{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Geol 101 Sedimentary rocks cont

Geol 101 Sedimentary rocks cont - • Coal o Plant remains...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
Geol 101 Sediments Continued 08/11/2007 14:16:00 How sediment becomes rock Diagenesis: o Chemical, physical, and biological changes that affect sediment from  deposition to lithification o Very low temperature, low pressure metamorphism o Processes Compaction Cementation (carbonate, silica, iron oxides) Recrystalization of less stable minerals. Argonite -> calcite(polymorphs) Chemical alteration Slow decay of organic matter -> peat Clasitc Sedimentary Rocks Classified on size of lithified grains: o Conglomerate (gravel) o Sandstone o Siltstone o Mudstone (clay) Chemical Sedimentary Rocks Lithification of chemical precipitates o Evaporate deposits o Banded iron formations o Phosphorus deposits o Chert (fine grained, interlocking quartz crystals) Biogenic Sedimentary Rocks Limestone (calcite): most abundant
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
o Coquina: coarse grained shell debris o Reef Limestone: cemented reef organisms o Chalk: compacted minute carbonate shells
Background image of page 2
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Background image of page 4
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: • Coal o Plant remains accumulate in swamps o From peat (60% C) o Peat is compressed (water loss/CH4 generation) o Converted to lignite o Coal • Oil Shale o Organic-rich clastic rock o Dead organisms buried in marine or lake muds contain organic oils and fats o With burial, wax-like substances are formed (oil shale) o When heated produces hydrocarbons ← Environmental Clues • Sedimentary rocks reflect their environment of formation (rounding). • Bedding planes o Ripple Marks o Footprints, trails, and raindrop impressions • Fossils o Some animals and plants are restricted to certain climates • Color o Dark colors: iron sulfides and organic detritus – low oxygen o Red/Brownish colors : iron oxides – plenty of oxygen • 08/11/2007 14:16:00 ← 08/11/2007 14:16:00 ←...
View Full Document

{[ snackBarMessage ]}