Characterization of sills associated with the U reflection on the Newfoundland margin : evidence for widespread early post-rift magmatism on a magma-poor rifted margin
Shillington, Donna J.
Tucholke, Brian E.
MetadataShow full item record
Drilling during ODP Leg 210 penetrated two post-rift sills (dated as ∼105.3 and ∼97.8 Ma) in the deep sediments overlying basement of the continent–ocean transition zone on the magma-poor Newfoundland margin. The sill emplacement post-dated the onset of seafloor spreading by at least 7–15 Myr. The shallower of the two sills coincides with the high-amplitude U reflection observed throughout the deep Newfoundland Basin, and strong reflectivity in the sub-U sequence suggests that a number of other sills are present there. In this paper, we use multichannel seismic reflection data and synthetic seismograms to investigate the nature, magnitude and extent of this post-rift magmatism in the deep basin. Features observed in seismic profiles that we attribute to sill injection include high-amplitude reflections with geometries characteristic of intrusions such as step-like aspect; abrupt endings, disruptions and junctions of reflections; finger-like forms; differential compaction around possible loci of magma injection and disruption of overlying sediments by apparent fluid venting. Interpreted sills occur only over transitional basement that probably consists of a mixture of serpentinized peridotite and highly thinned continental crust, and they cover an area of ∼80 000 km2. From analysis of synthetic seismograms, we estimate that sill intrusions may comprise ∼26 per cent of the sub-U high-reflectivity sequence, which yields a crude estimate of ∼5800 km3 for the total volume of sills emplaced by post-rift magmatism. This is significant for a margin usually described as 'non-volcanic'. We discuss competing hypotheses about the source of the magmatism, which is still uncertain.
Author Posting. © The Authors, 2010. This article is posted here by permission of John Wiley & Sons for personal use, not for redistribution. The definitive version was published in Geophysical Journal International 182 (2010): 113-136, doi:10.1111/j.1365-246X.2010.04635.x.
Showing items related by title, author, creator and subject.
Evolution of a Canada Basin ice-ocean boundary layer and mixed layer across a developing thermodynamically forced marginal ice zone Gallaher, Shawn; Stanton, Timothy P.; Shaw, William J.; Cole, Sylvia T.; Toole, John M.; Wilkinson, Jeremy P.; Maksym, Ted; Hwang, Byongjun (John Wiley & Sons, 2016-08-22)A comprehensive set of autonomous, ice-ocean measurements were collected across the Canada Basin to study the summer evolution of the ice-ocean boundary layer (IOBL) and ocean mixed layer (OML). Evaluation of local heat ...
Evolution of oceanic margins : rifting in the Gulf of California and sediment diapirism and mantle hydration during subduction Miller, Nathamiel C. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2013-06)This thesis investigates three processes that control the evolution of oceanic margins. Chapter 2 presents seismic images of a ~2-km-thick evaporite body in Guaymas Basin, central Gulf of California. In rifts, evaporites ...
Lam, Phoebe J.; Bishop, James K. B. (American Geophysical Union, 2008-04-09)Here we show that labile particulate iron and manganese concentrations in the upper 500 m of the Western Subarctic Pacific, an iron-limited High Nutrient Low Chlorophyll (HNLC) region, have prominent subsurface maxima ...