Marine Science A100 Lecture Notes - Lecture 7: Siliceous Ooze, Mid-Atlantic Ridge, Terrigenous Sediment
15 May 2020
School
Department
Course
Professor
Marine Science A100
Manuel Kellogg
What are some features of the deep-ocean floor?
● Oceanic Ridges
● Hydrothermal Vents
● Abyssal Plains and Abyssal Hills
● Seamounts and Guyots
● Trenches and Island Arcs
Divergent plate boundaries
Mid-ocean ridge – Mid Atlantic ridge
● Center, cut by a deep v shaped valley called a rift
○ Perpendicular to the ridge cut fractures (transform)
● Hydrothermal vents are within active spreading centers and venting hot water that seeps
into seafloor
Seamounts – underwater volcanoes formed adjacent to mid ocean ridges. Never becomes an
island – pointy tip
Guyot – flat topped seamount (eroded by waves)
Abyssal plains – flat featureless areas of the seafloor as a result of sediment deposition covering
the basaltic sea floor
Convergent Boundaries
● Trenches – boundary where one plate is subducting beneath another making a deep
trench parallel to the coast
● Plate convergence forms island arcs
● Trenches and island arcs form in subduction zones
● Sediments
● Sediment: particles of organic or inorganic matter that accumulate in a loose,
unconsolidated form.
● Largest to smallest:
● Boulder
● Cobbles/pebbles
● Gravel
● Sand>beaches
● Silt + clay (deeper offshore areas, quiet areas like harbors and bays)
Classify Sediments by Source
1. Terrigenous – land based sediments
Document Summary
Center, cut by a deep v shaped valley called a rift. Perpendicular to the ridge cut fractures (transform) Hydrothermal vents are within active spreading centers and venting hot water that seeps into seafloor. Seamounts underwater volcanoes formed adjacent to mid ocean ridges. Guyot flat topped seamount (eroded by waves) Abyssal plains flat featureless areas of the seafloor as a result of sediment deposition covering the basaltic sea floor. Trenches boundary where one plate is subducting beneath another making a deep trench parallel to the coast. Trenches and island arcs form in subduction zones. Sediment: particles of organic or inorganic matter that accumulate in a loose, unconsolidated form. Silt + clay (deeper offshore areas, quiet areas like harbors and bays) Well sorted 1 or 2 size make up more than 50% of sediment. Siliceous ooze more than 30% of the material is biogenous. Coccolithophores and foram > warmer and shallower than 4500 m.
