RESEARCH

Earliest Cretaceous Pacifi cward offset of the Klamath Mountains salient, NW California–SW Oregon

W.G. Ernst DEPARTMENT OF GEOLOGICAL AND ENVIRONMENTAL SCIENCES, STANFORD UNIVERSITY, STANFORD, CALIFORNIA 94305-2115, USA

ABSTRACT

Although Late Triassic igneous rocks are present, the Sierra Nevada–Klamath calc-alkaline arc began massive construction along the con- tinental margin at ca. 170 Ma during oblique underfl ow of paleo-Pacifi c oceanic lithosphere; intense activity continued throughout the volcanic-plutonic belt until at least ca. 140 Ma. This volcanic-plutonic arc supplied detritus to the Mariposa-Galice proximal clastic sequence starting by ca. 165–160 Ma. After onset of uppermost Jurassic Myrtle overlap sedimentation on the western fl ank of the Klamath Mountains, but before Hornbrook and Valanginian Great Valley Group overlap deposition on the eastern and southeastern sides, the Klamath Mountains salient was displaced ~200 km westward relative to the igneous arc. The orogen thus moved off the deep-seated magmagenic zone underly- ing the arc and did not participate in the massive Sierra Nevada igneous fl are-up between ca. 125 and ca. 85 Ma. I suggest that, beginning at ca. 140 Ma, underfl ow of a young, thin oceanic slab beneath the Klamath Mountains slid beneath the gently east-dipping stack of thrust sheets without disturbing their inclinations. Subduction and collision of much thicker oceanic lithosphere on both the north and south caused contraction, eastward relative displacement of the continental margin arc, and ductility-enhanced rotation of the superjacent stack of allochthons into near-vertical dips. After a magmatic lull, heightened igneous activity in the Sierra Nevada recommenced at ca. 125 Ma. The earliest Cretaceous oceanward plate junction rollback lay directly offshore the Klamath imbricate orogen, but to the south trapped the ca. 165 Ma Coast Range ophiolite on the North American side of the suture. After ca. 140 Ma, fi rst-cycle arc detritus began to accumulate on the mafi c igneous basement fl ooring the Great Valley forearc, and turbiditic clastic material also was carried oceanward across the forearc into the coeval Franciscan trench.

LITHOSPHERE; v. 5; no. 1; p. 151–159 | Published online 14 November 2012 doi:10.1130/L247.1

INTRODUCTION types, structures, ages of the rock packages, timing of the offset and proposes a speculative the progressive oceanward assembly of succes- mechanism to explain it. Arcuate, shallowly east-dipping thrust sheets sively younger geologic units, and their times of in the Klamath Mountains consist mainly of deformation (Davis, 1969; Davis et al., 1980; TIME OF OUTBOARD RELATIVE OFFSET Paleozoic through earliest Late Jurassic oce- Wright and Fahan, 1988; Wright and Wyld, OF THE KLAMATH MOUNTAINS anic basement terranes and overlying superja- 1994; Irwin, 2003). However, the juxtaposed cent units that were stranded along the North Sierran Foothill terranes stand nearly vertically, Geologic constraints suggest an earliest Cre- American margin by chiefl y transpressive plate whereas, in contrast, Klamath thrust sheets root taceous westward displacement of the salient motions. Although high-pressure, low-temper- gently to the east. relative to the Sierran Foothills. Whether the ature phase assemblages attest to episodes of Figure 1 shows that the Klamath Moun- Klamath Mountains province moved westward Paleozoic to early Mesozoic subduction, the tains concave-to-the-east contractional assem- geographically, or the Sierra Nevada Range accretion of variably metamorphosed ophiol- bly lies well outboard of the trend of the Sierra moved eastward, or both were displaced, is itic terranes overlain by distal turbidites refl ects Nevada Range. Judging by the map relation- unknown. Only the differential offset is consid- chiefl y transform and transpressive lithospheric ships, this salient appears to be situated ~200 ered here. slip (Saleeby et al., 1992; Ernst et al., 2008). km west of the formerly contiguous Sier- (1) Late Jurassic deposition of the Galice Old, fault-bounded Klamath Mountain units on ran segment of the curvilinear arc (Fig. 2). Formation in the westernmost Klamath Moun- the east are structurally high in the accretionary North of the Klamath Mountains promontory, tains (MacDonald et al., 2006) and the correla- stack, whereas the ages of successively added a major eastward jog toward apparently cor- tive deposition of the Mariposa Formation in the lower allochthons decrease progressively toward relative lithologic units in the Blue Mountains westernmost Sierran Foothills (Snow and Ernst, the west (Irwin, 1972, 1994). The tectonized, (LaMaskin et al., 2011; Schwartz et al., 2011) 2008) exhibit the full ~200 km of apparent sinis- imbricated collage of west-vergent lithostrati- suggests the possibility of a much greater tral offset; hence, these proximal siliciclastic graphic terranes consists of basal ophiolitic oceanward offset of the Klamath Mountains units evidently were laid down unconformably units, chiefl y overlain by cherts and fi ne-grained relative to the late Mesozoic accretionary on the western edge of a continuous Sierra- terrigenous strata (e.g., Frost et al., 2006), all continental margin of eastern Oregon (Snoke Klamath arc prior to most of the differential invaded by Jurassic calc-alkaline arc plutons. and Barnes, 2006). The manner in which this slip (Ernst et al., 2008). Uppermost Jurassic to The accreted terrane assembly of the Klamath tectonic offset of the Klamath Mountains col- Lower Cretaceous Myrtle clastic strata overlie Mountains has long been correlated with the lage was accomplished remains obscure. This the Galice Formation in SW Oregon (Imlay et northern Sierran Foothills based on similar rock paper summarizes geologic evidence for the al., 1959; Dickinson, 2008, fi g. 3A) and so were

LITHOSPHEREFor permission to| Volumecopy, contact 5 | Number [email protected] 1 | www.gsapubs.org | © 2012 Geological Society of America 151

Downloaded from http://pubs.geoscienceworld.org/gsa/lithosphere/article-pdf/5/1/151/3723189/151.pdf by guest on 01 October 2021 W.G. ERNST

Myrtle Fm Hornbrook Fm lith (U-Pb zircon age 136 Ma) and the preex- isting eastern Klamath basement directly north 124°W 122°W 120°W Cascade subduction zone 42°N of the Cold Fork–Elder Creek fault zone at the Cascade 42°N Arc northern end of the Sacramento Valley (Jones and Irwin, 1971; Blake et al., 1988, 1999).

125–85 Ma granitic rocks (3) Jones and Irwin (1971) recognized and documented an upward nonmarine-marine tran- Modoc 170–140 Ma granitic rocks sition in Great Valley Group strata bordering Klamaths the SE Klamath Mountains. They reported that SB Plateau Jurassic metasedimentary this Valanginian paleoshoreline was offset more and metavolcanic rocks MF than 100 km eastward to the south of sinistral Franciscan Paleozoic-Triassic metased. OF-SS (?) “tear faults,” which are now considered as mem- Coast Complex and metavolcanic rocks Ranges bers of the Cold Fork–Elder Creek fault system Paleozoic and Mesozoic CF-EC ultramafic rocks (Blake et al., 1999). Thus, these offsets must

Foothills Belt have occurred in post-Valanginian time.

SAF Location of Fig. 3 (4) Locations of erosional remnants of silici- Great Valley Group clastic strata bordering the Klamath Mountains 39°N are shown schematically in Figures 1 and 2. Cenozoic sedimentary Based on the spatial distribution of erosional and volcanic rocks Sierra Nevada Batholith remnants of the Myrtle, Galice, and Mariposa Mainly Cretaceous Great Formations overlying Jurassic and older base- Valley Group (Lower K tan) ment rocks, outboard relative displacement Uppermost Cretaceous- of the Klamath salient began by ca. 140 Ma. Miocene coastal belt N? This apparent westward offset was well under Mainly Upper Cretaceous way by ca. 136 Ma, prior to Hornbrook + Great Franciscan mélange and Valley Group overlap deposition on the Shasta Nacimiento belts Bally Batholith and other eastern Klamath units. Mainly Lower to mid-Cretaceous SGF The seaward offset of the Klamath Mountains Franciscan eastern belt Salinian Block apparently occurred during a brief interval of chiefl y left-lateral slip along the western mar- gin of North America (Saleeby, 1992; Saleeby N et al., 1992; Harper et al., 1994) that terminated shortly after development of the Kimmeridgian– Tithonian cusp in the American apparent polar SAF W E wander paths (May and Butler, 1986; Schettino S and Scotese, 2005). (5) Geologic relationships among the Klam- 0 100 200 km ath Mountains, the Franciscan Complex, and the Great Valley Group in the vicinity of the so-called Yolla Bolly triple junction (Blake et 34°N al., 1999) are shown in Figure 3. In addition to 117°W the terrane-bounding, NW-trending South Fork Figure 1. Geology of northern and central California, emphasizing the Klamath-Sierran calc-alkaline and Coast Range faults, a family of transverse arc, Great Valley Group forearc basin, and Franciscan trench lithotectonic belts, simplifi ed after the breaks transects Great Valley Group strati- U.S. Geological Survey and California Division of Mines and Geology (1966) geologic map, the ter- rane map of Silberling et al. (1987), and coastal geologic maps of Dickinson et al. (2005). Granitoids graphic units in this somewhat more detailed are of Jurassic and Cretaceous emplacement ages, except for the dominantly Jurassic plutons map area. Especially signifi cant faults include, of the Klamath Mountains. Mariposa and Galice strata occupy the western parts of the Jurassic from north to south, the Oak Flat, Sulphur metasedimentary and metavolcanic rock units in the Sierran Foothills and the western Klamath Spring, Cold Fork, and Elder Creek structures. Mountains, respectively. Klamath-margin locations of the Myrtle and Hornbrook Formations are The Oak Flat–Sulphur Spring structures strike also indicated. SB—Shasta Bally Batholith. Fault zone abbreviations: CF-EC—Cold Fork and Elder ENE and are appropriately oriented to repre- Creek; OF-SS—Oak Flat and Sulphur Spring; N—on-land section of the Nacimiento, N?—its off- sent the inferred zone of earliest Cretaceous shore segment; SGF—San Gregorio–Hosgri; MF—Mendocino; and SAF—San Andreas. sinistral slip, although the offset is slightly less than 80 km (see Figs. 2 and 3). On the south, the Cold Fork–Elder Creek fault zone has been also displaced oceanward by relative left-lateral the California-Oregon border (Sliter et al., 1984; interpreted by Wright and Wyld (2007) as an offset of the Klamath Mountains salient. Nilsen, 1993; Surpless, 2011) and so must have important junction accommodating several hun- (2) In marked contrast, the mid- and Upper accumulated after oceanward displacement. dred kilometers of dextral slip. Judging by the Cretaceous Hornbrook Formation was depos- Similarly, Valanginian-Hauterivian (i.e., Lower fi eld relations documented in Figure 3, the Cold ited with angular unconformity on the eastern, Cretaceous) Great Valley Group sandstones rest Fork–Elder Creek fault zone and its subparal- landward side of the Klamath Mountains near on the uplifted and eroded Shasta Bally Batho- lel breaks truncate the Oak Flat–Sulphur Spring

152 www.gsapubs.org | Volume 5 | Number 1 | LITHOSPHERE

Downloaded from http://pubs.geoscienceworld.org/gsa/lithosphere/article-pdf/5/1/151/3723189/151.pdf by guest on 01 October 2021 Klamath salient offset | RESEARCH

structures. Thus, outboard displacement of the 43°N Klamath promontory was pre-Hauterivian, prior to right-lateral motion described by Wright and Wyld—which would represent a post-Barre- H Klamath Mountains divisions mian event. Thicknesses of the Hauterivian– M Barremian (i.e., lowermost Cretaceous) Great Western Klamath terrane Valley Group sections in the Yolla Bolly triple W E Condrey Mountain terrane junction area monotonically increase north- Rattlesnake Creek terrane S ward, so this group of faults underwent at least Western Hayfork terrane some slip to ca. 125 Ma (Constenius et al., 2000; Eastern Hayfork terrane Wright and Wyld, 2007). (6) Although igneous activity commenced in Hayfork terrane undivided the Sierran arc in Late Triassic time (e.g., Stern North Fork terrane et al., 1981; Dilles and Wright, 1988), volumi- Stuart Fork terrane nous calc-alkaline granitic plutons intruded the Central Metamorphic terrane 41°N Klamath-Sierran arc over the interval 170–140 GVG E. Klamath terrane undivided Ma (Hacker and Ernst, 1993; Hacker et al., 1993; Irwin and Wooden, 1999; Irwin, 2003; 0 20 40 60 80 100 Km Snoke and Barnes, 2006); the 170 Ma to 140 Ma igneous bodies are scattered among the compa- rably abundant Late Jurassic granitoids, and at

OF-SS (?) least the Late Jurassic and earliest Cretaceous granitoids sparsely intrude the Galice and Mari- Location of Fig. 3 posa units on the west as well as the eastern Red Ant extent of the superjacent wall rocks. Thus, a Schist continuous Klamath–Sierra Nevada volcanic- Younger overlap strata (Klamaths) plutonic arc—now offset—clearly was located M = Myrtle Fm above the magmagenic zone supplying the calc- H = Hornbrook Fm alkaline arc at least until ca. 140 Ma. GVG = Great Valley Group (7) Recent thermochronologic research in the Western Klamath terrane reported by Batt et 39°N al. (2010) documented an episode of 40Ar/39Ar- based cooling-degassing of rocks and minerals at ca. 135–126 Ma, more or less compatible Sierran Foothills divisions with earliest Cretaceous rifting and transporta- Upper Jurassic accretionary sequence tion of the Klamath Mountains province away from the Sierra Nevada arc. Coupled with new Slate Creek complex fi ssion-track ages, Batt et al. also interpreted Jura-Triassic arc belt their data to refl ect thermal events associated Calaveras complex with Late Cretaceous thermal annealing–recrys- Feather River terrane tallization attending exhumation of the Klamath Northern Sierra terrane Mountains province and erosional stripping of a widespread, thick Hornbrook cover sequence (see also Sliter et al., 1984). (8) As a result of the oceanward projection of the salient, the convergent plate boundary rolled 37°N back to directly west of the Klamath Mountains. On the south, this earliest Cretaceous step-out of the transpressive plate junction stranded an 124°W 122°W 120°W inboard Middle and Upper Jurassic section of Figure 2. Generalized geologic map of the Klamath Mountains and the western Sierran Foothills, oceanic crust–capped lithosphere as the Coast modifi ed after Irwin (1981, 2003), Sharp (1988), Edelman and Sharp (1989), Ernst (1998), and Snow Range ophiolite, forming the western basement and Scherer (2006). The Western Klamath terrane includes the Galice Formation, and the Upper of the Great Valley forearc basin (Ernst et al., Jurassic Sequence in the Sierran Foothills includes the Mariposa Formation. Klamath-margin loca- tions of the northernmost Great Valley Group (GVG), Myrtle (M), and Hornbrook (H) Formations 2008; Ernst, 2011). Such a rollback of the oce- are indicated. Also shown is the Oak Creek–Sulphur Spring sinistral fault zone (OF-SS), but not the anic plate requires that re-establishment of the slightly younger Cold Fork–Elder Creek fault zone. Although the Klamath Mountains are displaced subduction-deprived magmagenic zone beneath ~200 km from the northern extension of the Jurassic Sierran arc, slip across the Oak Creek–Sulphur the Sierran arc would have involved a period Spring fault zone is substantially less than 200 km because of viscous drag and arcuate curvature of eastward underfl ow, possibly accounting for in the salient. the ca. 140–125 Ma magmatic lull observed in the Early Cretaceous Andean-type arc (Stern et

LITHOSPHERE | Volume 5 | Number 1 | www.gsapubs.org 153

Downloaded from http://pubs.geoscienceworld.org/gsa/lithosphere/article-pdf/5/1/151/3723189/151.pdf by guest on 01 October 2021 W.G. ERNST

40°20’N Klamaths

Oak Flat fault Great Valley Group Suphur Spring fault South Fork fault

Cold Fork fault

0 2 4 6 8 10 km

Coast Range f

Franciscan Complex

ault Elder Creek fault

W E S 0 2 4 6 8 10 km

40°05’N 123°00’W 122°15’W

Figure 3. Small portion of the Blake et al. (1999) 1:100,000 scale geologic map of the Red Bluff 30′ × 60′ quadrangle, showing structural relationships around the Yolla Bolly triple junction (see also Constenius et al., 2000; Wright and Wyld, 2007). The main groups of lithotectonic units are color coded: grayish brown—Klamath Mountain units; blue—Franciscan Complex; gray- ish green—Great Valley Group strata. From older to younger, the sense of dominant Early Cretaceous slip along major faults includes: (1) the Oak Flat–Sulphur Spring zone (sinistral offset of the Klamath Mountains); (2) the Cold Fork–Elder Creek zone (dextral strike slip within the Great Valley Group); and (3) the South Fork–Coast Range zone (subduction-exhumation zone).

al., 1981; Chen and Moore, 1982; Hacker et al., Upper Cretaceous erosion of the continental- positions (Kistler and Peterman, 1973, 1978; 1995; Wooden et al., 1999). margin arc supplied sedimentary debris to the Burchfi el et al., 1992) marks the approximate (9) Terrigenous debris derived from the Great Valley forearc directly east of the Klamath western margin of Precambrian-Paleozoic North landward calc-alkaline arc began to arrive at salient, as well as to the Cretaceous Franciscan American basement. This 0.706 line runs N-S the Franciscan oceanic trench and intervening trench on the west. through central Nevada, and on the north appar- Great Valley Group by ca. 140 Ma (DeGraaff- (11) Several periods of profound subduction ently is defl ected ~200 km to the east (Kistler, Surpless et al., 2002; Surpless et al., 2006). are attested to not only by landward volcanic- 1990; Cowan and Bruhn, 1992) at the latitude of Clastic turbiditic strata accumulated in the sub- plutonic arc assemblages and their erosional the Klamath Mountains—a rough mirror image duction zone and forearc basin over the next ~90 debris, but also by recovered high-pressure, of the posited westward relative offset of the m.y. (Blake et al., 1988; Cloos and Ukar, 2010; low-temperature blueschists and eclogites that Klamath salient. Much of the continental crust Ernst, 2011). The most voluminous sedimenta- recrystallized at ca. 225 Ma, ca. 170–155 Ma, west of the ancient North American basement tion took place over the interval ca. 125–60 Ma and ca. 135–85 Ma (e.g., Wakabayashi, 1992, edge consists of far-traveled oceanic terranes, so (Dumitru et al., 2010). 1999; Ernst, 2011). The generations of these any bilateral E-W extension would necessarily (10) Signifi cantly, the Klamath Mountains high-pressure metamorphic rocks testify to have been accommodated chiefl y within these did not participate in the Sierran and Peninsu- intervals characterized by substantial compo- Jurassic and older accreted terranes. lar Ranges fl are-up in igneous activity between nents of plate subduction—clearly, these were To conclude, the E-W relative offset of the ca. 125 and ca. 85 Ma (Stern et al., 1981; Bate- not times of across-the-arc transform fault- Klamath Mountains–Sierran Foothill belts man, 1992; Saleeby et al., 1992; Coleman ing along the Californian continental margin. apparently occurred during a brief period at the et al., 2003). This massive production of arc Aspects of these geologic constraints are sum- beginning of the Cretaceous, involving ~200 km intrusives ± extrusives may have resulted from marized in Figure 4. sinistral slip along the southern margin of the 87 86 rapid, nearly orthogonal oceanic plate subduc- (12) The ( Sr/ Sr)i = 0.706 isopleth for salient, and probably more substantial dextral tion (Ernst et al., 2009a). In any case, mid- and post-Paleozoic silicic igneous bulk-rock com- offset along its northern edge. The intrusion of

154 www.gsapubs.org | Volume 5 | Number 1 | LITHOSPHERE

Downloaded from http://pubs.geoscienceworld.org/gsa/lithosphere/article-pdf/5/1/151/3723189/151.pdf by guest on 01 October 2021 Klamath salient offset | RESEARCH

This geohistory seems to be well established (e.g., Hamilton, 1969; Dickinson, 1970, 2008; GVG forearc 80 sediments Irwin, 2003). However, the postulated westward 85 displacement of the arcuate, imbricate Klamath

low-grade Mountain terranes relative to the Andean-type 100 Franciscan margin probably refl ects an anomaly in the Franciscan blueschists plate-tectonic evolution of this sector of western trench North America. Lithospheric plates generally sediments are carried along by asthenospheric fl ow, so the 120 Klamath ultimate cause of emplacement of the Klamath Sierran and Hornb salient salient requires us to decipher the regional his- White-Inyo Fm tory of earliest Cretaceous upper-mantle cir- ranges 140 140 culation. However, ancient mantle kinematics Myrtle Fm must be ascertained from the effects of crustal deformation, and deep-seated forces responsible 155 high-grade Fran Age (Ma) for generating the Klamath Mountains salient 160 tectonic blocks, Red Ant Schist almost certainly would have been obliterated Mariposa- 170 Galice later along the convergent or transpressive plate overlap junction. 180 Klamath Mtns During Early Cretaceous time, the broad Far- allon plate evidently impinged against the west- ern edge of the continent in a dextral transpres- 200 sive mode (Engebretson et al., 1984; May and Butler, 1986; Schettino and Scotese, 2005; Sager, 2007; Wright and Wyld, 2007). Scenarios 220 Stuart Fork attempting to account for the structure and dis- blueschists placement of the Klamath Mountains salient rel- ative to the calc-alkaline arc involve the arrival Major lithotectonic belts and events of far-traveled oceanic lithosphere transport- Figure 4. Schematic representation of the timing and inferred late Mesozoic ing: (1) a mantle plume head; (2) a spreading interrelationships among calc-alkaline arc rocks, blueschists + eclogites, ridge; (3) a thermal anomaly localizing backarc oceanward migration of the Klamath Mountains oceanic terrane collage, spreading; (4) an exotic microcontinental frag- and clastic deposition of the Mariposa-Galice sequence, Myrtle, Hornbrook, Great Valley (GVG), and Franciscan clastic rocks in northern and central ment or island arc; (5) an oceanic plateau; or California. Plutonic emplacement age histograms are based chiefl y on zir- (6) a subparallel brace of major-offset transform con U-Pb–dated granitoids in the Klamath and Sierra Nevada–White-Inyo faults and bounding escarpments. ranges, simplifi ed after Irwin (2003), with more recent age data from Allen Underfl ow of a mantle plume head would and Barnes (2006), Ernst et al. (2009b), and Memeti et al. (2010). Plutonic have resulted in a high-heat-fl ow regime, likely volumes are assumed to be proportional to number of bodies analyzed. generating substantial amounts of ca. 140 Ma Erosional relics of the original comagmatic volcanic carapace (e.g., Hacker et al., 1995; Dunne et al., 1998; Scherer et al., 2008) are not widely pre- and younger mafi c + felsic magmas as well as served, but volumes could have been approximately similar in proportions extensional disruption of the Klamath arc, none to the plutons. See text for discussion. of which is evident in the geologic record. Colli- sion with a N-S–trending spreading ridge ought to show a lengthy set of continental-margin offsets and thermal highs ± postcollision igne- ca. 170–140 Ma granitoid bodies in the Klamath ORIGIN AND EMPLACEMENT OF THE ous activity, rather than the current curvilinear Mountains but complete absence of 125–85 Ma KLAMATH SALIENT calc-alkaline arc marked by just a single prom- plutons, so abundant in the Sierra Nevada, sug- ontory; thus, impingement of a long, segmented gest that outboard displacement of the Klamaths Paleozoic–Mesozoic construction of the ridge would not seem to replicate the Klamath began at ca. 140 Ma as the crustal assembly Blue Mountains–Klamath Mountains–Sierra Mountains salient. Widespread backarc spread- gradually migrated off the deep-seated magma- Nevada lithotectonic complex on the western ing would also result in post–140 Ma ophi- genic zone sited along or above the descending margin and nearby offshore of North America olitic rocks, but such are not recognized. The oceanic plate. Although minor westward rela- took place through episodic arrival and suturing only important, far-traveled microcontinental tive transport apparently continued beyond ca. of exotic ophiolitic terranes, accretionary assem- entity in the Klamath collage appears to be the 140–136 Ma, the most substantial slip occurred bly of largely clastic sedimentary units, and the Central metamorphic belt, and this lithostrati- after the onset of Myrtle deposition but before Middle Jurassic–Cretaceous construction of a graphic unit collided with the landward terrane that of Hornbrook overlap, i.e., prior to the calc-alkaline volcanic-plutonic arc. Exhumation assembly prior to Late Triassic blueschist-facies deposition of Valanginian Great Valley Group and erosion of the arc supplied massive amounts metamorphism developed in the outboard Stuart strata along the SE edge of the Klamath Moun- of fi rst-cycle detritus to the Great Valley forearc Fork terrane, so microcontinental collision also tains. Described and inferred geologic events bordering the continental margin, as well as to fails to account for the salient. However, the ear- are chronicled schematically in Figure 5. the outboard paleo-Pacifi c Franciscan trench. liest Cretaceous underfl ow of either a buoyant

LITHOSPHERE | Volume 5 | Number 1 | www.gsapubs.org 155

Downloaded from http://pubs.geoscienceworld.org/gsa/lithosphere/article-pdf/5/1/151/3723189/151.pdf by guest on 01 October 2021 W.G. ERNST

(A) Early Jurassic (B) Middle Jurassic (C) J/K boundary ——> (D) mid-Cretaceous (strike slip ca. 380–170 Ma) (transpressive underflow ca. 170–125 Ma) (sinistral slip ca. 140–136 Ma) (head-on subduction ca. 125–85 Ma)

Hayfork v M H

North Fork v

Stuart Fork Rattlesnake Creek (225 Ma) Eastern

Klamath v

Tren Sierran

Trend of 170 Ma arc volcanism-plutonism Central Met. Belt d of m +Trinity Peridotite

v Galice

id-Cretaceous

batholith

Fm GVG v

Feather River Peridotite Northern Sierra

G Franciscan trench b r a e

sal Coast Range Ophiolite v a Red Ant t Valley forearc basin

(170 Ma) v

Jura-Triassic arc

Mariposa Fm

Calaveras v v

Figure 5. Schematic petrotectonic scenario for the mid-to-late Mesozoic evolution of northern and central California, modi- fi ed from Ernst et al. (2008). It postulates: (A) late Paleozoic through Early Jurassic, mainly dextral strike-slip arrival of oceanic terranes along the continental margin; (B) an interval of calc-alkaline arc-building transpression at ca. 170–140 Ma; (C) arc activity temporarily decreased by westward displacement of the Klamath oceanic arc at ca. 140–136 Ma, oceanward step-out of the Farallon plate, and the stranding of a section of preexisting oceanic lithosphere, the Coast Range ophiolite, south of the Klamath Mountains salient; and (D) after a magmatic lull, rapid, nearly orthogonal subduction at 125–85 Ma. The brown and red dashed lines mark the trends of the Middle Jurassic emergent arc and the massive, mid-Cretaceous calc-alkaline arc, respectively, after the compilation by Irwin (2003). Abbreviations: M—Myrtle, H—Hornbrook, GVG—Great Valley Group.

oceanic plateau or a section of ancient, thick, on both north and south across ENE-trending ing would have aided the oceanward transport low-density oceanic lithosphere bounded to the transforms against old, much thicker oceanic of the Klamath Mountains, and at the same north and south by major ENE transforms could lithosphere—would have been largely decou- time resulted in the apparent eastern bulge in 87 86 produce fl ow-parallel–trending crustal faults pled from the overlying imbricate stack of gen- the ( Sr/ Sr)i = 0.706 isopleth in north-central bounding the Klamath promontory; subhorizon- tly east-rooting allochthons. In this case, minor Nevada. Whatever the genesis of the westward tal impingement of a thick, cold slab of litho- heating and subsequent cooling of the overly- relative displacement of the Klamath Mountains sphere characterized by a low-heat-fl ow regime ing Klamath crust could have been responsible at ca. 140–136 Ma relative to the Sierra Nevada would cause the extinction of calc-alkaline mag- for the Early Cretaceous argon degassing Batt Range (and Blue Mountains), it seems evident matism in the Klamath Mountains. However, et al. (2010) measured in units of the Western that the motive force responsible for the archi- the underfl ow an old, high-riding, thick litho- Klamath terrane. Collision of the much thicker tecture that developed in the near-surface crust spheric platelet resulting in oceanward instead oceanic lithosphere on both the north (Blue was located in the end-of-Jurassic to earliest of landward displacement of the salient relative Mountains) and south (Sierra Nevada) could Cretaceous upper mantle. to a curvilinear, vigorously active coeval igne- have been responsible for contraction and east- ous arc seems counterintuitive. ward displacement of the marginal arc rela- CONCLUSIONS Perhaps a more likely scenario, illustrated tive to the Klamath Mountains—which would schematically in Figure 6, involves the hypoth- thereby take on its salient confi guration. More- After scattered Late Triassic igneous activ- esized convergence of a young, relatively over, shortening in the Sierran Foothills might ity, a major calc-alkaline arc began to form in warm, thin segment of the oceanic plate sliding have induced rotation of the crustal collage of the Sierra Nevada and Klamath Mountains at beneath the Klamaths beginning at ca. 140 Ma. imbricate sheets to the present near-vertical ca. 170 Ma attending transpressive subduction According to this model, the slab—bordered stack of allochthons. Localized backarc spread- of paleo-Pacifi c oceanic lithosphere beneath

156 www.gsapubs.org | Volume 5 | Number 1 | LITHOSPHERE

Downloaded from http://pubs.geoscienceworld.org/gsa/lithosphere/article-pdf/5/1/151/3723189/151.pdf by guest on 01 October 2021 Klamath salient offset | RESEARCH

125°W 120°W the plate suture, forming the western basement Canada of the new forearc (Fig. 5). After ca. 140 Ma, arc detritus began to accumulate on the mafi c igneous fl oor of the Great Valley Group and the Figure 6. Diagrammatic seaward Franciscan Complex. Displaced off sketch of the hypoth- the magmagenic zone, the Klamath Mountains 45°N esized impingement of a 45°N Washington salient did not participate in the great Sierra segmented Farallon oce- Nevada fl are-up in igneous activity between anic plate beneath the (thick oceanic Blue western North American ca. 125 and ca. 85 Ma (Fig. 4). After a post- plate) Mountains margin at ca. 140–136 Ma. magmatic lull, this generation of calc-alkaline The thin, warm slab pass- arc intrusives ± extrusives supplied voluminous ing beneath the Klamath erosional products to the mid- and Upper Cre- Mountains evidently was taceous Great Valley forearc landward of the largely decoupled from Klamath Mountains, and to the Cretaceous (thin the overlying section of oceanic Oregon Idaho gently east-dipping thrust Franciscan trench oceanward of the salient. plate) Klamath sheets. In contrast, the 40°N Mountains postulated40°N thicker litho- ACKNOWLEDGMENTS sphere on both the north This speculative synthesis is based on geologic results and south was strongly obtained from a wide range of research projects conducted by coupled to the continental many workers. My own studies in the central Klamath Moun- tains have been supported by Stanford University, and earlier, margin crust, resulting in by the University of California–Los Angeles. Bob McLaughlin, contraction and rotation of Ray Wells, Norm Sleep, and Jim Wright gave me important the accreted collages into feedback on the draft manuscript. Sue Cashman, Cal Barnes, relatively steeply dipping and an anonymous reviewer provided helpful criticism for the sections. Arrows show journal review. I thank the above institutions and scientists for help, without which this work would not have been completed. (thick oceanic direction of relative crustal plate) shortening ± backarc Sierra Nevada extension (no differential REFERENCES CITED California 35°N Nevada plate motions); bounding Allen, C.M., and Barnes, C.G., 2006, Ages and some cryp- transforms of the Farallon tic sources of Mesozoic plutonic rocks in the Klamath Range Mountains, California, in Snoke, A.W., and Barnes, C.G., oceanic lithosphere are eds., Geological Studies in the Klamath Mountains assumed to have been sub- Province, California and Oregon: A Volume in Honor of 35°Nparallel, with ENE trends William P. Irwin: Geological Society of America Special only constrained by offsets Paper 410, p. 223–245. in the preexisting curvilin- Bateman, P.C., 1992, Pre-Tertiary Bedrock Geology Map of the 0 50 100 km Mariposa 1° by 2° Quadrangle, Sierra Nevada, Califor- ear arc. Arizona nia: U.S. Geological Survey Miscellaneous Investiga- tion Map I-1960, scale 1:250,000. Batt, G.E., Harper, G.D., Heizler, M., and Roden-Tice, M., 2010, Mexico Cretaceous sedimentary blanketing and tectonic rejuve- nation in the western Klamath Mountains: Insights from 120°W 115°W thermochronology: Central European Journal of Geosci- ences, v. 2, p. 138–151, doi:10.2478/v10085-009-0041-4. Blake, M.C., Jr., Jayko, A.S., and McLaughlin, R.J., 1988, Metamorphic and tectonic evolution of the Franciscan Complex, northern California, in Ernst, W.G., ed., Meta- the North American plate. Volcanism and plu- major right-lateral slip occurred along Cold morphism and Crustal Evolution of the Western United tonism were active throughout this Andean- Fork–Elder Creek fault zone, as proposed by States: Englewood Cliffs, New Jersey, Prentice-Hall, p. 1035–1060. type belt to ca. 140 Ma, refl ecting the build- Wright and Wyld (2007). Blake, M.C., Jr., Harwood, D.S., Helley, E.J., Irwin, W.P., Jayko, ing of a curvilinear Klamath Mountains–Sierra Speculatively (Fig. 6), underfl ow of a young, A.S., and Jones, D.L., 1999, Geologic Map of the Red Nevada arc until at least earliest Cretaceous warm, thin oceanic plate segment beneath the Bluff 30′ × 60′ Quadrangle, California: U.S. Geological Survey Miscellaneous Investigation Map I-2542, scale time. This belt supplied volcanogenic erosional Klamath Mountains at ca. 140 Ma caused the 1:100,000, and accompanying pamphlet, 15 p. debris to the Mariposa-Galice clastic sequence thermal annealing event in the Western Klam- Burchfi el, B.C., Cowan, D.S., and Davis, G.A., 1992, Tectonic by ca. 165–160 Ma. At the beginning of Cre- ath terrane reported by Batt et al. (2010). Col- overview of the Cordilleran orogen in the western United States, in Burchfi el, B.C., Lipman, P.W., and Zoback, M.L., taceous time, the Klamath Mountains salient lision of much thicker oceanic lithosphere on eds., The Cordilleran Orogen: Conterminous U.S.: Boul- was displaced ~200 km westward relative to both the north and south caused contraction, der, Colorado, Geological Society of America, The Geol- ogy of North America, v. G-3, p. 407–479. the curvilinear magmatic arc—after onset of rotation to essentially vertical inclination of Chen, J.H., and Moore, J.G., 1982, Uranium-lead isotopic the outboard Myrtle deposition but prior to that the stacked allochthons in the Sierran Foothills, ages from the Sierra Nevada batholith, California: of the inboard Hornbrook Formation and the and eastward displacement of the continental- Journal of Geophysical Research, v. 87, p. 4761–4784, doi:10.1029/JB087iB06p04761. Great Valley Group north of the Yolla Bolly margin arc relative to the west-projecting Cloos, M., and Ukar, E., 2010, Subduction initiation along the triple junction area. Some of the left-lateral Klamath Mountains. This earliest Cretaceous California plate margin: Timing and thermal evolution motion proposed in this paper was accom- westward step-out of the convergent plate junc- of the Franciscan Complex: Geological Society of Amer- ica, Abstracts with Programs, v. 42, no. 5, p. 576–577. modated along the Oak Creek–Sulphur Creek tion formed directly offshore from the Klamath Coleman, D.S., Briggs, S., Glazner, A.F., and Northrup, C.J., fault zone; much of the rest of the slip prob- Mountains imbricate orogen, whereas to the 2003, Timing of plutonism and deformation in the White Mountains of eastern California: Geological Society of ably was taken up by arcuate deformation of south, rollback trapped the ca. 165 Ma Coast America Bulletin, v. 115, p. 48–57, doi:10.1130/0016- the Klamath accretionary stack. Slightly later, Range ophiolite on the North American side of 7606(2003)115<0048:TOPADI>2.0.CO;2.

LITHOSPHERE | Volume 5 | Number 1 | www.gsapubs.org 157

Downloaded from http://pubs.geoscienceworld.org/gsa/lithosphere/article-pdf/5/1/151/3723189/151.pdf by guest on 01 October 2021 W.G. ERNST

Constenius, K.N., Johnson, R.A., Dickinson, W.R., and Wil- Sierran-Klamath source of mid- and Late Cretaceous Kistler, R.W., and Peterman, Z.E., 1978, A Study of Regional liams, T.A., 2000, Tectonic evolution of the Jurassic- Franciscan deposition and underplating: Tectonics, Variations of Initial Strontium Isotopic Composition of Cretaceous Great Valley forearc, California: Implications v. 28, TC6011, doi:10.1029/2008TC002352, 20 p. Mesozoic Granitic Rocks in California: U.S. Geological for the Franciscan thrust-wedge hypothesis: Geologi- Ernst, W.G., Saleeby, J.B., and Snow, C.A., 2009b, Guadalupe Survey Professional Paper 1071, 17 p. cal Society of America Bulletin, v. 112, p. 1703–1723, pluton–Mariposa Formation age relationships in the LaMaskin, T.A., Vervoort, J.D., Dorsey, R.J., and Wright, J.E., doi:10.1130/0016-7606(2000)112<1703:TEOTJC>2.0.CO;2. southern Sierran Foothills: Onset of Mesozoic subduc- 2011, Early Mesozoic paleogeography and tectonic evo- Cowan, D.S., and Bruhn, R.L., 1992, Late Jurassic to early Late tion in northern California?: Journal of Geophysical lution of the western United States: Insights from detrital Cretaceous geology of the U.S. Cordillera, in Burchfi el, Research, v. 114, B11204, doi:10.1029/2009JB006607, 13 p. zircon U-Pb geochronology, Blue Mountains Province, B.C., Lipman, P.W., and Zoback, M.L., eds., The Cordil- Frost, C.D., Barnes, C.G., and Snoke, A.W., 2006, Nd and Sr northeastern Oregon: Geological Society of America Bul- leran Orogen: Conterminous U.S.: Boulder, Colorado, isotopic data from argillaceous rocks of the Galice for- letin, v. 123, p. 1939–1965, doi:10.1130/B30260.1. Geological Society of America, The Geology of North mation and Rattlesnake Creek terrane, Klamath Moun- MacDonald, J.H., Jr., Harper, G.D., and Zhu, B., 2006, Petrol- America, v. G-3, p. 169–203. tains: Evidence for the input of Precambrian sources, in ogy, geochemistry, and provenance of the Galice Davis, G.A., 1969, Tectonic correlations Klamath Mountains Snoke, A.W., and Barnes, C.G., eds., Geological Studies Formation, Klamath Mountains, Oregon and California, and western Sierra Nevada, California: Geological Soci- in the Klamath Mountains Province, California and Ore- in Snoke, A.W., and Barnes, C.G., eds., Geological Stud- ety of America Bulletin, v. 80, p. 1095–1108, doi:10.1130 gon: Geological Society of America Special Paper 410, ies in the Klamath Mountains Province, California and /0016-7606(1969)80[1095:TCKMAW]2.0.CO;2. p. 103–120. Oregon: A Volume in Honor of William P. Irwin: Geologi- Davis, G.A., Ando, C.J., Cashman, P.H., and Goullaud, L., 1980, Hacker, B.R., and Ernst, W.G., 1993, Jurassic orogeny in the cal Society of America Special Paper 410, p. 77–101. Geologic cross section of the central Klamath Moun- Klamath Mountains: A geochronological analysis, May, S.R., and Butler, R.F., 1986, North American Jurassic tains, California: Summary: Geological Society of Amer- in Dunne, G.C., and McDougall, K.A., eds., Mesozoic apparent polar wander; implications for plate motion, ica Bulletin, v. 91, p. 139–142, doi:10.1130/0016-7606 Paleogeography of the Western United States—II: Soci- paleogeography and Cordilleran tectonics: Jour- (1980)91<139:GCSOTC>2.0.CO;2. ety of Economic Paleontologists and Mineralogists nal of Geophysical Research, v. 91, p. 11,519–11,544, DeGraaff-Surpless, K., Graham, S.A., Wooden, J.L., and McWil- (Pacifi c Section), Book 71, p. 37–60. doi:10.1029/JB091iB11p11519. liams, M.O., 2002, Detrital zircon provenance analysis Hacker, B.R., Ernst, W.G., and McWilliams, M.O., 1993, Gen- Memeti, V., Paterson, S., Matzel, J., Mundil, R., and Okaya, D., of the Great Valley Group, California: Evolution of an esis and evolution of a Permian-Jurassic magmatic arc/ 2010, Magmatic lobes as “snapshots” of magma cham- arc-forearc system: Geological Society of America Bul- accretionary wedge, and reevaluation of terranes in the ber growth and evolution in large, composite batho- letin, v. 114, p. 1564–1580, doi:10.1130/0016-7606(2002) central Klamath Mountains: Tectonics, v. 12, p. 387–409, liths: An example from the Tuolumne intrusion, Sierra 114<1564:DZPAOT>2.0.CO;2. doi:10.1029/92TC02250. Nevada, California: Geological Society of America Bul- Dickinson, W.R., 1970, Relations of andesites, granites, and Hacker, B.R., Donato, M.M., Barnes, C.G., McWilliams, M.O., letin, v. 122, p. 1912–1931, doi:10.1130/B30004.1. derivative sandstones to arc-trench tectonics: Reviews and Ernst, W.G., 1995, Timescales of orogeny: Jurassic Nilsen, T.H., 1993, Stratigraphy of the Cretaceous Hornbrook of Geophysics and Space Physics, v. 8, p. 813–860, construction of the Klamath Mountains: Tectonics, v. 14, Formation, Southern Oregon and Northern California: doi:10.1029/RG008i004p00813. p. 677–703, doi:10.1029/94TC02454. U.S. Geological Survey Professional Paper 1521, 89 p. Dickinson, W.R., 2008, Accretionary Mesozoic-Cenozoic Hamilton, W., 1969, Mesozoic California and the underfl ow Sager, W.W., 2007, Divergence between paleomagnetic and expansion of the Cordilleran continental margin in Cali- of Pacifi c mantle: Geological Society of America Bulle- hotspot-model–predicted polar wander for the Pacifi c fornia and adjacent Oregon: Geosphere, v. 4, p. 329– tin, v. 80, p. 2409–2430, doi:10.1130/0016-7606(1969)80[ plate with implications for hotspot fi xity, in Foulger, 353, doi:10.1130/GES00105.1. 2409:MCATUO]2.0.CO;2. G.R., and Jurdy, J.M., eds., Plates, Plumes, and Plan- Dickinson, W.R., Ducea, M., Rosenberg, L.I., Greene, H.G., Harper, G.D., Saleeby, J.B., and Heizler, M., 1994, Formation etary Processes: Geological Society of America Special Graham, S.A., Clark, J.C., Weber, G.E., Kidder, S., Ernst, and emplacement of the Josephine ophiolite and the Paper 430, p. 335–357. W.G., and Brabb, E.E., 2005, Net Dextral Slip, Neogene Nevadan orogeny in the Klamath Mountains, Califor- Saleeby, J.B., 1992, Petrotectonic and paleogeographic set- San Gregorio–Hosgri Fault Zone, Coastal California: nia-Oregon: U/Pb, 40Ar/39Ar geochronology: Journal of tings of U.S. Cordilleran ophiolites, in Burchfi el, B.C., Geologic Evidence and Tectonic Implications: Geologi- Geophysical Research, v. 99, p. 4293–4321, doi:10.1029 Lipman, P.W., and Zoback, M.L., eds., The Cordilleran cal Society of America Special Paper 391, 43 p. /93JB02061. Orogen: Conterminous U.S.: Boulder, Colorado, Geo- Dilles, J.H., and Wright, J.E., 1988, The chronology of early Imlay, R.W., Dole, H.M., Peck, D.L., and Wells, F.G., 1959, Rela- logical Society of America, The Geology of North Amer- Mesozoic arc magmatism in the Yerington district of tions of certain Upper Jurassic and Lower Cretaceous ica, v. G-3, p. 653–682. western Nevada and its regional implications: Geo- formations in southwestern Oregon: The American Saleeby, J.B., Busby-Spera, C., Oldow, J.S., Dunne, G.C., logical Society of America Bulletin, v. 100, p. 644–652, Association of Petroleum Geologists Bulletin, v. 43, Wright, J.E., Cowan, D.S., Walker, N.W., and All- doi:10.1130/0016-7606(1988)100<0644:TCOEMA>2.3 p. 2770–2785. mendinger, R.W., 1992, Early Mesozoic tectonic evolu- .CO;2. Irwin, W.P., 1972, Terranes of the western Paleozoic and Tri- tion of the western U.S. Cordillera, in Burchfi el, B.C., Dumitru, T.A., Wright, J.E., Wakabayashi, J., and Wooden, assic belt in the southern Klamath Mountains, Califor- Lipman, P.W., and Zoback, M.L., eds., The Cordilleran J.L., 2010, 2010, Early Cretaceous (ca. 123 Ma) transition nia: U.S. Geological Survey Professional Paper 800-C, Orogen: Conterminous U.S.: Boulder, Colorado, Geolog- from nonaccretionary behavior to strongly accretionary p. C103–C111. ical Society of America, The Geology of North America, behavior within the Franciscan subduction complex: Irwin, W.P., 1981, Tectonic accretion of the Klamath Moun- v. G-3, p. 107–168. Tectonics, v. 29, TC5001, doi:10.1029/2009TC002542. tains, in Ernst, W.G., ed., The Geotectonic Development Scherer, H.H., Ernst, W.G., and Hanson, R.B., 2008, 2008, Dunne, G.C., Garvey, T.P., Osborne, M., Schneidereit, D., Frit- of California: Englewood Cliffs, New Jersey, Prentice- Geologic implications of new zircon U-Pb ages from sche, A.E., and Walker, J.D., 1998, Geology of the Inyo Hall, p. 29–49. the White Mountain Peak metavolcanic complex, east- Mountains volcanic complex: Implications for Jurassic Irwin, W.P., 1994, Geologic Map of the Klamath Mountains, ern California: Tectonics, v. 27, TC2002, doi:10.1029 paleogeography of the Sierran magmatic arc in eastern California and Oregon: U.S. Geological Survey Miscel- /2007TC002141. California: Geological Society of America Bulletin, v. 110, laneous Investigations Map I-2148, scale 1:500,000. Schettino, A., and Scotese, C.R., 2005, Apparent polar wander p. 1376–1397, doi:10.1130/0016-7606(1998)110<1376: Irwin, W.P., 2003, Correlation of the Klamath Mountains and paths for the major continents (200 Ma to present): A GOTIMV>2.3.CO;2. the Sierra Nevada: Sheet 1—Map Showing Accreted paleomagnetic reference frame for global plate tectonic Edelman, S.H., and Sharp, W.D., 1989, Terranes, early faults, Terranes and Plutons of the Klamath Mountains and reconstructions: Geophysical Journal International, and pre–Late Jurassic amalgamation of the western Sierra Nevada, scale 1:1,000,000; Sheet 2—Successive v. 163, p. 727–759, doi:10.1111/j.1365-246X.2005.02638.x. Sierra Nevada metamorphic belt, California: Geologi- Accretionary Episodes of the Klamath Mountains and Schwartz, J.J., Snoke, A.W., Cordey, F., Johnson, K., Frost, cal Society of America Bulletin, v. 101, p. 1420–1433, Northern Part of the Sierra Nevada: U.S. Geological C.D., Barnes, C.G., LaMaskin, T.A., and Wooden, J.L., doi:10.1130/0016-7606(1989)101<1420:TEFAPL>2.3.CO;2. Survey Open-File Report 01-490, 2 sheets. 2011, Late Jurassic magmatism, metamorphism, and Engebretson, D.C., Cox, A., and Gordon, R.G., 1984, Relative Irwin, W.P., and Wooden, J.L., 1999, Plutons and Accretionary deformation in the Blue Mountains Province, northeast motions between oceanic plates of the Pacifi c basin: Episodes of the Klamath Mountains, California and Ore- Oregon: Geological Society of America Bulletin, v. 123, Journal of Geophysical Research, v. 89, p. 10,291–10,310. gon: U.S. Geological Survey Open-File Report 99-0374, p. 2083–2111. Ernst, W.G., 1998, Geology of the Sawyers Bar Area, Klam- scale 1:800,000. Sharp, W.D., 1988, Pre-Cretaceous crustal evolution of the ath Mountains, Northern California: California Division Jones, D.L., and Irwin, W.P., 1971, Structural implications of Sierra Nevada region, in Ernst, W.G., ed., Metamorphism of Mines and Geology Map Sheet 47, scale 1:48,000, an offset Early Cretaceous shoreline in northern Cali- and Crustal Evolution of the Western United States: accompanying text 59 p. fornia: Geological Society of America Bulletin, v. 82, Englewood Cliffs, New Jersey, Prentice-Hall, p. 824–864. Ernst, W.G., 2011, Accretion of the Franciscan Complex attend- p. 815–822, doi:10.1130/0016-7606(1971)82[815:SIOAOE Silberling, N.J., Jones, D.L., Blake, M.C., Jr., and Howell, ing Jurassic–Cretaceous geotectonic development ]2.0.CO;2. D.G., 1987, Lithostratigraphic Terrane Map of the West- of northern and central California: Geological Society Kistler, R.W., 1990, Two different lithosphere types in the ern Conterminous United States: U.S. Geological Sur- of America Bulletin, v. 123, p. 1667–1678, doi:10.1130 Sierra Nevada, California, in Anderson, J.L., ed., The vey Miscellaneous Field Studies Map MF-1874-C, scale /B30398.1. Nature and Origin of Cordilleran Magmatism: Geologi- 1:2,500,000. Ernst, W.G., Snow, C.A., and Scherer, H.H., 2008, Contrast- cal Society of America Memoir 174, p. 271–281. Sliter, W.V., Jones, D.L., and Throckmorton, C.K., 1984, Age ing early and late Mesozoic petrotectonic evolution of Kistler, R.W., and Peterman, Z.E., 1973, Variation in Sr, Rb, and correlation of the Cretaceous Hornbrook Forma- northern California: Geological Society of America Bul- K, Na, and initial 87Sr/86Sr in Mesozoic granitic rocks tion, in Nilsen, T.H., ed., Geology of the Upper Creta- letin, v. 120, p. 179–194, doi:10.1130/B26173.1. and intruded wall rocks in central California: Geologi- ceous Hornbrook Formation, Oregon and California: Ernst, W.G., Martens, U., and Valencia, V., 2009a, U-Pb ages cal Society of America Bulletin, v. 84, p. 3489–3512, Los Angles, California, Society of Economic Paleontolo- of detrital zircons in Pacheco Pass metagraywackes: doi:10.1130/0016-7606(1973)84<3489:VISRKN>2.0.CO;2. gists and Mineralogists, Pacifi c Section, p. 89–98.

158 www.gsapubs.org | Volume 5 | Number 1 | LITHOSPHERE

Downloaded from http://pubs.geoscienceworld.org/gsa/lithosphere/article-pdf/5/1/151/3723189/151.pdf by guest on 01 October 2021 Klamath salient offset | RESEARCH

Snoke, A.W., and Barnes, C.G., 2006, The development of tec- Surpless, K.D., Graham, S.A., Covault, J.A., and Wooden, lera: Middle Jurassic (pre-Nevadan) regional metamor- tonic concept for the Klamath Mountains province, Cali- J.L., 2006, Does the Great Valley Group contain Juras- phism and thrust faulting within an active arc environ- fornia and Oregon, in Snoke, A.W., and Barnes, C.G., sic strata? Reevaluation of the age and early evolution ment, Klamath Mountains, California: Geological Society eds., Geological Studies in the Klamath Mountains of a classic forearc basin: Geology, v. 34, p. 21–24, of America Bulletin, v. 100, p. 859–876, doi:10.1130/0016 Province, California and Oregon: A Volume in Honor of doi:10.1130/G21940.1. -7606(1988)100<0859:AEVOJO>2.3.CO;2. William P. Irwin: Geological Society of America Special U.S. Geological Survey and California Division of Mines and Wright, J.E., and Wyld, S.J., 1994, The Rattlesnake Creek ter- Paper 410, p. 1–29. Geology, 1966, Geologic Map of California: U.S. Geo- rane, Klamath Mountains, California: An early Mesozoic Snow, C.A., and Ernst, W.G., 2008, Detrital zircon constraints logical Survey Miscellaneous Geologic Investigations volcanic arc and its basement of tectonically disrupted on sediment distribution and provenance of the Mari- Map I-512, scale 1:2,500,000. oceanic crust: Geological Society of America Bulletin, posa Formation, central Sierra Nevada foothills, Califor- Wakabayashi, J., 1992, Nappes, tectonics of oblique plate v. 106, p. 1033–1056, doi:10.1130/0016-7606(1994)106 nia, in Wright, J.E., and Shervais, J.W., eds., Arcs, Ophio- convergence, and metamorphic evolution related to <1033:TRCTKM>2.3.CO;2. lites, and Batholiths: A Tribute to Cliff Hopson: Geological 140 million years of continuous subduction, Franciscan Wright, J.E., and Wyld, S.J., 2007, Alternative tectonic model Society of America Special Paper 438, p. 311–330. Complex, California: The Journal of Geology, v. 100, for Late Jurassic through Early Cretaceous evolution Snow, C.A., and Scherer, H.H., 2006, Terranes of the western p. 19–40, doi:10.1086/629569. of the Great Valley Group, California, in Cloos, M., Sierra Nevada Foothills metamorphic belt, California: Wakabayashi, J., 1999, Subduction and the rock record: Con- Carlson, W.D., Gilbert, M.C., Liou, J.G., and Sorensen, A critical review: International Geology Review, v. 48, cepts developed in the Franciscan Complex, California, S.S., eds., Convergent Margin Tectonics and Associ- p. 46–62, doi:10.2747/0020-6814.48.1.46. in Moores, E.M., Sloan, D., and Stout, D.L. eds., Classic ated Regions: Geological Society of America Special Stern, T.W., Bateman, P.C., Morgan, B.A., Newell, M.F., and Cordilleran Concepts: A View from California: Geologi- Paper 419, p. 81–95. Peck, D.L., 1981, Isotopic U-Pb Ages of Zircon from the cal Society of America Special Paper 338, p. 123–133. Granitoids of the Central Sierra Nevada, California: U.S. Wooden, J.L., Kistler, R.W., and Tosdal, R.M., 1999, Strontium, Geological Survey Professional Paper H85, 17 p. Lead, and Oxygen Isotopic Data for Granitoid and Vol- Surpless, K.D., 2011, Detailed provenance of the Hornbrook canic Rocks from the Northern Great Basin and Sierra MANUSCRIPT RECEIVED 19 JULY 2012 Formation, Oregon and California: Understanding a Nevada, California, Nevada, and Utah: U.S. Geological REVISED MANUSCRIPT RECEIVED 25 SEPTEMBER 2012 critical link in Cordilleran paleogeography: Geologi- Survey Open-File Report 99-569, 20 p. MANUSCRIPT ACCEPTED 12 OCTOBER 2012 cal Society of America Abstracts with Programs, v. 43, Wright, J.E., and Fahan, M.R., 1988, An expanded view of no. 5, p. 42–43. Jurassic orogenesis in the western United States Cordil- Printed in the USA

Erratum

Metamorphic constraints on the character and displacement of the South Tibetan fault system, central Bhutanese Himalaya F.J. Cooper, K.V. Hodges, and B.A. Adams (v. 5, no. 1, p. 67–81, doi: 10.1130/L221.1) In the “RSCM Thermometry” section (page 74, paragraph 5), Cooper et al. stated that both the Beyssac et al. (2002a) and Rahl et al. (2005) RSCM calibrations used a micro-Raman system with a 514 nm wavelength laser. In fact, Rahl et al. (2005) used a 532 nm laser, as did this study. Despite this, they chose not to use the Rahl et al. (2005) calibration because of the greater uncertainty stemming from the addition of peak height as a variable in the calculation.

LITHOSPHERE | Volume 5 | Number 1 | www.gsapubs.org 159

Downloaded from http://pubs.geoscienceworld.org/gsa/lithosphere/article-pdf/5/1/151/3723189/151.pdf by guest on 01 October 2021