Types of Sediment Sediments are lithified into sedimentary rocks. There are seven types of sediment: –Epiclastic or terrigenous (normal) –Pyroclastic –Orthochemical –Allochemical –Residual or pedogenic –Cosmogenic –Polygenetic.

Characteristics of the Components of Sedimentary Rocks Clastic components –Mineralogy or for lithic clasts, petrography –Grain/clast size –Grain/clast morphology (sphericity, roundness) –Grain/clast sorting Orthochemical components. –Mineralogy, crystal size, crystal shape & fabric

Mineral Chemical Stability Series Most Stable: quartz, zircon, tourmaline –micro-quartz (chert & chalcedony) –Muscovite –K-feldspar –albite____________________________________ –plagioclase feldspars –hornblende, biotite –pyroxene –olivine –Least Stable: From albite and above minerals form in the sedimentary environment (authigenic).

Relative Abundance of Minerals Terrigenous Minerals Quartz 30-50%, Clay minerals 25-35, Metamorphic rock fragments 5-15%, Feldspar 5- 15%, Chert 1-4%, Micas %, Carbonates %, Heavy Minerals Chemical Minerals Carbonates 70-85%, Silica 10-15%, Sulphates and salts 2-7%, Miscellaneous 2-7%.

CARBONATE ROCKS Deposited Loose (may not be totally clear) >90% lime mud: mudstone (deposited loose) <90% lime mud: wackestone (deposited loose) grain supported with muddy matrix: packstone grain supported well sorted: grainstone Deposited bound together during deposition boundstone (e.g. stromatolite) No depositional texture preserved. crystalline carbonate.

CARBONATE STAINING Rocks and slides are stained using dilute acid and two dyes. Calcite is red if Fe-free, purple if Fe-rich Pure dolomite does not stain, Fe-dolomite stains blue.