Abstract
Extrusive rocks of Miocene and younger age have been dredged from the submerged insular slopes of the arcuate, 2,220-km-long Aleutian Ridge. Hornblende dacite porphyry recovered at station 70-B29 (lat 52.6/sup 0/N, long 174.8/sup 0/E; depth, 700 m) was extruded less than 610,000 yr ago. The dacite crops out approximately 80 km west of Buldir Island, the westernmost volcanic edifice of the 2,550-km-long Aleutian volcanic chain. The submerged dacite extends the westward limit of this chain of eruptive centers, which are the product of a distinct phase of late Cenozoic (chiefly early Pliocene to present) volcanism. This part of the ridge is not associated with a north-dipping Benioff zone, a fact that may imply that arc-type calc-alkalic magma can be emplaced along sectors of the ridge either obliquely underthrust by the Pacific plate or in strike-slip contact with it (western 800 km).
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
