Exam 1 Sed Strat

Review Sheet for GEOL 215 MidTerm Exam - 2025 - Physical weathering (wet/dry, thermal, overburden release, etc.) - produces source rock “residues” - Chemical weathering (hydrolysis, hydration, redox, ion exchange, etc.) - produces secondary minerals & soluble constituents -- Goldich Stability Series & how influential - Environments where weathering types may dominate - e.g. sandstones/conglomerates as cliff-formers in modern moist environments, carbonates as cliff-formers in modern desert regions - why? - Paleosols - what diagnoses them? - soil horizons, bioturbation, secondary minerals in crumbles - Fluid properties & why they are important in describing a fluid’s behavior (generally “get” viscosity) - Flow types (laminar/turbulent) - where, when, what goes into determining them? - Forces in entrainment - transport types (suspended, saltation, bedload/traction) - HJULSTROM!! & Stokes Settling Law & what’s important in the equation - Sediment gravity flows - types, where occur, what they produce, initiation, character of deposits - Sed descriptors - size, shape, sorting, fabric, texture, porosity - meanings…what do they tell us? - Sed structures - depositional/erosional/post-depositional - what do they mean environmentally? - Siliciclastic/Carbonate/Chert/Coal/Ironstones rock description - there won’t be rocks on the exam but there may be questions on overarching themes of rock characterization - Diagenesis of sedimentary rocks - processes & stages - shallow, deep, re-exhumation - Facies & Facies Associations - reading environmental conditions and change in sed rocks - Facies successions are deposited into basins, the sediments sourced to those basins are often derived from relative tectonic uplifts - Divergent basin types - Convergent basin types - Alluvial Fan construction and dynamics - distributary, coarsening upward sequence, toe, profiles in x-section, typical deposits & grain sizes w/in fan seds - Braided Fluvial - usually unvegetated in the braidplain - bars in middle of these systems often display cobble imbrication if coarse enough, other sed structures such as ripples, x-strat are common - Meandering Fluvial - cut bank, point bar, floodplain, mire/backswamp, crevasse splay, levee, channel migration, etc. - know where sediment types/sizes/structures are laid in these settings - Deltas - delta top/plain (topsets), delta front (foresets), prodelta (bottomsets), distributaries, etc. -- Shape differences among wave-, tide-, & river-dominated deltas - the record of delta progradation - Beach/Barrier/Lagoon - tidal range, beach structure/zones (shoreface, intertidal, foreshore, etc.), washovers, etc. Lots of terminology here. Know the basics of longshore currents and wave orbital motion. Transgression or regression successions in beach/barrier/lagoon systems? - Shelf & Slope Environments - Normal Sedimentation vs. Event Sedimentation - Tempestites, fluvial plumes, dustload, nepheloid flows (= turbid/”fogs” of VERY fine suspended sediment), ice rafting, oozes, turbidites - how would transgression or regression be reflected in shelf/slope depositional environments? - Where in the oceanic system carbonate is produced (reefs, photic zone, warm waters, etc.), how is it produced (biotic and abiotic), and where is it preserved (above CCD) - Siliciclastic and carbonate shelf shapes can vary based on sediment production regime & if subduction is closeby - Reef Environments - types, zones, life, and evolution with base level change - atoll formation - Desert/Eolian - climate sensitive sediments are abundant here - dune anatomy/shapes/dynamics, reading x-stratification for wind direction, evaporites -- desert pavements, ventifacts, interdune lags, mudcracks - Facies Models are “idealized” successions of deposits in a particular environment - be able to construct one for every environment we feature - variability?, progressive trend?, which sub-environments for which facies? - Walther’s Law - Environmental successions