Eastern Klamath Terrane Research Articles

Permian Carbonate Platform Development in an Island-Arc Setting, Eastern Klamath Terrane, California

The McCloud Limestone, eastern Klamath terrane, California, represents one of several areas of carbonate deposition in an Early Permian island arc west of North America. The McCloud formed isolated platforms about 30 km long. Platform development began on volcanic highs as bank deposits and ramps of mixed volcaniclastic and carbonate sediments. Continued bank growth resulted in slope deposits of argillaceous spiculitic wackestone, limestone conglomerates, and limestone turbidites. Lateral growth of platforms occurred by progradation of slope deposits, and platform top deposits consisted mainly of packstone and wackestone of subtidal origin. Rapid subsidence of platforms resulted in sediment accumulation rates of up to 30 cm/1000 yr. The data presented here help to characterize the tectonosedimentary regimes of island arcs in general.

Carbonate Bank Sedimentation in a Volcaniclastic Arc Setting: Lower Carboniferous Limestones of the Eastern Klamath Terrane, California

ABSTRACT Carboniferous volcaniclastic-arc deposits of the eastern Klamath terrane, California, include Late Visean/Namurian limestone lenses that formed as small carbonate banks. The limestone lenses, within the Bragdon and Baird formations, reach 17 m in thickness and 1.2 km in length. Slope deposits consist of argillaceous spiculitic wackestone, and bank-edge deposits include ooid grainstone, Striatifera packstone, argillaceous phylloid algal packstone, and argillaceous skeletal packstone. Bank-interior deposits include skeletal wackestone/packstone and argillaceous sandy mudstone. The limestone lenses overlie proximal deltaic deposits of thick-bedded volcaniclastic sandstone and conglomerate. Carbonate banks developed on delta lobes during intervals of minimal clastic sedimentation, ossibly related to sea-level rise and volcanic quiescence. The carbonate banks were short-lived depositional systems, and they were covered by prograding deposits of younger volcaniclastic sands.

Paleobiogeographic and paleogeographic significance of Permian brachiopod faunas of the Bilk Creek Limestone, Nevada, and the McCloud Limestone, California

The Bilk Creek Limestone of the Black Rock Terrane in northwestern Nevada and the McCloud Limestone of the Eastern Klamath Terrane in northern California contain a diverse and abundant Permian brachiopod fauna currently under study. The composite rock record of both limestones spans the Wolfcampian and Leonardian stages of the Permian, during which both terranes were part of a volcanic arc separated from the North American continent by a marginal basin of unknown dimension. Brachiopods of this volcanic arc provide important evidence bearing on current hypotheses of Permian paleobiogeography and paleogeography.The Bilk Creek/ McCloud brachiopods are best characterized as an endemic fauna of a unique province and not as a mixed, “Tethyan” and North American fauna. The central problem of these arc faunas is not how similar they are to faunas of the Tethyan basin but why they are so dissimilar from North American faunas. Overlying rock units in both terranes contain Guadalupian brachiopod faunas that are North American in character. The paleobiogeographic pattern is one of decreasing levels of endemism throughout the Wolfcampian and Leonardian, to ultimate deprovincialization during the Guadalupian. This is not consistent with a pantropic dispersal hypothesis.The temporal pattern is consistent with a paleogeographic hypothesis of initial, long-distance separation of arc and continent with convergence of the arc toward the North American continental margin. The dissimilarity of the arc brachiopod faunas to coeval, same-environment faunas of North America suggests that the marginal basin that separated the two must have been several thousand kilometers wide during the Early Permian, producing the endemic fauna. A Japan-style model, with arc and continent in close proximity is not supported.

Stratigraphic evolution of the Paleozoic Stikine assemblage in the Stikine and Iskut rivers area, northwestern British Columbia

The Stikine assemblage, the "basement" of Stikinia, extends 500 km along the western flank of the Intermontane Belt, east of younger Coast Belt plutons. Four different stratigraphic successions are characteristic of Lower to Middle Devonian, Carboniferous and Permian rocks in the Stikine and Iskut rivers area. West of Forrest Kerr Creek are penetratively deformed Lower to Middle Devonian island-arc volcaniclastic rocks, coralline limestone, and felsic tuff. Fringing carbonate buildups in an arc setting are best illustrated in the sequence at Round Lake where Lower Carboniferous mafic-dominated, bimodal submarine volcanic rocks grade upward into two distinctive coarse echinoderm limestone units and medial siliceous siltstone and limestone conglomerate. Conodont colour alteration indices for Lower Carboniferous rocks near Newmont Lake indicate an anomalously low-temperature thermal history. Upper Carboniferous–Permian polymictic volcanic conglomerate and Lower Permian limestone overlie these strata there. The Scud River sequence is distinguished by subgreenschist- to greenschist-grade Carboniferous(?) volcanic and sedimentary rocks overlain by a structurally thickened package (greater than 1000 m) of Lower Permian limestone. Local calcalkaline pyroclastic rocks interfinger with limestone near the top of the Scud River sequence. Basinal, shelf, and shallow-water carbonate facies developed in the Early Permian, giving way to calcalkaline volcanism in Late Permian followed by deposition of deep-water chert and argillite.The tectonic setting during the Devonian and Carboniferous is comparable with modern Pacific volcanic arcs and atolls, but there is no modern analogue for the shelf-carbonate accumulation during the Early Permian which characterizes the Stikine assemblage and permits Cordilleran-scale correlations. Permian fusulinid and coral species have very close affinity to those of the McCloud Limestone of the eastern Klamath Mountains, California. Other geologic events common to both Stikinia and the Eastern Klamath terrane are Devonian limestone breccia deposition, Lower Permian limestone accumulation with McCloud faunal affinity, Carboniferous and Permian calcalkaline volcanism, and Upper Permian tuffaceous limestone. Stratigraphic differences include the absence of quartz detritus in Devonian strata and lack of thick Upper Permian volcanic rocks in the Stikine River area.

The origin of geochemical variations in a late permian volcanic arc, eastern klamath mountains, California

Volcanic are remnants present in the eastern Klamath terranes record an intermittent volcanism from Ordovician to Early Jurassic times. The Upper Permian volcanics (Nosoni, Dekkas and Bully Hill formations) consist mainly of andesites with minor basalts and rhyolites, metamorphosed in the prehnite-pumpellyite facies. Their petrographic and geochemical characters indicate a mature island-arc setting, but their tholeiitic affinity suggests an intra-oceanic environment. Nd isotopic compositions of the Nosoni-Dekkas lavas ( εNd T = +4 to +8), as well as a preferential enrichment of light rare-earth over high-field-strength elements and systematic negative Ce anomalies, point to MORB-type mantle sources contaminated by a few percent of slab-derived sediments. Large variations in the chondrite-normalized La/Yb ratio (0.95 to 3.7) are interpreted in terms of variable depth and degree of partial melting. Two distinctive basalt-types are found at the top of the Nosoni Formation (Dekkas Saddle) and the Bully Hill Formation. The former are high-Mg basalts showing a strong enrichment in incompatible elements (La/Yb ∼ 50, 8.7 ppm Th, ∼ 50 ppm Nb) but low TiO 2, Al 2O 3, Yb, Zr and Sr contents, with a pronounced positive Eu anomaly. They may result from small degrees of partial melting of a refractory peridotitic source enriched by felsic melts derived from subducted MORB, with garnet in the residue. These lavas probably record a transient anomalous thermal regime in the deepest part of the subduction zone, and can be compared to some extent to the arc alkali series. On the other hand, the Bully Hill basalt shows boninitic affinities and probably originated from a shallower lithospheric mantle source. The large range of compositions recorded by the Permian arc lavas gives evidence of efficient extraction of melts segregated at different depths.

Permian and Triassic Paleogeography of the Eastern Klamath Arc and Eastern Hayfork Subduction Complex, Klamath Mountains, California: Evidence from Lithotectonic Associations and Detrital Zircon

Middle Permian and Middle Triassic volcanic-hypabyssal intrusive complexes form ensimatic arc deposits in the eastern Klamath terrane. Sedimentary matrix melange with blocks of sandstone, chert, and Tethyan fauna-bearing limestone compose the westward-lying eastern Hayfork terrane. Limestone olistoliths were derived from seamounts and incorporated into a subduction complex that was active during the Late Triassic and perhaps as early as the Permian. Geologic and biogeographic relations have previously been interpreted to imply a genetic relation between an ensimatic arc and subduction complex, constraining Permian(?)-Triassic subduction as eastward dipping.

Paleomagnetic study of the Eastern Klamath terrane, California, and implications for the tectonic history of the Klamath Mountains Province

Paleomagnetic study of Permian through Jurassic volcanic and sedimentary strata of the Eastern Klamath terrane has shown the remanent magnetization of many of these rocks to be prefolding and most likely primary. Similarities in magnetic declinations recorded by coeval strata over a broad area are consistent with the hypothesis that the terrane, in general, has behaved as a single rigid block. Paleomagnetic data indicate that the volcanic island arc represented by this terrane, the nucleus of the province, was facing toward the present southwest during late Paleozoic time, although its orientation during earlier periods is unknown. Whether the arc was separated from the North American craton by a small marginal basin or originated far offshore cannot be determined from paleomagnetic data. The declination anomalies for both Permian and Triassic strata are similar (average = 106° ± 12°), so we infer that clockwise rotation of the late Paleozoic arc did not begin until latest Triassic or earliest Jurassic time. The arc may have completed its initial rotation with respect to stable North America by Middle Jurassic time. After some retrograde motion, the arc was again facing west by the Late Jurassic, by which time some of the more westerly terranes of the province had become attached to the Eastern Klamath terrane. The composite Klamath Mountains terranes continued to rotate until the final 60° of clockwise rotation was nearly complete by the Early Cretaceous. Coincidence of the waning stages of rotation, at about 136 Ma, with the beginning of deposition of the basal Great Valley sequence onto the Klamath basement probably represents the completion of accretion of the Klamath Mountains terranes to the North American continent. Nearly all the rotation occurred while the Klamath Mountains terranes were part of a converging oceanic plate, with only about 20° of rotation in mid‐Tertiary time during Basin and Range extension. No data currently available show evidence for any significant latitudinal displacement of any Klamath Mountains terranes relative to cratonic North America.

Submarine-fan characteristics and dual sediment provenance, Lower Carboniferous Bragdon Formation, eastern Klamath terrane, California

The Carboniferous Bragdon Formation comprises sandstone, argillite, and conglomerate, which were deposited in a hybrid submarine-fan setting. The Bragdon Formation contains a crudely progradational succession of sand-rich turbidites and intercalated channel fill and debris flows. Apparent paucity of fine-grained rocks and relatively high sedimentation rates may suggest deposition within a small, rapidly subsiding, ponded basin. Three end-member petrologic sandstone types include (i) quartz-rich, chert-rich, and sedimentary-lithic-rich sandstone, (ii) volcanic-lithic- and feldspar-rich sandstone, and (iii) crystal-rich sandstone and tuffaceous argillite. The compositions reflect basement uplift, arc dissection, and the persistence of volcanism, respectively. Interbedded strata of differing provenance, together with little or no provenance mixing within beds, indicate multicomponent source terranes, line-source sediment dispersal pattern, and limited transport distances.Facies associations and provenance together suggest extension or transtension within an arc-related basinal setting during the Late Devonian and Early Carboniferous, resulting in deposition of epiclastic sediments that were rich in sedimentary rock fragments in a Paleozoic succession otherwise dominated by volcaniclastic rocks or fringing carbonates. Mid-Paleozoic chert-rich epiclastic strata are widespread within the western Cordillera in a variety of tectonic regimes that may be broadly related to the same oblique plate margin.

Extensional faulting in southern Klamath Mountains, California

Large northeast striking normal faults in the southern Klamath Mountains may indicate that substantial crustal extension occurred during Tertiary time. Some of these faults form grabens in the Jurassic and older bedrock of the province. The grabens contain continental Oligocene or Miocene deposits (Weaverville Formation), and in two of them the Oligocene or Miocene is underlain by Lower Cretaceous marine formations (Great Valley sequence). At the La Grange gold placer mine the Oligocene or Miocene strata dip northwest into the gently southeast dipping mylonitic footwall surface of the La Grange fault. The large normal displacement required by the relations at the La Grange mine is also suggested by omission of several kilometers of structural thickness of bedrock units across the northeast continuation of the La Grange fault, as well as by significant changes in bedrock across some northeast striking faults elsewhere in the Central Metamorphic and Eastern Klamath belts. The Trinity ultramafic sheet crops out in the Eastern Klamath terrane as part of a broad northeast trending arch that may be structurally analogous to the domed lower plate of metamorphic core complexes found in eastern parts of the Cordillera. The northeast continuation of the La Grange fault bounds the southeastern side of the Trinity arch in the Eastern Klamath terrane and locally cuts out substantial lower parts of adjacent Paleozoic strata of the Redding section. Faults bounding the northwestern side of the Trinity arch generally trend northeast and juxtapose stacked thrust sheets of lower Paleozoic strata of the Yreka terrane against the Trinity ultramafic sheet. Geometric relations suggest that the Tertiary extension of the southern Klamath Mountains was in NW‐SE directions and that the Redding section and the southern part of the Central Metamorphic terrane may be a large Tertiary allochthon detached from the Trinity ultramafic sheet. Paleomagnetic data indicate a lack of rotation about a vertical axis during the extension. We propose that the Trinity ultramafic sheet is structurally analogous to a metamorphic core complex; if so, it is the first core complex to be described that involves ultramafic rocks. We infer that Mesozoic terrane accretion produced a large gravitational instability in the crust that spread laterally during Tertiary extension.

Intra-arc sedimentation and tectonism: Late Paleozoic evolution of the eastern Klamath terrane, California

Rocks of the eastern Klamath terrane (Redding section) in northern California record deposition, magmatism, and tectonism in an island-arc setting. Volcanism and sedimentation persisted for more than 220 m.y., spanning Devonian to Middle Jurassic time, and yielding thick successions of water-laid volcanic debris and lavas, with interstratified carbonate and clastic sequences. This study focuses on the upper Paleozoic rocks within the section. The oldest rocks studied, within the Upper Devonian(?) and Mississippian Brag-don Formation, contain epiclastic debris that was deposited in a submarine-fan setting. Sandstone compositions indicate that quartzose sedimentary and metasedimentary rocks formed the source area for epiclastic debris and that volcanism persisted throughout sedimentation. Transitional shallow-water facies in the upper part of the Bragdon interfinger with the overlying Baird Formation, which contains abundant volcanic debris. Volcanogenic shelf and strandline deposits characterize the lower part of the formation, and volcaniclastic turbidites characterize the upper part. The Baird Formation is locally interfingered with the overlying Lower Permian McCloud Limestone, which records two stages of Early Permian carbonate platform development: early Wolfcampian and late Wolfcampian to early Leonardian. Only the younger of the two platforms is present within the study area, and it contains more distal facies than those preserved to the south. The strata contain abundant fusulinids and corals which provide age constraints for carbonate-platform development and form the basis for regional biogeographic correlation. The time-transgressive Upper Permian Bollibokka Group (Nosoni and Dekkas Formations) succeeds the McCloud Limestone, comprising thick sequences of volcanogenic debris, intercalated lava, and, in the upper part, lenses of shallow-water limestone. The Upper Permian strata reflect volcanism and rapid subsidence within the are. All upper Paleozoic units were intruded by small gabbroic bodies and diabase dikes which may be partly cogenetic with Upper Permian basalts in the upper Dekkas Formation. The upper Paleozoic succession records local pulses of magmatism and variable subsidence rates within the eastern Klamath arc. Mississippian epiclastic rocks reflect uplift of the volcanic-arc basement, which contained rocks similar to those now exposed in the adjacent Yreka terrane or Shoo Fly Complex. Pulses in volcanism were restricted to mid-Carboniferous and Late Permian time. Diminished volcanism during the Early Permian allowed development of carbonate platforms. Rapid fluctuations of sedimentation and sub-sidence rates; pronounced lateral facies and age variations; accumulation of thick, volcanic-debris aprons during episodic volcanism; and sporadic persistence of volcanism during apparent lulls characterized deposition within this succession and are common processes in modern volcanic arcs. The stratigraphic record is composed predominantly of volcanogenic rocks and lesser carbonates, reflecting events and processes within the arc itself. Evidence for nearby basins or landmasses is sparse. The Mississippian epiclastic rocks, however, which were derived from the arc basement, reflect an ultimate sialic crustal source. Comparison of volcanic-arc evolution with the late Paleozoic evolution of continental margin and basinal rocks to the east indicates possible paleogeo-graphic ties between the eastern Klamath volcanic arc and rocks of the Golconda allochthon or the North American continent.

Early Paleozoic magmatic events in the eastern Klamath Mountains, northern California

Research Article| February 01, 1988 Early Paleozoic magmatic events in the eastern Klamath Mountains, northern California E. Timothy Wallin; E. Timothy Wallin 1Department of Geology, University of Kansas, Lawrence, Kansas 66045 Search for other works by this author on: GSW Google Scholar James M. Mattinson; James M. Mattinson 2Department of Geological Sciences, University of California, Santa Barbara, California 93106 Search for other works by this author on: GSW Google Scholar A. W. Potter A. W. Potter 3Department of Geology, Oregon State University, Corvallis, Oregon 97331 Search for other works by this author on: GSW Google Scholar Author and Article Information E. Timothy Wallin 1Department of Geology, University of Kansas, Lawrence, Kansas 66045 James M. Mattinson 2Department of Geological Sciences, University of California, Santa Barbara, California 93106 A. W. Potter 3Department of Geology, Oregon State University, Corvallis, Oregon 97331 Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1988) 16 (2): 144–148. https://doi.org/10.1130/0091-7613(1988)016<0144:EPMEIT>2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation E. Timothy Wallin, James M. Mattinson, A. W. Potter; Early Paleozoic magmatic events in the eastern Klamath Mountains, northern California. Geology 1988;; 16 (2): 144–148. doi: https://doi.org/10.1130/0091-7613(1988)016<0144:EPMEIT>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract New U-Pb zircon ages for nine samples of tonalite and pegmatitic trondhjemite from the Trinity ophiolite and associated melange reveal a complex history of magmatic activity extending back into the earliest Cambrian, much older than previously believed. Earlier investigations, based on limited data, recognized lower Paleozoic crustal elements in the eastern Klamath terrane (EKT) ranging in age from Middle Ordovician to Early to Middle Devonian. The new work in the Yreka-Callahan area of the EKT confirms the Ordovician (440-475 Ma) and younger ages, but reveals for the first time the presence of tonalitic rocks that crystallized during a narrow time interval at about 565-570 Ma. We also recognize younger, Late Silurian magmatism at 412 Ma. In the context of available mapping, these ages indicate that the Trinity ophiolite is broadly polygenetic because parts of it yield crystallization ages that span approximately 150 m.y. Superjacent dismembered units of probable early Paleozoic age may be tectonostratigraphically equivalent to the Sierra City melange in the northern Sierra Nevada. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Paleomagnetic results from the Shasta Bally Plutonic Belt in the Klamath Mountains Province, northern California

Available paleomagnetic data show approximately 100° of clockwise rotation for Permian and Triassic strata of the Eastern Klamath terrane. Jurassic strata of this terrane are rotated approximately 60° clockwise, which is comparable to rotations reported for Jurassic plutons that occur elsewhere in the Klamath Mountains province. Paleomagnetic data obtained during the present study from the Shasta Bally belt of Cretaceous plutons indicate 25.7° ± 13.6° of clockwise rotation for the province since Early Cretaceous time (≃ 136 Ma). The waning stages of rotation at the time of emplacement of the Shasta Bally belt plutons, which was closely followed by deposition of basal strata (Lower Cretaceous) of the Great Valley sequence, probably represents completion of accretion of the province to cratonic North America.

Phanerozoic continental accretion and the metamorphic evolution of northern and central california

The late Paleozoic and younger tectonic fabric of California north of the Transverse Ranges consists of accreted exotic and parautochthonous lithic belts which extend north-south and northwest-southeast, separated from one another by subvertical strike-slip faults and gently to steeply east-dipping thrust faults. Where recognizable, folds in general verge to the west and stratigraphic tops face east, a rough but systematic westward decrease in geologic age and metamorphic intensity may also be recognized. Exotic terranes of uncertain provenance include the central metamorphic belt of the Klamath Mountains, and the Salina-Sur-Obispo composite block of the central Coast Ranges. Pre-Permian sections of the eastern Klamath terrane and portions of the Sierran Calaveras-Melones complex may also represent far-traveled crustal entities. Allochthonous oceanic basement, seamounts, and pelagic sediments are additional transported materials widespread in most of the parautochthonous lithotectonic belts that make up much of the rest of northern and central California, ophiolitic assemblages are especially abundant along the fault zones which mark boundaries between these units. The parautochthonous lithotectonic belts appear to have been constructed in the vicinity of the continental margin and/or an offshore arc, judging from the nature and provenance of their constituent igneous and sedimentary rocks, intimately associated tholeiitic-calc-alkaline complexes indicate that, at least locally, ophiolite generation occurred nearby. The Salinia-Sur-Obispo amalgamated terrane exhibits the effects of fragmentation and removal of crust—now represented by the suture juxtaposing the two blocks. Other areas may have been subjected to similar truncations, but relationships are not as clear. Far-traveled terranes are characterized by ages of formation and recrystallization foreign to surrounding units, the nature of the protoliths and grades of metamorphism developed within them contrast with those of juxtaposed lithotectonic belts. On the other hand, essentially in situ growth of many Californian lithotectonic belts is suggested by a gradually decreasing age of formation and both monotonically decreasing times and grades of metamorphism proceeding towards the Pacific basin. Some parautochthonous units as well as exotic terranes are locally bounded by discontinuous blueschist belts, the latter attesting to at least episodic preservation of the effects of subduction, metamorphism and offloading into the accreting continental margin. Phanerozoic evolution of northern and central California thus apparently consisted of a more or less in situ seaward encroachment of the continental margin relative to the craton involving occasional truncation and loss of section, with a concomitant semi-continuous or episodic incorporation of allochthonous seamounts, oceanic crust, and deep-sea sediments and the less frequent arrival and juxtaposition of exotic microcontinental fragments of problematic but distant source.

Paleomagnetism of the Devonian Kennett Limestone and the rotation of the eastern Klamath Mountains, California

The Devonian Kennett Limestone in the Eastern Klamath terrane in northern California has a stable magnetization that was acquired after the folding of the formation apparently in the very early Cretaceous. The mean paleomagnetic vector has the direction I = −49°, D = 219°, A95 = 7.2° and the parameters of the corresponding paleomagnetic pole are latitude = 57°, longitude = 332°, A95 = 7.4°. All of the stably magnetized specimens have a single polarity. We propose that the magnetization be associated with the emplacement of the Shasta Bally batholith during the M17 reversed interval at 134 Ma. The firmest conclusion that can be drawn from these data is that the Eastern Klamath terrane has undergone 70 ± 11° of clockwise rotation, since the Early Cretaceous. This result does not support earlier tectonic models in which either the entire Klamaths or terranes on the south side of the Klamaths rotated in a counterclockwise sense. The close agreement between the amount of clockwise rotation and that observed in the Oregon Coast Range to the north of the Klamaths suggests that both may reflect the same tectonic process. The data may suggest a few hundred kilometers of northwestward translation of the terrane since the Early Cretaceous.