Sandstone-Hosted U-V and Base Metal Deposits

Sandstone-Hosted U-V and Base Metal Deposits

• Both classes are hosted by continental to very shallow marine sediments

• The deposits are conformable, often associated with primary sedimentary features and is concentrated in bleached or grey-green organic and pyrite –rich beds

• The ores are diagenetic to epigenetic and, because of the prosity of the host sediments, are often characterized by a large number of brightly coloured secondary oxidation zone minerals

• Geographic Distribution: Western States, USA, Mesozoic fluviatile Sandstones and Siltstones

• Cu, Pb, Zn sulphide Deposits are concentrated into bleached horizons within reddened sequences, where they form syndiagenetic cements around elastic grains,

The primary and secoundary mineralization is controlled by the local prosity and permeability of the host rocks

Black Carbonaceous Shale Copper Deposits

Black Carbonaceous Shale Copper Deposits

• Stratiform deposits account for a significant proportion of the Worlds Cu reserves

• The sulphides are fine-grained reflecting primary sedimentary features

• Huge, essentially syngenetic/diagenetic ores found in shallow marine sediments associated with major transgressions.

• Anoxic conditions and bacterial reduction of sea water sulphate were importat controls on mineralization.

• The ores have both lateral and vertical mineralogical zonation related to paleogeographical conditions.

• Kupferschiefer: the zoning is: copper and silver passing upwards into bornitem then chalcopyrite and finally pyrite

• Zambian Copper Belt: chalcopyrite passing basinwards into bornite then chalcopyrite and finally pyrite

Questions in Sedimentary Rocks

Questions in Sedimentary Rocks

A: compare between each of the following?

1)   Matrix – Cement

2)   Conglomerates – Breccias

3)   Orthoconglomerate – Paraconglomerate

4)    Polymictic conglomerate – Oligomictic  conglomerate

5)   Mudrocks – Shales

6)   Grain fabric – Grain morphology

7)   Arenites – Wackes

8)   Litharenite – Sublitharenite

9)   Sphericity – Roundness

10)     Packstone – Wackestone

11)     Neomorphism – Cementation

Description of Sedimentary rocks

Description of Sedimentary rocks

1.    Components :(( Grains)) Qz %, Feldspars % (lamellar twinning), rock fragments %, other components.

                               ((Matrix)): (May be Qz or Feldspars or Clay) 

2.     Grain size : Gravel(more than 2mm) or Sand (1/16 to 2mm) or Silt (less than 1/16mm)

3.   Grain/Matrix ratio :

4.   Roundness : Very angular or sub angular or rounded

5.   Sorting : Poorly sorted or mod sorted or well sorted

6.    Grain shape : Spherical or tabular or rod shape or equant 

7.    Supporting : Grain supported or Matrix supported

8.    Cement chemical : Calcareous or Ferrigenous or Siliceous

9.    Maturity compositional: Mature (Qz more than 90%)  

                                                Immature ( Low Qz and   More  Matrix )       

Texture  : If  Matrix more than 15% so its Immature

                If Matrix less than 15% and low to mod sorting so it will be mature

If Matrix less than 15%and will sorted and will rounded it will be Super mature .

10. Name 

Earth Structure

Earth Structure

===========

The core

The inner part of the earth is the core. This part of the earth is about 1,800 miles (2,900 km) below the earth's surface. The core is a dense ball of the elements iron and nickel. It is divided into two layers, the inner core and the outer core. The inner core - the center of earth - is solid and about 780 miles (1,250 km) thick. The outer core is so hot that the metal is always molten, but the inner core pressures are so great that it cannot melt, even though temperatures there reach 6700ºF (3700ºC). The outer core is about 1370 miles (2,200 km) thick. Because the earth rotates, the outer core spins around the inner core and that causes the earth's magnetism.

The Mantle  

The layer above the core is the mantle. It begins about 6 miles(10 km) below the oceanic crust and about 19 miles(30 km) below the continental crust (see The Crust). The mantle is to divide into the inner mantle and the outer mantle. It is about 1,800 miles (2,900 km) thick and makes up nearly 80 percent of the Earth’s total volume.  

The Crust

The crust lays above the mantle and is the earth’s hard outer shell, the surface on which we are living. In relation with the other layers the crust is much thinner. It floats upon the softer, denser mantle. The crust is made up of solid material but these material is not everywhere the same. There is an Oceanic crust and a Continental crust. The first one is about 4-7 miles (6-11 km) thick and consists of heavy rocks, like basalt. The Continental crust is thicker than the Oceanic crust, about 19 miles (30 km) thick. It is mainly made up of light material, like granite.

The Atmosphere

 The Atmosphere

The earth is surrounded by all kind of gases. This layer is called the earth's atmosphere. Without this atmosphere life on earth isn't possible. The atmosphere gives us air, water, warmth and is protecting us against harmful rays of the sun and against meteorites. This layer around the earth is a colourless, odourless, tasteless 'sea' of gases, water and fine dust. The atmosphere is made up of different layers with different qualities. It consists of 78% nitrogen, 21% oxygen, 0,93% argon, 0,03% carbon dioxide and 0,04% of other gases. The Troposphere is the layer where the weather happens; above this layer is the Stratosphere. Within the Stratosphere is the Ozone layer, that absorbs the Sun's harmful ultraviolet rays. Above the Stratosphere is the Mesosphere, the Thermosphere - in which the Ionosphere - and the Exosphere. The atmosphere is about 500 miles (800 km) thick.

USES OF GYPSUM

USES OF GYPSUM

·        Wallboard − The use of gypsum-based wallboard, once common only in the US and Canada, has spread to virtually all developed countries. The gypsum core provides a strong, fire-resistant, and inexpensive construction material. The -100 mesh stucco (hemihydrate) form is used. Japan is the largest user of synthetic gypsum products in wallboard, because it lacks natural gypsum resources. The other major source of synthetic (FGD-based) product for this market is Germany, which serves all of Europe. Most of current US wallboard production is based on natural sources.

·        Portland cement − Uncalcined gypsum crushed to -11/2 +3/8 inch is used with portland cement to retard the setting time of concrete. This is the primary market in developing countries.

·        Soil conditioners − Gypsum rock ground to -100 mesh is used in treating alkaline, saline, and clayey soils, and as a source of sulfur. In the US its main application is in the cultivation of peanuts.

·        Other uses − The hemihydrate form is used in a wide variety of construction and industrial plasters. Minor amounts of purified gypsum are used in glassmaking and as a white filler (terra alba) in paint and paper. “Soluble anhydrite”, made by dehydrating gypsum into porous, highly absorbent granules, is used as a desiccant