U-Th-Pb geochronology of the Coast Mountains batholith in north-coastal British Columbia: Constraints on age and tectonic evolution

George E Gehrels, M. Rusmore, G. Woodsworth, M. Crawford, C. Andronicos, L. Hollister, J. Patchett, Mihai N Ducea, R. Butler, K. Klepeis, C. Davidson, R. Friedman, J. Haggarf, B. Mahoney, W. Crawford, D. Pearson, J. Girardi

Research output: Contribution to journalArticle

159 Citations (Scopus)

Abstract

Previously published and new U-Pb geochronologic analyses provide 313 zircon and 59 titanite ages that constrain the igneous and cooling history of the Coast Mountains batholith in north-coastal British Columbia. First-order findings are as follows: (1) This segment of the batholith consists of three portions: a western magmatic belt (emplaced into the outboard Alexander and Wrangellia terranes) that was active 177-162 Ma, 157-142 Ma, and 118-100 Ma; an eastern belt (emplaced into the inboard Stikine and Yukon-Tanana terranes) that was active ca. 180-110 Ma; and a 100-50 Ma belt that was emplaced across much of the orogen during and following mid-Cretaceous juxtapo sition of outboard and inboard terranes. (2) Magmatism migrated eastward from 120 to 80 (or 60) Ma at a rate of 2.0-2.7 km/Ma, a rate similar to that recorded by the Sierra Nevada batholith. (3) Magmatic flux was quite variable through time, with high (>35-50 km3/Ma per km strike length) flux at 160-140 Ma, 120-78 Ma, and 55-48 Ma, and magmatic lulls at 140-120 Ma and 78-55 Ma. (4) High U/Th values record widespread growth (and/or recrystallization) of metamorphic zircon at 88-76 Ma and 62-52 Ma. (5) U-Pb ages of titanite record rapid cooling of axial portions of the batholith at ca. 55-48 Ma in response to east-side-down motion on regional extensional structures. (6) The magmatic history of this portion of the Coast Mountains batholith is consistent with a tectonic model involving formation of a Late Jurassic-earliest Cretaceous magmatic arc along the northern Cordilleran margin; duplication of this arc system in Early Cretaceous time by >800 km (perhaps 1000-1200 km) of sinistral motion (bringing the northern portion outboard of the southern portion); high-flux magmatism prior to and during orthogonal mid-Cretaceous terrane accretion; low-flux magmatism during Late Cretaceous-Paleocene dextral transpressional motion; and high-flux Eocene magmatism during rapid exhumation in a regime of regional crustal extension.

Original languageEnglish (US)
Pages (from-to)1341-1361
Number of pages21
JournalBulletin of the Geological Society of America
Volume121
Issue number9-10
DOIs
StatePublished - 2009

Fingerprint

batholith
tectonic evolution
geochronology
magmatism
terrane
Cretaceous
mountain
coast
titanite
zircon
cooling
history
exhumation
Paleocene
Eocene
Jurassic
accretion
tectonics
rate

ASJC Scopus subject areas

  • Geology

Cite this

U-Th-Pb geochronology of the Coast Mountains batholith in north-coastal British Columbia : Constraints on age and tectonic evolution. / Gehrels, George E; Rusmore, M.; Woodsworth, G.; Crawford, M.; Andronicos, C.; Hollister, L.; Patchett, J.; Ducea, Mihai N; Butler, R.; Klepeis, K.; Davidson, C.; Friedman, R.; Haggarf, J.; Mahoney, B.; Crawford, W.; Pearson, D.; Girardi, J.

In: Bulletin of the Geological Society of America, Vol. 121, No. 9-10, 2009, p. 1341-1361.

Research output: Contribution to journalArticle

Gehrels, GE, Rusmore, M, Woodsworth, G, Crawford, M, Andronicos, C, Hollister, L, Patchett, J, Ducea, MN, Butler, R, Klepeis, K, Davidson, C, Friedman, R, Haggarf, J, Mahoney, B, Crawford, W, Pearson, D & Girardi, J 2009, 'U-Th-Pb geochronology of the Coast Mountains batholith in north-coastal British Columbia: Constraints on age and tectonic evolution', Bulletin of the Geological Society of America, vol. 121, no. 9-10, pp. 1341-1361. https://doi.org/10.1130/B26404.1
Gehrels, George E ; Rusmore, M. ; Woodsworth, G. ; Crawford, M. ; Andronicos, C. ; Hollister, L. ; Patchett, J. ; Ducea, Mihai N ; Butler, R. ; Klepeis, K. ; Davidson, C. ; Friedman, R. ; Haggarf, J. ; Mahoney, B. ; Crawford, W. ; Pearson, D. ; Girardi, J. / U-Th-Pb geochronology of the Coast Mountains batholith in north-coastal British Columbia : Constraints on age and tectonic evolution. In: Bulletin of the Geological Society of America. 2009 ; Vol. 121, No. 9-10. pp. 1341-1361.
@article{f3de9b14128444eb8b9957ed99657351,
title = "U-Th-Pb geochronology of the Coast Mountains batholith in north-coastal British Columbia: Constraints on age and tectonic evolution",
abstract = "Previously published and new U-Pb geochronologic analyses provide 313 zircon and 59 titanite ages that constrain the igneous and cooling history of the Coast Mountains batholith in north-coastal British Columbia. First-order findings are as follows: (1) This segment of the batholith consists of three portions: a western magmatic belt (emplaced into the outboard Alexander and Wrangellia terranes) that was active 177-162 Ma, 157-142 Ma, and 118-100 Ma; an eastern belt (emplaced into the inboard Stikine and Yukon-Tanana terranes) that was active ca. 180-110 Ma; and a 100-50 Ma belt that was emplaced across much of the orogen during and following mid-Cretaceous juxtapo sition of outboard and inboard terranes. (2) Magmatism migrated eastward from 120 to 80 (or 60) Ma at a rate of 2.0-2.7 km/Ma, a rate similar to that recorded by the Sierra Nevada batholith. (3) Magmatic flux was quite variable through time, with high (>35-50 km3/Ma per km strike length) flux at 160-140 Ma, 120-78 Ma, and 55-48 Ma, and magmatic lulls at 140-120 Ma and 78-55 Ma. (4) High U/Th values record widespread growth (and/or recrystallization) of metamorphic zircon at 88-76 Ma and 62-52 Ma. (5) U-Pb ages of titanite record rapid cooling of axial portions of the batholith at ca. 55-48 Ma in response to east-side-down motion on regional extensional structures. (6) The magmatic history of this portion of the Coast Mountains batholith is consistent with a tectonic model involving formation of a Late Jurassic-earliest Cretaceous magmatic arc along the northern Cordilleran margin; duplication of this arc system in Early Cretaceous time by >800 km (perhaps 1000-1200 km) of sinistral motion (bringing the northern portion outboard of the southern portion); high-flux magmatism prior to and during orthogonal mid-Cretaceous terrane accretion; low-flux magmatism during Late Cretaceous-Paleocene dextral transpressional motion; and high-flux Eocene magmatism during rapid exhumation in a regime of regional crustal extension.",
author = "Gehrels, {George E} and M. Rusmore and G. Woodsworth and M. Crawford and C. Andronicos and L. Hollister and J. Patchett and Ducea, {Mihai N} and R. Butler and K. Klepeis and C. Davidson and R. Friedman and J. Haggarf and B. Mahoney and W. Crawford and D. Pearson and J. Girardi",
year = "2009",
doi = "10.1130/B26404.1",
language = "English (US)",
volume = "121",
pages = "1341--1361",
journal = "Geological Society of America Bulletin",
issn = "0016-7606",
publisher = "Geological Society of America",
number = "9-10",

}

TY - JOUR

T1 - U-Th-Pb geochronology of the Coast Mountains batholith in north-coastal British Columbia

T2 - Constraints on age and tectonic evolution

AU - Gehrels, George E

AU - Rusmore, M.

AU - Woodsworth, G.

AU - Crawford, M.

AU - Andronicos, C.

AU - Hollister, L.

AU - Patchett, J.

AU - Ducea, Mihai N

AU - Butler, R.

AU - Klepeis, K.

AU - Davidson, C.

AU - Friedman, R.

AU - Haggarf, J.

AU - Mahoney, B.

AU - Crawford, W.

AU - Pearson, D.

AU - Girardi, J.

PY - 2009

Y1 - 2009

N2 - Previously published and new U-Pb geochronologic analyses provide 313 zircon and 59 titanite ages that constrain the igneous and cooling history of the Coast Mountains batholith in north-coastal British Columbia. First-order findings are as follows: (1) This segment of the batholith consists of three portions: a western magmatic belt (emplaced into the outboard Alexander and Wrangellia terranes) that was active 177-162 Ma, 157-142 Ma, and 118-100 Ma; an eastern belt (emplaced into the inboard Stikine and Yukon-Tanana terranes) that was active ca. 180-110 Ma; and a 100-50 Ma belt that was emplaced across much of the orogen during and following mid-Cretaceous juxtapo sition of outboard and inboard terranes. (2) Magmatism migrated eastward from 120 to 80 (or 60) Ma at a rate of 2.0-2.7 km/Ma, a rate similar to that recorded by the Sierra Nevada batholith. (3) Magmatic flux was quite variable through time, with high (>35-50 km3/Ma per km strike length) flux at 160-140 Ma, 120-78 Ma, and 55-48 Ma, and magmatic lulls at 140-120 Ma and 78-55 Ma. (4) High U/Th values record widespread growth (and/or recrystallization) of metamorphic zircon at 88-76 Ma and 62-52 Ma. (5) U-Pb ages of titanite record rapid cooling of axial portions of the batholith at ca. 55-48 Ma in response to east-side-down motion on regional extensional structures. (6) The magmatic history of this portion of the Coast Mountains batholith is consistent with a tectonic model involving formation of a Late Jurassic-earliest Cretaceous magmatic arc along the northern Cordilleran margin; duplication of this arc system in Early Cretaceous time by >800 km (perhaps 1000-1200 km) of sinistral motion (bringing the northern portion outboard of the southern portion); high-flux magmatism prior to and during orthogonal mid-Cretaceous terrane accretion; low-flux magmatism during Late Cretaceous-Paleocene dextral transpressional motion; and high-flux Eocene magmatism during rapid exhumation in a regime of regional crustal extension.

AB - Previously published and new U-Pb geochronologic analyses provide 313 zircon and 59 titanite ages that constrain the igneous and cooling history of the Coast Mountains batholith in north-coastal British Columbia. First-order findings are as follows: (1) This segment of the batholith consists of three portions: a western magmatic belt (emplaced into the outboard Alexander and Wrangellia terranes) that was active 177-162 Ma, 157-142 Ma, and 118-100 Ma; an eastern belt (emplaced into the inboard Stikine and Yukon-Tanana terranes) that was active ca. 180-110 Ma; and a 100-50 Ma belt that was emplaced across much of the orogen during and following mid-Cretaceous juxtapo sition of outboard and inboard terranes. (2) Magmatism migrated eastward from 120 to 80 (or 60) Ma at a rate of 2.0-2.7 km/Ma, a rate similar to that recorded by the Sierra Nevada batholith. (3) Magmatic flux was quite variable through time, with high (>35-50 km3/Ma per km strike length) flux at 160-140 Ma, 120-78 Ma, and 55-48 Ma, and magmatic lulls at 140-120 Ma and 78-55 Ma. (4) High U/Th values record widespread growth (and/or recrystallization) of metamorphic zircon at 88-76 Ma and 62-52 Ma. (5) U-Pb ages of titanite record rapid cooling of axial portions of the batholith at ca. 55-48 Ma in response to east-side-down motion on regional extensional structures. (6) The magmatic history of this portion of the Coast Mountains batholith is consistent with a tectonic model involving formation of a Late Jurassic-earliest Cretaceous magmatic arc along the northern Cordilleran margin; duplication of this arc system in Early Cretaceous time by >800 km (perhaps 1000-1200 km) of sinistral motion (bringing the northern portion outboard of the southern portion); high-flux magmatism prior to and during orthogonal mid-Cretaceous terrane accretion; low-flux magmatism during Late Cretaceous-Paleocene dextral transpressional motion; and high-flux Eocene magmatism during rapid exhumation in a regime of regional crustal extension.

UR - http://www.scopus.com/inward/record.url?scp=70449381490&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=70449381490&partnerID=8YFLogxK

U2 - 10.1130/B26404.1

DO - 10.1130/B26404.1

M3 - Article

AN - SCOPUS:70449381490

VL - 121

SP - 1341

EP - 1361

JO - Geological Society of America Bulletin

JF - Geological Society of America Bulletin

SN - 0016-7606

IS - 9-10

ER -