Vol. 22 No. 3 Maritime Sediments and Atlantic Geology December, 1986 Late Carboniferous Tectonostratlgraphy In the Avalon Terrane of Southern New Brunswick R. Damian Nance Department of Geological Sciences Ohio University, Athens, Ohio 45701 Development of the basement-involved, fold-thrust belt in coastal southern New Bruns- wick is attributed to dextral transpression associated with regional. Carboniferous strike-slip displacements. In the vicinity of Saint John, deformation strongly influenced Westphalian sedimentation in the penecontemporaneous Lancaster and Balls Lake Formations and reflects sustained NW-SE shortening that coincides with a major compressive bend in the E-W, Cobequid-Chedabucto fault system which records significant, right-lateral Pennsylvanian displacement. Purple conglomerates and lithic wackes of the Balls Lake Formation record syntectonic, NW-progradation of an alluvial fan in response to the uplift of a source to the SB and display facies depicting proximal to mid-fan, mid-fan, and distal settings. Locally interfingering and laterally equivalent, grey lithic arenites of the Westphalian Lancaster Formation are the product of major, NE- flowing, meandering streams partial - ly influenced by the prograding distal fan. Initial deformation (Dj) produced NW-directed, basement-involved thrusts that struc- turally invert regional stratigraphy. Associated lower greenschist facies metamor- phism accompanied development of a widespread, SE-dipping fabric (Si), variably expressed as a slaty cleavage, protomylonitic solution cleavage and orthomylonitic foliation. The fabric locally bears a strong but variably oriented mineral lineation (Li) and is axial planar to NW-vergent, isoclinal microfolds and regional overturned structures (Fi) that plunge gently NE and SW. Renewed thrusting (D2 ) and back- thrusting (D3 ) produced conjugate fold sets coaxial with Fi that verge both NW (F2 ) and SE (F3 ). Associated axial planar crenulation cleavages (S2 and S3 ) overprint §1 and dip SE and NW respectively. On-strike variations In deformational style and timing, coupled with the presence of steeply dipping, en echelon zones of Intense deformation, suggest the fold-thrust belt is segmented by right-stepping, convergent wrench faults synthetic to the deeply listric, Cobequid-Chedabucto system. These faults may shallow into thrusts to form positive flower structures, and locally terminate in thrusts associated with anomalous NW-SE trends in D^ and Dy. Thrust uplift in response to transpression on locally downward-steepening, en echelon faults subparallel to the Fundy shore is proposed to account for the source area of the syntectonic Balls Lake fan. Further displacement and telescoping resulted in structural inversion of regional stratigraphy and deposi- tion of the Balls Lake and Lancaster Formations in advance of an overriding allochthon to the south. On impute le dAveloppement d'une zone orogAnique chevauchante solidaire du socle au littoral du Nouveau-Brunswick meridional A une transpression dextre accompagnAe de dAcrochements rAgionaux carbonifAres. PrAs de Saint John, la deformation, qui a fortement marque la sAdi mentation westphalienne dans les formations syncbrones de Lancaster et de Balls Lake, provient d'un raccourcissement soutenu NW-SE ayant coincide avec un important coude en compression dans le systAme de failles E-W de Cobequid-Chedabucto. Ce dernier reprAsente un coulissage A droite de grande valeur d'age pennsylvanien. Les poudingues pourpres et les wackes lithiques de la Formation de Balls Lake soulignent la progradation syntectonique NW d'un cdne de dejection et traduisent la MARITIME SEDIMENTS AND ATLANTIC GEOLOGY 22, 308-326 (1986) Received April 9. 1986 0711-1150/86/030308~19$3.85/0 Revision Accepted August 25. 1986