~N. 41° E. to S. 41° W., ±16°. Geometry and approximate timing of Wilbur Springs Dextral Hook formation is similar to larger-scale dextral hook formed
by northward translation of the Salinian block since the early to middle Miocene. Upper Cretaceous–Paleogene rotations in southern Sierra Nevada-Tehachapi block, east-vergent crustal wedging, and unroofing of the Franciscan Complex accompanied shallow subduction of overthickened Farallon Plate and was followed by northward translation of the Salinian block during the Miocene (Chapman and others, 2010, 2012; Saleeby, 2003; Ernst and McLaughlin, 2012). See text for further discussion. Fault abbreviations: CASSZ, Cascadia Subduction Zone; GARFZ, Garlock Fault Zone; HAY-CAFZ, Hayward-Calaveras Fault Zone; MAAFZ, Maacama Fault Zone; MFZ, Mendocino Fault Zone; NBSFZ, Northern Bartlett Springs Fault Zone; NSAFZ, Northern San Andreas Fault Zone; RC-HLDFZ, Rodgers Creek-Healdsburg Fault Zone; SAFZ, San Andreas Fault Zone; SG-HFZ, San Gregorio-Hosgri Fault Zone; WW-KCFZ, White Wolf-Kern Canyon Fault Zone.
5 Ma
10 Ma15 Ma
Western Transverse Ranges block (present)
Wilber Springs Dextral Hook
SAFZ
NSAFZ
NSAFZ
SAFZSG-HFZ
GARFZ
WW
-KCF
Z
Mojave block
Southern Sierra Nevada/Tehachapiblock
Northern Sierra Nevada block
NBSFZ
NBSFZMAAFZ
MFZ
CASSZ
HAY-CAFZ
RC-HLDFZ
Salinian block
Coastal Belt
Salinian block
San Francisco
Eureka
Bakersfield
Monterey
San GabrielMountainsblock
Santa Rosa
Klamath block
Round Valley
FUTURE NBSFZ
FUTURE NBSFZ
Reconstructed Bartlett Springs synform
0
0 25 50 75 MILES
50 100 150 KILOMETERS
0
0 5 10 15 MILES
10 20 30 KILOMETERS
EXPLANATION
Nonmarine basin deposits (Quaternary)
Volcanics and deposits of Clear Lake area (Holocene–Pliocene)
Eel River forarc basin (Neogene)
Crystalline basement rock
Western Transverse Ranges block
Central Belt (Upper Cretaceaous and older)
Eastern Belt (Upper Cretaceous–Upper Jurassic)
Coastal Belt (Tertiary and younger)
Coast Range ophiolite and ophiolitic mélange (Lower Cretaceous and Upper–Middle Jurassic)
SYMBOLS
Upper Cretaceous—Neogene clockwise rotation in southern Sierra Nevada Batholith and Tehachapi Mountains block (Chapman and others, 2010)
Approximate location of buried tip of Franciscan tectonic wedge—Barbs on roof thrust side of wedge
Fault—Arrows show relative movement
Thrust fault
Vectors of maximum compression—From orientation of fold axes
MAJOR FOLD AXES
Antiform
Synform
31-90°
PACIFIC RIDGE ANTIFORM
PACIFIC RIDGE ANTIFORM
8/10/16 M 5.1 main shock
8/10/16 M 5.1 main shock
8/10/16 M 5.1 main shock8/10/16 M 5.1
main shock
8/10/16 M 5.1main shock
BARTLETT SPRINGS FAULT ZONE
BARTLETT SPRINGS FAULT ZONE
BARTLETT SPRINGSFAULT ZONE
Cross Section B–B’–B’’
BARTLETT SPRINGS FAULT ZONE
Snow Mountain
++
+
+
+ +
0
-5
-10
-15
-20
t4
t2-6
Dept
h (km
)
0
-5
-10
-15
-20
Dept
h (km
)
0
-5
-10
-15
-20
Dept
h (km
)
Distance (km) Distance (km)
Distance (km)
Distance (km)
0
-5
-10
-15
-20
Dept
h (km
)
0
-5
-10
-15
-20
Dept
h (km
)
t4t3t2-6t1
t5
t1
B' Part of structure section B–B’–B“ Part of structure section C–C’
Structure section E–E’
t3
Figure 12. Seismicity cross sections showing hypocentral depth distribution of earthquakes along sections t1, t2-6, t3, t4, and t5 (see fig. 5 for locations). Hypocenters are projected into seismicity cross sections along lines perpendicular to the sections from ~5 km north and south of the section lines. Depths of the 8/10/16 main shock and its aftershock sequence are, respectively, the large pink and small orange triangles. In t1, t2-6, t3, and t4, post-1984 hypocenters are plotted as small green dots. In section t5, red dots are hypocenters projected into the section from southwest of the plane of the cross section; green dots are hypocenters projected into the section from northeast of the cross-section plane. Intersection of
the Northern Bartlett Springs Fault with plane of t5 is approximated from intersection of the fault’s projection in t2-6, t3, and t4 with plane of t5 (magenta hexagon symbol). In seismicity cross sections t1, t3, and t5, we superpose parts of structure sections B–B'–B", C–C', and E–E', respectively, that correspond with the seismicity cross sections. See the structure sections for explanation of lithologic units. Note that the axis of a major antiform (Pacific Ridge Antiform) in Franciscan rocks northeast of the Northern Bartlett Springs Fault Zone forms prominent high topography in the hanging-wall block of the Northern Bartlett Springs Fault (sections t3 and t5).
EXPLANATION
EARTHQUAKE HYPOCENTERS
8/10/16 M 5.1 main shock
8/10/16 through 9/16/16 aftershock sequence
Microseismicity 1984–2011
Fault block motion toward observer
Fault block motion away from observer
Bartlett Springs Fault Zone—Arrows show relative strike-slip motion across fault
CROSS SECTION T5 (E–E‘) ONLY
Intersections of Northern Bartlett Springs Fault crossing northeast–southwest cross sections t1 (B–B‘–B‘‘), t2-6, t3 (C–C‘), and t4, with the plane of northwest–southwest section t5 (E–E‘)
Hypocenters located behind (northeast) of plane of E–E‘
Hypocenters located in front (southwest) of plane of E–E‘
BEN
D IN
SECT
ION
SECT
ION
E–E’
SECT
ION
B–B’
–B“
SECT
ION
C–C’
SECT
ION
E–E’
SECT
ION
t5
SECT
ION
E–E’
Distance (km)
