Tectonic evolution of the Jurassic-Cretaceous Great Valley forearc, California: Implications for the Franciscan thrust-wedge hypothesis

K. N. Constenius, Roy A Johnson, W. R. Dickinson, T. A. Williams

Research output: Contribution to journalArticle

54 Citations (Scopus)

Abstract

Interpretation of seismic reflection data and restoration of depositional geometries of Cretaceous forearc basin strata in the northwest Great Valley of California provide important controls on structural reconstructions of the western margin of the Sacramento Valley and northern Coast Ranges. Monoclinal eastward dips of Great Valley Group strata and fault systems striking northwest-south-east, which are features proposed as evidence for a west-dippling blind Great Valley-Franciscan sole thrust and related backthrusts, instead are expressions of bedding geometry that resulted from folding of the Paskenta and related synsedimentary normal faults, depositional onlap, and a major structural-stratigraphic discontinuity. The discontinuity separates east-dipping Aptian and younger Great Valley Group strata from beds of lower Great Valley Group and Coast Range ophiolite that were deformed and erosionally or structurally truncated by mid-Cretaceous time. Dip divergence imaged between the supracrop and subcrop of the discontinuity is not unique to the ancient Great Valley forearc, but is also observed in modern forearc basins. Advocates of the Franciscan thrustwedge model have also proposed that west-dipping, shingled patterns of seismic events imaged beneath the Sacramento Valley are imbricate thrust slices of the Great Valley Group. This hypothesis, however, is incompatible with borehole, potential-field, and seismic-refraction data that characterize the Sacramento Valley basement as ophiolitic. Seaward-dipping reflections in the ophiolitic basement of the Sacramento Valley are analogous to layering developed in the oceanic crust of volcanic rifted margins or generated along midocean ridges. Thus, late-stage tectonic mechanisms are not required to interpret a forearc that owes much of its present-day bedding architecture to processes coeval with deposition. Thickening of the Great Valley Group stratigraphic section (Valanginian- Turonian) in the hanging walls of the Paskenta, Elder Creek, and Cold Fork fault zones, combined with attenuation or complete omission of preextensional units (including the Coast Range ophiolite) and geometric evidence based on seismic reconstructions, suggest that these faults are Jurassic-Cretaceous normal faults that developed in a submarine setting. Down-structure views of the Great Valley outcrop belt simplify otherwise complex map relations and portray the Paskenta and related faults as half-graben bounding faults that accommodated significant northwestward tectonic transport of hanging-wall rocks. It is significant that these faults sole into the Coast Range fault, an enigmatic forearc structure that juxtaposes rocks of the Franciscan Complex (blueschists) with rocks of the Coast Range ophiolite and Great Valley Group that have sustained only zeolite-grade metamorphism. Discovery of Jurassic-Cretaceous crustal-scale extension in the Great Valley forearc suggests that a significant part of Coast Range fault-related attenuation developed early in the history of the subduction complex.

Original languageEnglish (US)
Pages (from-to)1703-1723
Number of pages21
JournalBulletin of the Geological Society of America
Volume112
Issue number11
DOIs
StatePublished - 2000
Externally publishedYes

Fingerprint

tectonic evolution
thrust
Jurassic
Cretaceous
valley
coast
ophiolite
discontinuity
forearc basin
hanging wall
normal fault
geometry
tectonics
Valanginian
blueschist
potential field
seismic refraction
Turonian
Aptian
wall rock

Keywords

  • Coast range ophiolite
  • Forearc basins
  • Franciscan complex
  • Great valley
  • Sacramento basin
  • Seismic reflection profiles

ASJC Scopus subject areas

  • Earth and Planetary Sciences (miscellaneous)

Cite this

Tectonic evolution of the Jurassic-Cretaceous Great Valley forearc, California : Implications for the Franciscan thrust-wedge hypothesis. / Constenius, K. N.; Johnson, Roy A; Dickinson, W. R.; Williams, T. A.

In: Bulletin of the Geological Society of America, Vol. 112, No. 11, 2000, p. 1703-1723.

Research output: Contribution to journalArticle

@article{05b90c31cf5140d0b2df05aa6afd25af,
title = "Tectonic evolution of the Jurassic-Cretaceous Great Valley forearc, California: Implications for the Franciscan thrust-wedge hypothesis",
abstract = "Interpretation of seismic reflection data and restoration of depositional geometries of Cretaceous forearc basin strata in the northwest Great Valley of California provide important controls on structural reconstructions of the western margin of the Sacramento Valley and northern Coast Ranges. Monoclinal eastward dips of Great Valley Group strata and fault systems striking northwest-south-east, which are features proposed as evidence for a west-dippling blind Great Valley-Franciscan sole thrust and related backthrusts, instead are expressions of bedding geometry that resulted from folding of the Paskenta and related synsedimentary normal faults, depositional onlap, and a major structural-stratigraphic discontinuity. The discontinuity separates east-dipping Aptian and younger Great Valley Group strata from beds of lower Great Valley Group and Coast Range ophiolite that were deformed and erosionally or structurally truncated by mid-Cretaceous time. Dip divergence imaged between the supracrop and subcrop of the discontinuity is not unique to the ancient Great Valley forearc, but is also observed in modern forearc basins. Advocates of the Franciscan thrustwedge model have also proposed that west-dipping, shingled patterns of seismic events imaged beneath the Sacramento Valley are imbricate thrust slices of the Great Valley Group. This hypothesis, however, is incompatible with borehole, potential-field, and seismic-refraction data that characterize the Sacramento Valley basement as ophiolitic. Seaward-dipping reflections in the ophiolitic basement of the Sacramento Valley are analogous to layering developed in the oceanic crust of volcanic rifted margins or generated along midocean ridges. Thus, late-stage tectonic mechanisms are not required to interpret a forearc that owes much of its present-day bedding architecture to processes coeval with deposition. Thickening of the Great Valley Group stratigraphic section (Valanginian- Turonian) in the hanging walls of the Paskenta, Elder Creek, and Cold Fork fault zones, combined with attenuation or complete omission of preextensional units (including the Coast Range ophiolite) and geometric evidence based on seismic reconstructions, suggest that these faults are Jurassic-Cretaceous normal faults that developed in a submarine setting. Down-structure views of the Great Valley outcrop belt simplify otherwise complex map relations and portray the Paskenta and related faults as half-graben bounding faults that accommodated significant northwestward tectonic transport of hanging-wall rocks. It is significant that these faults sole into the Coast Range fault, an enigmatic forearc structure that juxtaposes rocks of the Franciscan Complex (blueschists) with rocks of the Coast Range ophiolite and Great Valley Group that have sustained only zeolite-grade metamorphism. Discovery of Jurassic-Cretaceous crustal-scale extension in the Great Valley forearc suggests that a significant part of Coast Range fault-related attenuation developed early in the history of the subduction complex.",
keywords = "Coast range ophiolite, Forearc basins, Franciscan complex, Great valley, Sacramento basin, Seismic reflection profiles",
author = "Constenius, {K. N.} and Johnson, {Roy A} and Dickinson, {W. R.} and Williams, {T. A.}",
year = "2000",
doi = "10.1130/0016-7606(2000)112<1703:TEOTJC>2.0.CO;2",
language = "English (US)",
volume = "112",
pages = "1703--1723",
journal = "Geological Society of America Bulletin",
issn = "0016-7606",
publisher = "Geological Society of America",
number = "11",

}

TY - JOUR

T1 - Tectonic evolution of the Jurassic-Cretaceous Great Valley forearc, California

T2 - Implications for the Franciscan thrust-wedge hypothesis

AU - Constenius, K. N.

AU - Johnson, Roy A

AU - Dickinson, W. R.

AU - Williams, T. A.

PY - 2000

Y1 - 2000

N2 - Interpretation of seismic reflection data and restoration of depositional geometries of Cretaceous forearc basin strata in the northwest Great Valley of California provide important controls on structural reconstructions of the western margin of the Sacramento Valley and northern Coast Ranges. Monoclinal eastward dips of Great Valley Group strata and fault systems striking northwest-south-east, which are features proposed as evidence for a west-dippling blind Great Valley-Franciscan sole thrust and related backthrusts, instead are expressions of bedding geometry that resulted from folding of the Paskenta and related synsedimentary normal faults, depositional onlap, and a major structural-stratigraphic discontinuity. The discontinuity separates east-dipping Aptian and younger Great Valley Group strata from beds of lower Great Valley Group and Coast Range ophiolite that were deformed and erosionally or structurally truncated by mid-Cretaceous time. Dip divergence imaged between the supracrop and subcrop of the discontinuity is not unique to the ancient Great Valley forearc, but is also observed in modern forearc basins. Advocates of the Franciscan thrustwedge model have also proposed that west-dipping, shingled patterns of seismic events imaged beneath the Sacramento Valley are imbricate thrust slices of the Great Valley Group. This hypothesis, however, is incompatible with borehole, potential-field, and seismic-refraction data that characterize the Sacramento Valley basement as ophiolitic. Seaward-dipping reflections in the ophiolitic basement of the Sacramento Valley are analogous to layering developed in the oceanic crust of volcanic rifted margins or generated along midocean ridges. Thus, late-stage tectonic mechanisms are not required to interpret a forearc that owes much of its present-day bedding architecture to processes coeval with deposition. Thickening of the Great Valley Group stratigraphic section (Valanginian- Turonian) in the hanging walls of the Paskenta, Elder Creek, and Cold Fork fault zones, combined with attenuation or complete omission of preextensional units (including the Coast Range ophiolite) and geometric evidence based on seismic reconstructions, suggest that these faults are Jurassic-Cretaceous normal faults that developed in a submarine setting. Down-structure views of the Great Valley outcrop belt simplify otherwise complex map relations and portray the Paskenta and related faults as half-graben bounding faults that accommodated significant northwestward tectonic transport of hanging-wall rocks. It is significant that these faults sole into the Coast Range fault, an enigmatic forearc structure that juxtaposes rocks of the Franciscan Complex (blueschists) with rocks of the Coast Range ophiolite and Great Valley Group that have sustained only zeolite-grade metamorphism. Discovery of Jurassic-Cretaceous crustal-scale extension in the Great Valley forearc suggests that a significant part of Coast Range fault-related attenuation developed early in the history of the subduction complex.

AB - Interpretation of seismic reflection data and restoration of depositional geometries of Cretaceous forearc basin strata in the northwest Great Valley of California provide important controls on structural reconstructions of the western margin of the Sacramento Valley and northern Coast Ranges. Monoclinal eastward dips of Great Valley Group strata and fault systems striking northwest-south-east, which are features proposed as evidence for a west-dippling blind Great Valley-Franciscan sole thrust and related backthrusts, instead are expressions of bedding geometry that resulted from folding of the Paskenta and related synsedimentary normal faults, depositional onlap, and a major structural-stratigraphic discontinuity. The discontinuity separates east-dipping Aptian and younger Great Valley Group strata from beds of lower Great Valley Group and Coast Range ophiolite that were deformed and erosionally or structurally truncated by mid-Cretaceous time. Dip divergence imaged between the supracrop and subcrop of the discontinuity is not unique to the ancient Great Valley forearc, but is also observed in modern forearc basins. Advocates of the Franciscan thrustwedge model have also proposed that west-dipping, shingled patterns of seismic events imaged beneath the Sacramento Valley are imbricate thrust slices of the Great Valley Group. This hypothesis, however, is incompatible with borehole, potential-field, and seismic-refraction data that characterize the Sacramento Valley basement as ophiolitic. Seaward-dipping reflections in the ophiolitic basement of the Sacramento Valley are analogous to layering developed in the oceanic crust of volcanic rifted margins or generated along midocean ridges. Thus, late-stage tectonic mechanisms are not required to interpret a forearc that owes much of its present-day bedding architecture to processes coeval with deposition. Thickening of the Great Valley Group stratigraphic section (Valanginian- Turonian) in the hanging walls of the Paskenta, Elder Creek, and Cold Fork fault zones, combined with attenuation or complete omission of preextensional units (including the Coast Range ophiolite) and geometric evidence based on seismic reconstructions, suggest that these faults are Jurassic-Cretaceous normal faults that developed in a submarine setting. Down-structure views of the Great Valley outcrop belt simplify otherwise complex map relations and portray the Paskenta and related faults as half-graben bounding faults that accommodated significant northwestward tectonic transport of hanging-wall rocks. It is significant that these faults sole into the Coast Range fault, an enigmatic forearc structure that juxtaposes rocks of the Franciscan Complex (blueschists) with rocks of the Coast Range ophiolite and Great Valley Group that have sustained only zeolite-grade metamorphism. Discovery of Jurassic-Cretaceous crustal-scale extension in the Great Valley forearc suggests that a significant part of Coast Range fault-related attenuation developed early in the history of the subduction complex.

KW - Coast range ophiolite

KW - Forearc basins

KW - Franciscan complex

KW - Great valley

KW - Sacramento basin

KW - Seismic reflection profiles

UR - http://www.scopus.com/inward/record.url?scp=84879879436&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84879879436&partnerID=8YFLogxK

U2 - 10.1130/0016-7606(2000)112<1703:TEOTJC>2.0.CO;2

DO - 10.1130/0016-7606(2000)112<1703:TEOTJC>2.0.CO;2

M3 - Article

AN - SCOPUS:84879879436

VL - 112

SP - 1703

EP - 1723

JO - Geological Society of America Bulletin

JF - Geological Society of America Bulletin

SN - 0016-7606

IS - 11

ER -