Ex 6 Sedimentary Rocks and Structures

Discontinuous Series

Olivine, pyroxene, amphibole, biotite

Continuous Series

Plagioclase

Residual Phases (last to crystallize)

K-Spar, muscovite, quartz

Which mineral is the most unstable at Earth’s surface?

Olivine

Which minerals are the most stable at Earth’s surface?

K-Spar, muscovite, quartz

Why are clays the most abundant fragmental minerals?

Because of the abundance of plagioclase feldspar

Graded Bedding

a sedimentary structure where the grain size of sediment gradually decreases from the bottom of a layer to the top

Cross Bedding

a sedimentary structure characterized by layers that are inclined or angled to the main bedding planes

Ripple Marks

a sedimentary structured indicating agitation by water or directly by wind

Mud Cracks

sedimentary structures formed as muddy sediment dries and contracts

Sole Marks

sedimentary structures formed on the base (sole) of a bed, indicating past flow directions and other depositional conditions

Trace Fossil

geological records of the activities and behaviors of past life