sills and dikes at later stages of subduction in the presence of slab rollback-induced extension. The rare occurrence of or the lack of sheeted dikes can be explained by much higher spreading rates and higher mantle temperatures in the Archean than at present or in the Phanerozoic (Bickle, 1986; Hargraves, 1986). These conditions would A dike is vertical and a sill is horizontal. A dike cuts across layers of Earth and a sill squeezes in between layers. ... sheeted dike, radial dike, ring dike, cone sheet CiteSeerX - Document Details (Isaac Councill, Lee Giles, Pradeep Teregowda): Recent models of magma chambers at fast-spreading ridges are based on the idea that the entire gabbro section of the oceanic crust crystallizes from a thin melt lens located just below the sheeted dike complex. Oct 07, 2015 · These inclined magmatic structures, combined with the inclined magmatic contacts between the gabbros and their host-rock, show that these two gabbro bodies, instead of being horizontal sills, more likely are inclined intrusions that cut obliquely through the sheeted dike complex.