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GEOREF RECORD

Galapagos Islands; a Holocene analogue to the Wallowa accreted terrane, western North America; with Suppl. Data 91-18

David L. Malmquist
Galapagos Islands; a Holocene analogue to the Wallowa accreted terrane, western North America; with Suppl. Data 91-18
Geology (Boulder) (July 1991) 19 (7): 675-678

Abstract

The ecology and biogeographic affinities of fossil bivalve faunas from the late Holocene of the Galapagos Islands and the Triassic of the Wallowa accreted terrane are markedly similar. These similarities provide further evidence that the Wallowa terrane originated as an oceanic island arc and that it lay in the eastern proto-Pacific during the Late Triassic, and they corroborate leomagnetic and lithologic evidence for the allochthonous, low-latitude origin of the Wallowa terrane and define the limits of its Triassic longitude relative to North America. Similarity between Galapagos and Wallowa bivalve faunas is based on (1) comparisons of living and fossil Galapagos bivalve faunas and (2) faunal comparisons between a Galapagos fossil locality and a Wallowa one. The first indicates that fossilization has not significantly biased the ecologic and biogeographic signature of the Galapagos "parent" community. This supports the validity of comparisons of fossil faunas from accreted terranes with counterparts on modern oceanic islands. The second shows that Galapagos and Wallowa fossil localities both exhibit the "hybrid" biogeographic pattern characteristic of oceanic islands. This pattern comprises a variable endemic component, coupled with an array of species from diverse faunal provinces. Quantitative ecologic comparisons of Galapagos and Wallowa faunas show that their species are generally similar in feeding habits and substrate preferences. Differences can be explained by the post-Triassic adaptive radiation of infaunal bivalves.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 19
Serial Issue: 7
Title: Galapagos Islands; a Holocene analogue to the Wallowa accreted terrane, western North America; with Suppl. Data 91-18
Author(s): Malmquist, David L.
Affiliation: Univ. Calif. at Santa Cruz, Earth Sci. Board, Santa Cruz, CA, United States
Pages: 675-678
Published: 199107
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 34
Accession Number: 1991-036836
Categories: Quaternary geologyStratigraphy
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sketch map
S01°30'00" - N01°00'00", W92°00'00" - W89°00'00"
N45°04'60" - N46°00'00", W117°55'00" - W116°30'00"
N45°13'60" - N45°45'00", W117°43'00" - W117°10'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 1991
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