Database for the geologic map of the Mount Baker 30-minute by 60-minute quadrangle, Washington (I-2660)

Tabor, R.W.; Haugerud, Ralph A.; Hildreth, Wes; Brown, E. H.

doi:10.3133/ds205

Cited by 27 publications

(90 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…2,3). Major components of this nappe are termed the Orcas Chert and Deadman Bay Volcanics in the San Juan Islands, and the Bell Pass mélange in the Cascades (Vance 1975;Blackwell 1983;Brandon et al 1988;Tabor et al 2003). The units consist mostly of Triassic ribbon chert and associated ocean-island basalt.…”

Section: San Juan Islands -Northwest Cascades Thrust Systemmentioning

confidence: 99%

“…This rock is named the Vedder Complex in the Cascades and Garrison Schist in the San Juan Islands. Other exotic materials are Permian limestone with Tethyan fusulinids, the large Twin Sisters dunite slab, and latest Early Cretaceous sandstone in the Bell Pass mélange (Vance 1975;Danner 1977;Brandon et al 1988;Sevigny and Brown 1989;Tabor et al 2003;Brown and Gehrels 2007). (This structural assemblage in the Cascades is termed the "Welker nappe" by Tabor et al 2003.…”

Section: San Juan Islands -Northwest Cascades Thrust Systemmentioning

confidence: 99%

“…Lithology and age of the Spieden Formation suggest a possible correlation with the Nooksack Group (Brandon et al 1988), but this connection is not supported (although not disproven) by comparison of detrital zircon age distributions in the two units ). Vance (1975), , Brandon et al (1988), England and Calon (1991), Tabor (1994), Tabor et al (2003).…”

Section: San Juan Islands -Northwest Cascades Thrust Systemmentioning

confidence: 99%

“…Another possible correlative unit in the Cascades is the Bald Mountain conglomerate (near the US -British Columbia border, Fig. 2 ;Misch 1966;Jones 1984;Lapen 2000;Tabor et al 2003). This rock is an interbedded sequence of Vance (1975), Garver (1988), and this study.…”

Section: Upright Head and Blakely Islandmentioning

confidence: 99%

“…In previous studies of the San Juan Islands and northwest Cascades, correlation of terranes and structures between the two areas is recognized (e.g., Brown and Vance 1987;Brandon et al 1988), but structural analyses have mostly focused on the two regions separately (e.g., Misch 1966;Brown 1987;Brandon et al 1988;Tabor 1994;Bergh 2002;Tabor et al 2003;Schermer et al 2007). The present study integrates structures across the thrust system as a whole and, together with new U-Pb zircon ages, further defines the geometry of the nappe pile and the process of its formation.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Obducted nappe sequence in the San Juan Islands – northwest Cascades thrust system, Washington and British Columbia

Brown

2012

Can. J. Earth Sci.

Self Cite

View full text Add to dashboard Cite

The San Juan Islands -northwest Cascades thrust system in Washington and British Columbia is composed of previously accreted terranes now assembled as four broadly defined composite nappes stacked on a continental footwall of Wrangellia and the Coast Plutonic Complex. Emplacement ages of the nappe sequence are interpreted from zircon ages, field relations, and lithlogies, to young upward. The basal nappe was emplaced prior to early Turonian time (∼93 Ma), indicated by the occurrence of age-distinctive zircons from this nappe in the Sidney Island Formation of the Nanaimo Group. The emplacement age of the highest nappe in the thrust system postdates 87 Ma detrital zircons within the nappe. The nappes bear high-pressure -low-temperature (HP-LT) mineral assemblages indicative of deep burial in a thrust wedge; however, several features indicate that metamorphism occurred prior to nappe assembly: metamorphic discontinuities at nappe boundaries, absence of HP-LT assemblages in the footwall to the nappe pile, and absence of significant unroofing detritus in the Nanaimo Group. A synorogenic relationship of the thrust system to the Nanaimo Group is evident from mutually overlapping ages and by conglomerates of Nanaimo affinity that lie within the nappe pile. From the foregoing relations, and broader Cordilleran geology, the tectonic history of the nappe terranes is interpreted to involve initial accretion and subduction-zone metamorphism south of the present locality, uplift and exhumation, orogen-parallel northward transport of the nappes as part of a forearc sliver, and finally obduction at the present site over the truncated south end of Wrangellia and the Coast Plutonic Complex.Résumé : Le système de chevauchement formé par l'archipel San Juan et le nord-ouest de la chaîne des Cascades dans l'état de Washington et la province de la Colombie-Britannique est composé de terranes anciennement accrétés et qui sont maintenant assemblés, au sens large, en quatre nappes composites empilées sur l'éponte inférieure continentale de la Wrangellie et du complexe plutonique côtier. Les âges de la mise en place de la séquence des nappes ont été détermi-nés à partir d'âges de zircons, de relations sur le terrain et des lithologies; ils sont plus jeunes vers le haut. La nappe à la base a été mise en place avant le Turonien précoce (∼93 Ma), ce qui est indiqué par la présence de zircons à âge distinctif provenant de cette nappe dans la Formation de Sidney Island du Groupe de Nanaimo. L'âge de la mise en place de la nappe supérieure dans le système de chevauchement est plus tardif que les zircons détritiques âgés de 87 Ma dans cette nappe. Les nappes comportent des assemblages de minéraux de haute pression -basse température (HP-BT) indiquant un enfouissement profond dans un prisme de chevauchement; toutefois, plusieurs caractéristiques indiquent que le métamorphisme est survenu avant l'assemblage de la nappe : des discordances métamorphiques à la limite des nappes, l'absence d'assemblages HP-BT dans l'éponte inférieure de l'empilement d...

show abstract

Section: San Juan Islands -Northwest Cascades Thrust Systemmentioning

confidence: 99%

Section: San Juan Islands -Northwest Cascades Thrust Systemmentioning

confidence: 99%

Section: San Juan Islands -Northwest Cascades Thrust Systemmentioning

confidence: 99%

Section: Upright Head and Blakely Islandmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Obducted nappe sequence in the San Juan Islands – northwest Cascades thrust system, Washington and British Columbia

Brown

2012

Can. J. Earth Sci.

Self Cite

View full text Add to dashboard Cite

show abstract

A 1‐D morphodynamic model of postglacial valley incision

Tunnicliffe

Church

2015

JGR Earth Surface

View full text Add to dashboard Cite

Chilliwack River is typical of many Cordilleran valley river systems that have undergone dramatic Holocene degradation of valley fills that built up over the course of Pleistocene glaciation. Downstream controls on base level, mainly blockage of valleys by glaciers, led to aggradation of significant glaciofluvial and glaciolacustrine valley fills and fan deposits, subsequently incised by fluvial action. Models of such large-scale, long-term degradation present a number of important challenges since the evolution of model parameters, such as the rate of bedload transport and grain size characteristics, are governed by the nature of the deposit. Sediment sampling in the Chilliwack Valley reveals a complex sequence of very coarse to fine textural modes. We present a 1-D numerical morphodynamic model for the river-floodplain system tailored to conditions in the valley. The model is adapted to dynamically adjust channel width to optimize sediment transporting capacity and to integrate relict valley fill material as the channel incises through valley deposits. Sensitivity to model parameters is studied using four principal criteria: profile concavity, rate of downstream grain size fining, bed surface sand content, and the timescale to equilibrium. Model results indicate that rates of abrasion and coarsening of the grain size distributions exert the strongest controls on all of the interrelated model performance criteria. While there are a number of difficulties in satisfying all model criteria simultaneously, results indicate that 1-D models of valley bottom sedimentary systems can provide a suitable framework for integrating results from sediment budget studies and chronologies of sediment evacuation established from dating.

show abstract

Transfer of Metasupracrustal Rocks to Midcrustal Depths in the North Cascades Continental Magmatic Arc, Skagit Gneiss Complex, Washington

et al. 2017

View full text Add to dashboard Cite

The metasupracrustal units within the north central Chelan block of the North Cascades Range, Washington, are investigated to determine mechanisms and timescales of supracrustal rock incorporation into the deep crust of continental magmatic arcs. Zircon U‐Pb and Hf‐isotope analyses were used to characterize the protoliths of metasedimentary and metaigneous rocks from the Skagit Gneiss Complex, metasupracrustal rocks from the Cascade River Schist, and metavolcanic rocks from the Napeequa Schist. Skagit Gneiss Complex metasedimentary rocks have (1) a wide range of zircon U‐Pb dates from Proterozoic to latest Cretaceous and (2) a more limited range of dates, from Late Triassic to latest Cretaceous, and a lack of Proterozoic dates. Two samples from the Cascade River Schist are characterized by Late Cretaceous protoliths. Amphibolites from the Napeequa Schist have Late Triassic protoliths. Similarities between the Skagit Gneiss metasediments and accretionary wedge and forearc sediments in northwestern Washington and Southern California indicate that the protolith for these units was likely deposited in a forearc basin and/or accretionary wedge in the Early to Late Cretaceous (circa 134–79 Ma). Sediment was likely underthrust into the active arc by circa 74–65 Ma, as soon as 7 Ma after deposition, and intruded by voluminous magmas. The incorporation of metasupracrustal units aligns with the timing of major arc magmatism in the North Cascades (circa 79–60 Ma) and may indicate a link between the burial of sediments and pluton emplacement.

show abstract

Database for the geologic map of the Mount Baker 30-minute by 60-minute quadrangle, Washington (I-2660)

Cited by 27 publications

References 30 publications

Obducted nappe sequence in the San Juan Islands – northwest Cascades thrust system, Washington and British Columbia

Obducted nappe sequence in the San Juan Islands – northwest Cascades thrust system, Washington and British Columbia

A 1‐D morphodynamic model of postglacial valley incision

Transfer of Metasupracrustal Rocks to Midcrustal Depths in the North Cascades Continental Magmatic Arc, Skagit Gneiss Complex, Washington

Contact Info

Product

Resources

About