Modes of extension at oceanic spreading centers: evidence from the Solea graben, Troodos ophiolite, Cyprus

摘要: Abstract The Solea graben in the Troodos ophiolite, Cyprus, represents a preserved Cretaceous-age axial valley formed during brief period of amagmatic seafloor spreading. Structural analysis all crustal levels reveals two periods deformation; an extensive early phase extensional deformation associated with spreading and later minor obduction doming complex Tertiary-Recent. Amagmatic produced networks normal faults that dip toward axis sole into regional detachment fault located at sheeted dike-plutonic contact oriented subparallel to ophiolite pseudostratigraphy. Individual segments are essentially planar but link approximate listric geometries locally. Bulk structural rotation blocks bounding occurred about NNW-trending axis, parallel present trend. Average dips within central portions suggest 40–50° rotation, although this is minimum figure because dike not simple function magnitude. Tensor populations shows σ 3 was approximately perpendicular axis. Late, near-axis segmented along faults. Obduction-related uplift expressed by thrust, reverse strike-slip principally developed reactivation pre-existing low-angle zones deformation. faulting 1 N—S 2 alternated position style documented supports recent speculation for Basin Range-style slow-spreading ridge crests low magma budgets, such as parts Mid-Atlantic Ridge near large-offset transform Natural cross-sectional exposure how structures might depth beneath demonstrates importance brittle crust prior establishment large-scale (ore-forming) hydrothermal circulation cells.