Relay Mountain Group, Tyaughton-Methow basin, southwest British Columbia: A major Middle Jurassic to Early Cretaceous terrane overlap assemblage

Paul J Umhoefer, Paul Schiarizza, Matt Robinson

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

The upper Middle Jurassic to Lower Cretaceous Relay Mountain Group is the lower part of the northern Tyaughton-Methow basin, southwestern British Columbia. The Relay Mountain Group consists of 32700-3400 m of clastic rocks that we subdivide into three formal formations. The Callovian and lower Oxfordian Tyoax Pass Formation is marine shale and sandstone turbidites. The Teepee Mountain Formation consists of upper Oxfordian to Valanginian shallow marine clastic rocks with common Buchia and fluvial and marginal marine facies in the upper part of the unit in the northwest. These rocks overlie the lower formation across an abrupt conformable to disconformable contact. The Hauterivian (and Barremian?) Potato Range Formation consists of clastic rocks that are marine in the southeast, mainly nonmarine to the northwest, and derived from the west. This unit displays an abrupt conformable to disconformable contact with the middle formation and locally rests above the lower formation across an angular unconformity. The Relay Mountain Group and correlative strata of the southeastern Coast Belt form an overlap assemblage above the Bridge River and Cadwallader (including Methow) terranes and link them by late Middle Jurassic time. The early Relay Mountain Group appears to have been a fore-arc basin, possibly along an oblique-convergent margin in the middle unit. The upper unit indicates major changes to a back-arc basin linked to the Ottarasko, and possibly Gambier, arc to the west. This is the oldest probable link (∼130 Ma) between the southeastern and southwestern Coast belts.

Original languageEnglish (US)
Pages (from-to)1143-1167
Number of pages25
JournalCanadian Journal of Earth Sciences
Volume39
Issue number7
DOIs
StatePublished - 2002

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terrane
Jurassic
Cretaceous
clastic rock
mountain
basin
Oxfordian
Hauterivian
Valanginian
convergent margin
Callovian
Barremian
coast
potato
unconformity
shale
sandstone
river
rock

ASJC Scopus subject areas

  • Earth and Planetary Sciences (miscellaneous)

Cite this

Relay Mountain Group, Tyaughton-Methow basin, southwest British Columbia : A major Middle Jurassic to Early Cretaceous terrane overlap assemblage. / Umhoefer, Paul J; Schiarizza, Paul; Robinson, Matt.

In: Canadian Journal of Earth Sciences, Vol. 39, No. 7, 2002, p. 1143-1167.

Research output: Contribution to journalArticle

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