Non clastic sedimentary rocks

A brief discussion of a few of the non-clastic sedimentary rocks, specifically carbonates (limestone), evaporites, and siliceous non-clastic sedimentary rocks.

1. NOBORA, JAMES PRESENTER OF TOPIC THE NON-CLASTIC (First Half)

2. THE CARBONATE ROCK SEDIMENTARY LIMESTONE

3. Limestone Limestone is a  sedimentary rock  composed primarily of calcium carbonate (CaCO 3 ) in the form of the mineral  calcite . It most commonly forms in clear, warm, shallow marine waters. It is usually an organic sedimentary rock that forms from the accumulation of shell, coral, algal and fecal debris. It can also be a chemical sedimentary rock formed by the precipitation of calcium carbonate from lake or ocean water.

4. Limestone (Origin) Limestones may be deposited in seas , lakes , rivers , and on the lands . Circulation , and presence of land-derived detritus , such as arenaceous, argillaceous, and ferruginous materials, are factors of importance. Certain forms, such as algae , Foraminifera , and corals , are important rock builders, while others are rarely so. Limestones may also form through evaporation .

5. Limestone (Texture) The texture of limestones are variable and unequalled by any other group of rocks. -some are clastic (cementation of sand and/or mud by calcite) -others result from processes of organic accretion -others are formed by postdepositional changes -some are coarsely crystalline, and others are fine-grained or even aphanitic. -oolitic or pisolitic (chemically deposited limestones) -consist of carbonate grains all of uniform size, whereas others are mottled large crystals scattered through a matrix of finer grains -porous (owing to algal structures) -other carbonate structures are so interlocked

6. Limestone (Varieties) Chalk Coquina

7. Limestone (Varieties) Fossiliferous limestone Lithographic limestone

8. Limestone (Varieties) Oolitic limestone Oolitic limestone ( calcium carbonate " oolites“)

9. Limestone (Varieties) Travertine Tufa

10. THE CARBONATE ROCK SEDIMENTARY EVAPORITES

11. Evaporites Formed by precipitation of salts from landlocked bodies of concentrated solutions or brines are common where lakes form and then evaporate in a desert, or in shallow and warm arms of the ocean adjacent to desert areas are light in color, and so can be readily recognized, even from a great distance

12. Varieties of Evaporites Rock Gypsum - is formed by the evaporative deposition of gypsum from solution. It is mainly composed of gypsum and can be scratched with your fingernail. Rock Salt -is a chemical sedimentary rock formed by the evaporation of seawater and the precipitation of halite. It is mainly composed of Halite. Large enclosed bodies of seawater and desert lakes commonly form rock salt deposits.

13. Varieties of E vaporites Anhydrite – typically occurs as uniformly bedded deposits with mosaics of interlocking anhedral grains, or with large, well-shaped crystals that are set in a mosaic of fine-grained base. Mainly composed of anhydrous calcium sulfate. It represents gypsum without its water of crystallization and it alters readily to gypsum, from which it differs in crystal form (anhydrite is orthorhombic) and in being harder and slight less soluble.

14. Varieties of E vaporites Chemical Limestones Travertine Tufa

15. SILICEOUS S EDIMENTARY ROCKS 2

16. Siliceous Sedimentary Rocks Siliceous rocks  are  sedimentary rocks  that have  silica  (SiO 2 ) as the principal constituent. The most common siliceous rock is  chert  other types include  diatomite . They commonly form from silica-secreting organisms such as  radiolarians ,  diatoms , or some types of  sponges .

17. Siliceous Sedimentary Rocks (Origin) commonly form from silica-secreting organisms such as diatoms ( s keletons are mainly silica, known as siliceous oozes, and when they are formed in the rocks (ex. thru diagenetic process), these rocks are diatomites or diatomaceous earth ) , radiolarians ( accumulates forming a siliceous deposit known as "radiolarian oozes" ), or some types of sponges (Class demospongia - Astylospongia primosia)

18. Siliceous Sedimentary Rocks (Texture) Usually dense Layered (bedded cherts) Cryptocrystalline (Novaculite, Flint) Microcrystalline (Chert) Texture of unglazed porcelain (Porcellanite)

19. Siliceous Sedimentary Rocks (Varieties) Chert Flint

20. Siliceous Sedimentary Rocks (Varieties) Jasper Tripoli

21. Siliceous Sedimentary Rocks (Varieties) Novaculite Porcellanite

22. Siliceous Sedimentary Rocks (Varieties) Diatomite Looks like chalk, but does not fizz in acid. It is made of microscopic planktonic organisms called diatoms. It may also resemble kaolinite, but is much lower in density and more porous. It is formed when accumulation of diatoms and radiolarian tests develop deposits of siliceous sediments.