Research about Newfoundland and Labrador

USGS2014

Preliminary report on the North Atlantic deep‐sea cores taken by the Geophysical Laboratory, Carnegie Institution

A series, of 11 cores from the North Atlantic sea‐bottom between the Newfoundland Banks and the banks off the Irish Coast have been studied by a group of geologists of the United States Geological Survey. These cores were taken by Dr. C. S. Piggot of the Carnegie Institution's Geophysical Laboratory from the cable ship Lord Kelvin with the explosive type of sounding‐apparatus, which he designed (C. S. Piggot, Apparatus to secure core‐samples from the oceanbottom, Bull. Geol. Soc. Amer., v. 47, pp. 675–684, 1936). This preliminary report is based largely on the results obtained by M. N. Bramlette, who studied the lithology, and Jos. A. Cushman, who studied the forarainifera. The geographic position, the depth of water at each station, and the length of core obtained are given in Table 1. ©1937. American Geophysical Union. All Rights Reserved.

Newfoundland and Labrador↗

USGS2012

The seismic velocity structure of the Newfoundland Appalachian orogen

The deep structure of the Newfoundland Appalachian orogen is investigated by analyses of three intersecting seismic refraction/wide-angle reflection profiles which traverse the Gander and Dunnage zones or central mobile belt of Newfoundland. A simultaneous travel time inversion for velocity and interface was applied to the in-line seismic refraction/wide-angle reflection data and constrained by synthetic amplitude models. The results of the modeling procedure show a subhorizontally layered crust with upper crustal velocities ranging from 5.4 to 6.2 km/s, a midcrustal velocity of 6.25–6.35 km/s, and a lower crustal velocity of 6.7±0.2 km/s. The top of the lower crust is marked by a series of prominent reflections between 18 and 23 km depth which suggest a complex layered velocity interface. Strong laterally coherent Moho reflections indicate a sharp crust-mantle transition at 35 ± 3 km. The uppermost mantle has a velocity of 8.0±0.2 km/s, and a reflecting horizon at 55 km depth suggests an increase to velocities approaching 8.5 km/s. Normal moveout corrections applied to fan profiles provide constraining evidence for the reflecting horizon at the top of the lower crust and laterally continuous Moho reflections at 11–12 s two-way travel time. Comparisons with a coincident deep seismic reflection profile show that the refraction and reflection Mohos match to better than 2–3 km. Bulk Poisson's ratios of 0.23–0.24 for the whole crust calculated from P m P / S m S travel times suggest a crust dominated by quartzofeldspathic lithologies and a notable absence of voluminous mafic additions to the lower crust. The absence of a deep crustal root, coupled with the bulk intermediate composition inferred for the lower crust from the seismic refraction/wide-angle data, implies that the crust beneath central Newfoundland has undergone multiple periods of reactivation and equilibration following successive orogenic episodes.

Newfoundland and Labrador↗