Tectonic rotations of dikes in fast-spread oceanic crust exposed near Hess Deep

J. A. Karson, S. D. Hurst, P. Lonsdale

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Oceanic crust that initially formed at the fast-spreading (130 mm/yr) East Pacific Rise at ~1 Ma is exposed in the walls of Hess Deep rift at the northern edge of the Galapagos microplate. Steep fault scarps expose a dismembered vertical sequence of pillow basalts, sheeted diabase dikes and gabbroic rocks. Diabase dikes in these units are dominantly vertical; however, extensive outcrops of steeply to moderately dipping dikes exist in some places. The nonvertical attitude of the dikes may be the result of tectonic rotations attending sea-floor spreading at the East Pacific Rise or the result of complex rotations of fault blocks during the opening of the Hess Deep rift at ~0.65 Ma. -Authors

Original languageEnglish (US)
Pages (from-to)685-688
Number of pages4
Issue number8
StatePublished - Jan 1 1992


ASJC Scopus subject areas

  • Geology

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