Primary and secondary structural features in the eastern portion of the South Mountain Batholith, southwestern Nova Scotia: implications form regional stress orientations during intrusion
Authors: Horne R. J. , Corey M. C. , Ham L. J. , MacDonald H. A. 
Published: September 2014

Primary flow features (schlleren banding, negacryat-xenollth alignment end blotlte foliation) within the eastern portion of the South Mountain Bathollth (SMB) reflect the geometry of intrusions and divides the study area into two distinct domains. In the eastern half the primary flow features display roughly concentric to random regional patterns related to differential flowage near contacts. Northeast-trending linear patterns characterize the western half and may in part reflect regional stress.

Stereonet evaluation of prominent joints, dykes and veins Indicate four primary-regional joint sets (trends), all of which are steeply dipping. The dominant joints, trends 2 (063o) and 4 (145o) form a roughly orthogonal pair parallel and perpendicular, respectively, to the regional fold axes. Trends 3 (130o) and 5 (164o) form a conjugate set around trend 4. Quartz vein orientations coincide with trend 4 end maxima of dykes correspond to trends 3, 4 and 5. Trends 2 to 5 are Interpreted as resulting from horizontal compression parallel to trend 4 during a period of uplift. Trend 1 (042o) is associated with a major fault zone which has locally been superimposed on the pattern of primary-regional joints. Primary-regional joints have to some degree influenced the intrusion of the later phases of the SMB.

Mineralization within the SMB Is strongly controlled by the regional fracture patterns. Oraniuo mineralization generally occurs within altered trend 2 joints uhereas polymetallic veln-grelsen mineralization is generally associated with trend 4 joints.

R᳧SUM᳧

Lea caract᳻ristiquea de flux primaires (rubatmement schlleren, allgnement des m᳻gscristes et xenolites, foliation de la biotlte) dans la portion orientale du Batholite de South Mountain (BSM) reflᳺtent la g᳻om᳻trie des intrusions et divlsent la r᳻gion ᳻tudi᳻e en deux domaines distincts. Dans la dende orientale, les traits de flux primaires se foment en patrons r᳻gionaux, approximativement concentriques ᳲ al᳻stoires, relies au fluage diff᳻rentiel prᳺs des contacts. Des patrons lin᳻sires ᳲ tendance NE caract᳻risent la demie occidentale et pourraient repr᳻senter, en partie, une contralnte r᳻gionale.

Une ᳻valuation sur st᳻r᳻onet des diaclases, dykes et veines ᳻vidents r᳻vᳺle quatre families (tendances) de diaclases primaires r᳻gionales ayant toutes un pendage ᳻lev᳻. Domlnantes. les families directionnelles de fractures 2 (063o) et 4 (145o) foment une paire plus ou moins orthogonale, respectivement parallᳺle et perpendiculaire aux axes de plis r᳻gionaux. Les tendances 3 (130o) et 5 (164o) foment une famille conjugu᳻e autour de la tendance 4. L'orientation des veines de quartz coincide avec la tendance 4. Le nombre maximum de dykes correspond aux families directionnelles 3, 4 et 5. On lors d'une p᳻riode line ᳻valuation sur stereonet des diaclases, dykes et veines ᳻vidents r᳻vᳺle quatre families (tendances) de diaclases primaires r᳻gionales ayant toutes un pendage ᳻lev᳻. Domlnantes. les families directlonnelles de fractures 2 (063o) et 4 (145o) foment une palre plus ou moins orthogonale, respectivement parallᳺle et perpendiculaire aux axes de plis r᳻gionaux. Les tendances 3 (130o) et 5 (164o) foment une famille conjugu᳻e autour de la tendance 4. L'orientation des au patron des fractures primaires r᳻gionales, phases tardives du BSM.

Les patrons de fractures r᳻gionaux ont fortement contrᴀl᳻ la min᳻ralisation ᳲ l'int᳻rieur du BSM. La min᳻ralisation en uranium occupe g᳻n᳻ralement des families directionnelles 2 alter᳻es. Par contre, les min᳻ralisations de type greisen ou filon polym᳻tallique sont g᳻n᳻ralement associ᳻es aux diaclases de tendance 4.

[Traduit par le journal]