title: Counter-rotating microplates at the Galapagos triple junction.
abstract: An 'incipient' spreading centre east of (and orthogonal to) the East Pacific Rise at 2 degrees 40' N has been identified as forming a portion of the northern boundary of the Galapagos microplate. This spreading centre was described as a slowly diverging, westward propagating rift, tapering towards the East Pacific Rise. Here we present evidence that the 'incipient rift' has also rifted towards the east and opens anticlockwise about a pivot at its eastern end. The 'incipient rift' then bounds a second microplate, north of the clockwise-rotating Galapagos microplate. The Galapagos triple junction region, in the eastern equatorial Pacific Ocean, thus consists of two counter-rotating microplates partly separated by the Hess Deep rift. Our kinematic solution for microplate motion relative to the major plates indicates that the two counter-rotating microplates may be treated as rigid blocks driven by drag on the microplates' edges3.
authors.affiliation: Nicholas School of the Environment and Earth Sciences, Duke University, Durham, North Carolina 27708-0227, USA. ek4@duke.edu
authors.forename: Emily M
authors.initials: EM
authors.lastname: Klein
authors.forename: Deborah K
authors.initials: DK
authors.lastname: Smith
authors.forename: Clare M
authors.initials: CM
authors.lastname: Williams
authors.forename: Hans
authors.initials: H
authors.lastname: Schouten