Range-front fault scarps of the Sierra El Mayor, Baja California: Formed above an active low-angle normal fault?

Gary J. Axen, John M. Fletcher, Eric Cowgill, Michael Murphy, Paul A Kapp, Ian MacMillan, Ernesto Ramos-Velázquez, Jorge Aranda-Gómez

Research output: Contribution to journalArticle

55 Citations (Scopus)

Abstract

The Canada David detachment, a west-dipping low-angle normal fault, juxtaposes Pliocene and Pleistocene(?) sedimentary units over sheared bedrock in the Sierra El Mayor, Baja California. Along the west-central range front, the detachment is overlapped by Quaternary alluvial fans that are, in turn, cut by fault scarps up to 7 m high. Map relationships suggest that scarp-forming faults may sole into the detachment at very shallow depth (<200-300 m). Palinspastic restoration of a topographic profile across 15 north-striking scarps suggests that the ratio of net heave to net throw along scarp-forming faults is ~2, consistent with them soling into a low-angle (~30°) fault. These 15 scarps may have all formed in one earthquake, with rupture propagation from depth to the near-surface aided by clay gouge along the detachment. The detachment is abandoned in the footwall east of the scarps.

Original languageEnglish (US)
Pages (from-to)247-250
Number of pages4
JournalGeology
Volume27
Issue number3
DOIs
StatePublished - Mar 1999
Externally publishedYes

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normal fault
heave
footwall
alluvial fan
rupture
bedrock
Pliocene
Pleistocene
clay
earthquake

ASJC Scopus subject areas

  • Geology

Cite this

Range-front fault scarps of the Sierra El Mayor, Baja California : Formed above an active low-angle normal fault? / Axen, Gary J.; Fletcher, John M.; Cowgill, Eric; Murphy, Michael; Kapp, Paul A; MacMillan, Ian; Ramos-Velázquez, Ernesto; Aranda-Gómez, Jorge.

In: Geology, Vol. 27, No. 3, 03.1999, p. 247-250.

Research output: Contribution to journalArticle

Axen, GJ, Fletcher, JM, Cowgill, E, Murphy, M, Kapp, PA, MacMillan, I, Ramos-Velázquez, E & Aranda-Gómez, J 1999, 'Range-front fault scarps of the Sierra El Mayor, Baja California: Formed above an active low-angle normal fault?', Geology, vol. 27, no. 3, pp. 247-250. https://doi.org/10.1130/0091-7613(1999)027<0247:RFFSOT>2.3.CO;2
Axen, Gary J. ; Fletcher, John M. ; Cowgill, Eric ; Murphy, Michael ; Kapp, Paul A ; MacMillan, Ian ; Ramos-Velázquez, Ernesto ; Aranda-Gómez, Jorge. / Range-front fault scarps of the Sierra El Mayor, Baja California : Formed above an active low-angle normal fault?. In: Geology. 1999 ; Vol. 27, No. 3. pp. 247-250.
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