Sedimentary Rocks Identification Chart PDF

Preview

Summary

Rocks identification...

Description

Sedimentary Rock Classification Clastic Textures TEXTURE

Clastic

Composition

Mainly rock fragments and mineral grains (quartz, feldspar, clay) weathered from other rocks.

CLAST DESCRIPTION Size Rounding

Sorting

ROCK NAME

Angular

Poorly sorted

Sedimentary Breccia

Rounded

Poorly sorted

Conglomerate

Well rounded to angular

Well to poorly sorted

-

Well sorted

Gravel (> 2 mm) embedded in sand, silt, and/or clay Sand (2.0 - 1/16 mm) Mud (< 1/16 mm) Silt (1/16 mm – 1/256) Clay (< 1/256 mm)

DESCRIPTION Large, angular clasts indicate shorter transport distance. Rounded clasts indicate longer transport distance or high energy current

(> 50% mud-size particles)

Alluvial fan Alluvial fan, stream, beach

Mostly quartz, Well sorted-more transport

Dunes, stream, beach

Shale – fissile (splits easily) Siltstone – breaks into layers Claystone – crumbles

Floodplain, playa, shallow & deep marine

Sandstone (> 85% sand-size particles)

Mudstone

DEPOSITIONAL ENVIRONMEN T

a

Chemical, Biochemical, Bioclastic and Organic Textures TEXTURE Chemical, Biochemical & Bioclastic Chemical

Chemical & Biochemical Chemical Chemical Biochemical Chemical Bioclastic

Composition

Size

Hardness

Color

Calcite

Coarse-grained to microcrystalline

H=3

Variable

Microcrystalline

H = 3.5

(CaCO3)

Dolomite (CaMg(CO3)2)

Silica (SiO2)

Gypsum (CaSO4 * 2H2O) Halite (NaCl)

ROCK NAME

Limestone Carbonates (HCl)

Variable

Amorphous or Microcrystalline

H=7

Variable

Extremely variable

H=2

Clear - variable White - variable

Variable

H = 2.5

Variable

H=1

White to gray

Dolostone

Chert

Evaporites

Calcite

Shells

(CaCO3)

(< 1/16 mm)

Shell fragments

Shells

(CaCO3)

(> 2 mm)

-

Variable

Rock Gypsum Rock Salt Chalk

Carbonates (HCl)

Coquina

DESCRIPTION Reacts with HCl Inorganic – calcite precipitates Organic – micro-skeletons Reacts weakly with HCl (only when powdered), crystalline form of altered limestone Fractures on curved surfaces (conchoidal fracture) Inorganic chemical precipitate, may be biochemical (organic) Very soft, crystalline, inorganic chemical precipitates Salty, crystalline, inorganic chemical precipitates Weakly cemented microscopic shells (coccoliths), biochemical Poorly-sorted, poorlycemented shell fragments

DEPOSITIONAL ENVIRONMEN T Shallow marine lake, groundwater Nearshore marine Groundwater (nodule / layer) Marine (bedded) Playas, groundwater Playa Deep marine Beach, reef

Organic

Altered organic remains

-

H < 2.5

Brown to black

Coal

Several type (based on %C)

Peat, Lignite, Bituminous, Anthracite

Swamp...