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Late Cretaceous to early Tertiary subduction history of the Antarctic Peninsula

Joe J. McCarron and Robert D. Larter
Late Cretaceous to early Tertiary subduction history of the Antarctic Peninsula
Journal of the Geological Society of London (March 1998) 155, Part 2: 255-268


Quantitative estimates of the rates and azimuths of Phoenix plate convergence with the Antarctic Peninsula have been derived from plate rotation calculations for two periods in the Late Cretaceous and early Tertiary (83.0-67.7 and 61.1-53.4 Ma). Published marine magnetic anomaly identifications and ""flow lines"" interpreted from gravity anomaly maps were used in simple spherical geometry calculations to derive Phoenix-Pacific stage rotations. These were combined with published Pacific-Antarctic rotation data to determine contemporaneous Phoenix-Antarctic stage rotations. The results indicate a significant change in azimuths of relative motion between the Late Cretaceous and early Tertiary. Late Cretaceous, and perhaps earlier, oblique subduction probably caused migration of fore-are slivers along the margin, resulting in variations in width of the accretionary prism. Comparison between synthetic magnetic profiles and a 900 km long magnetic profile across ocean floor produced at the Antarctic-Phoenix ridge during the early Tertiary establishes the time of a major decrease in spreading rate, and hence also in convergence rate, as chron C23r (523 Ma). The associated change in subduction dynamics may have caused the dextral transtensional deformation observed in the George VI Sound region and initiated uplift of blueschist facies rocks now exposed on Smith Island. The calculated convergence history does not provide a simple explanation for the occurrence of high-Mg# andesite lavas on Alexander Island, which were erupted more than 20 Ma before the Antarctic-Phoenix ridge arrived at the margin. The existence of these lavas implies either earlier subduction of another ridge or slab break-up beneath Alexander Island.

ISSN: 0016-7649
EISSN: 2041-479X
Serial Title: Journal of the Geological Society of London
Serial Volume: 155, Part 2
Title: Late Cretaceous to early Tertiary subduction history of the Antarctic Peninsula
Affiliation: British Antarctic Survey, Cambridge, United Kingdom
Pages: 255-268
Published: 199803
Text Language: English
Publisher: Geological Society of London, London, United Kingdom
References: 59
Accession Number: 1998-039742
Categories: Solid-earth geophysics
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 4 tables, sketch maps
S77°00'00" - S63°00'00", W77°30'00" - W56°30'00"
Country of Publication: United Kingdom
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute.
Update Code: 199816
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