Crustal-scale reflection seismic investigations in the Bathurst Mining Camp, New Brunswick, Canada Saeid Cheraghi a, ⁎, Alireza Malehmir a , Gilles Bellefleur b a Department of Earth Sciences, Uppsala University, SE 75236 Uppsala-Sweden b Geological Survey of Canada, Ottawa, 615 Booth St. K1A0E9 Ontario, Canada abstract article info Article history: Received 29 September 2010 Received in revised form 13 April 2011 Accepted 19 April 2011 Available online 28 April 2011 Keywords: Bathurst Mining Camp Seismic reflection Mineral deposits Crustal structures The Bathurst Mining Camp, northern New Brunswick, Canada contains the super giant Brunswick No. 12 massive sulphide deposit and the smaller, now abandoned, Brunswick No. 6 deposit. Discoveries of additional base metal deposits in the camp require a better understanding of geological structures at depth. To this end, reflection seismic data in the Brunswick No. 6 area were acquired along three 2D profiles in 1999, with a total length of about 30 km. We have recovered, processed and interpreted these seismic data in conjunction with petrophysical and geological data from the study area. The seismic data and the borehole geophysical data allow a better understanding of both the shallow and deep structures (to 9 km depth) in the area. The seismic data show steeply dipping structures of the Brunswick No. 6 area, many of which reach the surface and allow for correlation with the surface and borehole geological information. Finite-difference modeling of major geological formations constrained with borehole petrophysical measurements indicates good correlation between the observed seismic and the synthetic data. A sequence of seismically reflective and transparent zones indicates a thrust stack in the Brunswick No. 6 area. The contact between the reflective and transparent zones is a series of faults bringing the two units over each other. A reflective package is observed in all three profiles and correlates well with the Brunswick horizon, the key mineralized zone in the study area. The Brunswick horizon extends down to depth greater than 3 km, increasing the hope for discovery of deeper base metal deposits. Two other sets of reflections are also observed in all three profiles in the depth range of about 5–8 km. We interpret them as two sets of thrusted sheets, which could be an indication that the Brunswick belt extends down to a maximum depth of 8 km. © 2011 Elsevier B.V. All rights reserved. 1. Introduction It is widely accepted that the future in mining and mineral explo- ration in established mining camps lies at deeper levels (N 1000 m) and those who search for deep-seated deposits and extract them will prosper (Eaton et al., 2003). This in turn is feasible in major mining camps where infrastructures and mining facilities are already in place. Understanding and imaging subsurface structures that control and/or are associated with mineralization in major mining areas are important prerequisites for planning and improving deep exploration strategies and optimizing drilling and exploitation expenses. Reflection seismic methods can be very helpful in understanding and imaging both shallow and deep structures (e.g., Dehghannejad et al., 2010; Juhlin et al., 2010; Malehmir et al., 2006, 2007, 2009b; Tryggvason et al., 2006) and in combination with other geological and geophysical data can provide a framework along which 3D geologic models can be created (e.g., Malehmir et al., 2009a). Successful 2D and 3D seismic reflection studies in major mining areas worldwide suggest that volcanic-hosted massive sulphide (VHMS) deposits and associated structures are suitable targets for investigation by seismic methods (e.g., Adam et al., 2003; Malehmir and Bellefleur, 2009; Milkereit et al., 1996; Milkereit et al., 2000; Pretorius et al., 1989; Pretorius et al., 2003; Stevenson et al., 2003). The poly-deformed Bathurst Mining Camp (BMC) in northeast New Brunswick, Canada, contains several mineral deposits including the super-giant Brunswick No. 12 and the No. 6 VHMS deposits (Fig. 1 and 2; Wills et al., 2006). The area near the Brunswick No. 6 deposit is the focus of this study. The Brunswick No. 6 produced a total of about 13 million tons of base-metal during its 20 years of production before closure in 1983 (Luff, 1995). The Brunswick No. 6 deposit amongst others in the BMC, are related to an Algoma-type iron formation, generally referred to as the Brunswick horizon (Gross and Mcleod, 1980). Several detailed geological studies indicate a direct relationship between this iron formation and VHMS deposits in the BMC (e.g., Peter, 2003; Peter and Goodfellow, 1996; Saif, 1983; Troop, 1984). Because of available infrastructure and global interest in base- metal exploration, the Brunswick No. 6 and adjacent areas are of great interest for targeting deep-seated mineral deposits. However, successful exploration requires a better understanding of upper crustal Tectonophysics 506 (2011) 55–72 ⁎ Corresponding author. Tel.: + 46 18 4717161; fax: + 46 18 501110. E-mail addresses: saeid.cheraghi@geo.uu.se (S. Cheraghi), alireza.malehmir@geo.uu.se (A. Malehmir), gbellefl@nrcan-rncan.gc.ca (G. Bellefleur). 0040-1951/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.tecto.2011.04.011 Contents lists available at ScienceDirect Tectonophysics journal homepage: www.elsevier.com/locate/tecto