Geochem (Sedimentary Petrology) - MIDTERM TOPICS

Clast

these are rock fragments with varying sizes

matrix

cementing material that bonds sediment together to form sedimentary rock

fissility

plane of weakness of mudstone (shale)

sediments

These are products of Erosion and transport of weathered rock fragments

1. Weathering of rocks

2. Erosion and transport of weathered rock fragments - sediments

3. Deposition of the sediments

4. Precipitation of the cementing material

5. Lithification

Process of origin of sedimentary rocks

Diagenesis

This is the process of Lithification (compaction and cementation) of older sediments due to the deposition of younger sediments

Diagenesis

Refers to the collective term for all the chemical, physical, and biological changes that take place after the sediments are deposited

Compaction

Refers to the process of adding sediments to the initially deposited sediments

cementation

Refers crystallization of minerals among the individual sediment grains

Detrital (Clastic) Sedimentary Rocks

Rocks that are formed from weathering, erosion, and compaction of sediments.

Chemical Sedimentary Rocks

Rocks formed from the precipitation of soluble material produced primarily by chemical weathering.

Organic Sedimentary Rocks

Rocks that are made up of organic materials from the remains of dead organisms.

1. Clast

2. particle size

3. Sorting

4. Sphericity and Roundness

5. Porosity and Permeability

6. Sediment Maturity

6 Classification of Clastic Rocks

Rock Fragments

Quartz

Clay Minerals

Feldspars

Micas

Fossils

Types of Clast

Halite

calcite

olivine

in Golidich stability series, what is the least stable and have fast Weathering

hematite

gibbsite

quarts

in Goldich stability series, what is the most stable and have low weathering

particle size

Used as a primary basis for distinguishing among various detrital sedimentary rocks.

1. Boulder

2. cobble

3. pebble

4. granule

what are the particle names of following gravel sizes:

___________ greater than 256mm

___________ 64mm to 256mm

___________ 4mm to 64mm

___________ 2mm to 4mm

Udden-Wentworth Scale

it defines gravel, sand and mud particles according to their mean diameter

gravel

a particles have diameters larger than 2.0 mm, about the size of a small grain of rice.

sand

particles have diameters between 2.0 and 0.0625 mm, the size range seen on sandpaper or between finely granulated sugar and small grains of rice.

mud

particles possess diameters smaller than 0.0625 mm, like processed flour or baby powder.

silt

particles, with diameters between 0.0625 and ~ 0.004 mm

clay

particles, whose diameters are less than 0.004 mm (4 micrometer).

sorting

Refers to the degree of similarity in particle size As the range of particle sizes decreases, sorting increases

Sphericity

It measures the degree to which a particle approaches the dimensions of a perfect sphere

porosity

It is simply the volume percentage of void spaces, called pores

Permeability

It expresses the rate of fluid flow through a rock.

clays

this sediment type usually has low hydraulic conductivity

gravel

this sediment type usually has high hydraulic conductivity

10^-6 cm/s

10^-4 cm/s

10^-2 cm/s to 10^-3 cm/s

10^-1 cm/s to 10^1 cm/s

Hydraulic conductivity of the following:

clay

Sediment Maturity

Refers to the length of time that the sediment has been in the sedimentary cycle

conglomerate

Coarse- to very coarse-grained sediments and have more spherical grains

breccia

Coarse- to very coarse-grained sediments have more angular grains

sandstone

Composed of sand-sized particles and Form in a variety of environments

pettijohn diagram

digram use in related criteria to organize sandstones into groups, similar boundaries to separate different types and related terms to name different varieties of sandstone

Shale or Mudrock

Collective term for fine-grained rocks composed of silt- and/or clay-sized particles

siltstone

claystone

mudstone

___________ silt size particle

___________ clay size particle

___________ another name for shale

chemical sedimentary rock

Rocks formed from the precipitation of dissolved ions that are carried in solution to lakes and seas.

organic

inorganic

The precipitation of materials occurs in two ways:

___________ Processes involving water-dwelling organisms

___________Processes involving evaporation and chemical activity

Allochem

It is a sand- and/or gravel-size carbonate particles

ooids

limeclast

peliods

Allochems include:

Spherical particles called ________

Clasts of carbonate sediment called ________

Smaller pellet-like particles called _________

Micrite

It is the silt- and clay-size carbonate particles in limestones and dolostones

Secretion by calcareous algae.

Micritization of pre-existing carbonate by microbes.

Mechanical abrasion of pre-existing carbonate grains.

Precipitation from solution.

The origin of carbonate mud particles or micrite:

Sparry Calcite

It is a coarse crystalline calcite cement which fills pore spaces in many limestones after deposition, formed by the precipitation of calcite from carbonate-rich solutions passing through the pore spaces in the sediment.

calcirudite or dolorudite

calcium carbonate or dolomite with size of gravel

Calcarenite or dolarenite

calcium carbonate or dolomite with modal particle size of silt

calcilutite or dololutite

calcium carbonate or dolomite with modal particle size of mud

Dunham Classification System

It emphasizes the texture of carbonate rocks, utilizing rather simple terminology

Folk Classification System

It revolutionized our understanding of carbonate rocks. It encouraged workers to pay careful attention to the components of carbonate rocks that lie at the heart of the classification scheme

limestone

Most abundant chemical sedimentary rocks

Mainly composed of calcite (CaCO3)

Coralline Limestone

Limestones made up of fossilized corals

Coquina

Limestones made up of shell fragments

trevertine

Limestones commonly found in caves

chalk

Limestones made up of the hard parts of microscopic organisms especially the coccolithophores

dripstone

Travertine that are precipitated from the endless dripping of water inside the cave.

dolostone

Rock composed of dolomite CaMgCO3

chert

Rock is composed of hard parts of an organism (like radiolaria) that is made up of microcrystalline quartz.

Flint

Dark-colored variety of chert

Jasper

Red variety of chert

Agate

Banded form of chert

bedded cherts

replacement cherts

Mode of formation:

Deposition and lithification - _________

Dissolution, migration, precipitation - ___________

evaporites

it is Rocks formed from precipitation of dissolved ions due to the evaporation of water

rock salt

rock gypsum

_________: Rock made up of Halite

_________: Rock made up of Gypsum

Organic Sedimentary Rocks

Rocks formed from the deposition of plant remains.

coal

it formed in a swamp environment where plants flourished during ancient times.

strata

the single most common and characteristic feature of sedimentary rocks

bedding plane

a flat surfaces along which rocks tend to separate or break

cross beds

layers within it that are inclined to the horizontal

graded beds

it refers to a single sedimentary layer that gradually changes from coarse at the bottom to fine at the top

ripple mark

small waves of sand that develop on the surface of a sediment layer by the action of moving water or air

mud craks

it indicate that the sediment in which they were formed was alternately wet and dry.