README for BBNAP19 model, mask and phase pick files.

A BOYCE 20/09/2019 (ab2568@cam.ac.uk)

This file contains details of phase picks added for the BBNAP19 model and the output velocity model to accompany the manuscript:

Boyce, A., I. D. Bastow, E. M. Golos, S. Rondenay, S. Burdick and R. Van der Hilst (2019), Variable modification of continental lithosphere during the Proterozoic Grenville orogeny: Evidence from teleseismic P-wave tomography, Earth and Planetary Science Letters, 525, 115763, https://doi.org/10.1016/j.epsl.2019.115763.

------------------------------------------------------------------------------------------------------------

The file BBNAP19_phase_SUMMARY.txt contains the details of direct P-phase absolute arrival-time picks derived from networks in southeast Canada. See main manuscript and appendix for further details.

The columns in this file are as follows:

evlat (deg), evlon (deg), evdepth (km), stlat (deg), stlon (deg), stelev (m), azimuth (deg), great circle arc distance (deg), ray parameter (XXX), predicted travel time (s), absolute arrival time residual (s), relative error (s).

------------------------------------------------------------------------------------------------------------

The file BBNAP19_MOD.txt is the file containing velocity model parameters for 50km intervals in depth given in the first column.

BBNAP19 is an adaptively parameterized, global absolute P-wave tomographic model following the methodologies of Li et al., (2008) and Burdick et al., (2017). ak135 (Kennett et al., 1995) is used as the global reference model. New data has been added in eastern U.S. and Canada, so we provide only the North American component of the model. While the adaptively parameterized grids at upper mantle depths can be in the supplementary material of published manuscript, here we provide the model sampled at 0.25x0.25 degrees and 50km depth to facilitate smooth plotting. The 3D grid contains the columns: depth (km), latitude (deg), longitude (deg), dVp (percentage relative to ak135), vp (absolute vp in km/s).

------------------------------------------------------------------------------------------------------------

The file BBNAP19_MASK.txt contains the masked regions used to plot grey shaded areas in Figure 5 of the main manuscript. 

Regions with less than adequate resolution in BBNAP19 are determined following the methodology of Burdick et al., (2014). Regions where the mask is on (i.e. equal to 1) are regions of low confidence or poor resolution. Regions where the mask is off (i.e. equal to 0) are regions of high confidence or good resolution. Values between these two extremes result from sampling the adaptively parameterized grid at 0.25x0.25 degree intervals to facilitate smooth plotting. The 3D grid contains the columns: depth (km), latitude (deg), longitude (deg), mask on (1/0). 