Preliminary report on the structural geology of the Clarence Stream - Moores Mills area, southwestern New Brunswick: implications for gold exploration

Abstract

Significant gold occurrences located in proximity to Devonian granitoid intrusions have been recently discovered in the Clarence Stream area of southwestern New Brunswick. The area straddles the Ordovician St. Croix Terrane and Silurian Mascarene Belt, which are variously affected by four phases of regional deformation. The St. David antiform is interpreted as a megascopic F2-F3 fold-interference structure, the southeastern limb of which is cut by the late-D3, dextral Sawyer Brook Fault. Mineralized quartz veins and breccia units within the Ordovician Cookson Group are structurally associated with thrust-related D2 high-strain zones and folds. Southward, the occurrence of mineralized quartz veins in the Silurian Waweig Formation is influenced by the competency of gabbroic bodies, whereas late-D3 high-strain zones control their present geometry. The distinct lithostratigraphic assemblages and the nature and location of structures hosting the gold mineralization indicate that exploration strategies should not be restricted only to the proximity of specific intrusions or shear zones.

The Ellsworth terrane, coastal Maine: Geochronology, geochemistry, and Nd-Pb isotopic composition--Implications for the rifting of Ganderia

“…West of Penobscot Bay, Ordovician rocks of the St. Croix terrane were deformed, metamorphosed, and intruded by Silurian granites (Berry and Tribble, 2002) before being broken by the Silurian Turtle Head fault zone (Stewart, 1998). That steep fault zone continues to the northeast in easternmost Maine as the Seavey fault (Fyffe et al, 1999) and in New Brunswick as the Sawyer Brook fault and the Taylor Brook fault; this steep fault zone has been shown to have had considerable right-lateral strike-slip motion (Castonguay et al, 2003).…”

Pre-Carboniferous, episodic accretion-related, orogenesis along the Laurentian margin of the northern Appalachians

“…Development of the recumbent or overturned folds and associated shear zones partly overlapped with high-grade metamorphism, dated at c. 418-414 Ma (Burgess et al 1995;van Staal et al 1994), and were intruded late syn-kinematically by Upper Silurian (421 -418 Ma) biotite + muscovite granites such as the Gaultois (c. 421 Ma, Piasecki 1988;Dunning et al 1990) andRose Blanche plutons (c. 418 Ma, van Staal et al 1992;ValverdeVaquero et al 2000). Correlative Gander margin rocks in southern New Brunswick (St. Croix belt) also may contain early southerly overturned structures (Fyffe et al 1991), although the dominant Acadian structural transport direction here and in adjacent Maine appears to be towards the NW (Tucker et al 2001;Castonguay et al 2003). Such a movement picture is consistent with the asymmetry of structures developed during the latest Silurian inversion of the La Poile and Mascarene intra-arc and/or back-arc basins in Newfoundland and New Brunswick/Maine, respectively (O'Brien et al 1991;Fyffe et al 1999;Tucker et al 2001).…”

Architecture of Gold Mineralization at Anomaly A of the Clarence Stream Deposits, Southern New Brunswick

“…The sense of motion on the fault is therefore undetermined. The fact that the mineralized zone is folded by F3 folds along with the F2 hinge surfaces suggests that it is probably a D2 structure, and it may weil represent a thrust fault as suggested by Watters et al (2003Watters et al ( , 2005.…”

“…The mineralized deformation zones are subparallei to axial surfaces of F2 folds which led previous workers (e.g. Watters et al, 2003Watters et al, , 2005 to suggest that they coincided with D2 thrusts. The potential for stacked mineralized horizons is indicated by the presence of smaller distinct zones above and below the main mineralization zone.…”