Roles of provenance and salt tectonics in diagenesis of clastic sedimentary rocks: A review and synthesis of the Mesozoic Scotian Basin, offshore southeastern Canada

The Scotian Basin is a tectonically complex passive margin basin. Triassic salt and Jurassic carbonates are overlain by clastic Cretaceous and Cenozoic rocks that locally form petroleum reservoirs. Its thermal history included mid-Cretaceous lithospheric heating and episodic up-dip flow of hot brines from the deep basin, controlled by salt tectonics. The diagenetic minerals in sandstones were influenced by detrital composition, depositional lithofacies and burial history. Meguma terrane detritus had abundant deformable feldspar, mica, chlorite, and lithic clasts leading to permeability loss during compaction. The Late Jurassic–Early Cretaceous Sable River supplied abundant polycyclic quartz and detrital ilmenite. The eastern basin received more low-grade metamorphic quartz, lithic clasts, micas and feldspars, resulting in more common clay cements. Meteoric water during sea-level lowstands corroded seafloor diagenetic minerals and precipitated kaolinite and anatase. Quartz overgrowths are widespread in sandstones, except where clay coats, now berthierine or chlorite, protected quartz grain surfaces. Remaining porosity was largely filled by Fe-calcite. At depths >2 km, K-feldspars dissolved and created secondary porosity or were partially replaced by albite where faulting or stratigraphic fairways allowed removal of diagenetic products; otherwise clays and carbonate cements were precipitated. Widespread secondary porosity formed during fracturing synchronous with hydrocarbon charge and was partly filled by diverse late minerals, including barite, brookite and illite. Diagenetic chlorite rims preserved porosity in rapidly deposited thick sandstones in areas of volcanic ash supply. Regional trends in detrital composition and diagenetic assemblages are partially obscured by local effects of sedimentary facies and flow of hot brines. • Passive margin basin, complex salt tectonics, detrital supply, and thermal history. • Sable River deposited linear sandstone fairways, up which deep basin fluids flowed. • Eodiagenesis influenced by lithofacies whereas mesodiagenesis by brine fairways. • Hot brine impacted cementation rates and apatite annealing, less so oil maturation. • Feldspar and mica supply favoured clay cement, volcanic ash favoured chlorite rims.