Syntectonic chlorite pressure fringes on framboidal pyrites record strain in Ordovician and Devonian shales from the Massanutten synclinorium. Total strains display no systematic relation to minor or major structures. Strain histories are related to the development of minor, rather than regional, structures. A two-component model is proposed for minor folding involving both flexural slip and pure shear. Curved fringes, straight fringe segments separated by sharp curvatures and multiple sets of fringes indicate that increments of pure shear were interspersed with continuous to episodic limb rotations accommodated by flexural slip. Similarities of deformation histories of Ordovician and Devonian shales indicate that in this area cover rocks experienced no penetrative deformation during the Taconic Orogeny. Fold geometries and cleavage fans of major structures are consistent with a ramp-fold origin for the Massanutten Synclinorium/Blue Ridge Anticlinorium fold couple. The deformation sequence is characterized by 1) a significant component of lateral shortening associated with minor folds, cleavage and penetrative strain, 2) amplification of the anticlinorium by asymmetric growth over a subsurface ramp. Rotation of the northwest limb to near-vertical during continued compression and transport resulted in local crenulation of the s₁ fabric. / M.S.

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Carbonate facies patterns and stratal architecture are the product of the complex interaction of internal (e.g., reef-building biota, sediment production) and external drivers (e.g., tectonics, climate, and relative sea level). In the Canning Basin of Western Australia, many of these drivers are in flux across the Late Devonian Frasnian--Famennian (F--F) boundary and significant variations in reefbuilding biota and long-term accommodation are observed. This study documents the evolution of the Canning Basin's Devonian reef complexes across the F--F boundary and proposes a new interpretation of the stratal architecture and paleobathymetric profile of the Famennian. Data presented here demonstrate the evolutionof a shelf-crest system in the Famennian, with beds expanding basinward and the reef growing in water depths of approximately 5-15 m. The paleobathymetric profile of the Famennian described by this study represents a departure from the well-documented barrier-reef system of the Frasnian. Digital outcrop models help capture the heterogeneity of the Famennian system and allow for characterization of the Devonian reef complexes across the F--F boundary. Syndepositional fractures are a ubiquitous feature of high-relief, reefrimmed carbonate systems and these features exert a profound influence on many facets of platform evolution. This study documents strong variability in syndepositional fracture patterns as a function of lithofacies and depositional setting and evidence for the temporal evolution of the mechanical properties of the Devonian reef complexes is presented. A statistically significant relationship is documented between syndepositional fracture development and variations in stratigraphic architecture, approximated here by platform-margin trajectory. This relationship implies a significant stratigraphic control on syndepositional deformation in carbonate platforms and suggests that external drivers are not required to generate early fractures in high-relief carbonate platforms.

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The Lower Devonian carbonate-clastic sequence of southwest Ellesmere Island accumulated in the Franklinian Basin at approximately 15(DEGREES)N latitude. A variety of depositional settings are represented, ranging from tidal flat to basinal environments. These environments can be recognized in Lower Devonian rocks across the Arctic Islands. / Progradation of the carbonate sequence of southwest Ellesmere Island occurred in the Early Devonian, but was periodically interrupted in the Zlichovian/Dalejan by transgressive events. Upward movement in the newly named Inglefield Uplift occurred throughout the Devonian, and shed clastic sediments westward that, in Middle to Late Devonian time, finally overwhelmed the marine carbonates and resulted in fluvial deposition on southern Ellesmere Island. / Certain formations in the Lower Devonian sequence are profusely fossiliferous, in particular the Blue Fiord Formation, which contains an abundant fauna including numerous species of coral and brachiopods. Both of these groups belong to the Old World Biogeographic Realm, and indicate a Zlichovian age for the lower Blue Fiord Formation of southern Ellesmere Island.

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